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02 CR250 cracked piston skirt.

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hi i took mt top end off to put a new piston in and noticed there was an inch long crack near the bottom back side of the piston. i dont know how many hours were on it. is this common the piston was cast and it had ART stamped on it. i also had the cylinder measured. it was 66.4. im hoping i dont need to go threw all this crap of paying 400 dollars to get the thing replated. its not scratched or scored.

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hi i took mt top end off to put a new piston in and noticed there was an inch long crack near the bottom back side of the piston. i dont know how many hours were on it. is this common the piston was cast and it had ART stamped on it. i also had the cylinder measured. it was 66.4. im hoping i dont need to go threw all this crap of paying 400 dollars to get the thing replated. its not scratched or scored.

It happens, that is why you need to change them at regular intervals. There is a lot of stress on piston skirts. Ive had one crack there as well. Do yourself a favor and change your piston its cheap insurance. As long as the cylinder isnt scratched or the plating isnt rubbed off your good to go.

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hi i took mt top end off to put a new piston in and noticed there was an inch long crack near the bottom back side of the piston. i dont know how many hours were on it. is this common the piston was cast and it had ART stamped on it. i also had the cylinder measured. it was 66.4. im hoping i dont need to go threw all this crap of paying 400 dollars to get the thing replated. its not scratched or scored.

i dont see why your complaining. engines wear out. if you cant accept that then sell the bike. plating can be shot but still look good. thats why they have measuring tools :smirk:. all the specs are listed in the oem service manual

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i dont see why your complaining. engines wear out. if you cant accept that then sell the bike. plating can be shot but still look good. thats why they have measuring tools :smirk:. all the specs are listed in the oem service manual

I suggest that you find somebody (other than yourself) to have sex with.:bonk:

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hoping i dont need to go threw all this crap of paying 400 dollars to get the thing replated.

sounds like complaining to me. buy a new bike next time and you wont have to worry if it has 1277456 hours. by the way replate is only $250

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hi i took mt top end off to put a new piston in and noticed there was an inch long crack near the bottom back side of the piston. i dont know how many hours were on it. is this common the piston was cast and it had ART stamped on it. i also had the cylinder measured. it was 66.4. im hoping i dont need to go threw all this crap of paying 400 dollars to get the thing replated. its not scratched or scored.

The stock piston is cast as you're aware and they will wear out after 5-200+ hours depending on your bike, riding type, tuning, etc. You'll hear many opinions on how many hours a cast piston can go. I've heard that, on average (for trail ridden & occasional track days, 2 strokes ridden by non-expert level riders) 125's will get 20-40 hrs, 250's 40-80 hrs, and 500's 100-200+. People who race motocross competitively will can wear out a piston in a race, supposedly. For reference, I have a CR125 and I just replaced my OEM cast piston after 40+ hours and it wasn't damaged (I didn't check specs on the piston because I don't own a caliper, but the ring end gap was still within spec and had .002" left.

When the clearance between the piston and cylinder become large from wear the piston skirts slap the cylinder on the front and back and typically will crack. Sometimes this is catastrophic and can send fragments into the crankcases, cylinder/head, etc causing costly repairs. You're lucky you caught yours before that happened.

I'd have your cylinder checked by a mechanic for size, taper, out-of-round, and plating inspection. If alls good then you can just throw in a new piston kit. Otherwise, you can have a cylinder replated at a number of places. Powerseal and Millenium have great reputations (Powerseal repaired mine perfectly!) and can plate/hone your cylinder for ~$200. If it needs welding from damage then add $40-50.

If you aren't very good at maintaining your bike and checking specs then you can go with a forged piston, which will be a little stronger and resist cracking like the cast pistons. However, I'd recommend buying OEM and just replacing them at a decent frequency depending on how you ride/take care of air filter, pre-mix, etc..

By the way, everybody claims the aftermarket plating companies have superior plating over the OEM's and is thicker and more durable. This will allow you to get more top ends before needing replating compared to just buying a new cylinder.

Good luck and keep up the maintenance on that thing!

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i dont see why your complaining. engines wear out. if you cant accept that then sell the bike. plating can be shot but still look good. thats why they have measuring tools :smirk:. all the specs are listed in the oem service manual

i wasnt complaing dont wirt me ass hole comments keep those to yourself. TROLL.

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sounds like complaining to me. buy a new bike next time and you wont have to worry if it has 1277456 hours. by the way replate is only $250[/QUOT keep your prick comments to your self dicky licker.what do you do get in a bad mood and go crashin in on people on the internet. i aint taking no shit off you jack ass.go suck a you know what.

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You know, at first, I was going to do some clean up here, perhaps provide an infraction however... I find the complainer is the worse infractor! So either I infract and delete this thread or simply leave, close it as an example on how not to behave.

Guess what I decided.

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You know, at first, I was going to do some clean up here, perhaps provide an infraction however... I find the complainer is the worse infractor! So either I infract and delete this thread or simply leave, close it as an example on how not to behave.

Guess what I decided.

You're getting soft. :smirk:

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