BMW R 51 / 2

BMW R 51 / 2 Date 1950 - 1951

Number sold 5.000

Price 2.750,- DM

Engine

internal designation 254 / 3
engine type four-stroke two-cylinder flat-twin
Bore/stroke 68 x 68 mm
Cubic capacity 494 cm3
Max power 24 PS at 5800 U /min
Compression ratio 6,4 : 1
Valves per cylinder ohv
Carburation system 2 carburettor Typ Bing 1/22/39 und 1/22/40
Engine lubrication forced-feed lubrication
oil pump gear pump

 
Power transmission

Clutch Einscheiben-TrockenClutch
Number of gears 4
shifting foot shifting (+ auxiliary manual lever on the gear block)
Gear ratios 3,6 / 2,28 / 1,7 / 1,3
Rear wheel ratio 1 : 3,89 (with sidecar 4,57 : 1)
Bevel/crown wheel 9 / 35 (with sidecar 7 / 32)

 
Electrical system

Alternator Bosch 6 V / 75 Watt
Ignition battery ignition
Spark plugs Bosch W 240 T 1

 
Suspension

designation 251 / 2
Type of frame Geschlossener Doppelstahlrohrframe
Front suspension telescopic fork
Rear suspension telescopic fork
wheel rims deep-bedwheel rims
Tyres front 3,50 x 19
Tyres rear 3,50 x 19
Brakes front drum brake, 200 mm (Halbnabe)
Brakes rear drum brake, 200 mm (Halbnabe)

 
Dimensions and weights

Length x width x height 2130 x 815 x 720 (saddle) mm
Ground clearance 120 mm
Tank capacity 14 l
Unladen weight, full tank 185 kg
load rating 400 kg
Fuel consumption ca. 4 l / 100 km
oil consumption ca. 1 l / 1000 km
Top speed 135 km/h