When to rebuild???

[hsr]

Well, I'll be going into my third season of mx on the stock piston and rings. I've added a Hotcam stage II, but that's about it. I am not afraid to tear into a motor, I've done a couple of 4 stroke top ends in the past, but this thing is running flawless, maintaining compression, not using any oil, and running strong. I just don't feel comfortable not freshening up the top end. Or do I go by the old saying "Don't fix what ain't broke" . Some input on this would be much appreciated. Thanks! She does have some hard hours on her...

[DJJ450r]

If I were you I'd rebuild it, better safe than sorry and a new piston and rings is cheaper than a new cylinder, piston, and rings:blah: plus you get a fresh motor:devil: I raced mine for 2 seasons and rebuilt it, and it needed it, the rings were shot:blah:

[N300exJ]

If your running it that hard id say inspect the valvetrain every month and the top end every 4 to 6 months. Change and fix whatever looks warn out and or damaged. And dont forget to change the oil after every race.