Information kindly supplied by P.Hawksley

www.bmbikes.co.uk

Start of Production

1931

Click to View Available Literature

End of Production

1932

Number Produced:

7,500 (All Series)

Price:

1.630 RM

Engine

 

Internal Designation

M 56 S 3

Motor Type

Four Stroke two cylinder flat twin

Bore x Stroke

78 x 78 mm (3.07 x 3.07 in)

Displacement

745 cc

Maximum Power

18hp at 3,400 rpm

Compression Ratio

5.5 : 1

Valves

Side Valve

Carburation System

Single carb. Type SUM CK 3/500 F 1

Engine Lubricating System

Forced Feed Lubrication

Oil Pump

Gear Pump



Power Transmission

 

Clutch

Two plate dry clutch

Number of Gears

3

Gear Shift

Manual

Gearbox Ratios

2.83 / 1.55 / 1.08

Rear Wheel Ratio

1 : 4.07  (1 : 4.75 with sidecar)

Bevel / Crownwheel

14/57  (12/57 with sidecar)



Electrical System

 

Ignition System

Magneto ignition

Generator

Bosch Magneto generator D2 BL or Magneto Ignition FF2

Spark Plugs

Bosch W 175 T1






Chassis

 

Designation

F 66 S 3

Frame

Twin loop pressed steel frame

Front Suspension

Plate spring, 9 laminae

Rear Suspension

Rigid

Wheel Rims

26 x 3.5 safety rims

Front Tyre

26 x 3.5 low pressure or 26 x 3.25 high pressure

Rear Tyre

26 x 3.5 low pressure or 26 x 3.25 high pressure

Front Brakes

Drum brake 200 mm / 7.87 in diameter

Rear Brake

Cardan brake, 55 mm / 2.16 in width




Dimensions/Weights

 

Length x Width x Height

2100 x 890 x 940 mm (82.67 x 35.03 x 37 in)

Wheel Base

1380 mm / 54.33 in

Fuel Tank Capacity

14 litres / 3.07 gal / 3.69 gal US

Unladen Weight with full tank

162 kg / 356 lb

Load Rating

210 kg / 462 lb

Fuel Consumption per 100 kilometres

4 - 4.5 litres approx / 70 - 62 mpg / 58 - 52 mpg US

Oil Consumption

1 - 2 litres per 1,000 kilometres

Top Speed

95 - 100 kph / 59 - 62 mph