I haven't had a chance to take it apart yet, but I think I damaged it this winter. Went out on the lake with 2 foot snow drifts and it sucked some snow in and the carbs froze wide open. had to keep hitting the kill switch to make it back in. Ran good for 3 trips after. This ride was just to keep it lubed and only lasted for 10 minutes and quit when I pulled in the driveway. I'll know for sure what happened because I've seen a few sleds that sucked snow in, a very specific pattern on the piston.