Hello everyone. I am new to this site. I have been borrowing my roomates TW200 for my girlfriend to ride and now I feel responsible to fix it. We've been hitting the desert trails here in az. It is a 93 with 824 miles on it and appeared to be running great. On our last attempt at a ride we got about 10 miles away from the house when the engine let out a squealing noise. I was able to start it and run it back to the house. It let out one more little squeal. It turns over, shifted through the gears, and didn't rattle. Does anyone have an educated guess as to the possible cause, and how much work I am looking at. I just rebuilt my snowmobile (1000cc two stroke) however I have never worked on a 4 stroke so any tips would help. I am a newbie at engine repair. Thanks in advance.