I have an interesting problem with one of my buddies sleds and am looking for some help. He has a 2001 600 Deluxe with about 2500 miles on it, bone stock. Last year riding his rpm's were pulling like 9400 on this thing. All the components are stock and he has the 8DN belt. Any ideas what is going on? His mileage started suffering late last year as well and has a backfire on a regular basis when he shuts it off. The two of these together makes me think there is some type of problem with the clutching and not the tach. Any ideas?