piston life??

[yfzrider310]

Ok if I have had my yfz since 2006 and have put about 400 hours on it when do you think I should rebuild my motor. It runs smooth now but next year im going to be racing motocross and cross-country so it needs to last. I was thinking about putting a new piston in the winter (gytr), do the cam mod, and oil mod. Does that sound good because I want power yet reliability. Any help is greatly appreciated and what im looking for is how long should I wait to do all this? (now, summer, or winter).

[Ride1Rob]

It's overdue for you to get a rebuild.

[86yota]

Originally posted by Ride1Rob
It's overdue for you to get a rebuild. how many hours should you go before a rebuild?

[jshtex]

The service manual says to check the top end every 20 hours. But thats seems a bit soon to me. We replaced ours every season along with a new cyl (around 40 to 50 hours) and we still had a piston failure so consider yourself lucky.

If you really have 400 hours you should at the very least have it tore down and checked out NOW.

While your in there replace some of the cheap stuff like timing chain and valve springs. It may not need them but they are cheap!

In the beginning they had trouble with the GYTR pistions, I don't know if that is still true or not.

[Ride1Rob]

What he said! These motors are built to perform and aren't going to last like a 400ex or Z400 without maintnance. It also depends on how you ride/abuse it. I pound mine when I ride it so I'll do a check at least every six months (Check valves, piston, crank). I intend on doing topend rebuild once a year, I'll change valves as needed, and change crank at least once every two years.