BMW R 51/3             1952 BMW R51/3

Date 1951 - 1954 Number sold 18.420 Price 2.750.- DM

Engine
Internal designation	252 / 1
Type	four-stroke, horizontal four-cylinder in-line engine, liquid-cooled
Bore/stroke	68 x 68 mm
Cubic capacity	494 cm3 / 30 inches3
Max power	24 HP at 5800 U /min
Compression ratio	6.3 : 1
Valves per cylinder	ohv
Carburation system	2 carburettor Typ Bing 1/22/41-1/22/42 or 1/22/61-1/22/62
Engine lubrication	forced-feed lubrication
oil pump	gear pump
Power transmission
Clutch	single discs, dry
Number of gears	4
shifting	foot shifting (+ auxiliary manual lever on the gear block)
Gear ratios	4.0 / 2.28 / 1.7 / 1.3 (bis Ende 1951: 3.6 / 2.28 / 1.7 / 1.3)
Rear wheel ratio	1 : 3.89 (with original BMW sidecar: 4.75 : 1)
Bevel/crown wheel	9 / 35 teeth (with original BMW sidecar: 7 / 32)
Electrical system
Alternator	Noris 6 Volt L 45/60 L
Ignition	magneto ignition
Spark plugs	Bosch W 240 T 1
Suspension
designation	251/3 (1951), 251/4 (1952/53), 251/4 (1954)
Type of frame	twin-loop steel tubular frame
Front suspension	telescopic fork
Rear suspension	telescopic fork
wheel rims	deep-bed 3 x 19
Tires front	3.50 x 19
Tires rear	3.50 x 19
Brakes front	drum brake, Ø 200 mm (1952: Duplex, 1954: full hub)
Brakes rear	drum brake, Ø 200 mm (1954: full hub)
Dimensions and weights
Length x width x height	84 x 31 x 39 inches / 2130 x 790 x 985 mm
Wheel base	55 inches / 1400 mm
Tank capacity	4.5 gals. / 17 liters
Unladen weight, full tank	419 lbs. / 190 kg (with original BMW sidecar: 705 lbs. / 320 kg)
load rating	783 lbs. / 355 kg (with original BMW sidecar: 1,322 lbs. / 600 kg)
Fuel consumption	52 MPG (ca. 4.5 liters / 100 km)
oil consumption	ca. 0.7l / 1000 km
Top speed	84 MPH / 135 km/h (with original BMW sidecar: 59 MPH / 95 km/h)