1928 BMW R42 Technical Analysis & Specification Breakdown
Built around BMW's allround motorcycle platform, the 1928 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.
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
