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2002 CR 125 Cylinder Tech

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Been a while since I have been on here. I bought a jeep :banana:🤣

ANYWAYS! I have my 02 CR 125. Well when I rebuilt the whole thing a year or 2 ago, (top and bottom), I didn't replace the chip in the cylinder because I was broke, it was minor, and I would deal with it later. Yeah well it is later. My question is, is there any other route besides dropping 250-300 bucks on a new cylinder? I dont really have the money and I WANT TO RIDE. So bad. I am pretty sure I cant sleeve it, and getting it replated will cost close to the same wont it?

Teach me the ways :banana:

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No, you don't have to get it replated. Chips aren't necessarily detrimental. 2-stroke cylinders are very tolerant. It's the pistons you have to worry about. I've run 2-stroke cylinders with the plating worn through to aluminum over large areas, I've run them with cracks, etc... The cylinders don't fail. Watch the piston hours and watch the skirt to cylinder clearances. On a 125, don't let the new piston to cylinder clearance exceed .0025" and don't let the worn clearances exceed .0045 inches and you wont see failures.

Also, think about the worst case. It's $200 to repair the cylinder like new so it wont fail. If it does fail and you gouge the **** out of it, it's $225 to repair the cylinder like new. You do the math and figure out what makes sense to you.

But, if you want to keep an engine reliable, just replace the piston regularly. I get about 20 hours of mixed trail riding on my CR250 before I'm absolutely due for a new piston.

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No, you don't have to get it replated. Chips aren't necessarily detrimental. 2-stroke cylinders are very tolerant. It's the pistons you have to worry about. I've run 2-stroke cylinders with the plating worn through to aluminum over large areas, I've run them with cracks, etc... The cylinders don't fail. Watch the piston hours and watch the skirt to cylinder clearances. On a 125, don't let the new piston to cylinder clearance exceed .0025" and don't let the worn clearances exceed .0045 inches and you wont see failures.

Also, think about the worst case. It's $200 to repair the cylinder like new so it wont fail. If it does fail and you gouge the **** out of it, it's $225 to repair the cylinder like new. You do the math and figure out what makes sense to you.

But, if you want to keep an engine reliable, just replace the piston regularly. I get about 20 hours of mixed trail riding on my CR250 before I'm absolutely due for a new piston.

Thats good news. I have to post some pictures up of it. See, I know I am losing compression over it most likely, but if it isnt damaging anything, and it is saving me money, maybe I can get a new top end now, then come summer, rebuild her right.

And when you are talking clearances, how do ya measure that? Feeler gauges?

Thanks for the help BTW!

On the other hand, I dont want to have spend 120 bucks on a top end if it isnt going to last as long, and i am going to replace it as well as a cylinder just after a few months. Grass should be growing again here soon, I have a job, and I will have prom, my new Jeep tires, and senior week paid off before I know it so hopefully my baby can get some lovin again. She is jealous of my new toy :banana:

SSPX0514.jpg

Edited by MXBoy11

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No, you don't have to get it replated. Chips aren't necessarily detrimental. 2-stroke cylinders are very tolerant. It's the pistons you have to worry about. I've run 2-stroke cylinders with the plating worn through to aluminum over large areas, I've run them with cracks, etc... The cylinders don't fail. Watch the piston hours and watch the skirt to cylinder clearances. On a 125, don't let the new piston to cylinder clearance exceed .0025" and don't let the worn clearances exceed .0045 inches and you wont see failures.

Also, think about the worst case. It's $200 to repair the cylinder like new so it wont fail. If it does fail and you gouge the **** out of it, it's $225 to repair the cylinder like new. You do the math and figure out what makes sense to you.

But, if you want to keep an engine reliable, just replace the piston regularly. I get about 20 hours of mixed trail riding on my CR250 before I'm absolutely due for a new piston.

Advice like this is what keeps repair shops in business.

If there is a chip in a port edge, then a decent mechanic should be able to chamfer it, and as long as the rest of the bore is in good shape you will probably be ok.

However, if the chip is between ports, or linking ports horizontally, then a replate should be done.

The rule of thumb is if you can catch a fingernail on it, you WILL catch a ring on it and do much more damage.

I recommend PowerSeal for replating work. They are the best I have used. http://www.powersealusa.com

-Steve

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Advice like this is what keeps repair shops in business.

If there is a chip in a port edge, then a decent mechanic should be able to chamfer it, and as long as the rest of the bore is in good shape you will probably be ok.

However, if the chip is between ports, or linking ports horizontally, then a replate should be done.

The rule of thumb is if you can catch a fingernail on it, you WILL catch a ring on it and do much more damage.

I recommend PowerSeal for replating work. They are the best I have used. http://www.powersealusa.com

-Steve

Well I went outside to look at the chips (theres 2 I forgot :banana:) and right now, you can catch a fingernail on them, so it will be no dice. I took it all apart about a year ago (holy shit, it doesnt feel that long) and it had been sitting since. But anyways, when I rebuilt it 2 years back (top and bottom) I left the chips in there like this. They didnt cause any problems, just a little loss in power. And then they burned themselves in nice and deep now. One is probably 5 times deeper, which is what worries me because nikasiling might cost a shit-ton now because it is so deep. I have never dealt with replating, but we shall find out. I may call for a quote

Chip is in the top of the picture

Cylinder004-1.jpg

Scoring

Cylinder003-1.jpg

Scoring

Cylinder002-1.jpg

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OKay so I just got sick of trying to explain. Here are all the ports

First three pics are the same port

IMG_3790.jpg

IMG_3791.jpg

IMG_3792.jpg

IMG_3793.jpg

IMG_3794.jpg

IMG_3795.jpg

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Send it to Millenium Technology. They will weld and replate that cylinder and it will look like a new cylinder. I just had my wifes 125 done and it was $237 with the shipping including welding. They did a nice job.

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Send it to Millenium Technology. They will weld and replate that cylinder and it will look like a new cylinder. I just had my wifes 125 done and it was $237 with the shipping including welding. They did a nice job.

Thats pretty damn good. I was wondering if it needed welding too. I should just port and polish it haha :banana:

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+1 on sending it to Millenium. I just had a cylinder done there and they did an awsome job!! From the looks of your cylinder it needs to be replated.

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+1 on sending it to Millenium. I just had a cylinder done there and they did an awsome job!! From the looks of your cylinder it needs to be replated.

What did you pay? And how bad was yours pncstod?

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Looking at the pictures, it doesn't appear that welding will be needed.

PowerSeal's price is $179 + shipping for a replate. You just have to make sure to strip all the stuffs from the cylinder (studs, power-valves, guides, etc...) If they have to pull those pieces out there will be an extra charge.

I've used UsChrome, Millennium, Langcourt, and PowerSeal. PowerSeal gets all my business now. Simply the best work I've seen, and by FAR the best customer service.

-Steve

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Looking at the pictures, it doesn't appear that welding will be needed.

PowerSeal's price is $179 + shipping for a replate. You just have to make sure to strip all the stuffs from the cylinder (studs, power-valves, guides, etc...) If they have to pull those pieces out there will be an extra charge.

I've used UsChrome, Millennium, Langcourt, and PowerSeal. PowerSeal gets all my business now. Simply the best work I've seen, and by FAR the best customer service.

-Steve

How much extra would it be to do all that? The last thing I need is to break off a cylinder stud trying to get it out.

I am used to working on Jeeps, where every bolt breaks. Is breaking a cylinder stud common?

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Looks good to me. Go in with a die-grinder radius the edges of the chip and remove that chunk of metal sitting there. Also, either wash the cylinder with a caustic solution like EZ-Off or run a ball hone through it to remove any aluminum deposits on the wall.

Your cylinder does not need to be replated... yet.

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Advice like this is what keeps repair shops in business.

-Steve

Advice like this keeps repair shops in business.

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My wifes cylinder was pretty bad. The whole motor grenaded. I didnt have the chunking where the ports are on yours but had gouging through the plating that required welding. Just double nut the studs and remove them, no big deal on removing the studs.

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PowerSeal is about 20 minutes from my house. :banana:

But the questions is...do I plate it or not hehe

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But the questions is...do I plate it or not hehe

It's your cylinder, and it will be you riding the bike. The better question would be: "do you trust it like it is?" If the answer to that question is not 100% yes, then have it replated.

If you go to PowerSeal, tell them Steve from Moto814 said hi!

-Steve

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