BMW 1940 R51 Sport 494 cc 2 cyl OHV 3508

BMW 1940 R51 Sport 494 cc OHV horizontally opposed twin frame # 514025 engine # 506030

In the late thirties BMWs are sold in considerable numbers, in spite of their high prices.
The make has built up an excellent reputation for quality and luxury: from 1938 on all BMWs have both front and rear springing, a feature which is at the time very uncommon for most other makes. From 1938 till the war stops production of civilian bikes all BMW twins share a common frame and cycle parts. All engines are interchangeable and share the same transmission, only the rear axle ratios are different. The R51 has many features in common with its predecessor, the R5. That boasts such features as a double cradle arc-welded frame made of oval tubes, hydraulically dampened telescopic forks, foot-operated gearchange, a new type of engine with two chan-driven camshafts, hairpin valve springs and quickly detachable and interchangeable wheels. New for the R51 is the plunger rear springing that gives extra comfort but also results in extra weight; the R51 is with its weight of 182 kg 17 kg heavier than the R5. Power delivered is the same with both models: 24 hp, good for a top speed of around 140 km/h. Production of the R51 ends in 1940, after 3775 machines have been produced.
The machine we present here was sold new in 1940 by Dutch dealer Arie Moeijes from Alkmaar, as shown by the dealer plate on the rear mudguard. The R51 then cost 975 guilders. A sporty Triumph Speed twin was 80 guilders cheaper and a DWK NZ 500 two stroke twin had a price ticket of 695 guilders. A modern utility machine like the new DKW RT 125 would cost 275 guilders. Understandably the expensive BMWs were relatively rare birds in The Netherlands at the time. Not a lot survived the war, because after the Germans had occupied the country many BMW dealers were visited and they were required to hand over lists of people that had bought a BMW in recent years; many of these bikes ended up in German hands again…
Our R51 has always stayed in the region where she was originally sold. She was used by a municipal official in the village of Schoorl till 1954 when the motorcycle was echanged for a car, and stayed in the family for many years. Around 1980 the former owner managed to procure the R51 from the original owner’s family. The machine was kept in storage for about 20 years and was restored in the early 2000s. The owner was used to ride American vintage machines and the BMW was a bit of an odd one out in his collection; it was cherished as a piece of local transport history but saw hardly any use.
Engine, cylinders and cylinder heads all bear the same number. The “OZ80”code stamped into the engine case above the engine number refers to Oktan Zahl, octane number. The OHV models wanted 80 octane, the side valves 74. This sporty prewar BMW is an older restoration with current Dutch registration.

Video: https://youtu.be/HXUzD5-VWsg