Bad Stator?

My 15 ride old '02 426 coughs, sputters, backfires and carbon fouls plugs. It runs but barely. Initially believed to be carburation trouble, I tried on from a friends bike. Then also the CDI, coil, and fuel. All to no avail. What else is left? I can't pull the stator from the bike i'm getting test parts from. Any suggestions? Isn't a carbon fouled plug and indication of week spark? The bike seems to run best when it is completely cold until it gets to temp. Then it's all down hill. I am going to double check the carb, cdi and coil on the "parts bike". Please help!

Check the flywheel. Does it have any cracks? See if there is any play in the crankshaft. Could it be bad crank bearings?

Get a spark tester. They sell these at the local auto parts store.

Check the timing.

Check valves, piston rings.

Have someone do a leak down test.

Is the exhaust ok?

It could be many problems. It is so new that the dealer should be helping you out. The more you mess with it the more likely it is for them to blame the problem on you.

My two guesses would be a bad exhaust (look for leak between manifold and header, big dents in header or plugged pipe) or a bad ignition. My first guess would be the plug, then the coils, then the CDI and then the stator. Go through the electrical checklist with a multimeter.

I would have said induction air leak between carb and intake manifold if not for the fouling.

Good luck,


Oh yes, if you are cleaning the plug, replace it. Once fouled plugs usually have to be run out each cold start until replaced.

Good luck,


There is a rock dent in the head pipe. Something large enough to consider replacement or removal but mostly for cosmetic purposes. The bike did run fine for a while after this was there. It runs better from half-full than from 0-half throttle but still not the way it should. Kind of the same but only faster. I used to have a '00 426 so i'm used to how it should run. I'm temped to just go ahead and order the stator. I'm not as into wrenchin' as racin'. Thanks for your help. Any other suggestions?

Before you spring for a new stator, give more information on your symptoms. You mentioned coughing and sputtering, but didn't describe when this occurred. Go into detail such as whether this happens when under full throttle...etc.

Hey thumper gang, since were on the subject of stators does anyone have a charge coil or both they might want to sell for a 84 yz 250 2 stroke ,one of the coils is dead . let me know if anyone has a set . thanks

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