Why Won't My Dirt Bike Start?
Engines need fuel, air, spark and compression. When a dirt bike will not fire, the cause is usually something simple. Work through this list before you call a mechanic.
1. The easy ones
- Kill switch: is it in the run position, and is the lanyard clip in?
- Fuel tap: is it on, and is there fuel in the tank?
- Neutral: is the bike in neutral (or the clutch pulled in)?
- Choke or hot start: use the choke when cold, and the hot-start lever when warm, if your bike has them
2. Old fuel
Petrol goes stale in a few weeks, and ethanol blends can gum up carburettors. If the bike has been sitting, drain the old fuel and refill. See our guide to storing and winterising your dirt bike.
3. Flooded engine
If you have kicked it a lot with the choke on, it may be flooded. Turn the fuel off, open the throttle fully and kick it over several times to clear it. Then try again with a little less choke or none at all.
4. Spark plug
Remove the plug. If it is wet, black or fouled, clean or replace it. Check there is a spark when it is held against the engine and the engine is turned over. A plug is cheap and a common cause.
5. Air filter
A clogged filter can stop the engine from starting well. See GearShed's guide to cleaning an air filter.
6. Battery (electric start)
If the bike has an electric start and it only clicks, the battery may be flat. Try the kick-start if there is one, and charge or replace the battery.
7. Starting technique
Four-strokes: find top dead centre, ease the kick-starter through the compression and give a firm, full kick. Two-strokes: a few firm kicks with a little throttle. Do not stab at the throttle.
8. Carburettor or injector problems
Blocked jets and pilot circuits are common after storage. A clean usually fixes it.
When to see a mechanic
If you have spark, fuel and a clear air filter and it still will not run, it may be a compression or timing issue. Get it checked, particularly if the bike has high hours, see how many hours is too many.
Stock up on maintenance products and see our dirt bikes in stock if it is time for a new bike.
ShowShed is a Hamilton dirt bike and quad dealer, back to the home page or browse every bike in stock. Gear for the ride is at our sister store GearShed.
Frequently asked questions
Why does my dirt bike start and then die?
Often a blocked carburettor jet, stale fuel or a fuel flow issue. A clean and fresh fuel is a good starting point.
How do I unflood a dirt bike?
Turn off the fuel, open the throttle fully and kick it over several times, then try again.
How often should I replace the spark plug?
Follow the manual. Many riders replace it every few rides or each service.