delayed full shiftout



Low mileage 73' GP292, ...runs great on the stand, but when I give it full throttle it shifts out about 3/4 (5,000rpm), and after a couple of seconds rpm continue to increase to full power peak 6,500rpm. and full shift out. I suspect a clutch tuning issue but there doesn't seem to be alot of adjustment on this sled, I have a good belt, ...cleaned both primary/secondary sheaves with scotchbrite pad, ...lubricated the secondary cam shaft and primary shaft and weights (all move freely). The throttle response seems good and low speed idle is excellent. I'm at odds with this one, ...any ideas?

Alignment is good. I posted on Snowmobilenews/Vintage as well and someone suggested I drill more holes in the fixed helix secondary (currently it only has one hole), ...this will allow me to squeeze the secondary a bit more, ...worth a try.