I just picked up a 02 YZ426F. It has a pretty rough time keeping an idle and it back fires really bad only when releasing off the throttle. The guy I got it off claims that it ran well until he pulled the carburetor and cleaned it. Obviously I take what he says with a grain of salt because I only paid $550 for it. Should I rebuild the carburetor or does this sound more like it needs a valve adjustment? It does have an FMF pipe on it, but I don't think it should back fire this bad. Also it takes a few kicks with the decompression on, and then with it off, it usually starts after a kick or two. Is this normal? Is it just me or does it feel like you need to be able to squat 400 pounds in order to kick this thing over, I'm use to two strokes so this is a whole new ball game for me. Thanks in advance!