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1939 BMW R12.jpg
Also called R12 Single Carb, R12 Twin carb, R 12
Production 1935 - 1942
Class Classic
Predecessor BMW R11
two cylinder boxer, four-stroke
Bore / Stroke 78.0mm x 78.0mm
Compression ratio 5.2:1
Top Speed 68 mph (110 km/h)
Horsepower 17.57 HP (13.1 KW) @ 3400RPM
Ignition magneto
Transmission Gear box: 4-speed

Final Drive: shaft

Clutch: dry multiplate-cable operated
Suspension Front: telescopic fork
Rear: rigid-
Brakes Front: expanding brake (drum brake)
Rear: expanding brake (drum brake)
Front Tire 3.5-19
Rear Tire 3.5-19
Wheelbase 54.33 inches (1380 mm)
Length 82.68 inches (2100 mm)
Width 35.43 inches (900 mm)
Height 37.01 inches (940 mm)
Weight 407.86 pounds (185.0 Kg) (dry), 185.0 kg (wet)
Fuel Capacity 3.7 Gallon (14.00 Liters)
Fuel Consumption 3.40 liters/100 km (29.4 km/l or 69.18 mpg)
Related BMW R17
Manuals Service Manual

The BMW R12 Single Carb was a two cylinder boxer, four-stroke Classic motorcycle produced by BMW between 1935 and 1942. It could reach a top speed of 68 mph (110 km/h). Claimed horsepower was 17.57 HP (13.1 KW) @ 3400 RPM.

History[edit | edit source]

1938 BMW R12 Army

The R12 along with its sister model, the R17 were milestone models in the evolution of motorcycling, being the first production machines to feature a hydraulically dampened telescopic front fork. This resulted in the R12 being the best selling pre-WWII BMW motorcycle, with 36,000 units sold from 1935 to 1942, with a great many going into military service.

Engine[edit | edit source]

The engine was a air cooled two cylinder boxer, four-stroke. A 78.0mm bore x 78.0mm stroke result in a displacement of just 745.0 cubic centimeters. Fuel was supplied via a standing valves.

Drive[edit | edit source]

The bike has a 4-speed transmission. Power was moderated via the dry multiplate-cable operated.

Chassis[edit | edit source]

It came with a 3.5-19 front tire and a 3.5-19 rear tire. Stopping was achieved via expanding brake (drum brake) in the front and a expanding brake (drum brake) in the rear. The front suspension was a telescopic fork while the rear was equipped with a rigid-. The R12 Single Carb was fitted with a 3.7 Gallon (14.00 Liters) fuel tank. The bike weighed just 407.86 pounds (185.0 Kg). The wheelbase was 54.33 inches (1380 mm) long.

1935 - 1942 BMW R 12[edit | edit source]

1935 - 1942 BMW R 12 1935 - 1942 BMW R 12 1935 - 1942 BMW R 12 1935 - 1942 BMW R 12 1935 - 1942 BMW R 12

The 1935 BMW R 12 has, at its heart, an air-cooled, four-stroke, 745cc, twin cylinder powerplant mated to a four-speed manual transmission and can produce a claimed 20 horsepower at 4000 rpm. It also comes with laced wheels, a large, round headlamp, a rear luggage rack, a telescopic front fork, a hard-tail rear suspension with a sprung single saddle, a drum braking system in the front and in the rear, a dual exhaust and a dry, double plate clutch.

In Media[edit | edit source]