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avi
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israel
Joined: 01/08/2014
Posts: 108

Hello
I have a problem in assembling new piston to R51 motor. The
Piston has an offset of 2 mm'
What is the proper way to mount the piston?

VintageSalesand...
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VBMWMO #7368
Corona, CA
Joined: 03/24/2008
Posts: 295
Offest

Hi,

Please describe the offset?

From what surface to what other surface?

jeff

Bruce Frey
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VBMWMO #6316
Texas Hill Country, USA
Joined: 10/27/2006
Posts: 574
Is there an arrow on the

Is there an arrow on the piston crown? It would usually point to the front.

Bruce

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6327
If anyone has Barrington's

If anyone has Barrington's book for the plungers, it would have the answer in there. Is it out yet??

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

avi
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israel
Joined: 01/08/2014
Posts: 108
Hi Jeff If you look at the

Hi Jeff
If you look at the hole in piston it is not in the center line ...

luca.stere
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Romania
Joined: 05/23/2013
Posts: 38
Piston

avi wrote:

Hello
I have a problem in assembling new piston to R51 motor. The
Piston has an offset of 2 mm'
What is the proper way to mount the piston?

It is very simple, the bigger part off the piston must be mounted on the rotation side.

avi
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israel
Joined: 01/08/2014
Posts: 108
It is very strange. The arrow

It is very strange.
The arrow appears both ways.
There ara not many obvious information on this subject( for bmw twin motor)on the internet

  • 20160310_175824.jpg
avi
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israel
Joined: 01/08/2014
Posts: 108
That's what i thought too, so

That's what i thought too, so the left side of motor with big gap piston upwards and right side downwards?

avi
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israel
Joined: 01/08/2014
Posts: 108
Jeff i just found this

Jeff
i just found this document ,this is very interesting topic.

  • 20160928_160322.jpg
  • 20160928_160230.jpg
luca.stere
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Romania
Joined: 05/23/2013
Posts: 38
Pistons position

I have made a picture for a better understanding, this is the position of the pistons:

  • pistons_offset.png
schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6327
luca -Interesting. Do you

luca -

Interesting. Do you know that the rotation circle of the crankshaft is biased slightly below the bores of the cylinder? I guess if the center of the rotation was directly in line with the center of the bore, then it wouldn't make any difference. That's why I ask about what you've drawn.

Thanks...

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

avi
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israel
Joined: 01/08/2014
Posts: 108
Thank you Now its very clear.

Thank you
Now its very clear.

luca.stere
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Romania
Joined: 05/23/2013
Posts: 38
Drawn

schrader7032 wrote:

luca -

Interesting. Do you know that the rotation circle of the crankshaft is biased slightly below the bores of the cylinder? I guess if the center of the rotation was directly in line with the center of the bore, then it wouldn't make any difference. That's why I ask about what you've drawn.

Thanks...

What I have drawn is a rule for all the engines (bikes, cars, trucks, etc) with piston offset.

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