Awesome! Let us know how the fine tuning goes!

 

Hello everybody. First time on here. Got this 2007 Chinese 250cc 4 stroke quad. Starter struggles or even stops spin completely. Release starter button, spin again, will start, but starter struggles a lot. Engine runs perfect. So far, new starter, new battery, new woodruff key, valve gap reset, new oil, exhaust not plugged, wiring all tight. does the same thing when jump the starter solenoid. Put on a jumper cable from car battery to ATV, same thing. i cant figure this out for the life of me. any help would be greatly appreciated, tks

 

If the starter clutch slips, it is most likely to do so just before TDC on the compression stroke, which is exactly when the plug fires, so the engine tries to run backwards, starter still trying to force it forwards. I have also had a Suzuki doing this when the starter idler gear bearing had failed. If it spins over better with the plug disconnected, then this is happening.

 

thank you, i will replace the clutch. cheap enough. Also, will let you know if that worked, tks

 

Seems the starter completely stops or locks. Would i be hearing any starter sound or any other sound when trying to spin?
PS, the engine does make a funny click noise just when this happens. That could be the clutch slipping. Whats your thoughts?

 

As I wrote above, take the plug lead off and see if that allows it to spin any better. However, it could be a bad connection on a thick lead, either battery to solenoid to starter, or battery to earths on engine or frame, so check all of them too.

 

new clutch assy, same thing.

 

Did you try spinning it over with the plug lead off?

 

Yes, works 100%. I even tried, with the plug wire off, turned the engine with starter, spins as expected, plug lead wire onto plug, stops instantly. works the starter button back and forth a few time. Starts and runs perfect.

 

Right, so ignition timing is over-advanced, or something is jamming up under load, such as the idler gear for the starter if it has one. You checked the flywheel key, but is the trigger coil mounted correctly? The trigger coil and the CDI's electronics control when the spark occurs so, if it is over-advanced, it is one of these at fault. I have heard that connecting the trigger coil backwards can alter timing, if it has two wires from trigger to CDI, it may be an idea to swap them round and see if it makes any difference.