BMW R47: history, specs, pictures

From CycleChaos
Jump to navigation Jump to search
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.

BMW R47
Manufacturer
BMW
Production 1927 - 1928
Engine
two cylinder boxer, four-stroke
Bore / Stroke 68.0mm x 68.0mm
Top Speed 68 mph (110 km/h)
Horsepower 17.57 HP (13.1 KW) @ 4000RPM
Fuel System carburetor. 20mm bmw spezial
Ignition bosh magneto
Battery 5.8:1
Transmission Gear box: 3-speed

Final Drive: shaft drive (cardan)

Clutch: dry-single plate-cable operated
Suspension Front: leading link
Rear: rigid
Brakes Front: expanding brake (drum brake)
Front Tire 3.50-27
Rear Tire 3.50-27
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)
Fuel Capacity 3.7 Gallon (14.00 Liters)
Fuel Consumption 3.00 liters/100 km (33.3 km/l or 78.41 mpg)
Manuals Service Manual


The BMW R47 was a two cylinder boxer, four-stroke standard produced by BMW between 1927 and 1928. It could reach a top speed of 68 mph (110 km/h). Claimed horsepower was 17.57 HP (13.1 KW) @ 4000 RPM.

Engine[edit]

The engine was a air cooled two cylinder boxer, four-stroke. A 68.0mm bore x 68.0mm stroke result in a displacement of just 494.0 cubic centimeters. Fuel was supplied via a overhead valves (ohv).

Drive[edit]

The bike has a 3-speed transmission. Power was moderated via the dry-single plate-cable operated.

Chassis[edit]

It came with a 3.50-27 front tire and a 3.50-27 rear tire. The front suspension was a leading link while the rear was equipped with a rigid. The R47 was fitted with a 3.7 Gallon (14.00 Liters) fuel tank. The wheelbase was 55.51 inches (1410 mm) long.