Prototype R75/5 ???

[lmo1131]

Posted on Facebook by John Lacko. https://www.facebook.com/groups/69295835989/?fref=nf

Can anyone shed any light on what this motorcycle is/was?

Photo was provided with an eBay auction of an aluminum gas tank (cannot locate auction).

Note:
HT leads coming from side of front engine cover
"Bumps" on valve cover
Small air cleaner housing
Front turn signals not mounted under headlight stanchions (as in final production)
Prototype CV carburetors (?)
Black "dot" over cylinder (too far aft to be flywheel inspection cover)
Strut to rear of muffler

 

[dbrick]

I think the black "dot" is the hole in the engine case where the spark plug HT wire emerged...before the wire was moved (nonstandard ignition module?) to the front cover. The hole is well forward of the flywheel.

 

[20774]

If there was a VIN with the engine, we'd know a bit more about where the bike stood in the production. My guess is it's a custom bike of some kind.

What dbrick says is correct for /2 engine cases. It might suggest that they continued that into the early early /5s and then thought better of it.

As for the spot where the spark plug wires are now coming out would kinda indicate that there was a magneto under the front cover. The /5 of course had coils under the tank, so wouldn't route the wires forward like that. Hmmm...how does one remove the front cover with the wires going through it?

 

[dbrick]

What dbrick says is correct for /2 engine cases. It might suggest that they continued that into the early early /5s and then thought better of it.

Right you are, Kurt. The through-the-case HT wire was indeed a /2 thing.

 

[james.a]

That would not be the first time somebody built a custom bike with the intent of making plausibly passed off as a prototype. The paint matched tail light housing is a nice touch. The modified tank suggests /2 at the fuel filler and R90S with the contouring just forward of knee pad. The re-shaped if filter clam shell makes one wonder what, if any air filter is inside. The blue pinstripes do not follow the contours of of OE striping, and the nuts for the ceramic roundel are not in a raised, embossed contour. This suggests that we are looking at a re-shaped /6 tank. The shape of the carburetor float bowl scream Mikuni to my eyes.

 

[9662]

Not what I have seen

I have a picture somewhere, in a book on the history of our bikes, of a /2 engine in what is close to a /5 frame. I think there were several prototypes, and that is one reason that we can swap engines /5 to /2. It has a much less finished appearance than that bike.

 

[lmo1131]

More shots from John Lacko's personal BMW Archive search...

early /5 prototype

later prototype, note "japanese" influenced head light/tail light and rear fender configuration.

Caption translation: In 1966, in Japan too, unnecessarily complex headlights were in fashion. The prototype of the 246 promised a beautiful lighter appearance (literal translation; weight).

later

later still, note 247 engine now installed, HT leads coming from under the tank.

Honda "UJM" styling influence is obvious; black frame, colored body parts.
1966 Honda CB160