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BMW R51/3 Specifications

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Start of Production

1951

BMW R51/3

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End of Production

1954

Numbers Produced

18,420

Price

2,750 DM

Engine

 

Internal Designation

252/1

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 5,800 rpm

Compression Ratio

6.3 : 1

Valves

OHV

Carburation System

2 x carburettor type Bing 1/22/41 - 1/22/42 or 1/22/61 - 1/22/62

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)

Gearbox Ratios

4.0 / 2.28 / 1.7 / 1.3 ('till the end of 1951: 3.6 / 2.28 / 1.7 / 1.3)

Rear Wheel Ratio

1 : 3.89 (1 : 4.75 with sidecar)

Bevel/Crownwheel

9 / 35 teeth (7 / 32 with sidecar)

Electrical System

 

Ignition System

Magneto ignition

Generator

Noris 6 V L 45/60 L

Spark Plugs

Bosch W 240 T1

Chassis

 

Designation

251/3 (1951), 251/4 (1952/53), 251/4 (1954)

Frame

Double loop 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 (1952:duplex, 1954: full hub)

Brakes, Rear

Drum brake 200 mm / 7.87 in diameter (1954: full hub)

Dimensions/Weights

 

Length x Width x Height

2130 x 790 x 985 mm (83.85 x 31.10 x 38.77 in)

Wheel Base

1400 mm / 55.11 in

Fuel Tank Capacity

17 litres / 3.73 gal / 4.49 gal US

Unladen Weight with Full Tank

190 Kg / 418 lb (with original sidecar, 320Kg / 704 lb)

Idle/Riding Noise

84 / 94 phon (from 7/7/1953: 81 / 85 phon)

Load Rating

355 Kg / 781 lb (with original sidecar, 600 Kg / 1321 lb)

Fuel Consumption

4.5 litres 100Km approx. / 62 mpg / 52 mpg US

Oil Consumption

0.7 litre per 1,000 Km approx.

Top Speed

135 Kph / 83 mph (95 Kph / 59 mph with original sidecar)

 

 

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