R25

1951 BMW R25 Technical Analysis & Specification Breakdown

Built around BMW's allround motorcycle platform, the 1951 BMW R25 pairs a 247 cc (15.1 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 5,600 rpm, transferring power to the rear wheel through a 4-speed gearbox and shaft drive (cardan) final drive. With a specific output of 48.6 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 R25 measures 140 kg (309 lbs) wet (curb), translating to a power-to-weight ratio of 0.09 HP/kg (11.67 kg per horsepower). 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 80 km/h (50 mph).

Within MotoLibrary's BMW archive, this model family spans 2 indexed model years from 1950 to 1951, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.