Start of Production

1925

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End of Production

1927

Numbers Produced

855

Price

1,870 RM

Engine

 

Internal Designation

M 40

Motor Type

Four-stroke single cylinder vertical

Bore x Stroke

68 x 68 mm (2.67 x 2.67 in)

Displacement

247 cc

Max Power

6.5 hp at 4,000 rpm

Compression Ratio

6.0 : 1

Valves

OHV

Carburation System

1 carburettor Type BMW Spezial 20 mm

Engine Lubricating System

Forced feed lubrication

Oil Pump

Gear pump



Power Transmission

 

Clutch

Single plate, dry

Number of Gears

3

Shifting

Manual

Gearbox Ratios

6 / 9.28 / 13.7

Rear Wheel Ratio

1 : 2.84

Bevel/Crownwheel

14 / 37 teeth



Electrical System

 

Ignition System

Bosch magneto generator type G 1.8V/15W

Generator

Bosch magneto ignition

Spark Plugs

Bosch W 175






Chassis

 

Designation

R39

Frame

Twin loop tubular frame

Front wheel suspension

Plate spring, 4 laminae

Rear wheel suspension

Rigid

Wheel rims

27 x 3.5 type CC 1

Tyres, Front

27 x 3.5 balloon or with 26 x 3 high pressure tyres

Tyres, Rear

27 x 3.5 balloon or with 26 x 3 high pressure tyres

Brakes, Front

Internal shoe drum brake 150 mm / 5.90 in diameter

Brakes, Rear

External shoe brake at the gearing on Cardan shaft




Dimensions/Weights

 

Length x Width x Height

2050 x 800 x 950 mm (80.70 x 31.49 x 37.40 in)

Fuel Tank Capacity

10 litres / 2.19 gal / 2.64 gal US

Unladen Weight with Full Tank

110 Kg / 242 lb

Fuel Consumption

Approx. 2.5 litres per 100 Km / 113 mpg / 94 mpg US

Oil Consumption

Approx. 1 - 2 litres per 1,000 Km

Top Speed

100 Kph / 62 mph

Information kindly supplied by P.Hawksley

www.bmbikes.co.uk