I am an engineer for a company that makes their own 2 stroke. If properly cared for, our engine will run in excess of 1,000 hours without issue. I should know because I endurance test about 10 per year in an application harsher than an ATV. Using the right oil is the key. Use only the oil specified by the manufacturer. Last year we did an endurance test on different types of 2 stroke oil and some 4 stroke oil. It make a huge difference in the life of the motor. By the way, you only have to rebuild when the compression gets low. Rebuilding before that is a wast of money. Oh yeah, rebuilding a 2 stroke is a peice of cake. No cam, no valves, no lifters. Just piston, rings, wrist pin and a cylinder hone. My next quad will probably be an LT250.