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250 Top End Life

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How many hours are you woods rider getting on a top end with the 250. I mean a decent maintenance schedule not the "I have 150 hours and it runs fine". :smirk:

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I put 80 on the stock piston. 25 of which was from the previous owner riding mx. I rode about 5 hours in glamis and the rest CO singletrack. Piston still looked good I mix at 36:1 or so with 2-r. You should be able to get about 100 or so but you can tell it's getting a little tired.

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I change em at 50 hours.

When clearances were getting on the large side (but still within service spec) I had a cast piston come out at 50 hours with cracks in the skirt, and it literally dropped a piece off as I set it on the bench.

I do ride fairly hard though, B level harescramble rider, did make it to A class for a little bit (but ride 1/50th what I used to now).

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I ran 65 hours last time and although it ran fine, you could hear a little piston slap when it was cold. :smirk:

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I pulled my first piston at 66hrs and could have left it in for another 60 probably. It was totally fine. I run my bike hard too. I've only used Amsoil Interceptor synthetic almost exclusively that whole time and kept the jetting pretty spot on.

My bike is now at about 115hrs but I think I'll wait another 25-30hrs before I replace the piston.

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These include ring changes? Forgot to mention I'd only use forge pistons, not the stock cast ones.

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These are my general consensus from the knowledgeable members I trust on these boards.

Re-ring and inspect at 25 hours and replace at 50 hours.

That is for mx riding. Putting around on trails or fields, and you could easily double or triple those times.

I ride pretty hard and my life in constantly in the hands of the mechanical condition of the bike. 150$ for a new piston is much cheaper than having a failure at the worst time.

Since you are woods riding, it just depends on the type of trails. If you're constantly lugging the bike through slow technical sections, I would increase those times.

If you're screaming around on sandy river banks, etc., those times won't hurt.

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I agree with the above post... I re ring at 25 and replace piston at 50 for mx.

On my play bikes which I do about 75% mx practice and 25% woods on I re rering at 50 and replace piston at 100. Never had one fail. Just from my experience. No rhyme or reason behind it, it just works.

Edit: this is with a Wiseco forged piston

Edited by ftball90

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I have seen too many cast skirts come unscrewed to push it past 50hrs on my bike. a forged one maybe.....but not as long as I have an income.

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I don't re-ring at all. IMO Aluminium is softer than steel, so the piston wastes earlier. 40 to 50 hours and a new top end is due, for me. I know a guy who runs his piston 'till his bike does not start any more. He is now at about 200 hours. The bike pisses spooge but it runs. It is a 125 though.

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I don't re-ring at all. IMO Aluminium is softer than steel, so the piston wastes earlier. 40 to 50 hours and a new top end is due, for me. I know a guy who runs his piston 'till his bike does not start any more. He is now at about 200 hours. The bike pisses spooge but it runs. It is a 125 though.

he prolly cleans the filter when it won't get on the pipe too....lol

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my friend has an 06 cr 250 that has been ridding the enduro circuit ever year since new plus lots of trail riding in between, it still runs but i think it has about 20 psi the way it acted last weekend, think he is going to top end it finally, no telling how many hrs he put on this thing, he never washes it, it gets washed going through steams or if it sets out over nite at a enduro it rains out, its a total heap and the stupid thing just keeps on running !

sad part is he has money for new ones but just won't spend it or do any repairs unless it breaks or falls off ! or in this case no more compression to start with. mine won't ever let me get away with such..................

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my friend has an 06 cr 250 that has been ridding the enduro circuit ever year since new plus lots of trail riding in between, it still runs but i think it has about 20 psi the way it acted last weekend, think he is going to top end it finally, no telling how many hrs he put on this thing, he never washes it, it gets washed going through steams or if it sets out over nite at a enduro it rains out, its a total heap and the stupid thing just keeps on running !

sad part is he has money for new ones but just won't spend it or do any repairs unless it breaks or falls off ! or in this case no more compression to start with. mine won't ever let me get away with such..................

He should probably budget for a re-plate.... At least. Probably a bottom end at the same time.

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Just took out my stock piston in my 2001 kx250 yesterday. . . It looks really good considering it has been in for 10 years and I ride almost every day for atleast an hour or two.

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Just took out my stock piston in my 2001 kx250 yesterday. . . It looks really good considering it has been in for 10 years and I ride almost every day for atleast an hour or two.

So 3650-7300 hours on it?

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He should probably budget for a re-plate.... At least. Probably a bottom end at the same time.

not unless it slings a rod out, he won't replace till the piston start hitting the head, some people can ride for ever, i can't be that lucky.

at one enduro the only thing holding his muffler on was bailing wire with just one twist and it was a extremely rough and rocky enduro .

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Just took out my stock piston in my 2001 kx250 yesterday. . . It looks really good considering it has been in for 10 years and I ride almost every day for atleast an hour or two.

my 92 i rode it a lot the first 4 years and then off and on again till 09 when i did a total resto, never turned a wrench on the motor, almost no carbon and everything looked to be in excellent condition, still had good cross hatch marking. you can get good mileage out of a engine if your not just trying to kill it every time you ride it, i raced mine in enduro's and few x-country's but i never abused it either since i was the one that had to pay for all my repairs.....

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Stories like that make me feel good about owning a 2 stroke.

Different kind of bike, but I knew a guy who had a kdx220 who ran that thing pretty hard for 7-8 years without doing a top end.

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I run the cast OEM piston and change it every 20-25 hrs. No re-ringing. Only MX riding.

I was always stumped why some people try to squeeze every last hour out of their pistons, at the risk of catastrophic failure. It gives me peace of mind changing it frequently (costing about 80 bucks) and I don't carry the risk of shattering a piston and ruining my head, cylinder, and possibly crank (costing up to $1000).

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