Brakes are serious business, and while most riders just use the handlebar brakes, the foot brake is there for a reason – It’s a backup. As problems go, a stuck brake pedal is an easy fix. And very shortly, you’ll be well on your way to having your foot brake working once again..

The rear brakes on an ATV commonly stick because corrosion has built up on the foot pedal shaft. Spaying a penetrating lubricant will help free up the pedal.

In this post, you’ll understand why the rear brake pedal is stuck; you’ll learn how to free it up and how to prevent it from happening again.

Why Does Rear ATV Brake Pedal Stick?

A rear ATV brake pedal commonly sticks for two principal reasons: 

1. The rear brake pedal is seldom used. As you know, ATVs are fitted with two independent brake systems – The handlebar-mounted hand brake and the foot pedal-operated rear brake. As the hand-operated handlebar brake is a far more effective and convenient brake, it’s the brake that is instinctively used. The foot pedal is very often forgotten and therefore goes unused.
2. Driving through deep water traps moisture between the hollow pedal sleeve and the fixed chassis-mounted pedal spindle. The trapped moisture promotes corrosion. Deep water excursions, wet weather environments, and power washing all contribute to pedal shaft corrosion. 

How To Free Up Rear ATV Brake Pedal

The fix for the problem is lubrication. Spraying lube between the hollow pedal sleeve which pivots on the brake pedal spindle, and the spindle itself will help break down corrosion’s hold.

This will require some patients, time, and a good penetrating oil such as WD40 or Rust Buster.

The process is as follows:

• Spray WD40 or alternative into the sleeve and spindle joint. It’s hit-and-miss as the joint is pretty tight. Jacking one side of the ATV will force the penetrant to flow down the inside of the spindle.
• It will take a little manpower to help free the pedal. Using your foot at first, get some movement going (if you can). Now work the pedal with your hand up and down, which will flex the joint clearance and promote oil flow between the sleeve and spindle.
• You’ll need to rinse and repeat, and the process could take a few days to complete. Penetrating oil needs time to work its magic. Working lit like this will help work the penetrant into the shaft.

How To Prevent Rear ATV Brake Pedal Sticking

Prevention is much like the fix, a healthy dose of penetration oil when maintaining your ATV or once a month. In addition, you’ll need to use the rear brake from time to time.

It’s a simple strategy but often forgotten. I find it helpful to develop a habit of running some simple maintenance chores at the beginning of the month. Doing so helps prevent issues like sticking brakes.

Alternatively, remove the brake pedal and apply a thick coat of copper grease to the shaft before refitting. This will prevent corrosion and sticking for years to come.

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The post ATV Rear Brake Pedal Stuck – Solved! appeared first on ATVFixed.com.

I’m a mechanic and fuel-related issue is amongst the most common ATV performance issues. You are in the right place for fuel pump testing and diagnosis, very shortly we’ll have this figured out.

There are five common ways to check if an ATV fuel pump is in good working order, they include:

1. Listen for pump sound
2. Check power at the pump
3. Check pump resistance
4. Visually check pump flow
5. Use fuel pressure gauge to test system pressure

In this post, we’ll cover faulty ATV fuel pump symptoms. We’ll cover the range of fuel pump tests open to you, and how to execute them. We’ll also cover fuel pump replacement.

Symptoms of Faulty ATV Fuel Pump

Because some electric fuel pumps don’t fail completely, the range of symptoms can vary. The most common symptom is as you guessed a no start and in many ways, a no-start is easier to diagnose than a poor performance issue. Anyhow here is a list of the most common symptoms associated with a fuel pump issue:

• No-start
• Extended crank (hard starting) (may also be caused by pump check valve)
• Idles but won’t take rev
• Poor top-end performance
• Starts then dies

If you have one or more of these symptoms we’ll suspect a faulty pump. But before we start ordering parts we’ll need to confirm our suspicions and that’s what we’ll do next.

ATV Fuel Pump Type

Not all ATVs have a fuel pump fitted some smaller older ATVs employ gravity feed. However, if your bike has a fuel pump then it will be either mechanical or electric.

Mechanical pump – Mechanical fuel pumps are fitted to older carburetor bikes. They usually employ a pulsing engine vacuum and a diaphragm to move gas from the tank to the carburetor.

Electric fuel pump – Most modern ATVs are fuel injected and therefore require higher fuel pressure which means they are fitted with an electric fuel pump. The pump is located inside the gas tank itself.

We will diagnose both mechanical and electric pumps in this post.

How to Diagnose ATV Electric Fuel Pump

An electric pump is as you know submerged inside the gas tank and usually requires tank cover and side shrouds etc removed before we can access the pump, fuel line, or wiring terminal block connector. That’s an investment of time and energy and so we’ll run a simple listening test first to confirm we have a fuel pump issue before pulling our bike apart needlessly.

Obviously, if our pump fails this first test we’ll need to strip a few covers.

Listen for pump sound

This test is simple, but you will need a charged battery and somewhere quiet to perform the test. Most electric fuel pumps emit an audible buzz or hum sound for about 3 seconds when the ignition is turned on initially. The pump does this so as to pressurize the fuel line and prime the fuel injector in preparation for starting.

The first test is simple then, turn the ignition switch on (position 2) and listen.

Two results are possible:

1 You hear a humming sound – Hearing the fuel pump hum, is a good sign, it means the wiring circuit and ECU are all doing their job, it also means the pump is working. and if you are chasing a no-start problem, the fuel pump likely isn’t the root cause.

But a hum from the pump doesn’t necessarily mean the pump is working as it should. The pump may not be supplying enough flow and that’s a common cause of symptoms such as extended crank or poor performance. If that is the type of problem you are chasing, we’ll need to remove some covers and access the pump for some testing.

2 You don’t hear a humming sound – There may be a few reasons you don’t hear the pump. The most common reasons are: the pump may indeed be faulty or the fuel pump fuse may be blown.

Since checking the fuse is a ton easier than pulling covers etc and checking the pump, we’ll check the fuse first.

Fuses commonly blow because:

• Amp rating too small
• Circuit short
• Faulty fuel pump

Some ATV fuses are located under the seat but you may need to consult your manual for fuel pump fuse location and fuse amp rating.

Check power at the pump

Ok, you already know you’ll need to strip out covers, etc to gain access to the pump terminal block connector. When you have gained access we’ll need a DVOM or test light to check for voltage. If you need tools for the job, check out the tools I use here on the ATV tools page.

The process is as follows:

• Locate and disconnect pump block connector

• Probe power and ground terminals (careful not to damage the terminals)

The power will only be present for 3 sec after ignition in position 2

Two results are possible:

1 You have power at the terminal, if so jump ahead to the resistance test here.

2 No power at the pump terminal, check power and ground independently using a test light.

Test power at the pump using the battery ground as per the picture.

The power will only be present for 3 sec after ignition in position 2

Test ground at the pump using the battery positive as per the picture.

The power will only be present for 3 sec after ignition in position 2

If you are missing either power or ground suspect a wiring break and chase them.

Check pump resistance

A resistance test is useful as it allows us to ascertain the pump circuit without having to remove it from the tank. When running a resistance test you must isolate the component from the circuit.

When testing resistance the meter sends a small charge down one side of the circuit and the second probe measures its progress.

Test as follows:

Set the DVOM to resistance Ω and probe both sides of the pump terminals.

Two results are possible:

Meter offers a resistance reading – A reading in the region of 6 ohms is typical but all bikes will have their own window of operation. You’ll need to check your reading is within it.

Meter offers an open reading – An open means the pump has an open circuit and is faulty. Pumps can’t be repaired, they are replaced. And we cover that below.

Visually check pump flow

For this test, we’ll need an empty water bottle, length of fuel line, and an appropriate small pick to remove the fuel line from the fuel pump. The pump wiring will need to be connected.

The process is as follows:

• Remove the fuel line from the pump
• Fit length of fuel line to fuel pump and feed into a water bottle
• Activate the pump (ignition switch position 2)

No fuel flow or a weak flow means the pump needs to be replaced.

A solid flow means it appears the pump is good, that said manufacturers do have a min quantity flow over a given time.

Use fuel pressure gauge to test system pressure

For this test, we’ll need a fuel pressure test kit. Your manufacturer will specify a min fuel pressure and head pressure specs for the pump.

I look for the pressure to be maintained with key on and then when running check the min spec is being maintained when the engine is loaded. Somewhere between 40 to 60 psi is typical.

The process is as follows:

• Connect fuel pressure gauge

• First check key on fuel pressure.
• Now check min pressure with the engine running.

If the pump fails this test, go ahead and replace it.

How To Change ATV Electric Fuel Pump

To fit a fuel pump we’ll need mostly regular hand tools but some models may require a special fuel pump release tool, but a good set of channel locks does the job too.

The process is as follows:

• Remove fuel line
• Remove pump wiring terminal
• Clean the area around the pump
• Mark the location of the keeper (lets you know how much to tighten later)
• Using channel locks loosen and remove the keeper
• Remove pump and sender unit

The pump and sender unit are usually removed as one unit, meaning we’ll need to remove the pump from the assembly.

The process is as follows:

• Move to a workbench and remove the filter mesh from the pump
• Remove the pump push-on wire terminals (take a pic first if needed)
• Remove fuel line
• Remove pump from sending unit

Refitting is the reverse. However, some new pump kits may include pump O-ring seals and fuel line length and clips. It depends on the pump type fitted.

Pump fitting tips:

• Use non-petroleum lube on rubber seals to help fitting and sealing (silicone grease)
• Use dielectric grease on electrical terminals helps prevent moisture
• Tighten pump keeper to your mark
• Check for leaks after rebuild

How to Diagnose ATV Mechanical Fuel Pump

The mechanical fuel pump is a lot easier to locate, test, and work on. The pump is usually small and located close to the gas tank. Following the fuel line from the gas tank will help you locate the pump.

It will employ a fuel line in (from the gas tank) and a fuel line out (to the carburetor) and a pulsing hose that’s connected to the engine crankcase breather system.

Some checks we can run before removing any components include:

• Check that we have sufficient fuel inside the gas tank
• Check the gas tap is turned fully on
• Check the vacuum hose to the pump (a split, perished or otherwise damaged hose will prevent the pulsing vacuum needed to power the pumping action)

With these simple checks out of the way, we can now begin to diagnose. The steps are as follows:

• Remove the carburetor fuel line and place the open end into a suitable clear container (an empty water bottle works great)
• Have helper crank over the motor
• Check fuel flow to the container

A good pump will pulse a plenty feed of fuel

A bad pump will supply no fuel or poor fuel flow

Replacing a mechanical is an easy task requiring only basic tools. But do check that vacuum line, it is critical to fuel pump operation. Replace fuel line clamps and check for leaks on completion.

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The post How to Tell ATV Fuel Pump is Bad? This is how … appeared first on ATVFixed.com.

Cranking and cranking and nothing, what a pain! I hear you. I’m a mechanic and very shortly we’ll check your timing and we’ll be well on the way to figuring out what’s going out with your dirt bike.

When a dirt bike timing is off, you may experience the following symptoms:

• No start
• Runs but no power
• Runs but backfiring
• The engine won’t crank just clicks
• Kickstart won’t move

In this post, you’ll learn, why dirt bike timing is important, you’ll learn how to check and reset the timing on both a 2 stroke and 4 stroke motor.

What is Dirt Bike Timing?

Timing is important but you already know that. But what is meant by timing? An engine needs three ingredients in order to run:

1. Fuel (air and gas mix)
2. Spark
3. Compression

When referring to timing on a regular 4 stroke motor we may be referring to ignition timing or valve train timing and we’ll get into that in a little more detail below.

When referring to timing on a 2 stroke we are referring to ignition timing only, since a 2 stroke doesn’t have a valve train there are no valves to time.

Checking and adjusting timing is different depending on what type engine your bike has. Checking and setting the timing on a two stroke as said relates to the ignition timing. If you have a two stroke bike you can jump ahead to checking and adjusting timing here.

Checking timing on a four stroke is a little more work and typically when we refer to timing on a 4 stroke bike we are referring to valve train timing, since ignition timing for most four strokes is not manually adjustable. The timing is advanced and retarded by the CDI/ECU controller only.

Four stroke engines

The purpose of engine timing is to prepare the combustion chamber so that the conditions are perfect for ignition (explosion). If the fuel mix is wrong (too much air or too much gas), if the plug doesn’t spark at the correct moment or the cylinder doesn’t compress, the mixture won’t ignite and the engine won’t start.

Most engines are known as four strokes and this describes the timing of how the three main ingredients are added to the mix, if you like.

An engine (4 stroke) may be thought of as unit with two halves, the bottom end, known as the block with the crankshaft being the main component, and the top end known as the cylinder head with the camshaft being the main component.

The two halves must work in harmony in order for your dirt bike to perform. And to do that the two components, the crankshaft, and camshaft must be synchronized.

An assembly known as a timing assembly is employed and charged with the task of synchronizing (timing) both these components. Typically a timing assembly includes sprockets, a chain, guides, and a tensioner.

Let’s take a look at those four strokes (stages) briefly now.

First stroke – The rotating crankshaft causes the intake valve to open and the piston to fall which in turn draws the air-fuel mix into the cylinder.

Second stroke – The rotating crankshaft causes the intake valve to close sealing the cylinder and allowing the rising piston to squash and compress the air-fuel mix into the top of the cylinder (combustion chamber).

Compressing the mix, heats it through friction making the conditions perfect for combustion.

Third stroke – The rotating crankshaft passes x° BTDC (Before Top read Center) which triggers the ignition system pickup sensor which in turn fires the spark plug through the CDI and coil.

This is known as the power stroke as the explosion pushes the piston down the cylinder.

Forth stroke – The rotating crankshaft causes the exhaust valve to open and the piston to rise forcing the spent gases out of cylinder.

And the process starts over at the first stroke.

How To Check 4 Stroke Dirt Bike Timing

Checking the timing is not difficult, all bike engines will have a crankshaft marking engraved which corresponds to a camshaft sprocket marking. Checking timing then is as simple as making sure they align precisely.

Some components may need to be removed in order to access the timing marks, but usually, manufacturers fit removable covers.

I covered the process below, but note all makers will approach this slightly differently, some will be single cam, some twin cam, and some older bikes may not be OHC (Over Head Cam) at all.

Timing check steps as follows:

• Remove spark plug.

• Remove the side cover timing inspection cover
• Remove flywheel fastener access cover

• Set the engine to TDC by turning crankshaft CCW until mark 1 (flywheel mark) aligns with side cover mark
• Now check the cam sprocket marks 2 and 3 align

This is a typical see up but your bike may be single cam, but I think you get the general idea.

If your marks don’t align then timing will need to be adjusted. We cover that below, but just before we jump to adjusting timing we should ask why the timing is off in the first place. It may be a warning sign of other issues which I cover below, you can check that out here.

Checking & Adjusting 2 Stroke Dirt Bike Timing

It should be noted not all 2 stroke bike timing is adjustable but this is something you can check in your owners manual before going to the trouble of pulling off a side cover.

Checking 2 stroke timing is usually undertaken in one of two ways. Tools however are required to nail this professionally.

Head cover on – For this process we’ll need a dial gauge to check and adjust the ignition timing. It’s not a difficult task, just a little tedious and you’ll need the specs for your make and model bike. If you don’t have a dial gauge you’ll find one here on the Dirt bike tools page here.

I’ve covered that below, note the side cover will need to be removed also.

Head cover off – If you already have the head off, then a simple timing tool may be used to check and set the piston to the correct ignition timing mark. If you don’t have a timing tool gauge you’ll find one here on the Dirt bike tools page here.

I’ve covered that below, note the side cover will need to be removed also.

Checking timing with head cover off

With the correct timing tool selected for your engine, use the following steps to time your engine:

• Place the timing tool on the jug and rotate the flywheel CCW until the piston kisses the tool.

• Now check the timing mark on the flywheel corresponding to the stator base plate.
• If not, loosen the stator baseplate fasteners and rotate so the markings align and tighten again.
• Job done!

Check timing with the headcover on

This process is very similar but since we don’t have the same access to the piston we’ll need a different tool. For this, we’ll need a dial gauge.

The process is as follows:

Remove the spark plug and fit the dial gauge at the appropriate height.

• Rotate the flywheel CCW to TDC
• Now zero out the dial gauge
• Rotate the flywheel CW to the specified measurement

• Now check the ignition timing mark on the flywheel (orange) corresponds to the stator baseplate mark (green)
• If not, loosen the stator baseplate fasteners and rotate so the markings align and tighten again
• Job done!

The engine is set to the correct ignition timing BTDC.

Some bikes may have three timing marks and that’s super useful for the MacGyver types that like to wing it.

The 3 marks represent the window of adjustment available to us. It’s a case of adjusting, testing, and readjusting until it feels right, who needs a dial gauge tool?

Why does Dirt Bike Timing go Out?

Engine timing is serious business when it’s out a little performance suffers but if the timing is out a lot or if timing assembly fails it often ends in disaster for the engine (4 stroke motor). So why does timing move out of sync in the first place?

As with checking and setting timing, why the timing moves out of sync depends on your engine type.

Why 2 Stroke timing goes out

A 2 stroke ignition timing typically needs adjusting after a rebuild and is often forgotten.

Why 4 Stroke timing goes out

The most common reasons a 4 stroke timing moves out of sync include:

• Worn chains – stretch with age and poor oil quality
• Worn timing sprocket – wear and tear and poor quality oil
• Incorrect fitting after rebuild
• Failed or worn chain tensioner
• Failed or worn timing chain guide

If you find worn timing components you’ll need to go ahead and replace the tensioner, guides, and the chain. In addition, you’ll need to replace the side gasket together with cam cover gasket.

To replace the chain guides and tensioner we’ll need to do the following:

• Remove the top side cam (replace gasket)
• Set timing to TDC
• Remove tensioner
• Remove cam caps (star pattern)
• Remove side cover (replace gasket)
• Pull flywheel (need flywheel puller) careful of key
• Remove chain guide and chain

Replace chain and guide and rebuild in reverse order and set timing as per below. Careful to follow correct torque specs in relation to flywheel and cam caps. Replace side cover gasket, cam gasket and tensioner gasket otherwise we’ll be chasing oil leaks.

How To Set 4 Stroke Dirt Bike Timing

Setting the timing isn’t difficult, we’ve already covered how to access and check the timing marks. Setting the timing then requires a few more steps. We’ll need to remove the tank, covers, air box, throttle body/carburetor, etc, wherever else we need to access the cam cover. For the following steps, we’ll assume you have clear access to the cam cover.

They are as follows:

• Remove spark plug
• Remove timing covers
• Remove cam cover
• Set engine to TDC
• Note timing marks

• Remove tensioner

• Loosen cam caps (star pattern)
• Remove or rotate the cam to realign the chain on the cam sprocket mark
• Refit cam cap and torque to spec (star pattern)

Careful to follow correct torque specs when tightening the cam caps and cam cover. Set the tensioner and fit (fit new gasket) and check tensioner has fired.

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The post Will Dirt Bike Start If Timing Off? Run this test appeared first on ATVFixed.com.

A coil is a critical ignition system component and your bike won’t run without them. A coil works hard, and for the most part, they are reliable, but they do fail. You are in the right place, I’m a mechanic and very shortly, you’ll know if your dirt bike coil is good or bad.

The top four symptoms of a bad dirt bike coil include:

1. No start
2. No spark from the spark plug
3. Hard hot starting
4. Shuts down when hot

In this post, you’ll learn what the symptoms of a faulty dirt bike coil are, how to diagnose a faulty coil, and of course how to fix it.

Symptoms of Faulty Dirt Bike Coil

Here we’ll look at the most common symptoms of a bad dirt bike coil in a little more detail. But just before we look at them, it is worth knowing that coils commonly fail in one of two ways. The symptoms associated with each type of coil failure are different.

1. Total failure – (stops working altogether)
2. Fails when hot – (works when the engine is cold)

Common dirt bike faulty coil symptoms are as follows:

No start – no start is the number one symptom associated with total coil failure. That said a dirt bike may not start for a ton of reasons and so this common symptom isn’t conclusive evidence of coil failure in itself.
No spark from the spark plug – no spark at the plug is if you like the first solid clue we are dealing with an ignition system fault and of course, as you know the coil is a major player in the ignition system so we’ll already suspect we could be looking at total coil failure. But as before we’ll need to check that coil first.
Hard hot starting – commonly associated with a failing coil as opposed to a totally failed coil. This type of intermittent failure can be irritating to catch as it isn’t always present and in some cases doesn’t even happen on every hot start.
Shuts down when hot – commonly associated with a failing coil. May be intermittent or regular as clockwork when the engine heats up. I’ve covered this exact issue previously and you can check it out here – Dirt bike won’t start when hot

While it’s true the coil is a major critical component of the ignition system that commonly fails, it must be said it isn’t the only component of the system that can cause issues. The presence of one or more of the above symptoms is not conclusive proof of coil failure.

And so before reaching for a new coil, let’s quickly test it and we’ll do exactly that right now.

How to Test Dirt Bike Coil

Checking spark at the spark plug is among the very first checks we make when we suspect a coil issue. Testing the coil though can be hit and miss without the correct tools. In the field, we can run a MacGyver-style hack by grounding the spark plug on the engine and checking for signs of life (we’ll cover that below).

The problem with this type of testing is, that it doesn’t load up the ignition system. And loading the system up and stressing is exactly what we want to do when testing.

First, let’s cover the MacGyver hack for in-the-field spark checking.

Checking spark MacGyver style as follows:

• Remove plug cap
• Remove the spark plug
• Refit the cap
• Ground the plug on the engine
• Crank over the engine
• Check plug for spark

Two results are possible:

1 No spark at the spark plug – Check the grounding. (Grounding the plug means making the metal body of the spark plug make good contact with bare metal on the engine.) If the plug isn’t grounded correctly the plug won’t fire and that often leads to misdiagnosis. If you are happy with the grounding, the plug should be swapped out with a spare to eliminate it as a possible cause of no spark

2 The plug sparks – Great! But remember this type of spark testing doesn’t stress the ignition system and so finding a spark isn’t conclusive.

The correct test is the inline ignition system test and we’ll cover that next.

The inline tool is especially useful when searching for intermittent hot start issues as the engine will run with the inline tool in place and of course, the tools inspection window may be viewed for signs of spark failure as the engine warms up and approaches its failure point.

The inline ignition system test is as follows:

• Remove plug cap
• Connect plug cap onto the inline tool
• Connect the inline plug cap to spark plug
• Crank engine
• Check for spark

Two results are possible:

1 The plug sparks – If you have a spark when testing with an inline tester, your ignition system is good. That said, if you still feel you have an ignition system issue, you can check the following:

• Check the correct type of spark plug fitted (heat range)
• Check plug condition and gap
• Check for grounding ignition system wiring (Kill switch)

2 No spark at the spark plug – It is very likely your coil is the root cause of the no start but there are as said other components that could cause no spark. To produce conclusive evidence we’ll need to check coil resistance.

A DVOM is also known as a voltmeter, but we won’t be checking voltage, we’ll be checking coil resistance. You can find a DVOM I use here on the ATV tools page.

Coil Test

When testing a coil we’ll run three tests:

1. Primary coil resistance test
2. Secondary resistance test
3. Plug cap resistance test

Before running this test you’ll need to isolate your coil by removing all block connectors and removing the coil cap. Running a resistance test while the coil is connected to the bike’s wiring circuit won’t work. Resistance must not be executed on a live circuit.

1 Primary coil resistance test as follows:

• Remove all coil wiring
• Set your meter to resistance Ω
• Test the primary windings by placing the probes as per the picture

The resistance readings 1.16 to 2.64 are typical but your bike’s spec will likely differ, check your online users manual.

2 Secondary resistance test as follows:

• Meter set to resistance Ω
• Test the secondary windings by placing the probes as per the picture

The resistance readings 8.64 to 12.96 are typical but your bike’s spec will likely differ, check your online users manual.

3 Plug cap resistance test as follows:

• Meter set to resistance Ω
• Test the secondary windings by placing the probes as per the picture

The resistance readings 1.16 to 2.64 are typical but your bike’s spec will likely differ, check your online users manual.

If your coil is within your manufacturer’s spec, your spark plug is correctly gapped, and it is the correct type of plug (heat range) then you are all good on the ignition system.

If your bike fails to start, check the following:

Air filter – a blocked or mouse infested air filter is top of the list for good reason

Following correct starting procedure – choke, kill switch, etc.

Flooded engine – constantly attempting to start a hard starting bike may cause flooding.

Fuel-related issues – bad gas, fuel starvation, dirty carb, etc. I’ve covered a hack for checking for fuel issues quickly in this post – ATV won’t start. Sure it’s an ATV but the principle is identical.

Valve lash – the engine must breathe and the valves allow air/fuel mix in and spent gases out.

Timing out – timing is important, spark must occur at a critical moment.

Compression issue – poor compression will cause a no-start.

Other Causes of No Dirt Bike Spark

Here’s a shortlist of other root causes of no spark:

• Faulty stator
• Faulty pickup
• Faulty ignition
• Faulty CDI
• Kill switch short

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The post Signs of Bad Dirt Bike Coil – Top 4 signs appeared first on ATVFixed.com.

A flat battery is a common everyday issue and easy to solve, you jumpstart her, right? But what do you do if even jumpstarting doesn’t solve the problem? Well, you are in the right place, I’m a mechanic and very shortly we’ll have it figured out.

Four common reasons an ATV won’t jumpstart, include:

1. Loose battery terminals
2. Wrong jumpstarting sequence
3. Faulty starter solenoid
4. Faulty neutral switch

In this post, we’ll cover all the common reasons your ATV won’t start, how to diagnose them and what you can do to fix them right now!

Pre Diagnosis Checks

Before we get into the actual diagnosis of the no start let’s first check we’re on the same page. To do that we’ll need to know what noise your engine makes when you attempt to jumpstart. The answer to this question will help determine what the likely cause is and therefore help get you back rolling quickly.

When jumpstarting and you hit the start button, commonly you’ll hear one of four sounds. Check out the links below that corresponds with what sound your ATV makes (if any) when you hit the start button.

The four likely sounds are:

1. Repeated clicking sound
2. Single click sound
3. No sound at all
4. The engine just cranks over, but doesn’t start (this is a biggie and I’ve covered it previously. You can check that out here – ATV won’t start)

Loose/Dirty ATV Battery Terminals

I’ve put this at the top of our list because it’s common and a one-minute fix, you’ll likely spend longer looking for the wrench than fixing the problem.

ATVs bounce about a lot and so it’s no surprise a few fasteners come loose from time to time. Of course, we should check the battery terminal fasteners are tight during maintenance checks, but given their location, they’re forgotten.

Anyhow, loose terminals create resistance to the flow of voltage both from the battery but also to the battery meaning your battery power can’t get to the starter motor, and nor can the charging system get voltage to the battery.

Diagnose: Access the battery and move the terminals from side to side, if they move they will create high resistance.

Fix: Use an adjustable wrench to snug them up, but not too tight, these guys can break if over tightened.

Dirty Battery Terminals

Dirty terminals will also cause resistance issues and is another common cause of hard starting. Corrosion can be seen as a white crusty buildup on the terminal itself. This is acid and will burn the skin, so use caution.

Diagnose White crusty buildup on the battery terminals.

Fix: Clean terminals but first neutralize the acid by mixing baking soda and some water into a paste and applying to the corrosion. After a few minutes, you are free to remove the terminal, clean it with sandpaper or wire brush snd refit, taking to tighten it securely.

Apply some petroleum jelly to help guard against future corrosion.

Wrong ATV Jumpstarting Sequence

Jumpstarting isn’t difficult, but sometimes when attempting to jumpstart in difficult conditions, terrain, or maybe in poor light, cables can get mixed up. Best to take a moment to check that the jumper cables are connected correctly.

Connect the cables in the following order:

1. ATV battery Positive (+)
2. Donor battery Positive (+)
3. Donor battery negative (-)
4. Ground point

You may use any 12-volt battery, or donor vehicle such as Car, Truck, Tractor mower, RV, etc. I’ve covered jumpstarting an ATV previously in greater detail and you can check that post out right here – How to jumpstart an ATV in 6 easy steps

A very common root cause of unsuccessful jumpstarting is not the fitting sequence but the cables themselves. Yep, bad quality or faulty cables are a pain because they lead you to believe you have a different problem. I’ve been caught once burning time because of faulty cables.

Anyhow make sure your cables are up to the job, weak crocodile clamps or frayed wires at the clamps are where they usually fail. I’ve listed a good-quality jumper set and a jump pack on the ATV tools page here.

Faulty ATV Starter Solenoid

The starter solenoid is a relay, it connects the battery to the starter motor when but only when the relay is activated by the start button. Solenoids work hard and fail regularly, a common tell-tale symptom is a single click sound when the water button is pressed.

That said a single click sound may be caused by some faults too low battery (although more often, a low battery offers several repeated clicks); valve lash out of spec; hydro locked engine; engine failure.

We’ll eliminate all of these as possibilities by checking the solenoid starter solenoid. After all it is the most likely reason we hear the departed clicking sound. However, if our solenoid tests is good, you’ll need to visit all these other possibilities just mentioned.

Testing the starter solenoid

To test the starter solenoid we’ll need two lengths of electrical wire one fuesed. In this test we’ll bypass the start switch and the ignition switch. The bike should be in neutral and parking brake applied, we’ll be cranking over the engine and if it’s in gear it will move. Testa as follows:

First locate the starter solenoid, usually close to the battery.

Access the two light gauge wires and remove them.

Using two jumper wires, (power fused) attach one to the positive battery and the other to the negative (as per picture).

Two outcomes are possible:

Your engine doesn’t crank over, it just clicks once. Most likely your starter solenoid has failed, as said they fail regurarly, and I’d just go ahead and replace it. That said there are a couple of other possible causes (less likely) and in the interest of a complete diagnosis you can check those out here in this post – ATV will only pull start

Engine crank over as normal – That’s great! But it means you’ll need to check out your safety lock-out system (neutral switch clutch switch etc,) or kill switch. Check out – ATV will only pull start, it covers the subject in more detail.

Faulty ATV Neutral Switch

A common cause of no sound at all when the start button is pressed is the Kill switch, worth taking a moment to check it’s in the RUN position. Hey, it happens.

However, for most, the more likely issue is a more technical issue such as a faulty lock-out system wiring or sensor issue. A transmission neutral switch is the most common sensor or switch used to prevent unintended in gear starts, but some may use a clutch lever too.

As you know the neutral light must be on in order for the starter to engage. If your light isn’t lit your bike’s CDI or ECU assumes the bike is in gear and won’t send power to the starter motor.

While obviously starting circuits vary from maker to maker but even the simplest ATV wiring circuits will incorporate a safety lock-out feature or maybe two.

I wrote an article on checking neutral light issues and you can check it out here – Neutral light always on

Other Possible Causes

Here you’ll find some other less likely but still possible causes of a no crank when attempting a jumpstart.

• Faulty starter motor – ATV will only pull start
• Hydro locked engine – ATV won’t start
• Engine flooded – ATV flooded with gas
• Faulty CDI/ECU
• Wiring issue
• Mechanical fault – ATV has spark and fuel but won’t start

You may also like the following posts:

ATV troubleshooting

How to tell if ATV fuel pump is bad

ATV won’t start after washing

ATV has spark and fuel but won’t start

How often should I service ATV?

The post ATV Won’t Jump Start – This will fix it appeared first on ATVFixed.com.

Stators are the unseen component, indeed most riders don’t even know it exists. Without the stator, we going nowhere, a stator is the birthplace of your dirt bike’s ignition system voltage.

All dirt bikes require a stator in order to produce voltage to run the ignition system, in addition, the stator provides power for lights, if fitted, and charges the battery if fitted.

In this post you’ll learn where a dirt bike stator lives and what it does, you’ll learn the symptoms of a faulty stator and finally, you’ll learn how to test a stator using a DVOM.

Where is a Dirt Bike Stator

The stator is fastened behind the left side aluminum cover of your engine (most engines).

It must be located there because it requires both a rotor and the rotating motion of the crankshaft in order to produce voltage.

What a Dirt Bike Stator Does

A stator is responsible for producing the voltage required to run your bike’s electrical system. Even bikes fitted with a battery and electric start only use that battery power to crank over the engine. As the bike starts the stator takes over responsibility for all the electrical demands, and in addition for battery-fitted bikes, the stator must also charge the battery, replacing spent voltage during the starting process.

But no matter if your bike has a battery fitted or not, it will require voltage to run the ignition system (fire the spark plug), and that’s the stator’s job.

So the stator is a really critical component, no stator means no spark plug activation and means no fun!

How Does it Work?

The stator consists of multiple coils of copper wire (bikes where a battery is fitted, coils are typically grouped together into three circuits) arranged in a circle and attached to the backside of the left engine side cover. When the side cover is fitted to the engine, the stator coil arrangement fits neatly inside a cavity on the rotor.

The rotor is fixed to the crankshaft and rotates as the engine is kickstarted or cranked over with the starter. As the rotor spins, magnets attached to the inner surface pass over the stationary stator coils and this excites the coils and produces voltage.

The voltage is however alternating current (AC) and must be converted to direct current (DC) before a dirt bike electrical system can make use of it. And to perform that function your bike is fitted with a rectifier. It rectifies the voltage, meaning it converts it from AC to DC.

For bikes fitted with a battery, a rectifier with an integrated regulator regulates how much voltage goes to charge the battery. Too little is no good obviously but too much is bad also, a faulty regulator will kill a battery by overcharging it.

Your bike’s stator likely also incorporates the pickup (most do). The pickup has a special function, it signals the CDI or ECU when it’s time to fire the spark plug.

A new stator will come with a new pickup.

Common Faulty Dirt Bike Stator Symptoms

Stators work hard, you already know that, so you won’t be surprised to know they fail regularly. Here are some common symptoms associated with stator failure.

• No start
• No start when hot
• Engine stalls when warm
• Engine misfiring
• Engine backfiring
• Engine won’t rev
• Engine no power
• Engine black smoke

How to Test Dirt Bike Stator

To test a dirt bike stator we have a couple of options. However, if our dirt bike isn’t running we have only one option open to us, the Static test. Let’s take a look at both of these right now and how to execute them like a pro.

You’ll need a DVOM tool in order to run these tests and you can check out the DVOM I recommend here on the AV tools page.

Dynamic Dirt Bike Stator Test

This test will suit you if your dirt bike runs and idles, conversely if your bike doesn’t run you’ll need to jump on down to the static test below.

In the dynamic test, we’ll unplug the stator wiring block connection and we’ll check AC voltage with the engine running (2500 rpm) using our DVOM.

The dynamic test is as follows:

Locate the stator block connector and disconnect.

With DVOM set to AC (~) voltage and the bike running check:

• A to B
• A to C
• B to C

As per the picture, typically the AC voltage reading between 15 and 60. Depending on spec and rpm, but check your makers’ spec.

Static Dirt Bike Stator Test

The static test suits a running dirt bike or a nonstarter just the same. For this test, we’ll use a DVOM set to resistance (Ω). We’ll be checking continuity in the circuit.

Continuity simply means we’ll be checking for broken wires within our copper coils. To do that, we’ll disconnect the stator wiring block connector. We use the DVOM to send a small charge through one terminal using the positive probe, and using the negative probe on a second terminal, we read how much of that voltage actually makes it through (if any).

The static test is as follows:

With the DVOM set to resistance (Ω) and the stator plug disconnected, measure the following:

• A to B
• A to C
• B to C

Typically a reading between .1 and 1 Ω is OK but check your makers’ spec.

In addition, we can check for a short to ground. With the DVOM set to resistance (Ω) and the stator plug disconnected, measure the following:

• A to G
• B to G
• C to G

No continuity means there’s no short.

You may find the following posts:

Dirt bike troubleshooting

Will dirt bike start if timing is off?

Will dirt bike start with low compression?

Dirt bike start without air filter?

How does dirt bike kill switch work?

Start a flooded 4 stroke dirt bike

The post Do All Dirt Bikes Have a Stator? A beginners guide appeared first on ATVFixed.com.

ATVs can be hard to steer at the best of times, especially when stationary. But you know your ATV and if it’s a lot stiffer than normal, you are correct to question it. I’m a mechanic and you are in the right place for ATV steering problem-solving.

Four common causes of hard to steer ATVs include:

1. Flat tire
2. Power steering fault
3. Seized ball joint
4. Wrong tires

In this post, you’ll learn why your ATV is hard to steer, you’ll learn how to diagnose the root cause and how to fix it right now.

1 Flat ATV Front Tire

ATVs like all vehicles have a recommended tire pressure setting for optimum performance and user comfort. The higher the tire pressure the smaller the contact patch on the terrain, that’s great for top speed, fuel economy, and maneuverability at low speeds, and likely offers a very bumpy ride that isn’t great for safety.

Conversely then an underinflated tire offers a greater contact patch with the terrain which increases resistance and hurts top speed, and gas mileage, and makes the steering heavy, especially at low speeds. Of course, low tire pressure is a safety hazard not to mention bad for the tire itself.

Diagnose: A soft tire isn’t always easy to spot, you’ll need to check the recommended tire pressure for your manufacturer and take into account the loaded and unloaded specifications.

Fix: Adjust tire pressure.

2 Faulty ATV Power Steering

Bigger more powerful ATVs mean they got heavier with bigger, wider tires which is great but it means we need some help steering these brutes.

The solution is power-assisted steering, some ATVs come with power-assisted steering as standard and on others, it’s an add-on.

If your ATV has power steering it will likely have a dash light symbol (EPS) and also illuminated green to indicate the current state of health.

ATV power-assisted systems aren’t hydraulic like a truck, instead, they are electric. ATV EPS systems are pretty sophisticated, they typically employ sensors, a motor, and a control module. The module collects input data such as speed, torque, records fault codes, and outputs power to the electric motor proportional to rider steering inputs.

The typical EPS system includes the following components:

Speed sensor – a speed sensor fitted to the transmission transmits the current speed to the EPS control unit. The control unit adjusts the amount of assistance proportional to ATV speed.

Electric motor – motor attached to the steering column and is integral to the steering system. When activated by the control unit, the motor assists the rider by turning the steering stem.

Torque sensor – the torque sensor senses rider inputs and signals the control unit.

CDI – CDI sends engine RPM to the control unit.

EPSCU (Electric Power Steering Control Unit) – the control unit receives speed and rider torque inputs and calculates the optimum electric motor assistance.

How to Diagnose?

It should be noted, most ATVs will shut the EPS system down to protect the motor if the EPS gets too hot. Excessive maneuvering could cause the system to overheat, if that’s the case the system will kick back in as the system cools.

We usually begin EPS diagnosis by running a visual check. Check for dash EPS warning lights. Check wiring and block connectors are in good shape too and from the motor, sensors, and control module.

Whenever you have an on-board computer that stores fault data, makes sense to read those fault codes early in the diagnosis process.

Typically disconnecting the control unit diagnostic loom and grounding it on the control unit calls the diagnostic function. The EPS warning light flashes out a two-digit code but that’s said not all ATVs will operate this way. You will need to read your operator’s manual to decipher the codes.

Bear in mind, your control module stores codes until they are removed, be sure you are reading the current fault code and not an old code. If in doubt, clear all codes and ride the bike once again to set the current fault, then go ahead and read the codes.

Typically clearing codes requires the operator to ground the control unit diagnostic pin on the control unit several times within a certain time frame, say 5 seconds.

But if you don’t want to read the fault codes, that’s OK we can still fault find by checking power, grounds, and running component resistance checks.

Power & Ground Checks

The motor and control module will require both power and good ground, these are both easy to check and are among the first items we check when fault finding. The absence of an EPS light on the dash panel is a clue that the power or ground is at fault.

Your EPS system will be fused and that’s first on our list of checks.

A simple test light is great for checking both power and ground on the control unit and motor.

EPS motor power side test

EPS motor ground side test

Control module power side test

Control module ground side test

Test speed sensor voltage – for this test we’ll need a DVOM set to DC and a helper.

Test as follows:

• Ignition on
• Red probe to ref voltage
• Black probe to ground

Reading should be 5v, if not check voltage along the loom back to back to the control unit.

If you still don’t have 5v, go ahead and now check your ground at the speed sensor. A test light works best here. And if that tests good suspect a faulty control unit.

If you do have 5 volts, go ahead now and move the red probe to the signal wire (center usually) and have the helper push the ATV forward.

Voltage should alternate from 0 to 6 volts. If not suspect a faulty speed sensor.

DVOM Resistance Checks

We also have the option of checking the resistance of the various components on the system. To do that we’ll need a DVOM set to measure resistance (Ω).

Check motor resistance – Check resistance between both motor terminals and also motor terminals and motor body (Ground). If outside spec, replace the motor.

Check EPS torque sensor resistance – somewhere between .875Ω and 1.625Ω is typical, but check your model’s specs.

Fix: Repair wiring, replace sensors, electric motor, or control module.

3 Seized ATV Ball Joint

ATV suspension and steering pivots on ball joints, they are critical components and make steering and suspension possible. A ball joint is exactly what it sounds like it’s a metal ball with an attached arm that pivots inside a cup. The ball and joint and press-fitted together at the factory and are not repairable.

Ball joints are under tremendous stress and wear out a lot. Some heavy-duty ball joints employ a greasing point but most are grease for life, meaning they wear out and become loose, which causes symptoms like vague steering, wandering, uneven tire wear, and rattles.

But not all ball joints fail by wearing out, some just seize solid, especially common on ATVs that hit the drink and lay idle for periods.

Diagnose: Your ATV front end likely has eight ball joints, that’s four on each side.

They are as follows:

Suspension

1 Upper A-arm ball joint

2 Lower A-arm ball joint

Steering

3 Inner tie rod ball joint

4 Outer tie rod ball joint

With so many ball joints makes sense to isolate the left side from the right side before further testing. To isolate the left side from the right side we’ll remove one outer tie rod.

The process is as follows:

Jack up the front of the ATV and remove either the left or right wheel. Locate the outer tie rod ball joint and remove the nut.

Use a ball hammer to strike the knuckle to loosen the joint.

With the tie rod removed from the knuckle, (check it pivots freely on the inner ball joint if it doesn’t replace it) the hub is free to turn independently from the opposite side.

Steer the hub (wheel) by hand, is it stiff? If not, check the opposite side.

Assuming you found one side to be stiff, which is common, jump on down to ball joint checks here.

If however, neither side is stiff, check the tie rod ball joint you just removed, is it stiff? If so replace.

Otherwise, investigate your steering column bearing positioned at the base of the steering stem.

The most likely cause is lower suspension A-arm ball joint seizure.

To test release the knuckle from the ball joint and check if seized, I’ve covered that previously in the following post How to check ATV ball joints? (covers the upper A-arm but the process is similar)

Fix: Replace the ball joint (How to check ATV ball joints?)

4 Wrong ATV Tires

Bigger tires offer greater ability when the terrain gets soft, but there is such thing as too much tire. Bigger boots as you know offer a bigger contact patch, but you also know that a bigger contact patch has a downside too – greater resistance.

Some typical complaints I hear when riders fit bigger tires, include :

• Steering feel heavy
• Down on power
• Lower top speed
• Harder on gas

ATV owner’s manual will likely not recommend you increase tire size and that’s because the steering, suspension, engine output, and transmission gearing have been designed to work with the OEM tires. Increasing the tire width means your ATV no longer operates within the manufacturer’s tested component tolerances.

You’ll find fitting bigger tires will not only have the aforementioned negative effects but in addition, will wear out components prematurely, components like ball joints and bushings, they may also cause frame welds to fracture.

Diagnose: Check your owner’s manual recommended tire size.

Fix: Fit original (OEM) tires and wheels.

Other Possible Causes Of Stiff ATV Steering

• Binding cables – ATV cables and brake lines are cumbersome and as you know they are routed from the handlebar controls down alongside the steering column. Common reasons for steering binds include incorrectly routed cables and foliage caught in the steering column.
• Steering column bearing – A bearing at the base of the steering stem and a bushing at the top of the column are responsible for maintaining the steering column securely and allowing for free column movement. Check the bearing and the bushing are in good condition.
• Driveshaft CV joint – The driveshafts are as you know responsible for getting power to the wheels. CV (Constant Velocity) joints allow the drive to flex both with the suspension but also with the steering. A failing CV joint may cause steering binding. Check the CV joints.

You may also like the following posts:

How to check ATV ball joints?

Does ATV tire width matter?

ATV troubleshooting

The post ATV Hard to Steer – Solved! appeared first on ATVFixed.com.

I’m a mechanic for twenty-five years, and bump starting engines is all part of the day job. If your dirt bike isn’t fitted with kickstart or even if it is, this post is for you. Very shortly you’ll learn a life skill and you’ll be tearing it up.

The top two ways to start a Dirt bike without using a kickstart include:

1. Hill bump-start
2. Push bump-start

In this post, you’ll learn the top two techniques for starting your dirt bike without using a kickstart. These techniques will work for all dirt bikes, however, fuel-injected bikes will require a functioning battery. we cover it all below, and we also some lesser-known dirt bike starting techniques.

1 The Hill Bump-start

The hill bump-start is the number one way to start a dirt bike without using a kickstart. It’s not only the easiest but it’s the safest technique also.

You’ll need a hill to perform the hill bump-start successfully. We’ll use gravity to propel the bike and rider downhill, then we’ll convert that motion into the energy we need to crank over the motor and start the engine. Sounds simple, right? Well, it is!

Tools you’ll need: Rider and a Hill

The Hill bump-start process:

Step One – Move the bike to the top of a hill – the steeper the better and somewhere the rear wheel will gain traction (a sealed surface is ideal, not a muddy trail)

Step Two – Turn the gas and ignition system “On”

Step Three – Straddle the bike, pull and hold the clutch lever, and place the bike in 2nd gear

Step Four – Push off and stand up (stand up on the pegs)

Step Five – When you’ve gathered sufficient speed, drop your weight (ass) onto the seat while simultaneously releasing the clutch lever (dropping your weight on the seat is important as it helps generate additional traction at the rear wheel precisely when it’s needed)

Step Six – Tear it up

For most riders, this simple hill bump starting hack works a treat. However, when it doesn’t, it is usually because of one of the following common reasons:

• The ignition system is not turned on
• Fuel not on
• The rider fails to gather enough momentum
• The rider fails to slam the seat at the correct time
• Bike flooded with gas
• Fouled spark plug
• Faulty battery (covered below)

2 Push Bump-start

The Push bump-start technique employs an identical starting technique to the Hill bump-start we’ve just covered above. But the push bump-start has a few extra steps that will require a higher skill level and some physical exertion.

This technique is used when the terrain doesn’t offer the rider the opportunity of taking advantage of a hill.

Tools you’ll need: Fit rider

The Push bump-start process:

Step One – Move the bike to a suitable space – a sealed surface would be ideal, somewhere the wheel can gain traction

Step Two – Turn the gas and ignition system “On”

Step Three – Stand on the left side of the bike, pull and hold the clutch lever, and place the bike in 2nd gear (note: some bikes may be challenging to push when in gear with the clutch pulled and held if so skip placing it in gear until you have built up sufficient momentum. This adds an extra degree of difficulty but not rocket science)

Step Four – Start pushing

Step Five – When you’ve gathered sufficient speed, through your leg across the bike and drop your weight (ass) onto the seat while simultaneously releasing the clutch lever (dropping your weight on the seat is important as it helps generate additional traction at the rear wheel precisely when it’s needed)

Step Six – Tear it up

Next, we’ll cover some of the common reasons this technique hasn’t worked. And you won’t be surprised to see that many of the reasons are related to the execution of the technique.

• Not gathering enough speed
• Taking too long to mount the bike and drop clutch
• Failing to coordinate weight on the rear wheel and dropping the clutch
• Faulty battery (covered below)

Other Techniques for Starting a Dirt Bike without Kickstart

Here you’ll find some other techniques for starting a dirt bike without using a kickstart. That said not all these techniques will suit all dirt bikes. To decide which options will work best, we’ll need to know:

A – If your bike is fitted with a battery and starter motor (electric start or not)

B – What type of fuel system your bike uses

Electric start

If your bike is normally electric start, you’ll have the greatest number of options available to you when it comes to starting your bike without a kickstart. The two most common types at the beginning of this post should have you covered, but in addition, you’ll have options such as Jump pack use, Jumpstarting, and crossing the solenoid. (all covered below)

That said, successful execution of these techniques will depend upon what components have caused your bike to fail to start on the button in the first place.

You can check out the electric start bike options here.

What Fuel System?

Most dirt bikes and all older bikes are fitted with a carburetor and more modern bikes especially higher-end modern dirt bikes will likely employ a fuel-injected fuel system. Either type may or may not have an electric start fitted.

The range of starting options, therefore, varies according to your bike’s spec.

Carburetor – carburetor bikes represent the majority of older dirt bikes and if your bike doesn’t have a battery fitted, it is a carburetor bike. That said, conversely having a battery fitted doesn’t make it a fuel-injected bike.

If in doubt, check your intake system. Although fuel-injected throttle bodies resemble carburetors in many ways they don’t employ a fuel bowl. If you find a bowl-shaped reservoir, it means your bike is fitted with a carburetor.

If in addition, your carburetor bike has an electric start, you can add the electric start techniques to the list.

Fuel-injected bikes – Fuel-injected bikes are sophisticated fuel systems that employ various electrical sensors – ATS (Air Temperature Sensor), Baro (Altitude sensor), TPS (Throttle Position Sensor), an electrically controlled fuel injector, an electric fuel pump, and an ECU (Engine Control Module (computer)).

While some dirt bikes are battery-less fuel-injected meaning they don’t need or have a battery fitted. A fuel-injected bike that’s designed to have a battery, won’t like to run without one.

A working battery is critical to many fuel-injected systems for obvious reasons. And while it may be possible to start some fuel-injected bikes with a faulty battery, it won’t run right until either battery voltage is restored or the battery is replaced. Certainly, fuel-injected bikes won’t like to run with the battery disconnected.

If in addition your fuel-injected bike also has an electric start, you can add the electric start techniques to the list.

Let’s go ahead and cover the various starting techniques open to each bike.

Electric Start Bike – Starting Options

No matter if your bike is carburetor or fuel-injected if it has an electric start you can use these starting options without using a Kickstarter.

• Jump starting – Jumpstarting is a process where we scavenge power from another bike or car (any 12-volt system) to start our bike. This works great if your bike has a battery that’s simply low on power, but won’t work if your starter or starter solenoid is at fault.

Jumpstart process as follows:

• ATV battery Positive (+)
• Donor battery Positive (+)
• Donor battery negative (-)
• Ground point

You’ll find a more detailed guide on jumpstarting here – How to jumpstart an ATV? (it’s an ATV but the process is identical)

• Jump pack – This is a process where we use a portable jump pack to start your engine. This works great if your bike has a battery that’s simply low on power, but won’t work if your starter or starter solenoid is at fault.
• Cross solenoid – This is a process where we cross the starter solenoid poles effectively bypassing the start button and solenoid. This works great if your bike has a fully charged battery and either the solenoid or start button is at fault.

If your solenoid is positioned close to the battery, avoid crossing the poles. Vented battery vapors could ignite from the arc caused by crossing the solenoid poles.

Crossing the solenoid as per the picture is a fast mechanics hack for bypassing the ignition system and testing the battery.

Be sure transmission is in neutral before crossing the solenoid otherwise the bike will lurch forward.

If the engine cranks over, it’s likely your solenoid has failed. I covered starter solenoid testing and fitting previously in this post – Dirt bike won’t start just clicks.

• Tow start – This is where a buddy pull starts your bike using theirs, you’ll need a tow rope and you’ll need to employ the bump start 2nd gear technique we covered at the beginning of this post.

Opsite footrest makes for a good towing point, and obviously, you’ll need to steer off-center.

• The belt-on-wheel technique – This isn’t recommended but in the interest of explaining all options, here it is. You’ll need a helper, a stand, and a ratchet strap belt. This is a process where you wrap a belt around the rear tire and place the bike on blocks and in 2nd gear (as per our bump-start technique at the beginning of this post) pull the belt to start the engine. The helper must be ready to clutch the bike as it’s in gear.
• Turning wheel technique – This one is highly dangerous, but we’re all adults here. You’ll need a helper and a stand. Placing the bike on stand and in 2nd gear (as per our bump-start technique at the beginning of this post) pull the rear type over using brute force. The helper must be ready to clutch the bike as it’s in gear and the puller must use extreme caution, getting a limb caught is a very real risk and not something I would recommend attempting.
• Wheel to wheel technique – Need a second bike, an experienced rider, and two stands for this one. Place the bikes on stands rear wheel to rear wheel.

This is a process where the experienced rider runs their bike in 2nd gear causing your rear tire to spin also. Releasing the clutch on your bike (as per our bump-start technique at the beginning of this post). You must be ready to clutch the bike as it’s in gear and on a stand.

• Wheelie technique – This is dangerous and I can’t recommend this one either. This will require a helper. The process is as follows. Apply the rear brake and tilt the bike upright onto the rear wheel. Place bike in 2nd gear and (as per our bump-start technique at the beginning of this post). While upright, push the bike forward, jump on and dump the clutch James Bond style!

Carburetor Bike – Starting Options

Here’s the list of starting options available to carburetor bikes, and as said, some carburetor bikes will also have an electric start. If that’s your bike, you can add the list of electric start options found above to this list.

• Tow start
• The belt on wheel technique
• Turning wheel technique
• Wheel to wheel technique
• Wheelie technique

Fuel-injected Bike – Starting Options

Since all fuel-injected bikes are equipped with a battery, you know you’ll need a functioning battery before she’ll run right. And as we said earlier, your bike may be an electric start also, and if that’s the case and it is for many fuel-injected bikes, you can add the electric start list of starting options found above to this list.

Fuel-injected starting options:

• Tow start
• The belt on wheel technique
• Turning wheel technique
• Wheel to wheel technique
• Wheelie technique

You may find the following posts helpful:

Will dirt bike start with low compression?

Dirt bike not getting fuel

Do all dirt bikes have stators?

The post Start Dirt Bike Without Kickstart – Like a Pro! appeared first on ATVFixed.com.

A flat battery is a royal pain in the ass and there’s never a good time to have one, that said as problems go it’s a simple fix. I’m a mechanic, you are in the right place and very shortly we’ll have this figured out.

To jumpstart an ATV you’ll need a donor battery and a set of jumper cables. Connect the cables in the following sequence:

1. Positive on ATV
2. Positive on Donor
3. Negative on donor
4. Ground on ATV
5. Start engine

In this post, you’ll learn how to jump-start your ATV quickly and safely. You’ll also learn how to charge your battery, how to check your battery health, and how to check your alternator output, let’s get to it.

Jumpstarting ATV Procedure

Jumpstarting an ATV is a simple procedure every rider should know. The procedure is not without risk, batteries contain acid and vent flammable vapors. Arcing a jumper cable is enough to cause the vapors to ignite. While this is a small risk, it is possible if you fail to follow the set jumpstarting sequence set out below.

In addition, connecting the jumper cables incorrectly can damage both the donor vehicle/battery and your ATV’s electrical system, so it’s important to get this correct.

Tools we’ll need:

Donor vehicle/battery – Obviously we’ll need a donor vehicle or battery. Most vehicles run the same voltage system as your ATV, it’s known as a 12-volt system (although these systems are actually 12.65 volts). This is great news as it means we have a wide choice of vehicles we can use as a donor vehicle.

Cars, including hybrids and even EVs, are suitable as they run a 12-volt system alongside their higher voltage drive systems. Trucks, RVs, Riding mowers, and Dirt bikes, all use 12 volt systems and are perfect for a jumpstart.

To check your donor vehicle is a 12-volt system, go ahead and locate the battery and check the battery casing label, it will clearly state – 12 volt

There’s is also the option of using a jumper pack instead of a donor vehicle to boost start your ATV and we’ll cover that procedure below also.

Jumper cables – A good quality set of jumpers are important, poor quality jumpers will create resistance to the flow of power between batteries. Cheap cables are pain and in my opinion a waste of money. Cheap cables typically use cheap narrow gauge wire and poor clamps which as said make poor connections. Check out the ATV tools page to see the jumper set I recommend.

The process of jumpstarting is as follows:

• Access your ATV battery (usually under the seat)
• Check both battery terminals are clean and tight
• Park your donor vehicle close to your ATV
• Access the battery and identify the battery poles (embossed on the battery casing and/or terminal cover).

• The Positive terminal is marked by a PLUS symbol (+) and maybe color-coded RED. The Negative terminal is marked by a Minus symbol (-) and color-coded BLACK

The positive terminal connects to the fuse box and the negative terminal connects to chassis ground (Grd)

Connect the cables as follows:

1. ATV battery Positive (+)
2. Donor battery Positive (+)
3. Donor battery negative (-)
4. Ground point

A ground point (Grd) is any metal on the chassis or engine. We use the ground point instead of the negative terminal of the ATV battery as the final cable often causes a small arc (spark). The arc as said could potentially ignite battery vapors if connected close to the battery vent.

Starting your ATV

With all cables connected, go ahead and start your ATV and allow the engine to idle as normal. Avoid revving while jumper cables are connected.

A repeated clicking sound as you hit the start button means the batteries aren’t making a good connection, readjust them and try again.

If your ATV fails to start and offers a single click sound, you likely have a failed solenoid and not a flat battery, I wrote a post previously that covers starter solenoid testing and you can check it out here – ATV won’t start

Removing the jumper cables

While your ATV is idling, remove the jumper cables in reverse order to how we fitted them.

Remove 4, 3, 2, and 1.

If your battery is generally healthy, and your charging system is in good shape simply riding your bike for thirty minutes or so without using electrical consumers such as lights, etc, is enough to charge the battery.

However, if you have a weak battery, bad alternator, or parasitic drain you’ll be visiting this problem again before long. Makes sense to test your battery and charging system to make sure all is in order, and we cover exactly that below, but first I’ll cover boost starting your ATV using a jump pack.

How to Boost Start ATV with Jump Pack

Boost starting from a jump pack is similar to the jumpstarting process only a ton easier. A jump pack is a really useful tool to have, modern jump packs are small enough to fit in the glove box of a car and yet powerful enough to start a diesel truck, these little guys pack. Check out the ATV tools page to see the jump pack I recommend.

The jump pack process is as follows:

• Connect the Red Jump pack clamp to battery Positive (+)
• Connect black jump pack clamp to battery Negative (-)
• Start engine

Jump packs employ an anti arc feature which prevents the risk of igniting battery vapors, however, as an alternative you can connect a jump pack black clamp to a chassis or engine ground also.

How to Check ATV Battery Health

Checking your battery’s state of health is a two-step process. First, we’ll need to check battery voltage and then we stress the battery by running the Crank test. We run a voltage test first to check the state of battery charge because running the crank test on a partially charged battery will lead to misdiagnosis.

The tool you’ll need:

In this test, I use a voltmeter (DVOM) but you can also use a dedicated battery tester which is also capable of running a charging system test (covered below). The battery tester uses a traffic light system and is easy to use, the voltmeter is a little more work, anyhow you’ll find both tools here on the ATV tools page.

Check Battery Voltage – Let’s go ahead and check battery voltage using our voltmeter as follows:

• Place the red meter probe on battery Positive (+)
• Place the black meter probe on battery Negative (-)
• Read meter

Crank test – A battery may display full voltage (12.65 v), but that doesn’t mean the battery is good. When stressed it could fail and as you know that’s why we run the Crank test.

If your battery isn’t at least 12.5 volts, go ahead and charge it before running the crank test. To charge it you can run the engine or use a battery charger.

• Place the red meter probe on battery Positive (+)
• Place the black meter probe on battery Negative (-)
• Crank over the engine
• Read meter

What the results mean

A reading below 9.6 volts indicates a weak battery

Reading above 9.6 volts indicates the battery is good

How to Charge ATV Battery

Batteries don’t like sitting idle, they are designed to be used, charged, and discharged continuously. That’s what keeps a battery vibrant. And that’s why I recommend using a smart battery charger also known as a trickle charger when your bike is laying up for more than a week.

The smart charger is designed to monitor your battery state of charge and turn on and off as needed. Check out the ATV tools page to see the smart charger I recommend.

If your battery state of charge is very low your charger may not turn on, this is a safety feature.

To override this connect a donor battery and then connect the career as per the picture. The donor battery may be removed after 30 mins and continue to charge as required.

To charge your battery, follow these steps:

• Remove the negative terminal (helps remove any risk of electrical system damage caused by voltage spikes)
• Check the battery terminals are clean
• Attach the red battery clamp to battery positive (+)
• Attach the black battery clamp to battery Negative (-)
• Set charger to 12 volts, plug in and turn on

Charge time will depend on how low your ATV battery is, its amp rating, and the amp rating of the charger. Typically 3-4 hours.

How to Check ATV Alternator Output

This is a simple check and to nail it like a pro you’ll need either a Voltmeter or a battery/alternator tool and a helper would be useful. You’ll find both these tools on the ATV tools page here, but not the helper.

First, we’ll need to access the battery, then follow these steps:

• Start the bike and allow it idle (helper)
• Set the voltmeter to 20 v DC
• Place red meter probe on battery positive (+)
• Place the black probe on battery negative (-)
• Take the revs up to about 3000rpm (helper)
• Check the meter reading

What the results mean

A reading below 12.65 volts indicates your charging system isn’t working, further investigation is needed. Possible faulty stator, rectifier/regulator, or wiring circuit.

A reading above 13 volts and below 15.5 volts indicates your charging system is charging and working as it should.

A reading above 15.5 volts indicates your rectifier/regulator is faulty

If you suspect an intermittent charging issue, repeat the test with lights, etc turned on. A healthy system will offer the same results as per the previous test.

Common Causes of ATV Flat Battery

A flat battery happens to us all, sometimes it’s operator error and if that’s the reason you have a flat battery, consider yourself lucky, your work is done here, if not we may need to do a little detective work.

The most common reason for a flat battery is battery failure and we’ve covered battery testing above.

Other causes include the following:

Loose battery terminals – ATVs bounce about a lot, it’s not uncommon for battery terminals to come loose. Loose terminals will create resistance (obstruction to the flow of power), it stops battery power from getting to the starter motor but the reverse is true also, the charging states can’t get full voltage to the battery.

Dirty battery terminals – Leaking acid and arcing can cause a build-up of corrosion on the terminal which results in high resistance with the same results as a loose battery terminal.

A faulty rectifier/regulator – The rectifier regulator is a critical charging system component. It takes alternating voltage (AC) produced by the stator and converts it into direct current (DC) used by your ATV.

In addition, the regulator monitors and adjusts battery charging voltage which is critical for a healthy battery. A faulty rectifier/regulator commonly causes premature battery failure as it overcharges the battery.

In addition, a neglected faulty rectifier/regulator may damage the CDI box, which results in an ignition system failure and a no-start.

Short to ground – A short is common in older more experienced ATVs, loose or trapped wiring shorts off the ground (chassis or engine metal frame). The short causes a constant drain on the system.

Accessories are a common source of electrical shorts since the wiring isn’t factory fitted they tend to come to loose more often.

Failed Stator – The battery is responsible as you know for starting the engine but the stator generates all the voltage needed to run the bike and replace spent battery voltage. A faulty stator will affect battery charging and may in some cases drain the battery.

You may also find the following posts helpful

ATV troubleshooting

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ATV has spark and fuel but won’t start

The post How do You Jump Start an ATV? In 6 easy steps appeared first on ATVFixed.com.

There’s never a good time to break down but not to worry, I’m a mechanic, and very shortly we’ll have this figured out.

6 Common reasons an ATV won’t start, include:

1. Flat battery – jump or charge battery
2. Loose battery terminals – tighten terminals
3. Fouled spark plug – clean or replace plug
4. Flooded engine – dry out cylinder
5. Stale gas – drain and refill
6. Faulty starter solenoid – test & replace

In this post, you’ll learn how to fault find your no-start ATV like a pro. We’ll cover diagnosis and you’ll learn some insider tips and hacks to speed up the process of both diagnosis and repair.

Mechanics advise for fault finding ATV

A mechanic/technician uses two main strategies when fault finding. We typically use the Common causes approach and the top-down approach.

Now it should be noted, that many latest bikes store fault codes in their ECU (on-board computer) and if your bike is fuel-injected and if a problem is flagged by the ECU, that fault code will be stored and is accessible. Reading these fault codes is obviously a great place to start your diagnosis.

As each manufacturer has a slightly different method for reading and interpreting their fault codes, it is best to google your make and model first. Typically, connecting a fault code harness wire causes the ECU to communicate the codes by flashing dash lights a number of times.

All that said you can still use this article to fault find both carburetor and fuel injected bikes without reading the fault codes.

1 Common Causes Approach

The common causes approach is self-explanatory. Most technicians look at the symptoms of a problem ATV and using their experience (in our case – common ATV no-start causes) set about testing their hypothesis.

Most often, checking the common causes yields success and for obvious reasons, but every so often you’ll meet an exception, you’ll exhaust all the common causes with no luck and so the diagnosis must take our second approach, the top-down approach.

2 Top-Down Approach

A top-down approach is a systematic approach to fault finding. A technician still reads symptoms to direct their firepower but thereafter begins the test and evaluation process until the fault yields.

This type of fault-finding is hard work and often time-consuming and that’s why we’ll look at the common causes approach first before moving to test from the top down.

So let’s go ahead and start by checking those common causes right now.

1 Common No Start ATV Causes

Common causes obviously vary by make and model. Many ATVs, for example, employ auto choke, and most late models are fuel injected and so eliminate a ton of common faults associated with carburetor models, but at the same time, open up new common cause territories.

There is some overlap between the carburetor and fuel-injected bikes, but as their fueling system are different, we’ll deal with those systems separately. Remember, the list below isn’t a complete list of no start causes, just the common ones. We deal with a more complete list later in the second approach.

Common No-start ATV causes, symptoms & fix (carburetor & fuel injected)

Common (fuel injected) No-start ATV causes, symptoms & fix

Common (carburetor) No-start ATV causes, symptoms & fix

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2 Top-Down ATV Troubleshooting

If the common causes didn’t work out for you, not to worry the top-down approach and some patience will force a submission. We’ll need a few test tools along the way, but I’ll let you know what they are and, of course, how to use them.

Check a fact is a fact

As a technician, I’ve worked for GM, VW, Landrover, Jaguar, and Volvo dealers, and all their dealer product training employs a very similar concept. When presented with a reported problem – page one, step one – “Check the reported problem is in fact a problem”

In many cases, the error isn’t with the machine, it’s the operator, and so in the next section, we’ll quickly check that all those facts are in fact, facts.

Easy fix No-Start ATV Causes

Let’s start by looking at some of the easy-to-fix causes of ATV no-starts. In many cases, as said, a small oversight by the operator is the root cause. I know you know how to start your ATV; you’ve likely started it hundreds of times. But this step won’t take but a moment, and then we can move on and do some proper diagnosis, promise!

Okay, let’s quickly eliminate some common operator errors as root causes of our no-start.

Check the following:

Gas level – Gas in the tank is obviously crucial; running out of gas is common and has caught us all out. Yes, even mechanics!

Kill switch – The kill switch, as you know, shuts down the motor. The switch must be set to “Run” in order for the engine to restart.

Check your kill switch is set to “Run”.

Choke use – A choke adds extra gas and is required to start a cold engine. Some ATVs employ a manual control and if that’s yours, it will need to be set to the “ON” position.

Many modern bikes employ auto choke, and if your bike is fuel injected, (lucky you), cold start fueling is automatic; it’s controlled by the onboard computer, and no action is required.

Correct starting procedure – ATVs, as you know, employ a safety lockout procedure, meaning if you don’t follow a set starting procedure, the engine won’t crank over or start.

Typically, the bike transmission needs to be in neutral; some will require a clutch held and some the brake applied.

Check your make, and model starting procedure online.

Gas tap “On” – The gas tap is also known as Petcock or Gas valve. Most bikes are fitted with a gas tap, when in use it prevents gas flow from the tank to the engine. Commonly the tap is turned off when a bike is parked up.

Check Petcock is set to “On”.

OK, that’s the low-hanging fruit out of the way, now let’s do a little detective work.

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ATV No-start Pre-diagnosis Detective Work

I’ve been a mechanic for over twenty-five years, and I’ve found when fault finding you can learn a ton and get a head start on fixing the problem without even looking at the machine.

Simply taking a few moments to listen to the customer explain the issue and asking a few probing questions often sets us on the correct path.

The main question to consider is – What were the factors at play prior to the engine stalling out or not restarting? (whichever is applicable)

For example:

• Did you just refuel? – gas could be stale or contaminated
• Bike won’t start when hot? – engine could be flooded by excessive choke use
• Bike won’t start when cold? – choke or temperature sensor (fuel injected bikes) may be at fault
• Did you drive through water? – the electrics could be wet
• Has the bike been laid up for a time (month plus)? – gas tap may be off or the fuel may be stale
• Have you added mods, like exhausts, free flow air filter or wired accessories, etc.? – some performance mods will require carburetor fuel adjustment
• Have you been working on the engine when it quit? – carburetor tuning, engine timing, and valve lash are all common no start causes after engine repairs/adjustments/modifications

Having spent a few moments considering the above, we’ll assume for now it wasn’t fruitful, and so we’ll move to the next phase where we’ll attempt to broadly identify and label the root cause of your ATV no-start.

What do you Hear when you Hit ATV Start Button?

When diagnosing, I find it helpful to broadly categorize symptoms and assign them to labeled buckets, metaphorically speaking.

Within these buckets, I’ll make a list of the various components that are a likely root cause of that buckets symptom (label).

Thinking in these terms helps to exclude a broad range of issues and conversely causes us to focus on a narrower more likely range of possible causes.

Each bucket, as said will contain the most likely components to cause issues and we’ll look at all these in more detail a little later. But for now, let’s go ahead and categorize your ATV starting symptom so that it fits neatly into one of our five buckets.

And to do that successfully, we’ll need to pay particular attention to what noise your ATV makes when we attempt to start the engine, ie crank the engine over. For those that aren’t familiar with the term “crank engine over” – it describes the cycling (also known as turning over) of the engine as the start button is pressed.

Go ahead and categorize your symptom, assign it to one of the following buckets and begin diagnosing.

Your engine makes one of the following noises when the start button is pressed:

• Bucket 1 – Engine makes a REPEATED clicking sound
• Bucket 2 – Engine makes a SINGLE click sound
• Bucket 3 – Engine cranks over but sounds SLOW
• Bucket 4 – Engine makes NO sound at all
• Bucket 5 – Engine cranks over, it sounds NORMAL, but won’t start

Bucket 1 – ATV Engine makes a REPEATED clicking sound

If your engine makes a repeated clicking sound when you hit the start button, then consider yourself lucky.

This type of issue is common and is by far one of the easiest faults to diagnose and fix.

The most likely issue is a flat battery, but wow there! Let’s now jump to conclusions, there are some other possibilities, but all the fixes for this symptom are easy, and frankly, I’m jealous!

Faults are listed below in order of how likely they are. Follow each highlighted link, in turn, to diagnose and eliminate it from the list of possible issues, rinse and repeat until you nail it.

Battery Terminals Loose

Loose terminals are common and really easy to diagnose and fix.

Diagnose – Access the battery (usually under the seat) and wiggle the terminals.

Tools: Adjustable wrench

Fix – If they are loose, tighten them – problem solved.

Battery Terminals dirty

Dirty terminals are another really common issue and almost as easy to fix as loose battery terminals.

An acid weep from the battery combined with arcing causes battery terminal corrosion.

And corrosion causes resistance to the flow of power from the battery to the starter motor. The dirty terminals conversely prevent alternator voltage recharging the battery.

Diagnose – It’s easy to spot, it forms a white crusty deposit on the terminal.

Tools:

• Disposable gloves
• Eye protection
• Baking soda and water
• Rag
• Small adjustable wrench
• Sandpaper or wire brush
• Petroleum jelly

Fix – The fix is simple, remove the corrosion. But wow, not so fast, acid will burn the skin and eyes, we’ll need to neutralize it first.

The whole process is as follows:

• Add a tablespoon of baking soda to some water and work into a paste.
• Using an old cloth and gloves or brush add the paste to the terminal
• Allow a few minutes for the paste to work its magic before wiping clean
• Remove battery terminals (need a wrench)
• Using sandpaper or a wire brush clean the terminals
• Refit the terminals and tighten
• Add a coat of petroleum jelly to terminals (prevents corrosion)

Battery Flat

We’ve all suffered a flat battery at some point in time. Sometimes it’s all on us (leaving the ignition switch on), but more commonly, it’s because either the battery hasn’t been maintained correctly or the battery is in the early stages of complete failure.

Either way, we’ll need to check the voltage and charge the battery back up. A flat battery obviously won’t start your engine, but we can’t test a flat battery either.

Tools:

• To test the battery we’ll need a DVOM (voltmeter)
• To charge the battery we’ll need a battery charger
• If you wish to boost start we’ll need a jump pack or jumper cables

You’ll find all these tools here on the ATV tools page.

Diagnose – A repeated clicking sound from the engine is a pretty good indication we have a battery issue. Of course, no sound at all is another symptom of a totally flat battery. To confirm this, even without breaking out a voltmeter, you could turn the lights on full; if they are dim, you can be sure your battery charge is low.

Next, we’ll use a voltmeter to confirm this; however, if you just want to get rolling, you can jump ahead to battery charging or, for immediate results jumpstarting.

Checking ATV battery voltage with DVOM (voltmeter) as follows:

• Set meter to 20 DC
• Red probe on + battery terminal
• Black probe on – battery terminal
• Read meter

A voltage reading below 12.4 volts may struggle to start your engine, especially in cold weather. Batteries don’t like laying idle either, they much prefer being used ie discharged, and recharged, it keeps them vibrant.

If you park your ATV up for weeks on end, I’d advise using a battery maintainer, also known as a smart charger. Fit them to the battery plug them in and forget them. They turn on and off automatically and use little energy. A good charger will save you money in the longer game. You can check out the smart charger I use here on the ATV tools page.

Fix: The fastest way to get rolling again is jumpstarting. Starting the vehicle will use your ATVs alternator to charge the battery. But you should note, if the battery is faulty or the charging system is at the root cause of the flat battery you’ll be visiting this problem again. After charging the battery it’s best to have it tested, and we cover that below.

To jumpstart you will require a donor vehicle, it doesn’t need to be another ATV, any 12-volt vehicle will work. A car, truck, motorbike, tractor mower, RV, etc all run a regular 12-volt system.

If in doubt check the battery casing where it states the battery voltage. (12 volt systems are referred to as 12 volts but actually are 12.65 volts).

Jumpstarting

The jumpstart process is as follows:

Connect cables as per diagram:

• Connect 1,2,3 and 4
• Start engine
• Remove 4,3,2 and 1

Don’t want to jumpstart, Ok our second option is to charge the battery. Obviously, we’ll need a battery charger for this fix. Note – Many battery chargers employ a fail-safe system that won’t allow the charger to turn on if battery volts are too low.

You can check out the charger I recommend here on the ATV tools page.

Battery Charging

Connect a battery charger as follows:

• Connect red to battery +
• Connect black to battery –
• Plug in charger
• Charge for 3-4 hours (depending on battery state of charge and charger Amp rating)

To override this connect a spare battery to turn the charger on, the donor may be removed after 30 minutes and continue to charge for approximately a further 3-4 hours.

Battery Faulty

Batteries wear out and die, even well-maintained batteries eventually give up. batteries typically last 4 to 6 years, sure some batteries last longer but they tend to be the exceptions.

Tools:

• We’ll need a DVOM (voltmeter) to test the battery
• We’ll need an adjustable wrench to swap out the battery

Diagnose: Diagnosing a battery isn’t difficult. It is a two-step process. We first establish the state of charge before running the step two crank test. We check the voltage (step one), first because unless the battery is charged to at least 12.5 volts, step two will not give a true state of battery health.

In this test, I use a DVOM, and a helper to read battery voltage. It’s not difficult, but it is laborious when compared to a battery test tool designed for the job. And so if you prefer to use a battery tester, I have listed an easy-to-use plug-and-play type battery tester that uses a simple traffic light system to test your battery.

You can check out the battery tester I recommend here on the ATV tools page.

Crank test is as follows:

• Set meter to 20v DC
• Set to MIN/Max
• Red probe to battery +
• Black probe to battery –
• Helper cranks motor over

A reading below 9.6v indicates a failing battery.

Fix: Replace the battery

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Back to Bucket 1

Bucket 2 – ATV Engine makes a SINGLE click sound

A single-click sound from the engine when you hit the start button is a common sound to many an ATV rider. It’s the sound of a faulty starter solenoid.

As problems go, a faulty solenoid is an easy fix, but just before we make the mistake of misdiagnosis let’s first test it and if it checks out OK, run the other tests in this list.

Faults are listed below in order of how likely they are. Follow each highlighted link, in turn, to diagnose and eliminate it from the list of possible issues, rinse and repeat until you nail it.

Starter Solenoid

A failed starter solenoid is a very common cause of a single-click sound. The solenoid is a relay and as you know they are responsible for sending power to the starter motor. Solenoids just wear out. In truth, some of the places solenoids are positioned invite trouble. Some models place them under the fender and surprise surprise they fail regularly.

Anyhow I covered testing the solenoid in greater detail previously right here – ATV will only pull start

You may find this post helpful also – ATV click no start

Hydro-locked Engine

A hydro-locked engine isn’t common but it can happen under certain circumstances. Hydro-locking is where the cylinder fills with fluid and since the fluid isn’t compressible the piston can’t move inside the cylinder.

How did the fluid get in there? Driving into the drink is one possibility, so too is a leaking carburetor float valve or a failed head gasket that allows coolant enters the cylinder.

Removing the spark plug releases the fluid, but it doesn’t fix the root cause.

I’ve covered Hydro-locking in greater detail previously, together with some other causes of an engine that’s stiff or refuses to turn over.

You can check it out right here – ATV won’t pull start

Check out – Can ATV go in the water?

Engine Restriction

A restricted crankshaft, piston, or valvetrain will prevent the engine from cranking over. And by restriction here, I’m thinking of a major mechanical failure.

The result is a single click sound when the start button is pressed, that sound is the solenoid doing its job, but the starter doesn’t follow up by rotating the engine.

We need to find out why.

Tools: Good socket and ratchet set including a plug socket and breaker bar

Diagnose:

• Remove spark plug
• Remove the engine side cover to access the crank fastener

• If your ATV has a pull starter you won’t need to remove the pull assembly
• Using the breaker bar & socket, attempt to rotate the engine slowly CCW or for pull starter, attempt to pull over the engine slowly with pull starter.

If the engine is locked tight, suspect engine damage, but before assuming the worst, best to remove the starter motor and repeat the test. A starter motor issue is still possible and starter motor testing is covered below in greater detail.

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Back to Bucket 2

Bucket 3 – ATV Engine cranks over but sounds SLOW

This is a very common symptom associated with a no-start especially in colder weather and after an ATV has been sitting idle for a time.

The usual root cause is a battery that is low on voltage, a jumpstart from any 12-volt vehicle is the fast fix but you could also charge the battery using a battery charger.

And although this is the most likely of the slow crank, it isn’t the only possible explanation, you’ll find the other in the list below.

Faults are listed below in order of how likely they are. Follow each highlighted link, in turn, to diagnose and eliminate it from the list of possible issues, rinse and repeat until you nail it.

Oil Level Overfull

An engine is designed to hold a set amount of oil, too much oil can cause problems. An engine requires a void inside the crankcase to deal with negative and positive crankcase pressure caused by the moving crankshaft, piston, and valvetrain.

Overfilling with oil then fills this critical void and causes other issues, a slow or no crank is among them.

Diagnose: Go ahead and check your oil level.

Fix: Remove excess oil

Oil Type

Oil type is important and we should always use the oil specified by the engine maker. That said if your ATV lives and works in extreme conditions you may need to move to a more suitable grade.

In colder temps, a heavier oil grade moves like treacle, and that can as you know cause engine damage, but also a slow crank speed and a no start.

Fix: Move to a lighter oil grade

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Back to Bucket 3

Bucket 4 – ATV Engine makes NO SOUND at all

This symptom has the potential to be a super easy fix or a troublesome one. I know that’s not the most helpful information but stick with me here and you’ll see what I mean.

Faults are listed below in order of how likely they are. Follow each highlighted link, in turn, to diagnose and eliminate it from the list of possible issues, rinse and repeat until you nail it.

Main Fuse Blown

The main fuse is so-called because it’s the parent fuse, meaning all circuit power passes through it.

If the main fuse is blown, power won’t flow.

Diagnosis: The main fuse is located close to the battery under the seat. Remove the fuse and check the element. Fuses commonly blow because there’s a short in the circuit, other reasons include incorrect fuse size (too small), failed component, or just an overloaded circuit (accessories drawing excessive amps).

Fix: If the fuse is blown replace it, be sure to use the correct fuse amp rating.

Kill Switch Issue

With the kill switch set to stop, power flow to the starter motor is blocked, and if the kill switch fails to engage in the run position, many ATVs will offer the no sound at all symptom when the start button is pressed.

As not all kill switches are wired the same, a wiring diagram would be useful. That said kill switches either open a circuit or close a circuit. So when testing, just make sure the DVOM reading changes when the switch is operated.

Tools: DVOM

Diagnose: Disconnect the switch block connector and check continuity. (Never test continuity on a live circuit)

Fix: Repair or replace the switch

Wiring Issue

Circuit wiring issues are common in older ATVs and the best way to approach a wiring issue is with a wiring diagram and a power probe. Check out the power probe I recommend here on the ATV tools page.

As power must move in a circle, using a power probe begin by checking the power side of the circuit, (fuses, etc) then move to check the ground side of the circuit.

Broken, loose, and corroded wiring or terminals are very common types of electrical issues. So too is rodent damage, mice love wiring insulation.

Neutral Switch

A neutral switch is a switch located on the transmission and is used by the CDI/ECU to identify when the transmission is in neutral. ATVs employ a safety lock-out procedure to prevent accidental in-gear starting.

The neutral switch plays a critical role, meaning if the neutral switch isn’t working the ECU/CDI may not permit starter motor activation.

Diagnose: Check if neutral light is on the dash panel when ATV is in neutral. I’ve covered neutral switch diagnosis previously and you can check that out here – Neutral light always on

Fix: Test and replace the neutral switch.

CDI Box Fault

CDIs and ECUs are difficult to diagnose. Most technicians will call them bad only after first exhausting all other possibilities. What we can check is power and ground to the modules and we can check the block terminal connector for loose block connectors, water, corrosion, or pin damage.

It should be noted, that a failed Rectifier/regulator will not only fry your battery but is also a common cause of CDI failure. If your ATV is overcharging the battery (over 15.5v) replace the rectifier/regulator.

CDIs and ECUs are pretty durable and are last on this list for good reason.

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Back to Bucket 4

Bucket 5 – ATV Engine cranks over, it sounds NORMAL, but won’t start

The list of possible no-start causes in this bucket is too large to list, and so in order to make it more manageable, this bucket contains 3 subcategories.

These categories, which we’ll call systems don’t contain a list of faults as per previous buckets, instead they contain a list of components.

The 3 systems are categorized as follows:

• (I) Ignition system
• (II) Fueling system
• (III) Compression system

We use just 3 categories because an engine needs these 3 main systems to work in harmony in order for the magic to happen. If one of these systems isn’t working, you’ve guessed it, you get a no-start.

As said each system contains a ton of components on which that system relies. Below, I’ve listed the main components under each system heading. One of these components within one of the 3 systems has failed and is causing our no-start.

I know the list below is long, but don’t be disheartened, I have a secret mechanics hack to short circuit the diagnosis process, meaning you won’t need to check all 3 systems or indeed all the components within the systems. So let’s check out that hack right now.

Gas Shot Test

The gas shot test is an elimination round and answers many questions very quickly. I use this hack in the workshop all the time. The idea is simple, the results of this test will indicate which of our 3 systems has likely failed. It won’t point to the failed component within that system, we’ll still need to do some detective work. But we will at least be searching in the correct category if you like.

Gas shot test

The test is easy and here it is:

• Remove spark plug
• Add a small amount of gas (about oil cap size capful) (gas must be fresh)
• Refit spark plug
• Attempt to start the engine

Mechanic top tip – Plug holes aren’t easy to access, a funnel with an attached hose or syringe makes adding gas to the cylinder a ton easier.

Analyzing the gas shot results

With the test out of the way now we’ll need to analyze the results, and the two results most likely are as follows:

Result 1 – The engine started, or fired (fired – meaning attempted to start). Firing may be identified as the engine not running but smoke seen puffing from the tailpipe when cranking.

This result tells us your ATV likely suffers from a fuel system issue. Bad gas, Choke not working, Faulty fuel pump (if fitted), Blocked gas filter, and Carburetor faults are all high on the list of possibles.

Jump to the Fueling system below and begin your diagnosis journey.

Result 2 – The engine doesn’t start and critically makes no attempt to fire. This result tells us you may have an ignition system or a compression system issue. Since ignition system issues are more common, we’ll diagnose the ignition system first before moving on and checking the Compression system, if needed.

Begin your Ignition system diagnosis below.

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Back to Bucket 5

(I) Ignition System

The ignition system is a collection of components dedicated to producing voltage so that the spark plug can do its thing – fire the spark plug. To that end, the ignition system relies on another important subsystem – the charging system which employs a stator to generate voltage. (More on the stator later)

The ignition system isn’t a one-trick pony, it’s also responsible for adjusting the ignition timing. Meaning it adjusts when the spark is actually fired.

Adjusting the timing is important because it takes a set amount of time for an ignition system to generate a spark at the spark plug and as you know that spark must be added to the mix at a very precise point of the engine cycle.

The faster an engine rotates, the earlier the ignition system needs to begin the spark generating process so that the voltage arrives at the spark plug in good time, and remember this is a moving target, meaning ignition timing needs to be constantly adjusted according to engine RPM.

Yep, your ignition system works like a dog.

Components are listed in order of failure rate (highest first)

The following sections are dedicated to outlining the basic function of the components within the ignition system. We’ll also cover diagnosing and testing the various components.

When faced with a possible ignition system issue makes sense to go straight to testing the spark and we’ll cover that next in the spark plug section.

For many of the following tests, we’ll need a DVOM or power probe. You can find all these tools here on the ATV tools page.

Spark Plug

The spark plug is top of our ignition system troubleshooting list for three reasons, it’s a common cause of no starts, it’s critically important and it’s easy to check.

A plug lives a hard life, consider for a moment what it does and what it must cope with. Thousands of volts pass through it, it must withstand chemical attack, compression pressures, and extreme combustion heat. And yet despite this plugs can last years (we should change them every two years or 1500 miles, of course).

As we suspect we have a spark issue we’ll run an ignition system test. Ideally, we’d use an inline spark tester, that way the whole ignition system is tested, and we’ll cover that below, but first, we’ll check spark MacGyver style.

The MacGyver spark test doesn’t test the whole system conclusively and isn’t a great test for intermittent spark issues. But it works great for no-starts.

The MacGyver spark test is as follows:

• Remove plug wire
• Remove plug
• Examine plug (see plug condition table below)
• Refit plug wire
• Ground plug (make contact with engine raw metal)
• Crank engine over
• Check spark

No spark means we have a problem, but be sure the plug is grounded securely, otherwise you’ll misdiagnose. Improvise with a jumper lead.

Now let’s check the spark using an inline ignition test tool.

Diagnose:

• Remove the plug cap and fit it to the inline tester
• Fit inline tester to the spark plug
• Attempt to start

Checking the test tool window quickly tells us if we have a spark or not.

Reading the plug condition is another useful check.

Spark Plug fouling is a dirty plug and it results in misfiring and no-starts. The reasons a plug becomes fouled in the first place are numerous Here are just some of the common causes of plug fouling:

• Too much oil
• Wrong oil type
• Wrong spark plug
• Bad gas
• Engine wear
• Vacuum leak
• Faulty ignition system
• Carbon build-up

Diagnose: Remove the spark plug and check

Fix: Clean & gap plug (see below)

Flooding is a condition where unburnt gas accumulates inside the cylinder and fouls the spark plug preventing it from firing. Often it’s the plug itself that is at the root of the problem, but there are tons of causes of flooding.

• Excessive use of choke
• Blocked air filter
• Leaking carburetor float needle

Diagnose: Remove plug and check

Fix: Dry out cylinder, clean & gap plug (see below)

I’ve covered how to diagnose and fix a flooded ATV engine previously – ATV flooded with gas

Spark plugs should be cleaned and gapped at least once every six months. Carbon deposits build up on the plug’s electrode and are, as you know a cause of plug fouling and flooding.

To clean a plug use a wire brush to clean the business end, if it’s wet use a flame to clean it or allow it to dry naturally.

Use a plug gapper or feeler gauge to adjust the gap, use pliers to either open the gap or tap it closed.

Coil & Cap

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

I’ve covered coil testing in greater detail previously. It’s a dirt bike but the process is identical. I test the coil primary, secondary, and resistor cap.

You can check it out here – Dirt bike won’t start when hot

Stator

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

I’ve covered stator testing in greater detail previously, you can check that out here – Will ATV start with bad stator

Pick-up

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

I’ve covered pick-up testing in greater detail previously. It’s a dirt bike but the process is identical.

You can check it out here – Dirt bike won’t start when hot

Starter Motor

The starter motor plays a pivotal role in ensuring there’s enough voltage at startup. Without a strong starter motor, the stator and pick-up may not provide enough voltage to fire the spark plug. I’ve covered starter motor testing in greater detail previously and you can check that out here – ATV will only pull start

Ignition Switch

Ignition switch wiring varies from model to model, an ECU will be quite different from a CDI bike. You will require a wiring diagram for your machine to fault find an ignition system systematically.

That said here are a few tips that will help:

• Check wiring at the steering column, flexing commonly causes wiring breaks.
• Try the wiggle test (move the switch loom by hand and see if the condition changes)
• Check power and grounds
• Check block connector pins are clean, dry, and tight

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(II) Fueling System

All engines need fuel, but fuel isn’t just gas alone, because gas won’t burn without air (oxygen). And so gas must be mixed with air, problem is engines are very particular as to the ratio of air to gas. We refer to the ratio as the Air Fuel Ratio (AFR). The sweet spot is 14.7 parts air to 1 part gas and this ratio is known as stochiometric.

It’s the job of the fuelling system to maintain this ratio and deliver it to the engine for every given throttle demand.

The fuelling system your ATV employs will dictate the type of fuel system components your bike has. ATV fuelling systems come in 2 main flavors – the old-school carburetor and the latest and greatest electronic fuel injection (EFI).

While these systems have the same goal, they use different components to arrive there. We’ll take a quick look at how each type goes about it right now.

The carburetor

The old-school carburetor is a mechanical device calibrated very precisely to supply gas to the engine in proportion to the volume of air that passes through it. Carburetors are simple and complicated all at once. But don’t be fooled, carbs are well-tried and tested; while they do have some shortcomings they are generally very reliable.

ATV carburetors come in two main flavors – the mechanical slide and the vacuum-activated Constant Velocity (CV) type.

Carburetors work like this:

CV type – The CV is the more common type of carburetor as they offer better all-round performance and are cleaner to the environment. On CV-type carburetors, the throttle cable is connected to the butterfly valve and when opened creates a vacuum which in turn lifts the slide (and attached needle) and draws gas into the engine through carburetor-housed metering jets.

The main downside to CV carburetors – as they are vacuum-operated, they are less responsive to throttle inputs.

Mechanical slide – The second common ATV carburetor type is the mechanical slide. It operates on the same principle as the CV type carburetor, however, there is one main difference.

The throttle cable is connected directly to the slide and so nailing the throttle lifts the slide with the attached needle and feeds gas to the engine. It is a very direct throttle response and is generally fitted to engines that are performance-focused. However, because it’s so direct in how it opens the slide, it commonly sufferers from bogging (lack of gas), until the vacuum catches up and feeds more gas.

In addition to these main differences, some carburetors may employ manual choke operation while others may have an automatic thermo-activated choke.

All carburetors however suffer from some common complaints, they include having to adjust for temperature and altitude, since both these conditions change the quantity of oxygen in the air, it causes a carburetor engine to run poorly. Typically the operator must make an adjustment to the carburetor. Not practical for most, and so the EFI was born.

EFI

While electronic fuel injection is not a new idea, it is relatively new to the world of small engines. Fuel injection brings some great advantages, it automatically adjusts for air temperature and altitude and it offers sharper performance since the fuel is delivered quickly and atomized, just the way the combustion chamber likes it.

To accomplish this the EFI system which is largely an electronic system employs a computer, sensors to collect data, and a fuel pump and fuel injector to deliver the payload.

A cool byproduct of EFI means bikes can be mapped (ignition and fuel system optimized) for greater power or efficiency with the touch of a button, something not possible with a carburetor bike.

EFI is a robust system. However, some bikes are susceptible to electrical gremlins caused by loose wiring. Fuel pumps wear out as do fuel injectors.

The EFI works like this:

An air temperature sensor (ATS) fitted to the air intake measures the temperature of the ambient air (important as oxygen density is proportional to air temperature)

Baro sensor feeds air pressure reading to the ECU (important, as a change in elevation changes oxygen levels) Baro and ATS are often integrated.

The throttle position sensor (TPS) reports the current throttle position to the ECU.

The throttle body resembles a carburetor in some ways but they don’t serve identical functions. The throttle body is fixed to the engine and houses the butterfly valve with the throttle position sensor attached and also houses the fuel injector.

The electric fuel pump supplies gas to the fuel injector.

The fuel injector is opened and closed by the ECU.

The engine control unit (ECU) manages the whole show. As it’s a pre-programmed computer it can make tons of calculations and very quickly works out the correct fuel quantity for every given throttle demand. By varying the fuel injector duty cycle (“on” time) it can respond to throttle demands.

Components are listed in order of failure rate (highest first)

Gas

Ethanol blended gas is everywhere now; we have no choice but use it. It does cause some problems in a small engine kit that lays idle for weeks on end, and so all small engines should now use a stabilizer in the gas.

The stabilizer helps repel moisture that ethanol attracts and prevents carburetor gumming and hard starting misfiring etc.

Stale ethanol gas is right up there on the list of no-start causes especially if your ATV has been sitting idle for a few weeks.

Diagnose: If your gas is older than a couple of months and your bike has been sitting idle, your gas is likely stale

Fix: Drain gas tank and carburetor bowl and fill with fresh gas

Carburetor

Carburetors cause lots of issues as they get older. They are like wind instruments in that they are finely tuned. If they supply too much or too little gas, your engine will protest. They are of course adjustable within a window but if the moving parts of your carburetor wear they allow air to sneak into the combustion chamber unmetered and this upsets the crucial Air to fuel ratio (AFR).

Carburetors tend to be difficult to diagnose, generally, there’s no smoking gun and often it is a process of elimination.

That said the number one cause of most carburetor problems is dirty jets. Contaminated gas is the usual culprit. Dirty gunge blocked up the tiny brass jet holes which starves the engine of fuel.

Diagnose: One of the first carburetor checks is a fuel flow check.

Check fuel flow as follows:

• Turn petcock off
• Open carb bowl drain
• Turn petcock on
• Check flow

Fix: A lack of gas flow points to a tank blockage, a fuel tap (petcock) blockage, or a carb float valve issue. (See pic)

If on the other hand, you have good gas flow, suspect blocked carb jets. A carburetor strip down and thorough cleaning will fix the issue.

You may find these posts helpful:

• ATV smells like gas
• ATV dies when I give it gas
• ATV only runs with throttle
• Why is my ATV running rich?
• Can I ride with choke on?

Air filter

Ail filters should be checked weekly and even more often in dry dusty conditions. Foam filters may be washed in warm detergent but should only be oiled if the manufacturer recommends it and of course only use recommended filter oil.

Diagnose: Remove the air filter and attempt to start the engine

Fix: Clean or replace the filter

You may find this post helpful:

Can I use WD40 on my air filter

Fuel filter

ATV filters may be inline clear filters where you can see the gas and dirt if present which is really useful for fast diagnosis; however, many ATVs use a carburetor mesh screen filter that can’t be viewed so easily. Many petcocks include an integrated fuel filter bowl.

Diagnose: Access the filter and check for blockage (may need to partially remove the carburetor)

Fix: Clean or replace the filter

You may find this post helpful:

ATV fuel filter not filling up

Fuel pump

Not all ATVs employ a fuel pump; for those that do two types are common, a vacuum-operated fuel pump and an electric pump. Carburetor bikes will either have no pump or a vacuum pump fitted.

Common vacuum fuel pump issues include perished vacuum lines and worn-out diaphragms.

Diagnose: Follow the fuel line from the carburetor back towards the tank. If you have a fuel pump fitted, you’ll find it on this line. Check all vacuum hoses and check for leaks.

Fix: Replace lines or pump

Gas tank, cap, and vent

Gas tanks don’t give trouble so much anymore; most are plastic and so are rust-free. However, faulty gas caps and vents may cause a no-start. A tank needs to breathe and so if a faulty cap or vent seals the tank gas stops flowing and the engine stalls and won’t restart.

Diagnose: Remove the cap and attempt to start the engine.

Fix: Replace the cap and vent

Fuel tap aka Petcock

Most ATV fuel taps are manual and don’t cause issues, that said older style petcocks employ a bowl that catches crap and can become blocked; if your ATV sufferers from a fuel blockage, check the petcock bowl. Some vacuum operated and when the internal diaphragm fails it allows gas to leak into the intake system causing the engine to over fuel and flood.

Diagnose: Remove the vacuum line and check for gas

Fix: Replace Petcock

*Electric fuel pump

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

*Fuel injector

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

*TPS

Run a resistance test using a DVOM to determine if it’s within your manufacturer’s spec.

*ATS

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

You may find this post helpful – ATV won’t start when cold

*Baro

Run a resistance test using a DVOM to determine if it’s within the manufacturer’s spec.

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(III) Compression System

This section is last for good reason, it is the least likely system to cause an issue; however, if your issue does lie within this section there’s a good chance your problem is a serious one. That said there are some easy-to-fix issues within this section and we won’t meet trouble halfway.

What is compression?

Compression is an engine’s ability to contain the pressure created by the piston, as it squeezes and squashes the contents of the cylinder (air & fuel) into the combustion chamber (area at the top of the cylinder around the spark plug).

Compression is important, the squeezing helps warm the air and prepare it for ignition (explosion).

An engine with low compression will therefore struggle to start or likely won’t start at all. The reasons for low compression are covered below together with how we go about testing same.

You should note, compression test readings vary from one engine maker to another and so you will need to know what your engine compression specs are. Generally speaking, a reading below 100 Psi is deemed low compression. That said some engines may have a min far above 100 Psi, so check your specs before condemning.

Components are listed in order of failure rate (highest first)

You may find these posts helpful:

ATV has spark and fuel but won’t start

How much compression should an ATV have?

When faced with a possible compression issue makes great sense to just go ahead and run a compression test. Doing so usually points us to the problem component.

Compression Issue

The problem is some engines don’t lend themselves to compression testing and here’s why.

A compression releases assembly also known as a decompression valve kicks in during cranking to lower compression so as to lessen the workload on both the starter motor and battery.

The problem is, this lowering of compression also skews the compression readings and renders them useless. In fact, many manufacturers won’t offer compression specs if their engines are fitted with decompression valves. In these cases, we use a leakdown tester and so I’ll cover both test types in this section.

Assume you have a decompression valve fitted if you can’t find compression specs for your engine; if that sounds like you, you’ll need to run a leakdown test. Indeed a leak-down test is my preferred way to test for compression issues.

Compression test

To run this test you’ll need some tools, a compression test kit or a leak-down test kit. If you use a leakdown tester you’ll also need access to compressed air. Either way, you’ll find the tools needed here on the ATV tools page.

We’ll run the compression test first. This test is a two-part test. First, we run the dry compression test, and then we run the wet test.

The dry test is as follows:

• Remove spark plug
• Ground coil (prevents coil damage)
• Fit compression tester
• Choke off
• Throttle wide open
• Crank over 6 – 10 times
• Read and note the highest reading

Now we run the second part of the compression test – the wet test is as follows:

• Add a cap full of engine oil to the cylinder
• Repeat the dry test as above
• Read and note the highest reading

Now we need to make sense of the results. One of three results is likely, they are as follows:

1 Readings are the same but compression is low – If the wet compression readings are the same as the dry reading from the first test (or close) and the compression readings are below spec (as per your engine maker), then it is likely you have a top-end issue.

Go ahead and check your spark plug is tight, the valve lash is within spec, and the head gasket is ok.

2 Readings are different and compression is low – If, on the other hand, the readings are very different meaning the wet compression readings are significantly higher. Then it is likely your engine suffers from worn rings or piston or cylinder or combo of all three.

You’ll need to strip your motor for inspection.

3 Readings are the same and compression is normal – If your readings test well above 100 psi and both wet and dry tests are similar, Congrats! Low compression isn’t your issue.

Instead, I’d direct my attention to engine timing.

Leak down test

A leak-down tester is likely a faster and more conclusive way to both test and pinpoints the root cause of a suspect compression issue. In this test, we’ll fill the cylinder with compressed air and we’ll use the test tool to measure the cylinder’s ability to hold pressure over a given time period.

See the leak-down tester I recommend here on the ATV tools page.

But before we do that we’ll need to set the engine to Top Dead Center (TDC).

I’ve covered setting the engine to TDC previously and you can check that out right here – ATV valve adjusting

The bonus of the leak-down tester is its ability to point to the area at fault. In a problem engine, the compressed air will be heard to leak from the cylinder. All we need do is identify where it’s leaking from.

Air leak diagnosis is as follows:

• Spark plug – Tighten the spark plug
• Oil cap or dipstick – Worn piston rings
• From muffler – Exhaust valve issue (worn seat or adjustment)
• From carburetor /airbox – Intake valve issue (worn seat or adjustment)
• Between cylinder head and block – Head gasket failure

With the leak-down test complete, we should now have a handle on the component at fault. See the list of likely culprits below and what we’ll need to do to fix them.

I will include links to tests and tools as needed to test, repair and or replace components.

Spark plug

If you are here because the leak down test pointed to a leak around the spark plug, you are lucky, this is an easy fix. A spark plug provides a spark you already know that, but it has another job, it must seal the combustion chamber.

A loose plug will allow compression escape. Truthfully a loose plug may not be the most common cause of low compression but it is easy to check and a super-easy fix, and that’s why it’s first on our list.

Tools needed – for this we’ll only require a plug socket and ratchet. You’ll find one here on the ATV tools page.

Diagnose – A loose plug will allow compression to escape which may in fact be heard as the engine cranks over. A damaged spark plug washer is also a possible reason a spark plug fails to seal. Remove and check the washer is ok.

The fix – Check the plug is tight.

Valvetrain

The valvetrain comprises various components but the two most common valve train issues associated with low compression are damaged valves and poor valve adjustment. Valve adjustment is also known as valve lash.

If the leak down test pointed to the exhaust or carburetor then it’s the respective valve that is at issue. A valve that’s too tight, meaning it’s held open will lower compression and cause a leak when tested. That’s one explanation for a valve leak and the other is a bad valve face or seat.

We can eliminate one of these easily by testing valve lash and I’ve covered that below, but remember if valve lash is within spec, it’s likely a bad valve seat or valve face that is damaged and it will need to be replaced.

Lash should be checked before assuming we have valve damage.

Valve lash

Valve lash is set at the factory but as an engine wears as you can imagine lash moves out of spec. For most ATVs lash should be checked every year or about 1500 miles, most aren’t checked. However, overhead cam engines require less attention.

While excessive lash could cause a no-start it won’t cause a low compression issue. However, a tight valve will.

A tight valve is less common than excessive lash but it remains a very good explanation for low compression and so well need to check and adjust it as necessary.

I have covered this exact topic in greater detail previously and you can check out that post right here – ATV valve adjustment in 6 steps.

Timing

The timing of your engine is obviously important. The top half of the engine (cam and valves) are very precisely timed to the crankshaft and piston. If the valves aren’t opening when they should, the engine won’t run or may run but run poorly. This will also lead to poor compression readings.

Not only that, an interference engine may cause your valves and piston to collide, that’s never a good outcome. An interference engine means the valves and piston use the same space, all be it at different times, so you can see how important timing is to an interference engine.

If you suspect a timing issue, we’ll need to get that checked, I’ve covered checking engine timing previously and you can check that out here – How to tell ATV jumped time.

Head gasket

A blown head gasket will cause a drop in compression. The head gasket is a graphite material sandwiched between the cylinder head and the jug. It helps seal and prevents the mixing of oil, coolant, and combustion passages.

Gaskets fail with age but also may fail as a result of an overheating issue or lack of proper coolant system maintenance. Straight water in coolant systems causes corrosion and that’s a common cause of premature gasket failure.

Head gasket failure is common however, you should have some additional symptoms prior to the no-start. Common symptoms include coolant loss, overheating, hard hot starting, white smoke from the tailpipe.

A leak-down test is great at exposing head gasket failures, and also showing where it has failed. Bubbles in the coolant system mean as you know the gasket has failed between the coolant passage and combustion chamber.

Sometimes of course it may not be conclusive as the engine may need to be hot before the leak presents itself and so if I suspect such a gasket failure but can’t identify it with the leakdown test ill use a chemical combustion leak test kit.

You’ll find a combustion leak test kit I recommend here on the ATV tools page.

Rings

Worn rings are the last thing any ATV owner wants to hear. Common symptoms include hard starting, long crank, oil consumption, blue smoke, lack of power, spark plug fouling, and misfiring.

If your leak-down test blows air through the dipstick or the wet compression test shows a large difference when compared to the dry test, it likely means an expensive tear-down and a rebuild.

You are also looking at a couple of weeks of downtime given parts lead time and workshop schedules, etc. It is possible to DIY it but you’ll need a workshop manual and some special tools like a torque wrench, ring compressor, and feeler gauge.

Battery & Starter Motor

A strong battery and starter motor are important components for easy engine starting. Both components are key players and directly affect two of the three systems critical for internal combustion engines to run.

A battery and starter motor together provide all the power and muscle to crank over the motor, but critically they must do so with sufficient speed to cause two important things to happen.

1 the engine must crank over fast enough (Min 400 rpm) in order to excite the stator and create a voltage strong enough to fire the spark plug.

The pick-up also relies on a spinning crankshaft to produce a voltage which is used to signal the ECU/CDI and fire the spark plug.

2 the engine must crank over fast enough to create sufficient compression to prepare the air/fuel mixture for ignition.

Any issue that prevents the engine from cranking over fast enough may prevent the fuel igniting.

A fast way to eliminate this possibility is to try jumpstarting; if the engine starts, you know you have a battery issue, which is more likely than a starter motor issue. I’ve covered battery testing at length previously in this post, you can jump to it here battery testing.

I’ve covered starter motor testing in greater detail previously and you can check that out here – ATV will only pull start

You’ll find all these tools here on the ATV tools page.

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I’ve covered a ton of other common ATV issues and you can check them out on the ATV maintenance & troubleshooting page

You find the following posts helpful:

• ATV No-Start page
• ATV maintenance
• ATV care page
• ATV tools page
• ATV parts page

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