Hello new to the forum! I have an 06 660 with a fresh rebuild due to broken flyweel bolts and oil consuption (valvle stem seals and rings): 719 Hotrods kit w/11:1 JE piston; Hotcams stage II cam; matching valve springs; no head work; billet middle drive plate; Dynatec pragramagable ignition (high compression pump gas setting) w/coil; stock carb w/ 45 pilot, 165 main, and large spacer under needle on first notch; stock intake w/K&N, gibson exhaust w/spark arrestor removed (yeah it sucks), stock secondary spring and trinity primary w/14g weights. My old sheave crapped out, broke rollers, and part of sheave. Installed new trinity sheave and am only getting 45 on top end (great low end though). After the new intall i checked to see if the belt was riding all the way up the sheave and it was (checked in neutral). The slide that goes inside the sheave did have some wear where the guides insert into it. Could this be the reason? When everything was right it would run 60 (before rebuild but same engine w/mudbuster cam and Trinity Stage IV exhaust though)! I don't have a tach but the engine is screaming at 45. I also installed a new wet clutch while i was in the engine. Spark plug is a light brown with great power throughout RPM range, so i dont think tuning is a problem.