Hope someone can help ? I have a 98 foreman 460es. Trouble I'm having is lost of power. After riding awhile it sounds like the exhaust is louder than normal, like air blowing out of it, and losing power. It doesn't backfire when this happens. If you shut it off it starts fine and idles but when you start driving it has no power and has the air coming out of the exhaust sound and only able to go in first or second gear and hardly enough power to go up a small hill. Thanks