you should be able to get way more out of the 650.I hope to get at least 350hrs before breaking into my 650r
I have never changed my piston and my bike is stronger than ever. I don't really think you have to change the piston every 50 or so hours if you are not racing and running 8-10,000 rpms continuously. Unless you buy a piece of shit CRF-R or X that seems to break down every 10 minutes.