Hey how are you, my 11 year old brother has a 2005 can-am ds90. The problem is whenever we go over a hill or little bump it dosent move, it runs but has no power to go up the hill. He has to get off and push it. When we got it it was perfect no problems what so ever. We don't know where to start at first we thought it was the carb not getting enough fuel to help it "go", but whenever he's riding on flat land the atvs fine and flys. Then I started thinking it was the compression because it has no power for such trail challenges. Any help here?