R4 Series 3

1934 BMW R4 Series 3 Technical Analysis & Specification Breakdown

At the heart of the 1934 BMW R4 Series 3 allround motorcycle, BMW 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 14 HP (10.2 kW) at 4,000 rpm, transferring power to the rear wheel through shaft drive (cardan) final drive. With a specific output of 35.2 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 3 measures 137 kg (302 lbs) wet (curb), translating to a power-to-weight ratio of 0.1 HP/kg (9.79 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 12-liter (3.2 US gal) fuel tank paired with a rated consumption of 3.5 L/100 km provides an estimated theoretical range of roughly 343 km (213 miles) between fill-ups, while factory top speed is listed at 100 km/h (62 mph).