Going mental over this Chinese 110 cc quad. The starter turns fine on the bench, but put it on the quad, make sure the chain is on the starter cogs and tensioner is in place, cable jump it directly to the battery and all I get are sparks, doesn't even spin. Could something be seized-- the flywheel, sprag one-way clutch -- and how might I check those? This clueless individual would SO appreciate any clues....

 

The one way clutch isn't the culprit as it is supposed to be locked up when the starter is turning the engine. Is the engine seized? If the flywheel turns by hand when you have the cover off, it isn't. The alternative is the starter must have a fault, take it apart and find out.

 

Thanks very much for that, it helped a lot. I did as you said and the flywheel would barely move. It's up to the owner now whether he wants to proceed or not-- I recommended he take it to a small engine pro who has much more experience and better tools. Thanks again.