Can anyone help me with the tune on the GP420 motor? I have read on the internet the tuning instructions regarding this motor. When I first ran the motor, cruising at 20 mph, it was firing as smooth as silk. Then after around 5 miles, it started to bog out. I adjusted the high screw clockwise which fixed the acceleration bogging problem. But what I notice is this: when cruising at 20, it makes that dieseling sound, not the clear whine sound. When I am accelerating, the firing is smooth as silk but when I stop the acceleration to cruise speed, the dieseling sound returns, kind of a uh sound instead of the whee sound. I don't want to hurt the motor. Thanks in advance for any ideas.