The BMW R51 was one of the nicest looking motorcycles ever built, it was super clean with no wasted effort. This is one bike I want to own some day.
The BMW R51/3 was Bmw's second post-World War II 500 cc motorcycle, following the briefly produced R51/2. It featured a flat-twin engine and exposed drive shaft. In 1951, the R51/3 succeeded and modernized the 1950 R51/2, which was essentially a pre-war design that was produced after the war. The 600 cc R67, R67/2, and R67/3 series and the more sporting R68 model also followed the R51/2.