04 RM125 Fouling Plugs (Not Jetting) Questions

I am looking at a 2004 RM125 that has a plug fouling issue. The owner said the top end was rebuilt and about 2 riding hours later it began fouling plugs nonstop. He said he took it to a shop and they told him that the shop said the gasket between the crankcases is leaking. My question is: what would cause this to leak? He told me the bottom end has never been apart. He also said that there are no cranks in the cases and its not blown up. How likely is it that the gasket is the problem? Sounds like a crank seal to me. If not what else could it be? Think he is lying about the shop? If I go check out the bike, what should I look for? Anything I can do to ensure the bottom end isnt toasted?


Thanks in advance!

A leak in the cases would make it run lean, burning the plug eventually or destroying the motor, so its not a case gasket. offer no more than you would for a bike needing a full rebuild anyway. Probably something easy to fix, but you need to disreguard all this guys ideas/info. Shop was probably trying to sell a full rebuild to cover all bases. Unless he shows you a reciept for a leakdown test, its all bull, and opinions.

Edited by ickfinger

probably right hand crank seal, or he does have it jetted wrong (some people think they know how) or many other things can be causing his rich condition. has he ever drained the tank is his airfilter plugged or overoiled, etc

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