5600 miles and not a single problem. I inspect my sled after every weekend, keep the oil on high so all the parts get soaked, mainly the bottom end, I use Klotz. I never give it more than 1/4 throttle until it is warm...about 2-3 miles. I run the sled on a stand to warm up the track and belt and generally take care and not hot rod or drag race. I just ride the thing, average 300 miles a weekend. I give it good gas and use dry gas at all times. So there, all these motor explosions are not always a mfg defect, you need to take care of these motors and not treat it like a red headed step child. Yeh, my carb boots went south but I caught it because I knew there was a problem with these, Just wanted to tell the other side to these motors. I am really tired of all the posts about blown motors. In fact I hardly believe 1/2 of them.