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piston orientation
- Bruce Frey
- Posts: 536
- Joined: Fri Oct 27, 2006 3:00 am
The small side on the right
I think the arrow is the small symbol preceding "Vor" and points to the right of the picture. If that is correct, the small side of the piston should be on the top of the picture.
Bruce
I have measured and found the
61 R27 and boy do I need parts-- got any?
Oh no, wifes coming home- get the engine out of the oven!
"Are those bearings in the freezer?!" she calmly inquired
- Bruce Frey
- Posts: 536
- Joined: Fri Oct 27, 2006 3:00 am
Sorry....you're right. If
It appears that the old saying, "he doesn't know which end is up," applies to me.
Bruce
Thanks Bruce. I figured it
Thanks all for the help. I am sure more questions are to come. Stay tuned.
Now, where did I put those valves????????????
61 R27 and boy do I need parts-- got any?
Oh no, wifes coming home- get the engine out of the oven!
"Are those bearings in the freezer?!" she calmly inquired
Sad tale of woe...
Re: piston orientation
This is my first time on the forum so apologies if my question is misplaced. I'm trying to make sure I'm installing my Nural pistons correctly since there is no VORN markings on both pistons - see picture. Any help is appreciated. Thanks
'69 R69US
- schrader7032
- Posts: 9017
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
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Re: piston orientation
I went to the Barrington manual and I'm a little disappointed in what is written. It says "should there be a front-rear orientation demanded by the piston". Seems to me that the manual could have spelled it out for stock pistons. I suppose they're hedging their bets for someone installing non-stock pistons.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
Re: piston orientation
Thank you again
'69 R69US
- jwonder
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Re: piston orientation
To be clear, for people reading the forum and to ensure that the proper information is disseminated, some models have an offset piston, while others do not.schrader7032 wrote: ↑Fri Jan 14, 2022 11:16 amWelcome to the forum! I believe the /2 bikes don't have the "vorn" or arrow marking meaning they can go in any direction. The reason for the orientation would be due to the offset of the wrist pin...if it is not in the center of the piston, then it needs the offset. On my R69S rebuild, I put the pistons in so that I could read the writing. I just wanted something that I could remember or write down as to the orientation.
I went to the Barrington manual and I'm a little disappointed in what is written. It says "should there be a front-rear orientation demanded by the piston". Seems to me that the manual could have spelled it out for stock pistons. I suppose they're hedging their bets for someone installing non-stock pistons.
See https://vintagebmw.org/library_data/Wor ... R60S69.pdf Page 26 of the PDF, 25 of the doc. R 50 and R 50 S have the offset while the R 60 and R 69 S do not.
For the R 27 see https://vintagebmw.org/library_data/Wor ... rm_R27.pdf on page #23 pf the PDF, page 21 of the document, both the R 26 and the R 27 have offset rod bores in the pistons on the thrust side.
I hope this helps clear this up.
Vice President, Vintage BMW Motorcycle Owners
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Long Island, New York
- schrader7032
- Posts: 9017
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
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Re: piston orientation
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.