When to change piston

[corndog]

HI guys, I ride a RMX 250, My two main riding buddies have very different ideas on when to change the piston. My Scottish friend changes the rings once every two years (cheap) on his Gas Gas 200, my ex road racer mate changes piston every six months (about every four rides) on his Gas Gas 250.

I do most of my riding on trails with the odd MX session thrown in, never rev it hard (cos it just throws me off the back :ohmy: )

What would you guys do?

 

[a454elk]

I go once a season and that seems fine. If you race then changing it out every other race is what you need to do to keep the edge. Once a season is a safe bet, unless you ride every week then go every 6 months.

 

[Z0RR0]

Don't change it for nothing.
During the off-season (if any), just remove the head and cylinder. It's very easy, and doesn't require anything else than basic tools and 2 seals. Then, you can see and measure the piston, and mesure the rings (put the rings in the cylinder, and measure the gap where it's open). You rmanual should tell you what the specs are. If you're good, don't bother unless you enjoy lightening your wallet of roughly 100$ ...
Never assume "6months, it's good". I did, and almost lost my engine. My bike is ported CR250, and when I opened it during winter, the piston was damaged, cracked ... you name it, and it was far from old. I will check it every 6 months, if not more often, but considering your bike is stock, you should be safe nonetheless.

 

[corndog]

Cheers, I strip and clean the powervalves every 500 miles so I look at the piston every 4 months, I put new rings on it over winter. A bloke at the local MX practice ground said that changing the piston regular keeps the burn nice and clean which is benificial for the RMX powervalves?