An important step forward in the development of BMW's long-running flat-twin occurred in 1936 with the introduction of the 494cc R5. Prior to that the BMW engine had been recognisably related to the first of its type, the 1923 R32, and like those of its (500cc) predecessors, the R5's engine dimensions were 'square' at 68x68mm bore/stroke. However, the overhead-valve R5 engine broke new ground by adopting two chain-driven camshafts, a move that permitted shorter pushrods and higher revs. In 1938 the model was up-dated as the R51, gaining a telescopic front fork and plunger rear suspension, and continued in production until 1940.

BMW recommenced civilian production in December 1948 with the R24 single, but it would be another 12 months before a twin-cylinder model became available again. This was the R51/2 based, as its designation suggests, on the pre-war R51. Improvements incorporated into the R51/2 included a two-way damped front fork, gearbox main-shaft damper and strengthened frame. In truth, the R51/2 was only a stopgap model to get production under way while BMW worked on something more modern. Its replacement, the R51/3 - arrived in February 1951, and despite the similarity in designation had an entirely new and much neater looking engine incorporating a single gear-driven camshaft and crankshaft-mounted generator among a host of other advances.

It is believed that this matching-numbers R51/3 was delivered new to The Netherlands, as it comes with an old Dutch registration document dated 1961. The current vendor purchased the machine from the Belgian BMW specialists Oldlima in 2008, at which time it had covered a mere 25 kilometres since a full restoration. The BMW has been on static display since acquisition and is presented in magnificent condition; highly sought-after and collectible, it comes with old NL registration documents and a Belgian Demande d'Immatriculation.

BMW's don't come much more classic than this beautiful R51/3, which is guaranteed to turn more heads at a gathering of enthusiasts than any of the marque's more modern offerings...