R42

1927 BMW R42 Technical Analysis & Specification Breakdown

Positioned in BMW's allround motorcycle lineup, the 1927 BMW R42 utilizes a 494 cc (30.1 cu in) air-cooled two cylinder boxer, four-stroke layout. In factory specification, peak output is rated at 12 HP (8.7 kW) at 3,400 rpm, transferring power to the rear wheel through a 3-speed gearbox and shaft drive (cardan) final drive. With a specific output of 24.3 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 R42 measures 126 kg (278 lbs) wet (curb), translating to a power-to-weight ratio of 0.1 HP/kg (10.5 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,410 mm (55.5 in) wheelbase engineered for quick, flickable steering geometry.

Within MotoLibrary's BMW archive, this model family spans 3 indexed model years from 1926 to 1928, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.