BMW R 39

BMW R 39 Date 1925 - 1927

Number sold 855

Price 1.870,- RM

Engine

internal designation M 40
engine type four-stroke two-cylinder flat-twin
Bore/stroke 68 x 68 mm
Cubic capacity 247 cm3
Max power 6,5 PS at 4500 U /min
Compression ratio 6,0 : 1
Valves per cylinder ohv
Carburation system carburettor BMW Spezial 20 mm
Engine lubrication forced-feed lubrication
oil pump gear pump

 
Power transmission

Clutch single discs, dry
Number of gears 3
shifting manual
Gear ratios 6 / 9,28 / 13,7
Rear wheel ratio 1 : 2,64
Bevel/crown wheel 14 / 37 teeth

 
Electrical system

Alternator Bosch magneto ignition
Ignition Bosch magneto generator Type G 1, 6 V /15 W
Spark plugs Bosch W 175

 
Suspension

designation R 39
Type of frame twin-loop tubular frame
Front suspension plate spring, 4 laminae
Rear suspension rigid
wheel rims 27 x 3, 50 Typ CC 1
Tyres front 27 x 3, 50 balloon or with 26 x 3 high-pressure tyres
Tyres rear 27 x 3, 50 balloon or with 26 x 3 high-pressure tyres
Brakes front internal shoe brake (drum brake) 150 mm
Brakes rear external shoe brake at the gearing (on cardan shaft)

 
Dimensions and weights

Length x width x height 2050 x 800 x 950 mm
Tank capacity 10 l
Unladen weight, full tank 110 kg
Fuel consumption ca. 2,5 l / 100 km
oil consumption ca. 1 - 2 l / 1000 km
Top speed 100 km/h