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BMW R51 Specifications

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Start of Production

1938

BMW R51

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End of Production

1940

Numbers Produced

3,775

Price

1,595 RM

Engine

 

Internal Designation

254/1

Motor Type

Four-stroke two cylinder flat twin

Bore x Stroke

68 x 68 mm (2.67 x 2.67 in)

Displacement

494 cc

Max Power

24 hp at 5,600 rpm

Compression Ratio

6.7 : 1

Valves

OHV

Carburation System

2 x carburettor type Amal 5/423

Engine Lubricating System

Forced feed lubrication

Oil Pump

Gear pump

Power Transmission

 

Clutch

Single plate, dry

Number of Gears

4

Shifting

Foot shifting (+ auxiliary manual lever on the gear block), manual gear lever on request

Gearbox Ratios

3.6 / 2.28 / 1.7 / 1.3

Rear Wheel Ratio

1 : 3.89 (1 : 4.62 with sidecar)

Bevel/Crownwheel

9 / 35 teeth (8 / 37 with sidecar)

Electrical System

 

Ignition System

Battery ignition

Generator

Bosch RD 50/6 2800RS 15

Spark Plugs

Bosch W 225 T1

Chassis

 

Designation

251/1

Frame

Closed double steel tubular frame

Front wheel suspension

Telescopic fork

Rear wheel suspension

Telescopic suspension

Wheel rims

3 x 19 deep bed

Tyres, Front

3.5 x 19

Tyres, Rear

3.5 x 19

Brakes, Front

Drum brake 200 mm / 7.87 in diameter

Brakes, Rear

Drum brake 200 mm / 7.87 in diameter

Dimensions/Weights

 

Length x Width x Height

2130 x 815 x 960 mm (83.85 x 32.08 x 37.79 in)

Wheel Base

1400 mm / 55.11 in

Fuel Tank Capacity

14 litres / 3.07 gal / 3.69 gal US

Unladen Weight with Full Tank

182 Kg / 400 lb

Load Rating

210 Kg / 462 lb (max overall with original sidecar, 500 Kg / 1101 lb)

Fuel Consumption

4 litres 100 Km approx. / 70 mpg / 58 mpg US

Oil Consumption

1 litre per 1,000 Km approx.

Top Speed

140 Kph / 87 mph (110 Kph / 68 mph with original sidecar)

 

 

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Check out my other sites at: www.bmridersclub.com & www.boxerman.co.uk