The other flat twin engined, prewar BMW: the 1940 BMW R12
The BMW R6 and R12 were both powered by sidevalve, flat twin engines. Though BMW might have hoped the R6 would find favor with the German military, the Luftwaffe simply found the heavier and perhaps sturdier R12 more proficient at sidecar work.
While still rebuilding his R6, John Pavone started thinking about lining up his next project. Answering an online ad in a BMW forum, he managed to pick up a basket case BMW R12 that had originally been sold to the Luftwaffe in August 1940. “This fellow was selling the 1940 R12 as a project,” John says, “and he had collected a lot of parts before he sold it to me.
“I did the same,” John continues. “I collected a few more parts and had some machine work done, but around 2007 I lost interest and sold it to a guy up in Canada. I quickly had seller’s remorse, though, and called to ask if he’d sell it back to me. He didn’t want to, because he had the same plan I’d had. But in 2010 he called me and told me he was ready to sell.” This time, John followed through on his plans.
“I was going to do it in a civilian paint job, black with white stripes, but because it was originally a military bike I painted it myself a flat gray, and simply bolted on a lot of the parts as they sat, like the original saddle and knee pads.” John took care of the engine rebuild himself, which was made simpler because the R12 has a split case, unlike the tunnel case of the R6.
John sent the crank out for attention, but the cam had already been reground. The R12 features a timing chain as opposed to the gears of the R6, although both machines are sidevalve — or flathead — models, which John thinks makes the motorcycles look “old.” The 1940 BMW R12 is fitted with a single SUM carburetor, and John says both the R6 and the R12 are one-kick starters.
John has hooked a period-incorrect early 1950s Steib sidecar to the R12, and says running the machine down the road is “sort of like being aboard a fast-riding lawn mower. You drive it as opposed to ride it.” MC
Read about the BMW R6 in One-Year Wonder: The 1937 BMW R6.