I have a 2005 Sportsman 500 HO and when starting up and at low RPMs there is a clunking noise on the right side. Sounds like the piston is shot almost; however, it only has 83 hours and rides like a champ. I just changed all the fluids and the oil still looks new after a few hours. It just sounds horrible and yet it rides fine. I bought it used from an older guy and it was by far the best one I looked at. I tested others and they all seemed to be noisy. I may have forgotten how noisy they are or should I be weary.