Hey Guys,
new to the forum so hopefully some of you can help me out.
I just bought a 2004 sportsman 500 HO from an older man who bought it brand new. Not a lot of maintenance had been done to the wheeler because he only used it to plow his driveway. It actually only has 500 miles on it.

All the rides i take it on so far have been pretty fast just flyen down dirt roads, and it screams on flat ground. Runs perfect. but as soon as i head up a hill i get a total loss of power. never shuts off on my but i go from 35mph to 15 in no time on hardly any incline.

As soon as i bought it i took it in the my local polaris shop and had it completely looked over, carb cleaned, all new fluids. All the mechanics there say the things clean as a whistle. Any Ideas?

Maybe fuel pump?