XR200 Bogs in Wheelies

[cjreeder]

I just bought a "new to me" 1981 XR200R. The only reason I even own it is to master riding wheelies on it, and for the most part it runs great. But after about 20 minutes of wheelie practice, it misses (doesn't fire) on some strokes. This only happens, though, when actually in a wheelie. With both tires on the ground, it never misses a beat.

I suspect mixture issues to be the cause, but I don't know if it's too rich or to lean. I have 90W-140 gear oil on the foam filter, which is pretty hard to wring out, so the airflow may be restricted. I examined the spark plug, a Champion RA8HC, and it looks normal to me. I have fiddled with the pilot screw, but did not notice any significant change. The main jet is a Keihin 138.

Thanks,

 

[jmics19067]

check your float hieght and your needle and seat. while in the a wheelie the fuel will slosh to the back of the bowl possibley uncovering the jets.If your pilot jet gets uncovered it will be effectively an air leak causing a lean bog.

 

[Studboy]

Get rid of the gear oil on the filter and get some oil that is designed for foam filters. Then clean out your carb and check your float level.

 

[dthoms]

You also might want to check for a resistor in your spark plug cap. I believe this vintage has one. I would take it out and replace it with a piece of copper or welding rod.