I got a 2001 kx125 back in December and when I got it, it acted funny. When you would get about half throttle it would start kind of bogging but yet hitting the max rpm at the same time. I cleaned the carb, put 3 different jets in it, rebuilt the top end, and cleaned the power valves and it still does it. The only thing I could think of would be the carb boot is kind of dry rotted and needs replacing but would that suck enough air into the engine to cause this? I'm getting too aggravated at this thing.