97 rm 250 fouls plugs

Joined
May 28, 2007
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#1
I have been having trouble with my 97 rm 250. It runs great on mid to top end and pulls hard. Going up hills it has a lot of low end grunt at low rpm's all the way to WFO. The problem is going down hills it loads up very bad and fouls plugs. Even after being cleared out it barley idles when warm. When I start it from cold the idle is high. I checked the compression it is 230psi. clean filter, new silencer packing. The jets in it are 168 main, 40 pilot, NZOG needle 1st postion (top Groove) Air screw 1 1/2 turns out. # 7 slide. The air screw does not seem to change the way it runs I have tried 1 to 4 turns out with no change. I am thinking about trying a 35 pilot. I just rode about 50 miles this weekend on trails with a lot of long uphills and down hills and fouled 5 plugs. My brothers Cr 250 didn't foul any plugs. Any thought? I am frustrated with this bike.

Thank you,
Willie
 
Joined
May 1, 2007
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#2
I might be talking out of my a$$ here, but I would check your float height, and try going down a size or 2 on your pilot. I'm no expert, but that's what I would do...
 
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May 28, 2007
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#3
I measured the floats one side measured .675 and the other .630 Now they are both correct, at the stock setting of .630. I don't think the .675 would cause a rich condition though. The float valve is new. Vent hoses are clear. Would a larger diam. needle help?

Thank you,
Willie
 
Joined
Oct 9, 1999
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#4
I had the same problem and it was a worn out needle and main jet combined with a weak stator. The needle and jet get worn and let too much fuel through. I'd try replacing them and checking the resistance values of your stator. The stator made the problem worse but the root was the needle and main jet.