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Production 1926 - 1928
Class Classic
air-cooled, four-stroke, boxer twin cylinder, SV
Bore / Stroke 68.6mm x 68.6mm
Compression ratio 4.9:1
Top Speed 59 mph (95 km/h)
Horsepower 11.67 HP (8.7 KW) @ 3400RPM
Fuel System carburetor. 20mm BMW spezial
Transmission Gear box: 3 speed, manual

Final Drive: shaft

Clutch: dry, single plate
Suspension Front: plate spring, 5 laminae
Rear: hard-tail, sprung seat
Brakes Front: 150mm drum
Rear: external shoe brake at gearing (on cardan shaft)
Front Tire 27 x 3.5
Rear Tire 27 x 3.5
Wheelbase 55.51 inches (1410 mm)
Length 82.68 inches (2100 mm)
Width 31.5 inches (800 mm)
Height 37.4 inches (950 mm)
Weight 126.0 kg (wet)
Manuals Service Manual

The BMW R 42 was a air-cooled, four-stroke, boxer twin cylinder, SV Classic motorcycle produced by BMW in 1926. Claimed horsepower was 11.94 HP (8.9 KW) @ 3400 RPM.


A 68.6mm bore x 68.6mm stroke result in a displacement of just 494.0 cubic centimeters.


The bike has a 3 speed, manual transmission. Power was moderated via the dry, single plate.


It came with a 27 x 3.5 front tire and a 27 x 3.5 rear tire. Stopping was achieved via 150mm drum in the front and a external shoe brake at gearing (on cardan shaft) in the rear. The front suspension was a plate spring, 5 laminae while the rear was equipped with a hard-tail, sprung seat. The wheelbase was 55.51 inches (1410 mm) long.

1926 - 1928 BMW R 42[edit]

The R 42 from the House of Munich had, at its heart, an air-cooled, four-stroke, 494cc, boxer twin cylinder engine mated to a three-speed manual transmission, and could reach a claimed maximum power output of 12 horsepower at 3400 rpm. Standard features included laced wheels, long fenders, a small headlamp, wide handlebars, a plate string front fork, a rigid rear suspension with a sprung seat, a rear luggage rack that could be transformed in a passenger seat, and a front drum brake.