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.

You may find the following posts helpful:

Will dirt bike start with low compression?

Signs of bad dirt bike coil

Dirt bike troubleshooting

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

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

You may find the following posts helpful:

Will dirt bike start with low compression?

Dirt bike troubleshooting

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Signs of Bad Dirt Bike Coil – Top 4 signs 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

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Do All Dirt Bikes Have a Stator? A beginners guide 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?

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

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

No fuel equals no fun. Not to worry, as dirt bike problems go, a lack of gas flow is one of the easier and cheaper ones to fix. You are in the right place, I’m a mechanic with twenty-five years experience and I’ll bet you’ll be riding shortly.

The top six causes of a lack of dirt bike gas flow include:

1. Blocked tank vent
2. Blocked gas filter
3. Blocked gas tank
4. Carburetor adjustment needed
5. Faulty fuel pump
6. Mechanical issue

In this post, you’ll all the common reasons a dirt bike isn’t getting fuel. You’ll learn how to diagnose your problem and how to fix it right now.

Dirt Bike Fuel System Types

Before we get into the diagnosis of the root cause of no gas flow it’s important to know which type of fuel system your bike has, not all dirt bike fuel systems are identical.

Dirt bike fuel systems come in two flavors:

1 – Computer controlled fuel injected system

2 – Carburetor gravity feed fuel system

Because these systems are similar but not identical, the possible causes of no gas flow are also slightly different in places.

What’s the difference between the two fuel systems?

Both systems employ some similar components:

Carburetor Gravity Feed System – These types of fuel systems are typically in all older bikes and employ a mechanical carburetor that mixes air with gas. The gas is fed to the carburetor from the gas tank using only gravity. And that gas is held in the carburetor gas bowl (reservoir) and stands ready to feed the engine as needed.

Fuel Injected System – This type of system as you know employs some of the same components as a carburetor type but it is a way more sophisticated system. It employs sensors, solenoids, motors, and a computer to mix air and fuel and delivery it to the intake system. Some dirt bikes may require a battery to run the fuel-injected system and others don’t.

It’s a pressurized system and uses an integrated gas tank fuel pump to both move the gas from the gas tank quickly and to pressurize it.

How to identify which type you have?

Not always that easy to spot the difference without removing some covers and components. Often it’s better to check your owner’s manual or google search your model.

Diagnosis No Gas Flow

Now we’ll get down to the nuts and bolts of diagnosing where your fault lies. We’ll run through each of the likely no-fuel causes and I’ll indicate in advance if it’s applicable to carburetor or fuel injected or both type systems.

We’ll run through all the easy-to-check likely causes first, no sense removing seats and covers unless we need to.

Blocked gas tank vent (both carburetor and fuel injected)

Gas tanks need to breathe, meaning as the gas leaves the tank it must be displaced by air otherwise the flow of gas stops. This is true for both carburetor and fuel-injected systems. As you know the tank is vented through the gas tank gas cap and attached hose.

Diagnosis – We start with this test as it’s likely the easiest test of all. Gas caps get lost and are sometimes replaced with a makeshift cap and for many, that’s where the problem begins.

The gas tank vent could equally be at fault so to eliminate both the gas cap and the vent hose from the list, go ahead and remove the gas cap and attempt to start the bike. If gas now flows to the engine, you found your problem.

The fix – Replace the gas cap and vent hose.

Blocked gas filter (both carburetor and fuel injected)

Gas filters are fitted inline, some at the gas tank others may be carburetor integrated. A filter’s job is to catch the debris in the gas tank and prevent it from reaching the engine’s intake system. Gas filters should be replaced or cleaned once a year, many aren’t.

Diagnosis – Locate the gas filter and check for debris. Clear inline filters are the easiest to check. Removing the fuel line downstream of the filter (carburetor side) and checking flow is a fast way to eliminate a filter issue.

The fix – Clean or replace the gas filter. When replacing clear bottle gas filters, the filter arrow points to the carburetor.

Blocked gas tank (both carburetor and fuel injected)

A blocked gas tank isn’t hugely common anymore, plastic tanks have removed the corrosion issue associated with metal tanks. That said, a poor flow from the tank may well be caused by a tank blockage. Re-gas from contaminated refill cans can easily introduce debris.

Diagnosis – Removing the gas cap and peering in likely won’t reveal much. The best approach is to remove the gas line at the gas tank and check flow. A poor flow means you’ve found your issue.

The fix – If you suspect tank blockage, you’ll need to remove the tank to clean it thoroughly. That will mean removing the seat, side covers and removing the gas lines and tank fasteners. Once removed, turning the tank upside down will remove the debris. Rinse out using fresh gas.

Carburetor adjustment needed (carburetor)

A fuel starvation issue may be caused by a maladjusted carburetor float. The float’s job is to help control and maintain gas flow in the carburetor bowl. As its name suggests the float floats on the fuel inside the fuel bowl. The bowl is a reservoir of gas that stands ready to feed the engine.

As the engine uses gas, the float drops which allows more gas to flow in to replenish the spent gas. If the float tab is set too high, the bowl won’t fill.

Diagnosis – Remove the gas bowl and check the float level. You’ll need a caliper and the float spec for your engine.

The fix – Adjust or replace the float and valve needle.

Faulty fuel pump (fuel injected)

A fuel-injected system employs a gas pump located inside the fuel tank. Its job is to pressurize the gas and move it to the engine. Fuel pumps work hard and do fail a lot. A failed pump is for some easy to identify as a fuel pump emits a buzzing noise when in operation. That said it is possible for a fuel pump to emit a buzzing noise but not build sufficient pressure to feed the engine.

Diagnosis – To test a fuel pump thoroughly we’ll need to check fuel pressure and to do that we’ll need a fuel pressure test kit. A good pump will typically build pressure in the region of 45psi.

There are still some tests we can do without a fuel pressure test kit but we will need a DVOM. We can check pump resistance and to do that we’ll need to access the gas tank. That will mean removing the seat, side covers, and air intake.

Test fuel pump resistance gain accesses to the injector and check the electrical connector is secure. Now go ahead and remove the connector and set it aside. Using the DVOM set to ohms (Resistance) probe both terminals gently and note the meter reading of about 6 ohms works. If you measure excessive resistance or open, you found your problem.

The fix – Replacing the pump isn’t difficult, You will need to be careful when removing the fuel line connector, often brittle and when fitting the new pump the O-ring seal will require some oil.

Fuel injector faulty (fuel injected)

The fuel-injected system employs a fuel injector to spray a fine mist of fuel into the intake system, without the injector activating we won’t get fuel to the cylinder. To test the injector, we can check it for resistance, and do that we’ll need a DVOM.

Diagnosis – Access the injector and check the electrical connector is secure. Now go ahead and remove the connector and set it aside. Using the DVOM set to ohms (Resistance) probe both terminals gently and note the meter reading.

A reading of about 12 ohms indicates a good injector, outside this, and you’ve found your fault.

The fix – Replacing an injector is a simple process. Remove the electrical connector, fuel line a couple of fasteners, and it off. When replacing the injector, lube the O-ring to aid fitting.

Mechanical faults (carburetor)

Since a gravity-fed fuel system relies on gravity and engine vacuum to draw gas into the engine, compression, therefore, may cause a fuel flow issue. A lack of compression to most engine owners sets alarm bells, but it should be noted not all low compression issues are serious.

Common non-terminal low compression issues include:

• Valve adjustment required
• Loose spark plug
• Head gasket leak
• Valve seat wear

Diagnosis – I’ve covered compression issues and testing previously and you can check that post, right here “Dirt bike with low compression”

You may find the following posts helpful:

Dirt bike won’t start when hot

Dirt bike won’t kick start

Do all dirt bikes have stators?

Can I ride with choke on?

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Dirt Bike Not Getting Fuel – Check these first appeared first on ATVFixed.com.

Springtime is a fun time, or at least it was until you discovered your favorite toy didn’t make it through hibernation. Don’t worry about it. This is a common complaint, and as a mechanic, I see it a lot at this time of the year. This is something we can fix right now, and very shortly, you’ll have a big smile on your face!

A dirt bike that won’t start after winter likely suffers from stale gas and carburetor contamination. Draining the old gas, draining the carburetor bowl, and refilling with fresh gas will solve the problem.

In this post, you’ll learn why your dirt bike won’t start and what you need to do to fix it right now. I’ll also share some top tips for dirt bike storage.

Problem With Gas, Dirt Bikes & Winter Storage

The problem most commonly associated with dirt bike winter storage is stale gas. The problem is modern gas contains ethanol (E5 and E10), and ethanol gas begins to turn stale after about two months, but this varies depending on ambient conditions and how much exposure to the atmosphere.

In addition, ethanol attracts moisture which causes all types of carburetor issues.

Unlike modern cars and trucks, small engine kit such as dirt bikes employs an open-to-atmosphere gas tank. This allows the tank to breathe, which is crucial for fuel flow.

On the other hand, modern cars and trucks use sophisticated modules and valves that allow for a sealed gas tank. The advantage to a sealed gas tank is twofold; it protects the environment from harmful vented hydrocarbons and, at the same time, prevents moisture from entering the tank.

This moisture causes dirt bike fuel problems over the winter months.

How To Diagnose Dirt Bike Stale Gas

If your dirt bike has been sitting with gas in the tank over winter and that gas hasn’t been treated with a gas stabilizer, then you can be sure your gas is stale. To check, try removing a sample in a glass jar. Stale gas looks the color of pee. Still not sure?

Try the gas shot test. This test bypasses the fuel system and adds fresh gas direct to the cylinder.

To perform the gas shot, use the following steps:

• Remove the spark plug
• Add a capful of fresh gas to the cylinder
• Refit the plug
• Attempt to start the engine

Diagnosing the results

Two results are likely:

1 Engine starts or attempts to fire – Fires may be described as an engine that doesn’t start but tries to. You’ll know an engine that fires as it will puff smoke from the tailpipe as it tries to start. Under these test conditions, such an engine likely suffers from stale gas.

2 Engine makes no attempt to start – Likely an ignition system issue (lack of spark). I wrote a post about ignition system testing, and you can check that out here “Dirt bike won’t start when hot”

How To Drain Dirt Bike Stale Gas

In the workshop, I use a siphon to drain the gas tank, but removing the carburetor fuel feed line works too. Using a siphon is, however a ton easier; they only cost a few dollars, and a good siphon will lift oil, brake fluid, coolant, etc., so you’ll find a ton of uses.

To drain a gas tank using a siphon, open the gas tank cap, place the siphon tube into the gas tank, and pump the siphon. Easy!

Or remove the gas line to drain it manually.

To drain the tank manually, you’ll need a gas line clamp and a suitable container. Gas stinks; it’s best to drain the gas tank outdoors.

The draining process is as follows:

• Turn off fuel valve
• Remove gas cap
• Remove the gas line from the carburetor and place it in the container
• Turn the gas valve on and drain the tank

Most recycling centers will accept waste gas and oil.

After the tank has been drained, you’ll need to drain the carburetor bowl, which we’ll cover next.

Draining Dirt Bike Carburetor

All dirt bike carburetors employ a carburetor bowl. The bowl is a reservoir where gas and often dirt collects; draining the bowl helps clean the fuel system of contaminated gas.

The process is as follows:

• Turn the gas valve off
• Remove gas tank cap
• Gain access to the carburetor
• Located the carburetor bowl
• Locate the carburetor bowl drain fastener known as the bung (usually a small drain screw in the bowl base)
• Place rag under the carb bowl and open bung
• Open the fuel valve and add a small amount of fresh gas to the empty tank to help flush out the carburetor bowl
• Close the bowl bung

Top Tips For Dirt Bike Winter Storage

A dirt bike that’s stored correctly will start without issue come spring. Proper storage isn’t difficult and it requires little effort or expense.

Here are my top dirt bike storage tips:

• Change engine oil (4-stroke engine) – Removes internal engine moisture and acidic contaminants
• Use gas stabilizer in the fuel tank – See below
• Fill gas tank – Helps prevent condensation on inner tank walls
• Clean and oil air filter – Prevents trapped moisture and rodents
• Turn the gas valve off – Takes fuel pressure off the float and valve
• Inflate tires – Helps seal and protect tire walls
• Add oil capful engine oil to the cylinder – See below
• Set engine to top dead center (TDC) – See below
• Seal exhaust – Stuff tailpipe outlet with an old rag or plastic bag
• Remove chain – Remove the chain and seal it in a plastic bag with some oil
• Lift bike – Support chassis to lift tires clear of the ground
• Protect metal – Spray bike thoroughly (not rotors or pads) with WD40 or use Teflon coating (guards against corrosion)
• Rodent bait – Rodents love to eat wiring insulation
• Store indoors – Overwintering indoors is critical
• Breathable cover – A breathable cover keeps moisture trapping dust and dirt off the bike while allowing the bike to breathe.

Use gas stabilizer in the fuel tank

The gas stabilizer is specially formulated to repel moisture and keep ethanol gas fresh for up to twelve months. The gas stabilizer is strongly advised for your dirt bike; in fact, use it in all small engines, ATVs, Outboard motors, Tractor mowers, Chainsaws, etc.

The gas stabilizer is not a substitute for a two-stroke mix, so if your dirt bike is a two-stroke mix as usual then add the gas stabilizer. Mixing is easy; your gas stabilizer will recommend the mixing ratio.

A common ratio is 1/2 ounce stabilizer (about a tablespoon full) to every gallon of gas. Ride the bike about to help distribute the mixed gas throughout the fuel system. That’s it; your bike’s carburetor is protected from winter gumming.

Add engine oil to the cylinder

I like to add a capful of engine oil to the cylinder. Oil in the cylinder helps protect the walls from corrosion. The process is as follows:

• Remove the spark plug
• Use a syringe or funnel to add a capful of fresh engine oil to the cylinder
• Turn engine over to distribute oil

Set engine to top dead center (TDC)

Setting the engine to Top Dead Center closes the valves and seals the cylinder, which helps protect the engine cylinder walls from moisture and prevents sticking valves.

To set the engine to Top Dead Center (TDC), follow these steps:

• Remove spark plug
• Place a suitable non-metallic object into the cylinder to make contact with the piston crown (a pencil works fine)
• Using the Kickstarter or socket and ratchet, turn the engine over slowly so as to push the pencil from the engine
• When the pencil is pushed to it’s max from the cylinder, the engine is set to TDC
• Refit plug

Sum Up

It’s frustrating when you’re ready to hit the dirt trails on your dirt bike after a long winter, only to find that your bike won’t start.

If your dirt bike doesn’t start after sitting for a while, there are several steps you can take to troubleshoot the issue. From checking the battery and fuel to inspecting the spark plug and air filter, you can usually identify and fix the problem on your own.

Here are some steps you can take to troubleshoot the issue:

• Check the battery: If your bike has been sitting for a while, the battery may be dead. Charge it fully or replace it if necessary.
• Check the fuel: Drain the old fuel and replace it with fresh fuel. Stale fuel can cause your bike to have starting issues.
• Check the spark plug: A worn or fouled spark plug can also cause your bike to have starting problems. Remove and inspect the spark plug and replace it if necessary.
• Check the air filter: A dirty air filter can also cause starting issues. Remove and clean or replace the air filter if necessary.
• Check the carburetor: The carburetor may need cleaning if the bike has been sitting for a while. If you’re not comfortable doing it yourself, take it to a mechanic.
• Check the fuel lines: Ensure that the fuel lines are clear and not clogged with debris or dirt.
• Check the ignition switch: Make sure the ignition switch is turned on and functioning properly.
• Check the choke: Use the choke to help start the engine, but be sure to turn it off once the bike is running.
• Check for other mechanical issues: If none of the above steps work, there may be other mechanical issues causing your bike not to start. Take it to a mechanic for a diagnosis and repair.

About the Author

John Cunningham is a Red Seal Qualified automotive technician with over twenty-five years experience working on all types of equipment, ATVs, Dirt bikes, grass machinery, cars, and trucks. When not writing how-to articles, he may be found in his happy place – Restoring classic machinery.

You may find the following posts helpful:

• Dirt bike won’t kick start
• Will dirt bike start if timing is off?
• Signs of bad dirt bike coil
• Start a dirt bike without kickstart
• Can I ride with choke on?
• Dirt bike won’t start after washing
• Will dirt bike start with low compression?
• Dirt bike not getting fuel

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Spring Into Action: Common Reasons Your Dirt Bike Won’t Start After Winter appeared first on ATVFixed.com.

There may be many reasons why a dirt bike won’t start, and questioning engine compression is right up there on the list. Engine compression issues of course as you know can be serious, but I’ve seen a ton of compression issues in my workshop and they don’t all spell bad news. I’m a mechanic for more than twenty-five years and in this post, we’ll get your dirt bike figured out.

A dirt bike will not start with low compression. Three common causes of low dirt bike compression include:

1. Worn piston rings, damaged bore
2. Head gasket failure
3. Valve seat fault

In this post, you’ll learn how to quickly troubleshoot a no-start dirt bike from top-down. You’ll learn the symptoms of low compression, how to check compression including a few mechanics hacks.

Troubleshooting No Start Dirt Bike

A dirt bike requires three systems to work in harmony in order for the engine to start. It needs a healthy fuel supply, a spark to ignite that fuel and it requires a cylinder capable of being compressed. When these systems work together we get rotational crankshaft movement we can harness and convert into linear movement.

When a dirt bike won’t start, one or more of the systems is at fault. Troubleshooting is the process of finding which of these three systems is at fault.

You should note, if your dirt bike is a two-stroke engine, it won’t have valves. And so the section below on valve train issues won’t apply to your bike.

Understanding a little about each system will help speed up the process.

1 Dirt Bike Fuel

Fuel isn’t gas alone, fuel in this sense is air (oxygen) and gas combined. Since gas won’t burn without oxygen, both ingredients are equally important. That said they are not equally proportioned in the fuel mix. Engines have a preference for 14.7 parts air to 1 part gas. This is referred to as the AFR (Air Fuel Ratio).

And as said, an engine is very particular to this ratio. Two problem AFR conditions are common, they are:

1 Lean (Skinny) – Too much air or not enough gas in the mix is known as running lean

2 Rich (Fat) – Not enough air or too much gas in the mix is known as running rich

The symptoms of both these conditions largely differ (no-start is on both lists), and as you can imagine, vary in severity proportional to how out of shape the AFR is.

An AFR may be off for several reasons, some are easy to fix and some aren’t. The gas shot test below will go some way towards diagnosing a fueling issue.

Note – Stale gas is a common cause of small engine no starts. If your bike has been lying idle for a couple of months, it’s likely the gas is stale.

Draining the gas and refilling will solve the problem. Using a gas stabilizer will keep gas fresh for up to twelve months.

2 Dirt Bike Spark

You know the deal here, the spark plug needs to produce a strong spark and crucially at the correct time. A dirt bike ignition system employs the following components:

• Spark plug
• Plug wire cap
• Plug wire
• Coil
• Alternator
• Pick-up
• CDI
• Kill switch

Any of these components are capable of causing a no-start and some are a common cause of trouble. The gas shot test below will go some way towards diagnosing an ignition issue.

3 Dirt Bike Compression

And so we get to compression. Compression is as you know crucial, but what is compression? Without getting into the weeds here, compression is an engine’s ability to squash (compress) a cylinder’s contents, (fuel-air plus gas) into the cylinder’s combustion chamber (area at top of the cylinder) without that compression escaping.

When the compression escapes, compression is said to be “low”. And of course, there may be many reasons for the loss of compressions, some are bad news for the engine, but not all.

But before I run a compression test, I first run a mechanics hack – the gas shot test.

Dirt Bike Gas Shot Test

The gas shot test is fast and simple to perform, that’s why mechanics perform it regularly when faced with a no start. This test isn’t conclusive but it does usually point to the system which has failed – Fuel system, Ignition system, or Engine compression.

Note: this test must be performed with fresh gas, old gas goes stale, and using the same to diagnose will lead to incorrect conclusions.

And here it is:

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

Top tip – A funnel or syringe makes adding gas to the cylinder easier.

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

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

This result tells us that your dirt bike suffers from a fuel issue. Bad gas, choke not working, Faulty fuel pump (if fitted), blocked gas filter, carburetor fault are high on the list.

2 – The engine doesn’t start and critically makes no attempt to fire. This result tells us that you may have an ignition system fault or indeed a compression issue but an engine timing issue is possible too.

Generally, a lack of spark is a more common no-start cause than a lack of compression. I’ve covered checking spark previously and you can check it out here.

Symptoms Of Low Dirt Bike Compression

The symptoms of low compression vary depending upon how low compression is and those symptoms often change as the bike warms (assuming a bike runs). And so here’s a list of the most common symptoms, some of which you may recognize:

• Engine no-start
• High oil consumption
• Blue smoke at tail pipe when running
• Wet engine
• Oil leaks under the bike
• Back pressure seen at the oil filler with bike running
• Engine misfiring
• Oily plug
• Engine flooding
• Carbon on piston
• Oily tail pipe
• Overheating engine
• Engine

How To Check Dirt Bike Compression

Checking compression is a definitive way to check if we have a mechanical issue. Obviously, we’ll need some tools and a compression test kit.

We have another option, a Leak-down test kit will work also and in many ways is a faster way to find a compression issue. I’ll detail testing using both types of test equipment and what their results mean.

If you don’t have a compression tester, check out the MacGyver test procedure below.

Not all low compression issues are serious, a spark plug with a bad washer that isn’t sealing the cylinder for example is an easy fix.

Checking Dirt Bike Compression MacGyver Style

This test method isn’t scientific or very accurate, it’s loosely accurate, and that’s why I call it the MacGyver compression test. Anyhow if you don’t have the proper test kit, give this try.

Test as follows:

• Remove spark plug
• Ground plug against cylinder head or use a jumper cable to remotely ground. An un-grounded coil wire will give you a jolt and is also bad for the ignition system.
• Place your thumb over the the open plug hole (important to wear rubber glove)
• Have helper crank engine

Two results are likely:

1 You’ve got some compression – You feel the effects of good compression on your thumb (strong vacuum and then strong propulsion). I go ahead and check the engine timing now.

2 You have no compression – You feel the effects of no compression as your thumb will feel mild or no effects of vacuum and propulsion as the engine is cranked over.

A lack of compression will likely require the aforementioned Leak-down test kit to diagnose the root cause.

Checking Dirt Bike Compression Like a Pro

In this test we’ll use a regular compression tester, you’ll need a plug wrench. This is a two-step test. We’ll run a dry test first and then run a wet test, after which we’ll compare results and diagnose. It’s best to run a compression test on a warm engine, but if your engine is a no runner you’ll obviously test cold.

Dry test as follows:

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

Wet test as follows:

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

Next, we’ll look at what the different readings mean.

What Dirt Bike Compression Results Mean

Comparing the wet and dry measurements means we can determine where if any, the compression problem lies – in the bottom end or in the top end of the engine, or maybe you have no compression issue at all.

Diagnosis of results as follows:

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

Readings are different and compression is low – If, on the other hand, the readings are 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.

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. I would now go ahead and check engine timing.

What Should A Dirt Bike Compression Read?

A reading between 95-115 psi may be considered normal for some bikes but a fall for others. Some bikes run 150 or 200 psi, you really will need to check the spec for your make and model. All that said a reading below 95 psi means your bike may indeed have a compression issue.

Note, compression testing on modern bikes isn’t always possible or accurate as they are fitted with a decompression valve. The valve releases some compression during the starting procedure which aids kick starting. And so for many a leak-down test works better and we cover that below.

What Dirt Bike Leak-down Results Mean

The Leak-down test won’t suit everybody as it means not only will you need a Leak-down tester but you’ll need a compressor also. That said, a leak-down tester is likely a faster and more conclusive way to both test and pinpoint the root cause.

In this test, we’ll fill the cylinder with compressed air and we’ll use the tool to measure the cylinder’s ability to hold pressure over a given time period.

But the real 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.

Diagnosis as follows:

Air leaking from:

• 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

You may find the following posts helpful:

Start a dirt bike without kickstart

How do dirt bike kill switches work?

Do all dirt bikes have stators?

Will dirt bike start without kill switch?

How to start a flooded dirt bike?

Dirt bike won’t start when hot

Dirt bike not starting after winter

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Dirt Bike Start With Low Compression? Mechanic’s advice … appeared first on ATVFixed.com.

A dirt bike air filter should be checked regularly, ideally every time you ride. Especially if the track is dry and dusty. But I’m a mechanic and I live in the real world, I know many air filters aren’t cleaned when or how they should be. This post has you covered.

A dirt bike will start without an air filter, however, performance may suffer. Riding a dirt bike without an air filter risks carburetor contamination and engine damage over the longer term.

In this post you’ll learn the risks of riding without an air filter, you’ll learn how to clean and oil an air filter and how often you should do it.

Riding Without Air Filter

A dirt bike will run without an air filter, but doing so risks several critical components. In addition, as a dirt bike carburetor is calibrated (tuned) to run with an air filter, running without the filter may cause erratic fueling and poor engine performance.

While starting and riding your bike short-term likely won’t hurt it, you should be aware of what’s at risk, and that’s what we cover next.

What components are at risk when riding without an air filter?

You know what your air filter does, its job is to trap all that airborne junk and prevent it from entering the intake system. So what’s the big deal if the engine swallows a little dust? Well short term as you know, probably no real damage. However, riding long term without a filter, especially in dusty conditions risks severe carburetor, intake system, oil contamination, crank bearing wear, and premature cylinder and piston wear.

These are all expensive parts to replace/repair.

Although dust looks harmless it actually contains fine particles of silica, which for want of a better description are micro rocks. Now consider a dirt bike throttle cranked wide open…. Yep, all those micro rocks are sandblasting the inside of the carburetor, intake system, and inlet valve seat.

And as you know, that’s just for starters. The fine but hard silica is now like liquid sandpaper inside your engine moving around in the oil and getting into places only oil can reach.

An engine under this type of condition will degrade pretty quickly.

How Often Should I Clean Dirt Bike Filter?

A dirt bike air filter should ideally be inspected every day if you are riding hard in adverse conditions. Otherwise, every month or about every one hundred miles works fine.

Dirt bike air filters will last years if cared for correctly. But if when inspecting you find a tear or a split seam, it’s time to replace it. A damaged filter is the same as having no filter at all.

If it’s damaged, replace it ASAP.

How To Clean Dirt Bike Air Filter

Cleaning a dirt bike air filter is one of the easiest bike maintenance jobs ever. It requires very little prep work effort or materials. All track dirt bikes are foam air filters and are reusable.

If in the unlikely event your bike has a pleated paper filter fitted. They can’t be washed or oiled like a foam air filter. You can use compressed air to clean them but ideally, paper air filter elements should be replaced.

The foam air filter cleaning process looks something like this:

• Remove air filter – Commonly a tool-less task
• Prep container – Half fill a container with warm water and dish soap
• Soak – Place the filter in the container and agitate to release the debris, now allow to soak a while
• Rinse – Rinse with fresh water, and squeeze dry, careful not to tear or split the foam at the seam
• Air box clean – Using a damp cloth, clean the air box and clean the air box drain
• Dry – Allow the filter to air dry, typically takes about thirty minutes

We’re not finished just yet, we have one more important step – oiling the filter, and that’s what we’ll cover next.

Do Dirt Bike Air Filters Need To Be Oiled?

Yes, an engine that works in dusty conditions will benefit from an oiled air filter. But wow… not every air filter may be oiled. Paper pleated filters as said earlier can not be washed or oiled.

So oiling a filter is only possible if you have a foam filter, which to be fair will cover all dirt bikes and ATVs.

To oil a dirt bike filter like a pro, follow these simple tips:

• Place clean filter in a large disposable plastic bag
• Add specialized air filter oil (not regular oil)
• Message the oil into the filter
• Remove filter and ring out excess
• Refit the filter and you’re good to go

Can you use engine oil on an air filter?

Air filter oil is a special oil. It remains sticky and that’s what traps the fine dust particles. It is not cool to use engine oil, transmission oil, or WD40. Using these types of oils may offer some protection but are not up to the job at hand.

You may find the following posts helpful:

Start a flooded four stroke bike

Will dirt bike start without oil?

Dirt bike won’t start after washing

Will dirt bike start with low compression?

Dirt bike not getting fuel

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Will Dirt Bike Start Without Air Filter? Don’t do it! appeared first on ATVFixed.com.

A kill switch is important kit. It’s not just a convenient way to kill the motor. It could be a lifesaver too. I’m a mechanic and shortly you’ll understand how most dirt bike kill switches work.

Dirt bike kill switches have two positions, “RUN” and “KILL.”

1. “KILL” – Operating a dirt bike kill switch provides a ground path for the CDI Capacitor Discharge Ignition) box, shorting it out. The shorted CDI unit stops sending voltage to the coil and the engine stalls (lack of spark).
2. “RUN”- Setting the switch to “RUN”, removes the ground path to the CDI Box (Ignition “ON” also). When the engine is cranked over the CDI box is primed and sends voltage to the coil as per crank sensor signals.

By the end of this post, you’ll understand how a dirt bike kill switch works. You’ll also learn how to diagnose a fault and how to fix it.

What’s a Dirt Bike Kill Switch For?

Fumbling for an ignition switch with a stuck wide open throttle wearing riding gloves, while exciting, isn’t very practical. Of course, most dirt bikes won’t have an ignition switch fitted, however, some road-legal models may. If your bike doesn’t have a key and ignition, just ignore all references to it, either way, the ignition wiring circuit works the same.

The kill switch is designed for ease of use in case of an emergency. The rider can access the kill switch without removing their hand from the handlebars.

Emergency services are trained to locate the Bright red button when attending an accident.

Can You Use Kill Switch to Stop Your Bike?

Yes, that won’t hurt your bike in any way. As you’ll learn in this guide, using the kill switch is identical to using the ignition switch (If fitted).

However, manufacturers don’t recommend using the kill switch to shut down your bike for a couple of reasons:

1. Riders often forget to turn the ignition off after flicking the kill switch and that results in a flat battery.
2. Riders often forget to set the switch to run, the bike won’t start and floods with gas and runs down the battery.

Dirt Bike Kill Switch CDI Or ECU?

It must be said not all dirt bike kill switches are wired the same or operate in the same fashion. Some kill switches initiate a kill by providing a ground and completing a circuit, some remove ground and render the circuit open and other more sophisticated systems may use a power supply to signal kill.

It depends on the bike and what system is employed. Modern bikes may have an ECU (Engine Control Unit) which means the engine fueling and ignition system is controlled by a sophisticated computer, not unlike a car.

Older bikes will likely be fitted with the less sophisticated CDI box, they are also referred to as the black box, module, brain, etc. Each system handles the kill switch wiring differently, indeed each manufacturer handles their wiring differently no matter if they are CDI or ECU controlled.

In this post, we’ll cover the kill switch on a basic CDI circuit and also an ECU circuit. The circuit diagrams here are for illustration purposes only. To troubleshoot a faulty kill circuit you’ll need a model-specific wiring diagram to nail it successfully.

Older CDI bikes work like this:

Many basic CDI systems use a kill switch that when activated, shorts out the CDI power feed and others may short out the ignition coil feed itself. Either way, activating the kill switch provides a shorter ground path for the CDIs, effectively shorting it out and shutting down the engine. It’s a very simple setup.

The ignition coil, as you know, supplies the high voltage needed to fire the spark plug. No spark equals no fun.

And so to start a dirt bike with a basic CDI system we must reverse the process, ie remove the short to ground. To start a dirt bike, the ignition must be set to”On” (if fitted) and the kill switch set to run. Both the ignition and kill switch provide a ground path to the CDI box, which must be removed before the CDI box will operate.

Your ignition system consists of a few critical components. (your bike may not have an ignition switch)

A typical start procedure looks like this:

• Ignition switch “On” – Initiates system, by removing the ground path to the CDI box, and sending power to the start button
• Kill switch “RUN” – removes (opens the circuit) the secondary ground path to the CDI box
• Clutch/Neutral switch activated – Offers a ground path to the starter solenoid
• Start button pressed – Power flows to the starter solenoid which connects battery power direct to starter motor and cranks the engine (if equiped with starter motor)

The switch in the diagram below is set to run, closing the circuit, kills the engine.

• Stator – this is where the stroy begins, because it creates the voltage needed to make it all happen. It powers the CDI box as the engine cranks (also charges battery via rectifier/regulator if fitted)
• Crank sensor also known as the Pickup – creates a small voltage, used by CDI box to identify the correct time to fire the plug (timing)

• CDI box – processes the crankshaft signals and employing a Capacitor, Diodes, and an SCR, the timed voltage is sent to the coil
• Coil – produces high voltage by sending power through primary and secondary winding which is then sent down the plug wire where it arrives at the spark plug
• Spark plug – the final destination, the business end if you like. The spark plug provides an almost perfect path for the coil’s power.

It’s the imperfect path that makes the spark possible. As you know the coil’s voltage is always searching for a path to ground, recognizing an opportunity – it jumps the plug electrode gap and a spark is born. It’s a beautiful story.

Modern ECU bikes work like this:

Modern bikes work a little differently from CDI systems. The general idea is the same, but in many cases, the kill switch will be signaling the ECU to shut down the engine as opposed to a CDI system, where we make the physical change to the circuit directly – open or close a circuit.

ECUs allow for this more sophisticated type of system because they are programmed using computer code. And it allows for easy programming of fail-safe systems like kill the engine if the ECU detects the bike has fallen, don’t allow a start if the kickstand is down (if fitted), don’t allow start if Neutral not selected, etc.

As with the CDI dirt bike, bikes equipped with the starter motor, battery, and road-going dirt bikes with ignition switches will add complexity to the starting circuit. And as before a wiring diagram is essential to troubleshoot successfully.

Here’s the circuitry for a modern ECU bike with a brief explanation below of what’s going on. Remember not all ECU bikes will handle it this way.

In the above diagram, the kill switch is set to run which provides the ECU with a ground supply. Power, therefore, flows from the stator via the rectifier which provides power for both the ECU and the coil. The ECU receives an input signal from the pickup which as you know is triggered by the rotating crankshaft. The ECU uses the pickup input signals to control coil activation.

Additional inputs such as neutral switch, kickstand switch, ECU lean angle sensor (if applicable) may affect coil activation, depending on ECU programming and equipment installed.

Moving the switch to “kill” removes the ground and shuts down the flow of power.

Common Dirt Bike Kill Switch Problems

Generally, kill switches are pretty robust and don’t cause too many problems. Diagnoses of the kill switch are mostly associated with troubleshooting a no start/spark, and it’s a case of eliminating the switch as a possible root cause.

Common symptoms of a faulty kill switch or wiring include:

• No start – switch faulty or wire is grounding
• Switch not killing the engine – switch faulty or wire disconnected/broken
• Intermittent no start – faulty switch or wire grounding
• Engine stalls over rough terrain – faulty switch or wire grounding
• Backfiring – faulty switch or wire grounding

Switches are made from plastic and wear out. Common problems include:

• Loose switch action
• Brittle plastic
• Loose contact points
• Worn contact points
• Corroded/dirty contact points
• Wire disconnects
• Loose or corroded block connector pins
• Broken wiring (around steering column common)
• Wiring short to chassis ground

The symptoms of some of the above will vary, for some bikes, they may fail to shut off as opposed to failing to start, it depends on how the switch is wired.

Testing Dirt Bike Switch

This is a simple switch and checking it simply too. You can use a DVOM or a test light. I prefer the test light method, but only possible for battery-equipped bikes. I’ve listed both here on the ATV tools page.

We already know when the switch is set to run, the path across the switch for most bikes should be open (broken). We also know that when the switch is set to kill, the ground path across the switch is closed (connected). So with that knowledge, let’s go ahead and check the switch.

Note your switch may operate in reverse, meaning closed circuit for “run” and open circuit for “kill”. With that in mind, makes sense to focus on a change in meter readings when the switch is operated.

Using a Voltmeter

Let’s go ahead and test them now using a voltmeter first and then a simple test light. In this test, we’ll be checking resistance in the switch.

• Using a DVOM set to ohms, gain access to the wiring loom feeding the switch. If there’s a block connector, and there will be, disconnect it. Never check resistance on a live circuit, the circuit must be isolated first.

• Check the connector for loose or corroded pins
• Back probe either side of the pins and check for continuity when the kill switch is set to “Kill”, the value for most bikes should be 00.8 (continuity). (Some may read “1”, that could mean it’s faulty but could also mean your switch operates in reverse. What’s important here is that the resistance value actually changes when the switch is moved between run and kill. That’s what we’ll do next.

• Flick the switch to RUN, for most bikes the meter should read OL (Open Loop) or 1. Both readings indicate an open circuit which is correct for most basic CDI type bikes.

Using a Test Light

A test light is in many ways a better test. First off we can test the circuit live and that allows us to load the circuit. Checking resistance is Ok, but it doesn’t always show a fault. Loading a circuit with a test light will help show up partial resistance caused by broken wires, dirty or loose connectors.

A dim test might then let us know we have a problem. Of course, this test will only suit bikes with a battery. Here’s how I’d go about testing with a test light:

• Hook up your test light by connecting the crocodile clip to battery positive (we connect to positive because we’re checking for ground with the probe).
• Locate the kill switch block connector and disconnect it.
• Slide the switch to “Kill”, if your bikes kill switch is a basic ground side then the test light will light up.
• Sliding the switch to “Run” should turn the light out.

If you find your kill switch operates in reverse, that’s OK. As said, what’s important is that the two tests “Run” and “Kill” give a different result.

That’s it, you are a pro!

You may also like the following posts:

Will dirt bike start without kill switch?

ATV parts page

Will dirt bike start if timing is off?

Do all dirt bikes have stators?

Signs of bad dirt bike coil

Ok to pressure wash an ATV?

Dirt bike not getting fuel

Start a dirt bike without kickstart

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post How Do Dirt Bike kill Switch Work? (Troubleshooting guide) appeared first on ATVFixed.com.

Ever wondered what’s the point of a dirt bike kill switch and an ignition switch, do we really need both.

A dirt bike will start if the kill switch is disconnected. Your dirt bike kill switch serves an important function, it’s an emergency off button, and it must be fitted by law.

In this post, you’ll learn why a dirt bike will start when the kill switch is disconnected, and you’ll also learn the important function they serve.

What’s The Point Of A Kill Switch

The kill switch is a safety feature that’s fitted to all bikes. It serves as an emergency shut-off button and that’s why they are always easily accessible and colored red.

In the event of an accident, emergency services are trained to use the kill switch (aka e-Stop) or another road user could easily identify and operate the red kill switch button on the handlebars.

The button is designed to be used by the rider without removing a hand from the handlebars. Turning the ignition key off (most bikes) would do the same job, but the key is fiddly and can’t be as easily located or operated.

Consider experiencing a stuck wide-open throttle, while wearing riding gloves and fiddling with an ignition key, isn’t practical. I know many dirt bikes won’t be fitted with an ignition switch, battery, or starter motor and if that applies to your bike, just ignore the references to it.

Kill Switch Function

Kill switch wiring differs from bike to bike, but the net result is the same – hitting the kill switch turns off the engine. If your bike has an ignition switch also then the ignition will still be on and if your bike has a battery fitted the key will need to be turned off also, otherwise, the battery will drain.

Using the kill switch to shut your bike down as part of your normal shut-off procedure is perfectly OK. It’s a misconception by many riders that doing so long term will damage the battery or wiring. It’s not so, as in most cases, the kill switch and ignition switch are wired in parallel, meaning they are doing the same job.

Many bike handbooks state you should only use the kill switch in an emergency or electrical damage may occur. They are being diplomatic here, they are alluding to a couple of common human error situations:

1. Forgetting to turn ignition off after hitting the kill switch causes the battery to run down.
2. Forgetting to turn the kill switch back on when restarting, causes the rider to crank and crank, potentially running down the battery, cooking the starter motor and or flooding the engine with gas.

How Does Kill Switch Work

Kill switch’s wiring differs between all manufacturers and how they are wired also depends upon how your bike’s ignition switch is controlled. Most older bikes are the traditional black CDI box, but some newer models are computer-controlled.

The kill switch for either type is handled a little differently. I’ve outlined the two common ways for each type below, but to fault find a kill switch correctly a wiring diagram is the best place to start.

We’ll for now identify the two different types as CDI type and ECU (Engine Control Unit) type.

How the Basic CDI Box Type works

The kill switch for most bikes is a very simple on/off switch. When the kill switch is activated (switch in Kill position), it shorts out the voltage coming from the stator to the CDI box. The short (shorter path to ground) prevents power flow from the stator to the CDI and consequently to the coil.

The coil as you know makes the voltage for the spark plug, no spark equals no fun.

Your ignition system consists of a few critical components, a typical start procedure looks like this:

• Ignition switch “On” – Initiates system, by removing the ground path to the CDI box, and sending power to the start button (if battery and starter fitted)
• Kill switch “RUN” – removes the ground path (and secondary ground path, if ignition switch fitted) to the CDI box
• Clutch/Neutral switch activated – Offers a ground path to the starter solenoid.
• Start button pressed – Power flows to the starter solenoid which connects battery power directly to the starter motor and cranks the engine (if fitted)
• Stator – creates voltage and powers the CDI box as the engine cranks.
• Pickup aka Trigger or crank sensor – creates a voltage, used by CDI box to identify the correct time to fire the plug (timing).
• CDI box – processes the trigger signals and using Capacitor, Diodes, and an SCR, it controls the coil voltage
• Coil – produces high voltage through primary and secondary winding’s which is converted to a spark inside the combustion chamber by the spark plug.

How the modern ECU controlled type works

The more sophisticated ECU-type bike use sensors and pre-programmed code to control ignition timing and fuelling. Their kill switches typically work like this but as said earlier, different manufacturers will handle it differently.

• Kill switch “Run” – Initiates system by providing a ground path for the ECU. Unlike the CDI type, the grounding of the kill switch occurs after the load (ECU).
• Clutch/Neutral switch activated – Signals the gear position to the ECU
• Stator – Creates voltage box as the engine cranks (kicked over) which powers the ECU and coil via the rectifier/regulator.
• Pickup aka Trigger or Crank sensor – Creates a voltage, used by ECU to identify the correct time to fire the plug (timing).
• Coil – Produces high voltage through primary and secondary winding’s which is converted to a spark inside the combustion chamber by the spark plug

Can You Delete a Kill Switch?

You can remove a kill switch, but doing so isn’t advised. For a basic type as per the diagram above, removing or disconnecting the ground allows the bike to start, that’s assuming all else is operating correctly.

That said some basic types may be wired in reverse, meaning they require a ground to start. A wiring diagram is required to identify a kill switch circuit correctly.

But yes it is a pretty simple procedure to remove a kill switch, either removing a ground or adding a ground usually does the job.

Points to note:

• It’s is mandatory to have a kill switch fitted to a motorcycle, for road use, and parks and recreation areas may not permit motorcycles without an operating kill switch.
• Insurance companies may void insurance cover and reject claims if a kill switch is deleted.
• In the event of an accident, injury caused by a deleted could result in a prosecution.

You’ll find the tools I recommend here on the Dirt bike tools page and you’ll find common spare parts here on the Dirt bike parts page.

You may find the following posts useful:

How do kill switches work?

Dirt bike won’t start no click?

Signs of bad dirt bike coil

Should you dirt bike alone?

Will dirt bike start without an air filter?

Dirt bike not starting after winter

• About the Author
• Latest Posts

John Cunningham

John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.

www.atvfixed.com/about-john-cunningham/

• ATV Rear Brake Pedal Stuck - Solved!
• How to Tell ATV Fuel Pump is Bad? This is how ...
• Will Dirt Bike Start If Timing Off? Run this test

The post Will Dirt Bike Start Without Kill Switch? (Yes, here’s why) appeared first on ATVFixed.com.