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less than an hour cylinder

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I pulled my top end with less than 1 hour on my yz125 cause it just didn't seem right and this is how my cylinder looked. I just had the cylinder replated/repaired and matched to a wiseco piston. All work was done by powerseal. Any advice on why this happened? Should I be contacting powerseal ?

DSCN0568.jpg

DSCN0566.jpg

Edited by KJK_JR

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I pulled my top end with less than 1 hour on my yz125 cause it just didn't seem right and this is how my cylinder looked. I just had the cylinder replated/repaired and matched to a wiseco piston. All work was done by powerseal. Any advice on why this happened? Should I be contacting powerseal ?

Excuse me good sir, I believe you have forgotten your picture.

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Excuse me good sir, I believe you have forgotten your picture.

thanks :bonk:

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thanks :bonk:

No problem! Anyways, that looks really weird, I would get in contact with powerseal and see what they say.

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You've got bare aluminum showing on the exhaust bridge. That's not normal but it's not exactly detrimental. The bridge needs to be ground for extra clearance. It looks like it was ground a little thin. How does the piston look? I see a lot of scuffing down low, a lot for 1 hour of riding on a new cylinder. How was your piston to cylinder clearance? How hot did you get the piston? Jetting?

Edited by 1987CR250R

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You've got bare aluminum showing on the exhaust bridge. That's not normal but it's not exactly detrimental. The bridge needs to be ground for extra clearance. It looks like it was ground a little thin. How does the piston look? I see a lot of scuffing down low, a lot for 1 hour of riding on a new cylinder. How was your piston to cylinder clearance? How hot did you get the piston? Jetting?

The piston doesn't look bad aside from a few slight scuff marks (i'll post pics tomorrow). Like i said I had powerseal match the piston to the cylinder so I'll have to double check that measurement. I only went trail riding with it so i can't imagine it got too hot. Jetting was a little on the rich side.

Edited by KJK_JR

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Not a COMPLETE warm up before running full throttle. Simple,,a 15 second blast with a new cylinder can do this.

Also is this a Wiseco? does it have the oil holes drilled?

Edited by scalejockey

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Your cylinder was worn out when you sent it in to be re-plated, instead of repairing the cylinders surface then re-plating it, they simply replated it and honed it for you, you can see the worn out sections from the earlier wear pattern under the plated section.

Edited by ncc

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Not a COMPLETE warm up before running full throttle. Simple,,a 15 second blast with a new cylinder can do this.

Also is this a Wiseco? does it have the oil holes drilled?

I let it warm up properly before i rode it. The cylinder was warm as well the radiators before I rode it. It is a wiseco piston and I didn't drill any holes.

Your cylinder was worn out when you sent it in to be re-plated, instead of repairing the cylinders surface then re-plating it, they simply replated it and honed it for you, you can see the worn out sections from the earlier wear pattern under the plated section.

my cylinder was actually damaged and required welding

DSCN0271.jpg

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What mechanical failure caused that damage? Did you beak a piston or was that debris from the crankshaft?

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What mechanical failure caused that damage? Did you beak a piston or was that debris from the crankshaft?

not sure, i bought it like that. I think the circlip came out on that one.

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Well you can do piston to cylinder clearances on you bike by simply slipping a feeler gauge between the piston and cylinder. Do it at the bottom of the skirt. It never hurts to double check this. There is a lot of polishing down low in the cylinder. The missing plating on the exhaust bridge really doesn't concern me that much. I've run my Honda's for many many hours with worn through plating on the exhaust bridge.

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I let it warm up properly before i rode it. The cylinder was warm as well the radiators before I rode it. It is a wiseco piston and I didn't drill any holes.

my cylinder was actually damaged and required welding

DSCN0271.jpg

Even though they repaired the welded spot, in your picture you can still see the previous wear pattern from the piston through the replate on the exhaust side.I still think it was not round after the weld and then re-plated. IMHO

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Even though they repaired the welded spot, in your picture you can still see the previous wear pattern from the piston through the replate on the exhaust side.I still think it was not round after the weld and then re-plated. IMHO

I doubt it considering they strip the old plating, weld, then bore then replate with thicker plating before they finish hone.

On the other hand, it looks like the exhaust bridge got hot and swelled into the piston. Normally the exhaust bridge is relieved a bit by the plater to prevent that. also, the lube holes in the piston help too.

I would not consider running that again without contacting PowerSeal about it. The piston may not do any damage to that bridge, but the rings will keep tearing away at the aluminum and could tear the plating off of a larger part of the bore. As is, it should be re-plated.

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Your exhaust bridge is fine. Its purposley done that way specialy if it was modified (144?)to relieve the stress put on the piston at the bridge. If it was missing the plating wou would be able to clearly see it and catch it with your fingernail. I would also drill relief holes int the piston if your running vertex or wiseco prolite. As for the scores. thats pretty much inevitable. Ive tried every thing ever imaginable to keep dirt out of the cylinder. Some will always make it.

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can't seem to get a good pic of the piston, but it does have the holes drilled on the exhaust side of the piston.

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I contacted powerseal and they said to send the cylinder and piston in. So hopefully it's something thats covered under warranty. Here's a pic of the piston.

DSCN0576.jpg

DSCN0575.jpg

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Piston looks good... i would have to say that it was a minor issue in the repair process. My guess is that they will replate it and all will be good to go. Def not a cold seize issue or we would see other signs.

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Piston looks good... i would have to say that it was a minor issue in the repair process. My guess is that they will replate it and all will be good to go. Def not a cold seize issue or we would see other signs.

I agree.

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