i can go for a ride on my fathers big red 86, and she picks up speed great, with a worn cam, she does good, weak on the hills unless you have her in a high rpm, but when i get on my 85 big red, she seems slugish, and shes set to a 300 with a 300 fourtrax cam, i can get my dads to rev out, but mine cant, and would carb having anything to do with it, my dads has never been adjust, taken apart, or anything, the carb, timing, and all that is still left factory settings