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1939 R71 restoration
- caker
- Posts: 201
- Joined: Sat Nov 12, 2011 10:49 pm
- Location: Haddonfield, NJ, USA
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1939 R71 restoration
About two years ago I got serious with the project. Yesterday, I took it for the first ride.
Here's the result:
Lots of major problems with the motor. Rusty and crusty. The magnesium / electron oil pump was completely disintegrated into what looked like concrete bits - it was GONE just the gears left, and that stuff along with mud was everywhere in the motor. The front cam bushing carrier was also toast (it's also magnesium). Later, I started to make a new carrier on my small manual machines, but Mark Huggett started offering new replacements just then (!). The oil pump gear cover was seized into the casting and required welding on a nut and major torque, and then some thread repair in the casting (a huge 38mm tap, if I recall).
The first set of (matching-each-other) barrels were cracked base to top (!), the frame I used needed straightening and a bad tube replaced, my cam was shot and good replacements are difficult to find. Also, many of the used parts I had bought over the years were only good for reference. So, some lessons learned. And building a bike from nothing adds a lot of difficulty to begin with... this is just a sampling of the gripes
My friend Jeff Moore was a huge help with this project. The case blasting and repairs, cylinder and top-end machine work, tank stripping and lining, CAD plating, and his patience with me, and probably many other things I'm forgetting, were his contributions. Thanks Jeff.
I tried to do as much of the work as I could in my home shop. I learned a lot, which I will apply to the next one.
It needs more tuning and shakedown, but my short ride yesterday reminded me that yes, it was a fun project.
-Chris
- Darryl.Richman
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- caker
- Posts: 201
- Joined: Sat Nov 12, 2011 10:49 pm
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Re: 1939 R71 restoration
Thanks R68 - I'm pleased you chimed in - I've learned many things from your knowledge on here!
Details and some of the more rare items on this bike:
BMW Archives wrote:Engine and frame are from different bikes. While the engine No. 702134 belongs to a BMW R 71 that was delivered on September 25th, 1939 to the BMW dealer Auto-Henne in Munich, the frame could be from a BMW R 51, R 61, R 66 or R 71 from approximately the same time frame. Since the delivery books for these bikes are not complete anymore, we cannot find out any further details.
Nevertheless we hope this is helpful for you.
- Correct 10/36 final drive
- Correct Graetzin G24 carburetors (commissioned from Martina at Oldtimer Vergaser)
- Correct Bosch FD6 DS10 horn
- Early prewar fork triple tree (pinch bolt fore<->aft)
- An original Bosch JN7 tail light (this was almost more trouble than it was worth)
- An original civilian speedometer (km), but I will replace with a military version
- Original, but pitted, handlebar controls
- Original prewar gearbox, but I think this is a 1937 specific model - more on that in a later post
Re: 1939 R71 restoration
I've just spent two years on a box of bits supposed to be an R 35 and one learns a whole lot more than expected - and spends a whole lot more as well. But it's been fun meeting people, going to odd places and, when the wind, rain and cold are over, I will enjoy riding it.
Did you use any Russian or Chinese parts? I've been trying to work out whether the Nazis gave the, then obsolete, R 71 and the machinery to make it to the Russians or whether the Russians back-engineered to make the M72. At the moment, it seems the former.
Anyway, I hope it rides and works well,
Charlie.
- jwonder
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Re: 1939 R71 restoration
Lots opf work but it is well worth it in the end!
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York
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Re: 1939 R71 restoration
R69S - R60/2 - R67/2 - R51/3 - R69