We have a pred 90 with a Hetrick pipe, no limit cdi, alpha clutch, and 110 main jet. All this dramatically improved overall performance,but the bottom is still not what we had hoped for. Smaller rear tires and a smaller rear sprocket were added and seemed to have helped some(I know the sprocket size should go the other way, but this is yhe best combo we have hit on).I see kevlar belts for racing and it got me to wondering about belt stretch and slippage. Anyone have experience in this area?

 

I'm guessing that you need to fine tune the roller weight.
Tell Rich your problem, I'm sure he can help.