Who doesn’t like a clean bike! But some muck is just better left where it is. Don’t panic. We’ll get her figured out in the next few minutes.
The top 5 reasons a dirt bike won’t start after washing include:
- Spark plug wet
- Spark plug flooded
- Water in fuel system
- Wet electrics
- Hydro-locked engine
In this post, you’ll learn the top 5 reasons your bike won’t start after washing, how to diagnose them and what you can do to fix them right now.
Your dirt bike may or may not be an electric start, and so you may not have a battery, starter motor, starter solenoid, or ignition switch. This post covers both types, so just ignore what’s not applicable to you.
1 Wet Plug
Your spark plug lives at the front of the bike and is usually protected by a rubber boot. The boot sits snug around the plug and protects against water splash and flying debris. While the rubber boot is weatherproof, it’s not waterproof, so directing a power washer at the plug will cause water to soak the plug, plug hole, and cap resister.
The ignition coil lives in the neighborhood also, while it’s usually protected from water spray, it is possible to get it wet by directing a pressure washer in its direction. Check the coil and dry it if wet.
Drying the plug will solve the problem. Compressed air is the fastest way to dry out the plug, but a shop towel and some WD40 will get the job done too. If drying out the plug doesn’t help, try an ignition system inline test to verify the spark.
If you have an in-line spark plug and ignition system tester, now’s the time to break it out.
2 Flooded Plug
What’s a flooded plug? Cranking an engine that won’t start causes gas to soak the plug. If water caused your spark plug to become damp, cranking compounds the problem by soaking the plug with raw gas.
Power washers can produce 2000psi and more, which is plenty powerful to penetrate the intake ducting if directed at it, and when attempting to start water may be sucked into the cylinder. A water-soaked plug electrode, either gas or water won’t produce a spark.
You’ll need to remove the plug, dry it, clean it and check the gap.
3 Water In Fuel
Water in the fuel system will stop your bike, dead. Power washing around the fuel cap and vent can cause water ingress.
Draining the fuel bowl and changing the filter should get you back rolling.
4 Wet Electrics
Electrics don’t like water, solenoids, relays, fuses, sensors ignition switches. Dry out all the electrics using compressed air or WD40 will help drive out water.
Check safety lockout switches like kickstand sensor and wiring and neutral switch wiring is in place and secure.
Check also that none of the following electrical connectors are disconnected, or loose:
- Battery terminals
- Solenoid terminals
- Stator wiring
- Engine pickup wiring
- Spark plug wire
- Coil wires
- CDI, ECU terminals
- Rectifier/regulator
- Starter motor wiring
And check the main fuse, you’ll find it under the seat usually.
5 Hydro Locked Engine
Laying your bike on its side to power wash the skid pan is a common mistake to make. Gas and oil can easily move into and fill the cylinder. Oil and gas won’t compress, so depending on how much flowed in, your piston may not move. In addition, your spark plug is likely wet.
How to diagnose? Remove the spark plug, and turn over the engine slowly. If gas sprays from the cylinder, you found your problem.
How to fix it? With the plug removed, crank over the engine to dry out the cylinder. Dry the plug or replace it.
Check the oil level and start the engine, the engine will smoke, but it will clean.
Power Washing
Power washing can do a lot of damage. It washes protective grease from chains, and the pressure of the water can penetrate bearings and seals, causing rust and premature failure of components like stator and pickup.
I don’t like to power wash using high pressure. There’s just too much risk of damage, less pressure is better, and avoiding risky areas is best. Before washing, spray the electrics with WD40 and turn the pressure down. Turn your petcock off and avoid laying your bike on its side which causes gas to flood the motor.
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:
Okay, to leave bike in the rain?
Will bike start without a kill switch?
Will dirt bike start without an air filter?
- About the Author
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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.