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1950 R51/2 crankshaft anyone?

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TwoShoes
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Joined: Wed Feb 08, 2017 5:46 am

1950 R51/2 crankshaft anyone?

Post by TwoShoes »

Hi,

Kind of a longshot, but I'm looking at a basket case R51/2 for sale but it is lacking several pieces, the most worrisome is the crankshaft (and perhaps the camshaft, not sure yet). I'm wondering if perchance someone might have one on a shelf somewhere? It doesn't need to be in great shape, I'm not picky :-) would send it along somewhere for a rebuild.

Regards

Rob

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jwonder
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Re: 1950 R51/2 crankshaft anyone?

Post by jwonder »

I am restoring an R 51/2 right now. The camshafts (2) are available (I just bought them).

The crankshafts I am not too sure of. After looking at mine I feel an R 50 crank might fit at first but I would need to ask others about that. I will measure both cranks tomorrow and let you know.

If you can share pictures of the motor and the chassis number and and I can tell you more about it.
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

TwoShoes
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Re: 1950 R51/2 crankshaft anyone?

Post by TwoShoes »

Wow, what are the odds!

It wouldn't be surprising if the R50 cranks would fit as from what I gather, the big changes in the engine came in 1951 for the /3 models. Unfortunately I don't have any good pictures as it's still not mine, only this one, but the serial number on the engine case appears to be 518662
case.jpg
I would suspect a crank from a R50 would be "easier" to find...

Thanks again,
- Rob

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Micha
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Re: 1950 R51/2 crankshaft anyone?

Post by Micha »

Michael Steinmann
R51/3 1952
Engine Nr. 529466

p. museum2020
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Re: 1950 R51/2 crankshaft anyone?

Post by p. museum2020 »

Hello Rob,

Not such a longshot after all. We just completed a two year build of a 1950 R51/2 sport bike while working on a restoration and service manual for the R51/2 and have an extra crankshaft as well as a quite a few other R51/2 parts including a rebuilt transmission, rebuilt generator and complete distributor remaining in storage that are available. I'll take a critical look at the crankshaft this morning and if you will confirm you are still in need of a crankshaft I'll get back to you with a report on the condition of my extra.

Christopher Betjemann
Barrington Motor Works Publications
Barrington, NH

TwoShoes
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Re: 1950 R51/2 crankshaft anyone?

Post by TwoShoes »

Oh wow! wasn't expecting that!

I'll reach out to the seller to confirm that it is still available and if so, I would certainly take the crankshaft! Even if it has issues, I could send it for a rebuild...

Thanks Christopher, one step closer to getting a R51/2 back on the road!

Rob

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