BMW R2

In 1925, BMW introduced the 247 cc R39, their first single-cylinder motorcycle. The R39 did not sell well and was discontinued in 1927. This led to the R2's introduction in 1931 in the form of the Series 1, of which 4,161 units were sold during its one-year production run until the introduction of the improved Series 2A the following year. It was known as the "people's bike", and was priced at 975 RM, compared to 1,750 RM for the 750 cc flat-twin R11 Series 2 of the same year. == Models ==

In all models, the 198 cc overhead valve four-stroke engine was mounted in a pressed-steel frame. It featured both sump oil and forced-feed lubrication provided by a geared oil pump, was coupled through a single-plate dry clutch to a three-speed gearbox, giving a top speed of . It also used drum brakes, like the larger twin of the BMW range. Power output was rated at , until the introduction of the British Amal carburetor, boosting the power output to . The coil electrical ignition system and the generator were supplied by Bosch. The engine was offset toward the right of the frame, to allow it to drive the rear wheel directly when in top gear. Variants Series 1 (1931): the only model to feature exposed valve springs on the top of the finned cylinder head Series 2A (1932): the previously exposed valve springs were covered Series 2/33 (1933): the option of the British Amal (as opposed to the German Sum) carburetor was offered (around 80 units were sold with this specification) and (from June 1933) a friction damper was introduced for improved steering control whilst riding Series 3 (1934): the Sum carburetor was withdrawn as an option, replaced by the British Amal, which increased the power output from 6 to 8 hp Series 4 (1935): smaller tank and modified headlight Series 5 (1936): changed ratio of the shaft drive and wider rear fender with license plate holder ==See also==