CR125 chipped cylinder

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2/27/2019 11:19 AM

Hello, I recently bought a 96 CR125. It was running but the motor locked so I rebuilt everything. The cylinder sleeve and piston showed signs of metal or dirt floating around, so I honed the cylinder, put in a new piston kit. I've cleaned everything and everything looks good. However, on the bottom of the cylinder jug, there's a chip of it missing (previous owners probably tried to redneck resleeve it) and it was crumbling a little bit. I did my best to grind it smooth, I'll probably have to do it again. I have a picture of it before I buffed it. My question is, should I just get another cylinder jug? Or can I grind it flat and be good? I understand I have to be careful that I don't touch the gasket surface or it won't seal. Photo It has a piston sleeve so I don't think it will affect the piston..

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2/27/2019 11:23 AM
Edited Date/Time: 2/27/2019 11:26 AM

king_halsey wrote:

Hello, I recently bought a 96 CR125. It was running but the motor locked so I rebuilt everything. The cylinder sleeve and piston showed signs of metal or dirt floating around, so I honed the cylinder, put in a new piston kit. I've cleaned everything and everything looks good. However, on the bottom of the cylinder jug, there's a chip of it missing (previous owners probably tried to redneck resleeve it) and it was crumbling a little bit. I did my best to grind it smooth, I'll probably have to do it again. I have a picture of it before I buffed it. My question is, should I just get another cylinder jug? Or can I grind it flat and be good? I understand I have to be careful that I don't touch the gasket surface or it won't seal. Photo It has a piston sleeve so I don't think it will affect the piston..

Looks like the sleeve is off center/rotated. That cylinder is trash and if they ground on the power valve those too. Look for a non-sleeved used cylinder or new OEM.

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2/27/2019 11:34 AM

king_halsey wrote:

Hello, I recently bought a 96 CR125. It was running but the motor locked so I rebuilt everything. The cylinder sleeve and piston showed signs of metal or dirt floating around, so I honed the cylinder, put in a new piston kit. I've cleaned everything and everything looks good. However, on the bottom of the cylinder jug, there's a chip of it missing (previous owners probably tried to redneck resleeve it) and it was crumbling a little bit. I did my best to grind it smooth, I'll probably have to do it again. I have a picture of it before I buffed it. My question is, should I just get another cylinder jug? Or can I grind it flat and be good? I understand I have to be careful that I don't touch the gasket surface or it won't seal. Photo It has a piston sleeve so I don't think it will affect the piston..

Hondas4Life3 wrote:

Looks like the sleeve is off center/rotated. That cylinder is trash and if they ground on the power valve those too. Look for a non-sleeved used cylinder or new OEM.

So I should just get rid of the cylinder core and get a new one? I prefer sleeving so if something screws up I can hone it instead of nikasil coating, I have all the stuff needed to do sleeving jobs.
As for the power valve I rebuilt that too, one of the sliding valve sleeves is cracked so that valve sticks, I'll need to replace that

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2/27/2019 12:36 PM
Edited Date/Time: 2/27/2019 12:39 PM

Yes new cylinder. A nikasil cylinder is superior to a sleeved cylinder. There is a reason manufactures went away with lined cylinders. If the engine is properly rebuilt and maintained a nikasil cylinder will last longer on the bore and have better heat transfer.

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2/27/2019 12:56 PM

Hondas4Life3 wrote:

Yes new cylinder. A nikasil cylinder is superior to a sleeved cylinder. There is a reason manufactures went away with lined cylinders. If the engine is properly rebuilt and maintained a nikasil cylinder will last longer on the bore and have better heat transfer.

Alright, I will do that. Where's the cheapest place to have a cylinder nikasil recoated?

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2/27/2019 1:30 PM

Hondas4Life3 wrote:

Yes new cylinder. A nikasil cylinder is superior to a sleeved cylinder. There is a reason manufactures went away with lined cylinders. If the engine is properly rebuilt and maintained a nikasil cylinder will last longer on the bore and have better heat transfer.

king_halsey wrote:

Alright, I will do that. Where's the cheapest place to have a cylinder nikasil recoated?

I’ve used power seal and millennium technologies... both put out excellent work... I stick with powerseal now because they are a little cheaper also they do a beautiful job chamfering the ports on a two stroke

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2/27/2019 3:00 PM
Edited Date/Time: 2/27/2019 3:01 PM

That looks like very poor workmanship to me.

Paw Paw

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2/27/2019 3:10 PM

Hondas4Life3 wrote:

Yes new cylinder. A nikasil cylinder is superior to a sleeved cylinder. There is a reason manufactures went away with lined cylinders. If the engine is properly rebuilt and maintained a nikasil cylinder will last longer on the bore and have better heat transfer.

king_halsey wrote:

Alright, I will do that. Where's the cheapest place to have a cylinder nikasil recoated?

Paul_Pitzonka wrote:

I’ve used power seal and millennium technologies... both put out excellent work... I stick with powerseal now because they are a little cheaper also they do a beautiful job chamfering the ports on a two stroke

I'll look into that. I also found a nickel coating place nearby, or I could buy a cylinder that's already been coated. Thanks everyone for the input, you probably saved me a lot of tears and regret

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2/27/2019 3:12 PM

Paw Paw 271 wrote:

That looks like very poor workmanship to me.

Paw Paw

They clearly hammered it in or something instead of doing it properly ?

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2/28/2019 5:49 PM

You can not plate a sleeved cylinder with Nikasil. You will need a new cylinder and piston to do the repair correctly.
Do not waste any money trying to get a new sleeve installed. The cylinder is trash.
It's also a bad idea to buy a bad cylinder on eBay that needs plating. Once Millenium receives a cylinder they often need to weld cracks, plating is usually 150/200. Those 1996 cylinders have been discontinued for many years. Most likely you'll have to buy a used cylinder that needs plating. Call Millenium and see if they have a cylinder for sale. Also, call LA sleeve for a cylinder. DO NOT LET LA SLEEVE TALK YOU INTO ANOTHER SLEEVED CYLINDER, THEY WILL TRY.
The CR125 hates sleeved cylinders. They seize easily if you don't run the jetting rich. I'd buy this one quick.
With the cylinder and power valves, this is a good deal.

ebay

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2/28/2019 7:21 PM

speed_racer wrote:

You can not plate a sleeved cylinder with Nikasil. You will need a new cylinder and piston to do the repair correctly.
Do not waste any money trying to get a new sleeve installed. The cylinder is trash.
It's also a bad idea to buy a bad cylinder on eBay that needs plating. Once Millenium receives a cylinder they often need to weld cracks, plating is usually 150/200. Those 1996 cylinders have been discontinued for many years. Most likely you'll have to buy a used cylinder that needs plating. Call Millenium and see if they have a cylinder for sale. Also, call LA sleeve for a cylinder. DO NOT LET LA SLEEVE TALK YOU INTO ANOTHER SLEEVED CYLINDER, THEY WILL TRY.
The CR125 hates sleeved cylinders. They seize easily if you don't run the jetting rich. I'd buy this one quick.
With the cylinder and power valves, this is a good deal.

ebay

Funny you say that, I had to rebuild the engine BECAUSE it seized while I was adjusting the carb ? not a good day
I'll call and see if they have cylinders, I just gotta scrounge up the money to buy one. Everyone here has pretty much talked me out of cylinder sleeves so I'll get a plated one.

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2/28/2019 8:06 PM

iron sleeves can be plated, CR500s get it quite often, as do vintage bikes, etc.

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vomiting equals disqualification.

2/28/2019 8:12 PM

BR8ES wrote:

iron sleeves can be plated, CR500s get it quite often, as do vintage bikes, etc.

I wasn't going to plate a sleeve I didn't even know anyone could do that. I've only heard to hone them if they're scuffed

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2/28/2019 8:18 PM

BR8ES wrote:

iron sleeves can be plated, CR500s get it quite often, as do vintage bikes, etc.

king_halsey wrote:

I wasn't going to plate a sleeve I didn't even know anyone could do that. I've only heard to hone them if they're scuffed

I had mine done, many others have as well. Not trying to sell that to you, just saying it is done. If you can find a proper cylinder and have it bored/replated, that would be wise.

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vomiting equals disqualification.

2/28/2019 8:20 PM

BR8ES wrote:

iron sleeves can be plated, CR500s get it quite often, as do vintage bikes, etc.

king_halsey wrote:

I wasn't going to plate a sleeve I didn't even know anyone could do that. I've only heard to hone them if they're scuffed

BR8ES wrote:

I had mine done, many others have as well. Not trying to sell that to you, just saying it is done. If you can find a proper cylinder and have it bored/replated, that would be wise.

Yeah I'm gonna just get a new one that's been plated and try to sell that one. Maybe someone else can fix it and use it

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