I have a 2001 Yamaha wolverine 350 4x4 with a problem that I can't figure out. The other day I was pulling sleds for about 2 1/2 hours I stopped because I noticed I lost some power. I took them off and went on a little ride 10 minutes later. I tried to climb a little hill that I have climb before in the snow but I had no power and couldn't make it up the hill this has me stumped. I have reset the valves, new piston rings, cleaned the carburetor, cleaned air filter, put fresh gas, new spark plug all the basics but still nothing works. I even disconnected the wires from the parking brake. (Read that this could be the problem.) please follow you know anything let me know, thanks in advance!