When is a good time to get a new top end?

Depends on how it was used. People will replace their top end sooner to avoid catastrophe ($$$$ if the top end explodes). Some replace it because they race, some replace because they notice power loss or compression loss.

My buddies 99 RM 250 went until this year on the same top end (well since he bought it in 2001). I convinced him to replace it and says there's no difference in power. But one less thing that old bike has to worry about.

I still have the stock top end on my 2005 YZ 250. It's due to be replaced soon. I don't race, or beat on my bike, I ride trails and the power is so good I usually lug it around in 3rd - 4th gear.

But it is still better safe than sorry.

My buddies 99 RM 250 went until this year on the same top end (well since he bought it in 2001)

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I still have the stock top end on my 2005 YZ 250

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You can't compare a 250 2t to a 125 in terms of piston/ring/cylinder wear. Not even close. Trail ridden 250 2t's can go a very long time on a piston. 125's however.... I'd honestly be surprised if the plating is in any sort of usable condition on a 125 that's run the stock piston/rings for 8 years.


Rich's answer is the best one this thread will get, btw.

Maybe the bike was only ridden once a year for about an hour at a time, then it'd sill have some life left.


Seriously though, I agree with Rich 100%. You've already gone WAY to long, even if the bike is only ridden once a month.

A good time to prevent catastrophic failure, and keep it running top notch, is clearly marked in every manual I have ever seen. Regardless of what ever a person can figure, an hour is a hour. A farmer or a racer, abuse and neglect are a dirt bikes worst enemies. Money and scared to jump in and fix it are the number one drugs of choice? About 200 people in the good old U.S.of A. are capable of riding the bike stock fast enough to need/be able to use more power. You and I are still going to go the same speed if we had a rocket bike! You CAN save yourself a lot of grief, or learn the other way. The damage is done, and getting a worn/abused motor back into shape is an expensive, and sometimes seemingly hopeless job. BUT, it can be fixed!