So I have been tweaking the engine im going to use on my scratch built suspension shifter bike build Fully built China Doll reed valve motor I built, stuffed, ported, arrow kit, YZ85 Expansion chamber... I have had it now to 41.5 mph on a 44 Tooth !!! The thing screams and turns 10,000 RPMS.. but the clutch is slipping, I replaced the friction material, ruffed the crap out of the clutch plate, and cranked the **** out of the preload spring (the big spring in the case) No matter what I do the motor will overpower the clutch and it will start slipping. Any help ?