Interesting vintage airhead on ebay

[UberXY]

No affiliation, etc

http://cgi.ebay.com/ebaymotors/BMW-R-Series-1938-BMW-R51-Racer-1938-BMW-R51-Racer-Rare_W0QQitemZ230409617931QQcmdZViewItemQQptZUS_mo torcycles?hash=item35a57bc20b#v4-36

[PAULBACH]

You have got to love the odometer reading. :whistle

[kgadley01]

WOW!!! thats just too cool.......

[Mika]

Thanks for the post.

[wezul]

Nice bike.
Is that the original tank?

[DarrylRi]

I wish I had more time this morning to look at this bike. It's certainly a bitsa, and not all of the bits are from before the war. Was it really a privateer bike originally?

The text about the only "shock absorber" bike before the war is just nonsense. First of all, this bike, like all of the other plunger frames from '38 onward, has a "plunger" setup, not shock absorbers (as we understand that term). There's no rear swingarm and the rear axle is allowed to travel vertically only. There's a big spring under that rubber boot on each side, and the spring is damped by grease. Much better than a hardtail bike, but not a real shock absorber. And all of the R51, R61 and R71 models built through 1941 had this same arrangement as well as the first postwar twins through 1955.

The forks appear to be off a '53-'55 bike. The front fender might be from an R68.

The transmission might be a postwar transmission (R51/2?) with the air cleaner mounting ground off. You can clearly see where there was once part of the air cleaner cavity at the back of the bell housing.

A privateer might have run Dell'Orto carbs, but I am not aware that the factory did.

I wonder how far this bike would actually travel. I base this skepticism on the fact that the hardy disk -- the hard, black rubber disk that serves to take up driveline lash, located between the transmission output flange and the front driveshaft flange -- has no steel support ring around it. The locking snap ring is visible, but there should be a heavy steel cylinder surrounding both the disk and the snap ring to keep the rubber from deforming under power.

It's nice to see the very original steering head badge, but it would also be nice to see the frame number and engine number stamps.

There is no doubt that some of the items, like the tank and the Magura racing control levers are period racing bits.

It is a very interesting bike, but the write up leaves me cold. I wish there were more information and a more knowledgable writer.