bought a 1999 4x4 Timberwolf that ran great but smoked like crazy. I took it apart, changed the rings, and then cleaned the carb since the bike had been sitting for a while. After I got it back together, the bike started and idles fine, but when you rev past 1/2 to full throttle, the bike starts reving up and down, as if I was puching the throttle open/close, and won't stay revved up. Like I said, when you leave it at idle, it purrs like a kitten. There is no sputter and no back firing. I checked the valve lash and the timing to ensure it is not out 180 degrees and all checked out fine. Anyone have any help please!!!

 

i would take that carb back off and see if the slide in the carb. is working free and not sliding hard.

 

sounds like your floats maybe sticking?? or maybe your getting air from other then the air box....when its idling try spraying wd-40 or ether around the head and carb manifold if it starts reving up its an air leak

 

I`ve had problems like this on mine and it ended up being an air leak. Check all the mating surfaces of the carb by spraying something like wd-40 at them and listen for the RPM`s to level out.