RM 250 fouling plugs

Hello my name is Rob i been visiting the site for a few months and this is my first post. I have a 96 RM 250 and all of a sudden after 40 hours this season the bike is fouling plugs. A little history the engine is stock (i think) it has an fmf fatty pipe power core 2 silencer. i put a fresh air filter in, i mix my bike 44:1 klotz r50 with premium/race gas 50/50. i run a 47 rear tooth sprocket and 13 front. this bike sees a lot of woods, some moto, and a fair amout of open field. i race with wixc up in wisconsin and this past winter i put new pro series reeds in and have 150psi compression. i did take the top end down lubed up the power valve and all that good stuff. It just odd the bike ran great no issues up until my last two races i fouled 3 plugs but only after the race never during. I got roughly 40 hours out of the first plug this season. the color when i pulled the first one was a deep coco color not tan and had some carbon deposits on the electrode. The plug br8eg i refuse to spend 30$ on the stock plug lol  lets see am i forgetting anything. lug my bike in the woods, only really get on the pipe in the fields or long straights i have a lazy riding style u could say thats all i can think of for now please any advice would be great thanks :thumbsup:

Try leaning out the mix with the air screw. if thats not good enough, try leaning out the mix by lowering the clip on the needle and playing with the air screw. If neither of those work, you need to re jet. Repack your silencer too.


And btw, those $30 iridium plugs are nice.

Edited by dan2581

Checked your tranny oil level? Low at all?  First guess is a leaking RH crank seal. 

Thanks everyone and tribal you were right the RH crank seal is leaking i have been noticing more smoke but didn't put it together until u mentiond it i just thought it was the weather change up here :thumbsup:

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