BMW R12

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BMW R12
BMW motorbike R 12 (aka).jpg
Manufacturer BMW
Production 1935-1942
Assembly Munich, Germany
Predecessor R11
Class boxer
Engine Two-cylinder boxer 745cm³ - 18 hp at 3400 rev / min (20 hp at 4000 rev / min in the version with two carburetors)
Bore / stroke 78 mm
Compression ratio 5.2: 1
Top speed 110 km (68 mi) - 120 km (75 mi)[1][2]
Power 18 hp (13 kW)[1]
Ignition type Magneto or battery ignition
Transmission Manual
Tires 3.50 x 19
Dimensions L: 210 cm (83 in)
W: 90 cm (35 in)
H: 94 cm (37 in)
Fuel capacity 14 litres
Fuel consumption 3.5-4L (every 100km)[1]
Related R17

The BMW R12 is a pre-World War II motorcycle that was produced by the German company BMW. The motorbike was first presented and developed in 1935.[3] A total of 36,000 motorcycles were built by 1942.

History[edit]

On 14 February 1935, BMW presented the R12 together with the BMW R17 on the German Automobile Exhibition in Berlin for the first time, being a direct successor to the BMW R11.[4] This and the R17 were the first in the world being produced with hydraulically damped telescopic forks.[5] By 1942, the total number of BMW R12 motorcycles manufactured was 36,000.[2] For military purposes, the Einvergasermotor was only available for the R12.[6]

Description[edit]

BMW R12 Motor engine

Engine[edit]

The engine, designated M 56 S 6 or 212, was a twin-cylinder boxer configuration - four stroke with a flathead design.[1] The BMW R12 with two carburetors used a battery and coil ignition, while R12s with a single carburetor used a magneto ignition, capable of working independently from the battery.

Drive[edit]

The BMW R12 had a four-speed manual gearbox, operated by a hand shift lever on the fuel tank's right side. Several detail variations were seen in production. In common with most BMW Motorcycles, final drive was via shaft, with the drive shaft on the right side of the motorcycle.

Suspension and brakes[edit]

Front suspension used a telescopic fork, while the frame was rigid with an un-sprung rear end supporting the final drive and a sprung seat for the rider. The R12 used drum brakes front and rear. Many R12's were equipped with a sidecar attached to the motorcycle's right side.

Specifications[edit]

Characteristics R 12 with a carburetor[1] R 12 with two carburetors [2]
Bore 78 mm
Stroke 78 mm
Capacity 745 cm³
Compression ratio 5,2 : 1
Performance 18 hp (13 kW) 20 hp (15 kW)
Top speed 110 km/h 120 km/h
Tare 162 kg
Fuel capacity 14 Liter

Surviving motorcycles[edit]

One example of a surviving BMW R12 motorcycle can be found in the Museum of Military History in Vienna, still bearing its original camouflage.[7]Many R12's remain in service with private collectors.

See also[edit]

References[edit]

  1. ^ a b c d e "BMW R 12 Einvergaser" (in German). BMW Archive Group. Archived from the original on 19 August 2014. Retrieved 3 March 2015. 
  2. ^ a b c "BMW R 12 Zweivergaser" (in German). BMW Group Archive. Archived from the original on 8 March 2015. Retrieved 3 March 2015. 
  3. ^ "BMW R 12 Schnittzeichnung der Telegabel" (in German). BMW Group Archive. Archived from the original on 19 August 2014. Retrieved 3 March 2015. 
  4. ^ "BMW präsentiert bei den Modellen R 12 und R 17 die weltweit erste hydraulische Teleskopgabel" (in German). BMW Archive Group. Archived from the original on 27 March 2014. Retrieved 3 March 2015. 
  5. ^ Setright, L. J. K. (1977). Bahnstormer: The story of BMW Motor cycles. Transport Bookman Publications. p. 47. ISBN 0-85184-021-3. 
  6. ^ Zeyen, Wolfgang; Leek, Jan (2004). BMW: die Motorräder seit 1923 (1. Auflage ed.). Stuttgart: Motorbuch Verlag. pp. 71–88. ISBN 3-613-02401-2. 
  7. ^ Rauchensteiner, Manfried (2000). Das Heeresgeschichtliche Museum in Wien (in German). Graz: Styria. p. 92. ISBN 978-3-222-12834-9. 

External links[edit]

http://www.bmwr12.com/