BMW R4: history, specs, pictures
The BMW R4 was a air-cooled, four-stroke, single vertical cylinder Classic motorcycle produced by BMW in 1932. Claimed horsepower was 13.95 HP (10.4 KW) @ 4000 RPM.
Manufacturer | BMW |
---|---|
Production | 1932 |
Class | Classic |
Engine | air-cooled, four-stroke, single vertical cylinder |
Bore / Stroke | 83.8mm x 83.8mm |
Compression ratio | 5.7:1 |
Horse Power | 13.95 HP (10.4 KW) @ 4000RPM |
Transmission | Gear box: 4-speed, manual Final Drive: shaft |
Suspension | Front: parallelogram fork Rear: hard-tail, sprung seat |
Brakes | Front: 160mm drum Rear: 160mm drum |
Front Tire | 3.50 x 26 |
Rear Tire | 3.50 x 26 |
Weight | (dry), 137.0 kg (wet) |
Manuals | Service Manual |
Tech Specs · Brochures · Reviews · Ads · Videos |
BMW produced 15,200 R4 motorcycles using innovative mass production techniques, setting new standards of design and quality. Pressed steel frame and components were quick and easy to stamp out and assemble, reducing manufacturing costs.
Introduced in 1932 and intended to bridge the gap between the 'budget' BMW R2 198cc single and the expensive twins, the R4 looked much like the former, whose channel-section steel frame and running gear it used almost unaltered. The 398cc overhead-valve engine featured enclosed valve gear and produced 12bhp, gaining an extra two horsepower in 1933 when the BMW R4 was updated to Series 2 specification with revised styling and a four-speed gearbox. A new cylinder head, tidier engine casings and changes to the toolbox and generator locations were introduced as the rugged R4 - a favourite with police forces and the German Army - progressed through to Series 5 before production ceased in 1936.
Engine
A 83.8mm bore x 83.8mm stroke result in a displacement of just 498.0 cubic centimeters.
Drive
The bike has a 4-speed, manual transmission. Power was moderated via the dry, single plate.
Chassis
It came with a 3.50 x 26 front tire and a 3.50 x 26 rear tire. Stopping was achieved via 160mm drum in the front and a 160mm drum in the rear. The front suspension was a parallelogram fork while the rear was equipped with a hard-tail, sprung seat.
1932 - 1937 BMW R 4
The 1932 BMW R 4 has, at its heart, an air-cooled, four-stroke, 498cc, single vertical cylinder engine mated to a four-speed manual transmission that can produce a claimed 14 horsepower at 4000 rpm. This classic machine had standard features such as laced wheels, full fenders, a hard-tail rear suspension with a sprung seat, a parallelogram front suspension, a large headlight, a rear luggage rack and an exhaust system with a large-diameter muffler.
In Media
Manufacturer | BMW |
---|---|
Also called | R4 Series 1, R4 Series 2, R4 Series 3, R4 Series 4, R4 Series 5 |
Production | 1932 - 1937 |
Engine | single cylinder, four-stroke |
Bore / Stroke | 84.0mm x 78.0mm |
Top speed | 59 mph (95 km/h) |
Horse Power | 13.68 HP (10.2 KW) @ 4000RPM |
Fuel system | carburettor. sum ck 3/500 fr |
Ignition type | battery |
Battery | 5.7:1 |
Transmission | Final Drive: shaft drive (cardan) Clutch: dry-single plate-cable operated |
Suspension | Front: cartridge Rear: rigid |
Brakes | Front: expanding brake (drum brake) Rear: expanding brake (drum brake) |
Front Tire | 3.50-26.00 |
Rear Tire | 3.50-26.00 |
Wheelbase | 51.3 inches (1303 mm) |
Dimensions | L 77.95 inches (1980 mm) W 33.46 inches (850 mm) H 37.76 inches (959 mm) |
Weight | (dry), 137.0 kg (wet) |
Fuel capacity | 3.17 Gallon (12.00 Liters) |
Fuel consumption | 3.50 litres/100 km (28.6 km/l or 67.21 mpg) |
Manuals | Service Manual |
Tech Specs · Brochures · Reviews · Ads · Videos |
The BMW R4 Series 5 was a single cylinder, four-stroke standard produced by BMW between 1932 and 1937. It could reach a top speed of 59 mph (95 km/h). Claimed horsepower was 13.68 HP (10.2 KW) @ 4000 RPM.
Engine
The engine was a air cooled single cylinder, four-stroke. A 84.0mm bore x 78.0mm stroke result in a displacement of just 398.0 cubic centimeters. Fuel was supplied via a overhead valves (ohv).
Drive
Power was moderated via the dry-single plate-cable operated.
Chassis
It came with a 3.50-26.00 front tire and a 3.50-26.00 rear tire. Stopping was achieved via expanding brake (drum brake) in the front and a expanding brake (drum brake) in the rear. The front suspension was a cartridge while the rear was equipped with a rigid. The R4 Series 5 was fitted with a 3.17 Gallon (12.00 Liters) fuel tank. The wheelbase was 51.3 inches (1303 mm) long.