Oh boy, you're in trouble now.
A lifeless bike is a dead bike and you'll know it when nothing happens when trying to start it up. And we mean nothing. You can kick or hit the start button as hard and often as you want but when you can't get the engine to crank panic mode sets in and for good reason. At best you're looking at a battery issue. At worst, catastrophic engine failure.
Understand, there's a difference between your bike not starting and not turning over. Even an empty gas tank allows the bike to crank, or at least try to start, but a serious engine problem refuses to give one inch.
So, if the engine fails to turn over there's work to be done and depending on the age and use of your dirt bike, it could be one of just a handful of problems.
Signs of Engine Failure
Often, the rider is enjoying an afternoon on the trails or putting in some laps on the track when the bike suddenly dies. Did I run out of gas? After failed multiple attempts at getting it restarted you realize the engine is dead. You'll know right away on the kick start - it won't move. A seized engine doesn't crank thus preventing the kick start from functioning. (On electric starts, all you'll hear is the "click" of the button as you push it.)
A number of issues cause an engine to seize and most require an adept mechanic to diagnose and remedy. If you find yourself in this position and want to troubleshoot, check the following:
- Failed crank/rod bearings
- Seized piston
- Broken or stretched rod
- Damaged wrist pin
- Damaged rings or piston circlips
- Broken or dropped valve (4 strokes)
- Cam chain, cam, rockers jammed by damaged valve train components (4 strokes)
- Power valve interference with piston/rings (2 strokes)
- Cylinder port damage causing interference or ring snag (2 stroke)
- Damaged kick start components
If you're a do-it-yourselfer and have trouble finding the exact cause it wouldn't be a bad idea to simply rebuild the top and bottom ends. That addresses most of the above issues. Besides, if you do zero in on the problem and it's, for example, a broken or stretched rod, you'll want to replace all the related components anyway.
It's the Transmission
A shot transmission prevents the engine from turning over and while it's pretty easy to diagnose, most transmission issues also need the capable hands of a seasoned mechanic. If your dirt bike refuses to change gears (usually fails to get into or out of neutral) pop it on bike stand and see if the rear wheel spins as you roll the starter. If it does - it shouldn't - thus you've probably got a transmission related problem.
KTM and Husky Riders or Aftermarket Electric Starters
If you ride a bike with an electric start you might be in luck as far as getting off easy. Actually a dead battery or bad wire contact/connections is the most likely case and if you're keeping diligent records of battery hours and you've gone past the life of the battery, this is the first place to check.
But, don't get fooled by the battery as it can read fully charged but the amps and voltage required to crank the engine abruptly drop when you hit the start button (cowards!). If this is the case, either the battery has short circuited, you've got a bad cell or a bad connection. Check the "ground side" for the bad connection.
Other electrical related issues include:
- Starter Relay/solenoid
- Start button
- Neutral safety equipment
- Wiring/contacts/connections/plugs/bad ground
- Starter clutch/one way bearing
Isn't owning a dirt bike fun? Makes you long to be a factory rider. Thankfully, if you're diligent on maintenance and keep track of riding hours it's unlikely you'll ever encounter a seized engine.