Information kindly supplied by P.Hawksley

www.bmbikes.co.uk

Start of Production

1938

Click to View Available Literature

End of Production

1941

Numbers Produced

3,458

Price

1,595 RM

Engine

 

Internal Designation

271/1

Motor Type

Four-stroke two cylinder flat twin

Bore x Stroke

78 x 78 mm (3.07 x 3.07 in)

Displacement

746 cc

Max Power

22 hp at 4,600 rpm

Compression Ratio

5.5 : 1

Valves

SV

Carburation System

2 x carburettor type Graetzin G 24

Engine Lubricating System

Forced feed lubrication

Oil Pump

Gear pump



Power Transmission

 

Clutch

Single plate, dry

Number of Gears

4

Shifting

Foot switching (+ auxiliary manual lever), manual gear lever on request

Gearbox Ratios

3.6 / 2.28 / 1. 7 / 1.3

Rear Wheel Ratio

1 : 3.6 (1 : 3.89 with sidecar)

Bevel/Crownwheel

10 / 36 teeth (9 / 35 with sidecar)



Electrical System

 

Ignition System

Battery ignition

Generator

Bosch RD 50/6 2800 RS 17

Spark Plugs

Bosch W 175 T1






Chassis

 

Designation

251/1

Frame

Twin 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

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

187 Kg

Load Rating

210 Kg / 462 lb (max. overall weight with sidecar 500Kg / 1101 lb)

Fuel Consumption

Approx. 4.5 litres per 100 Km

Oil Consumption

Approx. 1 litre per 1,000 Km

Top Speed

125 Kph (with original sidecar, 105 Kph)