Help, My 1996 Wolferine ATV has no power in mid range. Starts no problem all the time. Runs like crazy when I finally get this thing above
this long flat spot. Fuel & Air Filter is all new. Compreesion is good. Any ideas what could cause this. I just got this ATV.

 

valve adjustment? Also, your needle might be mis-adjusted. the needle controls the air-fuel mixture at 1/2 throttle. . . does this happen at full throttle only? your main jet might be too rich. Also, is the bike stock?? need for info!

 

Thanks for your reply! The ATV is stock. Look's all orginal to me. I just adjusted the valves, they were pretty much dead on. I was guessing carburator problem, but am not sure. It has a Mikuni Carburator. The mixture srew in the bottom of the carbuartor is tourned out 4 full turns. I think it is ready to fall out? If I turn it in more I have less power.
The ATV will not make it up a 25% slope if I turn that mixture screw in. It barely makes it now. It will make it if I can take a run at the hill and get the RPM above mid range before I hit the slope. Any more ideas?

 

Have you cleaned the air filter?
Any intake leaks? (Airbox to Carb, Carb to manifold)
How is the spark plug?

To me it sounds like your carb is all gummed up. Take it apart and clean with B12. Just watch out for the floats and other rubber items. Clean out with compressed air. Watch out for flying Carb cleanner!