Vintage BMW Motorcycle Owners

Thank you Kurt and James for your help, I had read BMW handbook, Clymers, Barrington's + online stuff and couldn't find definite answer to my question. Your feedback is priceless. Additionally, during my install ( original Nural) I noticed that although intake and exhaust recess in piston look " identical" they are not. Intake is slightly wider so I think that right piston " markings" should be upside down. Let me know what you think as my /2 journey just begun - this is my first beemer.
Thanks again

My R69US is almost done, some ignition and tuning to do. I'm proud and sad at same time. I may start looking for another one ....

Very nice restoration r69US
Quote:
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.

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.
James Wonder
Long Island, New York
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I replaced my R27 piston a few years ago from a well know vendor here in the US
It did not have a directional arrow, Called the vendor and was told it didn't matter

Also from Salis website it clearly states the their R27 Kolbenschmidt piston has no offset

https://bmwclassicmotorcycles.com/index ... 50-mm.html

How concerned should I be
Tommy

I honestly don't think it's that big of a deal, but would like some input from others on their thoughts.

Vorn goes on front side, pointing exhaust valve....

Thanks
Cant remember if mine has a vorn marking on replacement but will check and post back results
Tommy