i never took the bottom end apart or pulled the cam out the only things to come off the motor were the heads and intake. i have cleaned the center carb 2 times but today i noticed something when i looked at the fuel filter it wasnt filling up all the way and there were air bubbles sucking through it. whenever an air bubble would pass through the tone of the motor would change. that makes sense the pump wouldnt be pumping as fast at low rpm such as coming off idle so if it is sucking air that would be a big deal but at full throttle the engine is spinning a lot faster and the pump could compensate for sucking air this might explain why it is running fine a full throttle. im just basically thinking out loud