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How bad is this cylinder?


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well bought the bike (yz 125) off craigslist and the previous owner said the piston was never changed and the bike was run till it lost compression and then finally stopped running. Appears to be a decent score mark on the cylinder. Feels pretty deep. So can anyone tell me if this is gonna be repairable without having to change the bore size of the cylinder? (Pics aren't the best but couldnt get any better than that.) I am not really interested in having a yz144 i'd like to stay stock if i can.

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I know in the usual top end job, it normally requires an amount of boring and buying a specific sized piston to fit that bore in order to restore compression, and the capability of running again. I would say it is defiantly needed to bore this one, as in most top end jobs there can be NO disguising scoring marks of the cylinder, and boring is still needed.

How ever, you don't have to make it a 144cc. That's a performance up grade all over. Not one for replacing a top end. If the scores are deep enough, you may have to get it sleeved, then bored back out to original size. Then, in terms of cc's, i believe your bike will be completely stock.

I'm just now getting back into the two-strokes, so don't take what I say to be 100% correct. But if i were you, i would bore it out a few mm's(if the scores aren't to deep) and spend like $100 for a set piston and rings. I believe the usual price for boring is about 50 bucks, so that plus gaskets, Maybe $200 and you can have your self a fresh, running bike.

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nakasil plated cylinder requires boring and replating.

I bet you can find a good used cylinder somewhere.....

Its either bite the bullet and bore/plate, find used or buy new....

I dont think its repairable without boring

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I just had a 2003 YZ250 cylinder with similar ring damage above the exhaust port repaird by Power Seal USA. They charged me $240 including the return shipping, it took about three weeks total.

They strip out the old plating and weld up the damaged area, then they bore and re-plate the cylinder and hone it to spec.

Their work on my cylinder was flawless.

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Check out langcourt.com the company is Alabama. My 125 cylinder had been sleeved before I got it therefore I could not have it plated but the price they were going to charge me to replate it was about $175 or something like that. Instead, they bored the cylinder over 2 mm (and cut the powervalves back) matching it with a wiseco piston they got for me and shipped back for $155...I'd at least give them a call and see what they can do for you. Real nice people

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Thanks for the responses guys. I am gonna check out that "langcourt" place. Maybe power seal since they are right in PA. But it's all gonna come down to which place is cheaper and has good quality work as well.

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PowerSeals normal price is $180 for the plating, so they are right there with that Langcourt place (within $5).

All of the shops that do re-plating charge extra if you need welding, boring, powervalve work or any other work besides just a plain-vanilla strip and re-plate job.

Whatever you do, don't let anyone talk you into putting a sleeve in there. They do not perform as well as plating, nor do they last as long as plating.

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that can be fixed. millinum,us crome ericc gorr, they can fix that. i was riding an ericc gorr 144 yesterday it runs great i would definatly do it. and it only cost 500 for everything piston and gaskets cant beat it.

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nakasil plated cylinder requires boring and replating.

I bet you can find a good used cylinder somewhere.....

Its either bite the bullet and bore/plate, find used or buy new....

I dont think its repairable without boring

You don't bore a nikasil cylinder to repair it. The only reason to bore it is if you want to go bigger.

When you send a cylinder in for re-plating, they give it an acid bath to strip all the old plating. They then weld new material into any gouges and machine it back round. The new plating is applied, and the final step is to machine the plating to the correct clearances for the piston being used. You either have to send a new piston with the cylinder, or they will supply one, but they need the piston that is going to be run in order to machine to the proper clearances. They can simply machine to the original OEM specs, but if they actually measure the piston being installed the clearances will be perfect, rather than just approximate.

That cylinder is easily repairable, and it will come back better than new. Most re-platers use a higher quality composite than OEM, especially if you ride a Kawasaki with the OEM electrofusion hard-coat.

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