R4 Series 2

1933 BMW R4 Series 2 Technical Analysis & Specification Breakdown

Engineered by BMW for the allround motorcycle segment, the 1933 BMW R4 Series 2 pairs a 398 cc (24.3 cu in) air-cooled single cylinder, four-stroke architecture with road-focused gearing. In factory specification, peak output is rated at 12 HP (8.8 kW) at 4,000 rpm, transferring power to the rear wheel through shaft drive (cardan) final drive. With a specific output of 30.2 HP per liter, the engine character is prioritizing low-RPM tractability, mechanical longevity and relaxed throttle response over peak redline numbers.

On the scales, the R4 Series 2 measures 137 kg (302 lbs) wet (curb), translating to a power-to-weight ratio of 0.09 HP/kg (11.42 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,300 mm (51.2 in) wheelbase engineered for quick, flickable steering geometry. The 10-liter (2.6 US gal) fuel tank paired with a rated consumption of 3.5 L/100 km provides an estimated theoretical range of roughly 286 km (178 miles) between fill-ups, while factory top speed is listed at 100 km/h (62 mph).