just do what this guy did, it's a raptor 660 with a 900cc 2 stroke out of a sled. (if you look close i think it looks like it's running a CVT) unfortunately i didn't get to see him runX( but i talked to some guys who did and they said that the he raced the fastest shee out there (which i saw racing other people) and the shee might as well have been driving in the other direction.