There are many variables in clutching, you must keep an open mind and clutch the sled to you and your riding style. I just went through a learning curve on an 850 I bought from a friend. The previous owner thought the clutching was perfect, and in fact it was perfect for him and his riding style. He tuned for 7,000 - 8,600', pulled a hill with a relatively cool belt watched the tach and called it good. I would say I run the sled roughly 10 times as hard, heat the belts and clutches far above what he has ever done and probably weigh 20-30 more pounds with all my gear on, I also ride and tune for 8,600' - 10.500'. His perfect clutching turned into a belt slipping belt destroying nightmare for myself. When my RPM's would fall off at 10,000' the primary squeeze and backshift also fell off, resulting in belt slip. I sat on the hill, showed a clutching wizard my problem and we came up with a very simple next run trial. Our solution to the issue was run a couple less degrees of Helix angle with a stiffer secondary spring, resulting in more squeeze, cooler belts, better backshift, and about 150 more RPM's. I was able to achieve the result I wanted without going to lighter flyweights. This simple change resulted in the primary nearly cleaning itself in the first 10 miles. Had I not changed a thing I would more than likely had the fluctuating RPM's drive me nuts, had to clean sheaves daily and buy a new belt every few rides. Keeping an open problem solving mind is very important, what works for one may not work for another with an entirely different riding style.