I was just stating the parts that could not be replaced by the aftermarket. I was thinking the tranny, engine cases, and air box, and frame were about it. That was my point. If you were racing hard a top end would be in order at 100 hours at the latest. If you ride fairly easy, may be a tall gear instead of revving than i can see a couple hundred hours. I tend to replace more often just for peace of mind. 2% leak down is good but that only tells you the condition of the rings and valves, not potential piston skirt wear.