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rmichel13
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VBMWMO #9544
Joined: 01/26/2017
Posts: 21

I am rebuilding a r50/2 motor I just purchased. I found the space between the front connecting roe at the base is .012 in or 3.03 mm. can someone please give me some advice concerning this. The motor ran great and started with one kick with no odd sounds coming from it before I dismantled it.

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Bob Michel

pokie
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VBMWMO #70
Joined: 02/08/2015
Posts: 135
Crankshaft

That seems like a lot BUT, if it ran fine with no excessive noise, I'd be tempted to just leave well enough alone.

312Icarus
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Posts: 434
I’m not sure what “space” you

I’m not sure what “space” you are referring to. Can you describe differently?

Thanks.

bstratton
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Posts: 222
end play

It is the end play you need to measure - not side-to-side

You should measure end play with the bearings clean (no oil) and it should be approximately 0. If yo have any end play that can be felt probably a good idea to take it to a machine shop for a true measurement and possibly a re-build of the crank. If the end play can't be felt I would put it back as is. Take a good look at the small end (wrist pin) bushings. Again- no end play or wobble there either. Those bushings can be replaced and reamed to fit if you have the tools. I missed that on mine and had to replace the small end bushings with the motor in the bike. Sub-optimal at best but doable with the tool from Dan.

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Bstratton
1971 R60/5
1965 R50/2
MA

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6885
I was looking into a

I was looking into a vibration above 50 mph on my R69S and talked to Vech about what to check. I had checked just about everything else and he gave me some specs to check for movement of the crank. He said the limit for side to side movement at the nose of the crank was 0.0008". As to fore-aft, his spec was no more than 0.002". This was measured in the bike...I don't think he was suggesting it be with no oil. He basically said to set up the dial indicator and then actuate the clutch to provide force on the crank.

In the end, my problem ended up being something else, something I hadn't confirmed...the third or upper engine mount was not completely tight.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

wa1nca
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VBMWMO #8374
Ashfield Ma.
Joined: 09/27/2012
Posts: 586
Crank

Kurt
Vech was saying the side to side movement of the whole crankshaft not the side to side of the connecting rods

You can also look into the timing hole then actuate the clutch and if you see any movement the crank bearings are shot

Tommy

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Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US 68 Sears Allstate 250 (Puch)

schrader7032
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San Antonio, TX
Joined: 10/27/2006
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Tommy - I agree...he was

Tommy -

I agree...he was suggesting that I measure the side-to-side movement at the nose of the crankshaft. I was going to measure the fore-aft movement at the nose of the crankshaft since I was going to measure the lateral movement there as well. But when I discovered the non tight upper engine mount, I didn't have to go through the process of removing the alternator. My next ride on the bike proved that the vibration was gone with the simple tightening of that nut.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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