hello. I have an issue with my 03 sportsman 600 that my mechanic cannot figure out. i'll do my best to explain. i hop on my quad when engine is cold. start it up and i run it down that road say about 40-50 mph. everything is fine until i hit somewhere around 1 mile. then all of a sudden i have no power. the engine acts like it has a fuel restriction. it putters and putters. it does not die, it just does not let me rev very high. maybe 15mph is the top speed at this point. if i push the throttle more it just putters. this only happens at high speed down the road. i never have a problem putting around my property. i can run it all day just pulling a trailer at low speeds and have never had a problem. if i park the quad and let the engine completely cool down and try it later in the day, again everything is fine till about 1 mile down the road.

this is very annoying. so far the only thing I've done is change the fuel filter. my mechanic has no suggestions for me. others have pointed to vapor lock. then others say, "no way, do you know how hot the fuel would have to be for it to be vapor lock?"

so I'm look for suggestions. has anyone had this problem and successfully fixed it?

thanks
adam