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damaged plating

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Taking apart the top end this winter I found the plating has flaked off around the intake and exhaust port, but is perfect up where the rings are. Is this going to spell certain disaster? I just trail ride (1988 cr250r) really. Obviously the problem that started all this was the water pump rotting and pluggin my rads long enough to burn the piston. I have a new piston and I am wondering if some flakes will cause it to burn out in no time. Plating is over $300 so I'm looking to not do that.

Any thoughts?

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Millenium will plate the cylinder for right around $200. I Just had a cylinder done.

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Millenium will plate the cylinder for right around $200. I Just had a cylinder done.

By the time you pay shipping each way with insurance it is $300.00 or more.

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If the plating is flaking off the new piston probably won't last very long. IMO it would be a waste of money. I would either have the cylinder replated or buy a new one. Weigh out these two options and go with the cheapest route.

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I would either have the cylinder replated or buy a new one. Weigh out these two options and go with the cheapest route.

Yep, shop around, I got quoted a price for a replate and then a shop said he could get me a new cylinder for $100, more.

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thanks guys,

I have been shopping around since October, but there just don't seem to be any usable cylinders for an 88.

I have a guy looking at it right now to see if he can replate it. He is local, as in small town ontario and I'm not sure the material he uses but it is not the nika-sil or whatever most people use. It is the brother-in-law of the machine shop I dropped it off at, apparently the guy just does performance engine work so I assume he must have some idea of what he's doing.

I'll report back when I get the details.

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Have you talked to Millennium's distribitor in Canada, Fast Enterprises there near Winnipeg.http://www.mt-llc.com/Contact/contact.html

In B.C. most shops use mongoose for replating.

http://www.mongoosemachine.com/products.htm

Edit: On second thought you might be alright with the local guy, I got away with just a light hone on Nikasil, and the local guy did a really good job.

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By the time you pay shipping each way with insurance it is $300.00 or more.

Mine cost $237 with shipping. It was $30 more only because my cylinder required welding because the plating was worn through. A new cylinder was cosiderably more money than the replate was. When you get it back its tough to tell it apart from a new cylinder.

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If there is any way that you can swing it, get the cylinder re-plated. You'll be good to go for a long time then.

:banana:

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It's ok to run a cylinder with missing plating as long as the piston to cylinder clearances are within reason (think .0035"ish max with a new piston and replace by .0045". and the bore isn't severely tapered (usually loose in the top and middle and tight in the bottom. Plating usually wears through first at the bottom of the ports. I've run cylinders with 1/4 inch diameter sections of plating missing. They've ran for 2-3 pistons without failures before finally going to the platers.

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I have the same problem on my cr250r '04, another option that I have considered is getting a sleeve put in, $90 for e sleeve, then about $50 for a machine shop to bore out and install the sleeve.

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It's ok to run a cylinder with missing plating as long as the piston to cylinder clearances are within reason

No. Aluminum (piston) running on aluminum (bare spot on cylinder) is not good and will result in galling and eventual seizure. Unless the cylinder is cracked or has major damage your best bet would be to have it replated.

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how come on my 83 xr80 I can run it without plating? I had it bored over with a new piston last summer and no issues, is it just with 2-strokes that you plate?

since it would be $150 to get the welder to fix the cracked skirt and $300 for the new plating I bought a cylinder off ebay for $80. the bore looked a touch corroded but we'll see what a quick hone will do...

Does anyone out there know if normal nickel plating will hold up? part of my job involves replating in silver and nickel but nothing else. I could easily touch up any bad spots with straight nickel.

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how come on my 83 xr80 I can run it without plating?

Your XR80 comes with a steel sleeve from the factory.

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Don't sleeve your plated cylinder. Plating is far superior and the cost isn't much greater. Plus, it will save you money in the long run because plating will last for many pistons while sleeves have to get bored during piston changes which costs extra.

Forshee, yes aluminum pistons riding in an aluminum cylinder will gall and seize. But, when running a piston in a cylinder with only a few bits of plating missing is ok. Basically what happens is that bare aluminum spot wears away so quickly vs. the plating surrounding it that it no longer makes contact with the piston skirt. Therefore, the galling and seizing doesn't happen. Beyond that, I said that the plating usually wears through below the ports first. At that part of the piston's stroke, combustion pressures are already negligeable so blowby isn't an issue.

Heck, my bike eats up pistons faster now that I've had it replated (I think US Chrome botched the honing). Anyways, I've run and seen cylinders run with missing plating, cracked exhaust bridges, etc... The plating is never the cause of failures in these engines, it's always excessive piston hours. Change those pistons often.

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