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R60/2 my first /2 engine rebuild

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

R60/2 my first /2 engine rebuild

Post by Kurt V »

Like the title says, the first time I have rebuilt one of these engines. However, in the past, I’ve rebuilt a number of motorcycle engines, and car engines, including my 1986 Porsche 911. So I know if I take my time, and follow the directions in the Barrington manual, I should be able to do this. But I am going to have lots of questions from the group! I will try to keep all of my questions in this one thread so as not to clutter up the board.

My first one is, as you can see, the right side piston has scuffs on it. Any idea how they might have occurred? I would think the piston rings would keep the pistons far enough away from the cylinders to keep them from scuffing. Thanks!

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Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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Micha
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Re: R60/2 my first /2 engine rebuild

Post by Micha »

Can you also pls uploade pictures of the cylinder bore?
Michael Steinmann
R51/3 1952
Engine Nr. 529466

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: R60/2 my first /2 engine rebuild

Post by Kurt V »

Micha wrote:
Sat Dec 04, 2021 5:44 pm
Can you also pls uploade pictures of the cylinder bore?
I just wiped down the cylinder. I think I’ve got a problem. What would’ve caused this pitting? And is the cylinder no longer good?

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Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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Micha
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Re: R60/2 my first /2 engine rebuild

Post by Micha »

Yep, looks like a problem alright.
How long has the motorcycle been in your possession?
Could it be that in the past it had a problem with oil supply? Do you still have contact with PO?
Does the engine receives clean air? Dust free?
Did the machine stand for a long time? Out side? Can also be rust pitting.
There are many reasons that can cause this condition, and I think you need to go through a re-bore, which means also new piston & rings. Honing stones will not be able to help here. Sounds daunting but it's not that bad 8-) .
This is a good opportunity to go through a total engine check that will also include the famous slingers, oil supply bores, carburetors etc.

But let's wait for the real experts to come in and express their opinions.

Edit:
Kurt, the more I look at the pictures, the more confident I am that this is also a case of a piston that was "caught" inside its cylinder (don't know the english term for it) and then the piston was released again, hence the marks on it.
And, I'm quiet sure that if you will look carefully, you will find that the wear marks are mostly on the bottom of the piston, the side facing the ground: Apparently the engine was motionless for some time, and the rust developed there. It is very likely that after resting this way, that the engine was used and therefore the rust disappeared, but the pitting in the cylinder wall remained
Michael Steinmann
R51/3 1952
Engine Nr. 529466

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: R60/2 my first /2 engine rebuild

Post by Kurt V »

Michael, thanks for your response. The previous owner has a little knowledge of the engine. Your explanation makes sense. I agree, the bike probably sat around for sometime in the past.

I think my options are to either get a new cylinder, or at least a new to me cylinder, try and get it nikasil plated or see if it can be honed out and get an oversize piston.
Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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Micha
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Re: R60/2 my first /2 engine rebuild

Post by Micha »

I think it would be a shame to buy a new cylinder. You can easily re-bore the existing ones (yes, you will of course have to perform the operation on both sides) and purchase new suitable pistons and rings. Nikasil coating is AFAIK expensive and unnecessary in my opinion but that's up to you to decide (keep in mind that if you make this coating, you will in my humble opinion also have to purchase matching rings for such a coating).

What's most interesting here is why all this happened because it does not look like normal wear.
I think you should check those oil slingers, air supply etc.
Michael Steinmann
R51/3 1952
Engine Nr. 529466

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: R60/2 my first /2 engine rebuild

Post by Kurt V »

Michael, my first choice will be to get the cylinders bored out if it’s possible to do considering how deep the pits are. I think you’re correct in that the bike, sometime in the past, must have sat around and accumulated moisture in the cylinder.

I’m going to go ahead and do a complete engine teardown just to make sure everything else is looking good and to get the slingers cleaned out!
Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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Micha
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Re: R60/2 my first /2 engine rebuild

Post by Micha »

That's great - good luck!
Every cylinder can be re-bored or - if it is already on its limit - it can be re-sleeved and go back to std again.
That's what I have done with mine.
Pls keep us informed :D
Michael Steinmann
R51/3 1952
Engine Nr. 529466

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jwonder
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Re: R60/2 my first /2 engine rebuild

Post by jwonder »

Kurt,

The piston was seized at one time. It very well could have run fine after that with a bit of noise. What concerns me is that the seize mark is off to the side and not directly in the center. This tells me your crank is probably not perfect and in need of a rebuild as well.

The cylinders can be bored and honed to the next size larger, but you need to know what size your are now. Look at the top of the piston and see what the size is. You will most likely need to scratch the carbon off the top. If you are at the maximum I would suggest finding some on eBay.
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: R60/2 my first /2 engine rebuild

Post by Kurt V »

Thanks for the suggestions James! I’m going to soak the piston tops and see what size pistons I have.
Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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