Hi, I have 2001 Super Sport with 1700 miles that I just bought from a dealer. The dealership I bought it from said they got it from somebody that doesn't ride it anymore and has just been sitting in his garage for the last five years. They also said that they cleaned the carbs and clutches and replaced spark plugs. It starts up right away and I don't have any issues til I get up to 55mph and it just loses power but the sled never shuts off. I can have the throttle pinned and the machine jolts a bit but even if I'm steadily accelerating, once it reaches 55 it jolts again. Sorry I'm not that knowledgeable about snowmobiles and the best way to describe the sound the engine makes is like MMMMmmmmMMMMmmmm, like it's reving up and down but I'm not moving the throttle at all. It also is going through way to much gas. I used 91 non oxy in it and I filled it up full before going out today but after only riding about 30 miles I was at a 1/4 of a tank. My thought is that it's getting to much gas when the throttles pinned and at higher speeds but I could be completely wrong and not even sure what to fix if it is getting to much gas so any and all help is appreciated, thanks.