How long has it been since you cleaned the power valves? If you bought bike used then probably never been touched. Dirty sticking power valves will cost all your low end. Regardless of compression, I would rec'm pulling the top end, inspecting and cleaning power valves, have cylinder and piston checked, and then either install next over piston or if piston and cylinder are still in spec install new rings. If power valves have been sticking then you more than likely have some damage to the power valve plastic gears which would have to be replaced.