BMW R47

From CycleChaos
Jump to navigation Jump to search
Bmw-r-47-1928-1928-1.jpg
BMW R47
Manufacturer
BMW
Production 1928
Class Classic
Engine
air-cooled, four-stroke, boxer twin cylinder, OHV
Bore / Stroke 68.6mm x 68.6mm
Compression ratio 5.8:1
Top Speed 68 mph (110 km/h)
Horsepower 17.57 HP (13.1 KW) @ 4000RPM
Transmission Gear box: 3 speed, manual
Clutch: dry, single plate
Final Drive shaft drive (cardan)
Suspension Front: plate spring, 5 laminae
Rear: hard-tail, sprung seat
Brakes Front: 150mm drum
Rear: external shoe brake at the 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 30.98 inches (787 mm)
Height 37.4 inches (950 mm)
Weight 130.0 kg (wet)
Fuel Capacity 3.7 Gallon (14.00 Liters)
Manuals Service Manual


The BMW R 47 was a air-cooled, four-stroke, boxer twin cylinder, OHV Classic motorcycle produced by BMW in 1928. Claimed horsepower was 17.97 HP (13.4 KW) @ 4000 RPM.


1927 BMW R47
BMW R47

BMW's first sports model, the BMW R37, appeared in 1924, joining the original BMW R32 tourer. The BMW R37 boasted a new overhead-valve engine producing 16bhp, almost double the R32's power output, but was produced for little more than a year before being replaced by the improved BMWR47. The latter was introduced in 1926 alongside the sidevalve-engined R42 tourer, both models benefiting from a redesigned and more powerful engine boasting detachable alloy cylinder heads and cooling fins set at 90 degrees to the cylinder axis. The engine was set further back in the duplex loop frame, which improved weight distribution and enabled straight front down-tubes to be used. The braking too came in for attention: the old block-and-pulley type rear brake being replaced by a drum on the driveshaft gripped by external contracting bands. Electric lighting was still regarded as an 'extra' and would not be standardised until 1928. Maximum power output of the R47 was 18bhp and its top speed in the region of 70mph (113km/h). R47 production lasted for just two years, 1,720 machines being sold.

Engine[edit | edit source]

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

Drive[edit | edit source]

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

Chassis[edit | edit source]

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 the 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.

1928 BMW R 47[edit | edit source]

The House of Munich has launched the 1927 R 47 with an air-cooled, four-stroke, 494cc, boxer twin cylinder powerplant mated to a three-speed manual transmission, that could produce a claimed 18 horsepower at 4000 rpm. It comes with a front drum brake, a plate spring fork, a hard-tail rear suspension, a single sprung seat, a rear luggage rack, pull-back handlebars, laced wheels, long fenders, and a small luggage rack in the front.