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EuroIron
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VBMWMO #7266
Joined: 04/23/2007
Posts: 414

I have some slightly odd plunger frames that acid has failed to lift any traces of serial numbers......

other locations to look besides the left rear upper shock perch...... for lack of knowing the proper nomenclature??

Darryl.Richman
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VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
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are any of the older bikes with un-numbered frames?

I believe the prewar plunger frame bikes had a serial number on the right side, but as I don't own one, I'm not 100% certain of this.

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EuroIron
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VBMWMO #7266
Joined: 04/23/2007
Posts: 414
are any of the older bikes with un-numbered frames?

thank you sir, I'll get them cleaned and see what the hydrochloric reveals

perhaps I'll post up some pix and see if any experts can be envoked

Bruce Frey
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VBMWMO #6316
Texas Hill Country, USA
Joined: 10/27/2006
Posts: 574
are any of the older bikes with un-numbered frames?

Prewar plunger frames will have their 6 digit frame number stamped in upper plunger "perch" on the driveshaft side. The frame number should be preceded and followed by a BMW rondel. Numbers will be from 501001 to 515164. These numbers were shared among all the plunger models except for the 1941 models where they had matching engine and frame numbers.
1941 R61 607001-607340
1941 R66 662001-662039
1941 R71 703001-703511

If you look in the "Bogus R71" folder here:

you will see some examples of what to look for.

There were also some Eastern European copies of plunger frames for sale in recent years.

I know that postwar plunger frames should have matching engine and frame numbers, but I am not certain about where they are stamped. As you might guess, I am not too interested in postwar bikes.

Best regards,

Bruce

EuroIron
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VBMWMO #7266
Joined: 04/23/2007
Posts: 414
are any of the older bikes with un-numbered frames?

Thank you for the wealth of info, so my pre-41 R66 would not have a matching frame number?

I have a R66 title and even head badge but will have to go look to see if they match and if the title matches the engine or badge.

have acid on the right perch and if that doesn't work....... I'll see what can be lifted electronically

should a prewar bike be titled by the frame or engine?

my guess would be by the frame as long as it is supposed to have numbers.

also, are the stamped figures/font the same for the prewar bikes as they are for the postwar vintage bikes?

I know that HD changed number stamp sets more often than they cured well known under-engineered designs

Very curious has been many requests for say......... just an R68 or R67 type engine and without the frame

I can't imagine why anyone would want such unless they had access to the correct stamps

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