The BMW R2 was a 198 cc
overhead valve
An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located b ...
single-cylinder
motorcycle
A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...
produced by
BMW between 1931 and 1936, the smallest motorcycle ever to enter series production with the firm (In 1948, a 125cc 2 stroke flat twin, designated R10, was developed but did not enter production). Despite its much smaller design and engine capacity, the R2 retained many features of the larger
boxer twin motorcycles in the range, such as
cardan shaft
A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power (physics), power and torque and rotation, usually ...
drive and a pressed-steel duplex
frame
A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent.
Frame and FRAME may also refer to:
Physical objects
In building construction
*Framing (con ...
. The R2 was the smallest in the range of singles produced during the 1930s by BMW, with its big brothers being the 305 cc
R3 and the 400 cc
R4.
Background
In 1925, BMW introduced the 247 cc R39,
their first single-cylinder motorcycle. The R39 did not sell well and was discontinued in 1927.
Following the collapse of the
Weimar Republic
The Weimar Republic (german: link=no, Weimarer Republik ), officially named the German Reich, was the government of Germany from 1918 to 1933, during which it was a constitutional federal republic for the first time in history; hence it is ...
economy during the
Wall Street Crash of 1929
The Wall Street Crash of 1929, also known as the Great Crash, was a major American stock market crash that occurred in the autumn of 1929. It started in September and ended late in October, when share prices on the New York Stock Exchange coll ...
, BMW's premier large capacity, expensive motorcycle range was hard hit, with fewer customers able to afford their premium purchase costs. BMW therefore felt the need to introduce a smaller bike into their range, which offered both cheaper purchase costs and less expensive running costs. The firm also wished to expand their range by making a bike available to riders without a motorcycle licence, which was not required for bikes under 200 cc.
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
A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both pistons move inwards and outwards at the same ti ...
R11 Series 2 of the same year.
Models
In all models, the 198 cc overhead valve
An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located b ...
four-stroke engine
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...
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
*History of BMW motorcycles
BMW's motorcycle history began in 1921 when the company commenced manufacturing engines for other companies. BMW's own motorcycles—sold under the BMW Motorrad brand—began in 1923 with the BMW R 32, which was powered by a flat-twin engine ( ...
*BMW Motorrad
BMW Motorrad is the motorcycle brand of BMW, part of its Corporate and Brand Development division. It has produced motorcycles since 1923, and achieved record sales for the fifth year in succession in 2015. With a total of 136,963 vehicles sold i ...
- the division of BMW that manufactures motorcycles today
References
External links
Historical BMW motorcycles
at BMW Motorrad international website
{{BMW motorcycles
R2
Shaft drive motorcycles
Motorcycles introduced in the 1930s