1950 BMW R51 2 Technical Analysis & Specification Breakdown
Engineered by BMW for the allround motorcycle segment, the 1950 BMW R51 2 relies on a 494 cc (30.1 cu in) air-cooled two cylinder boxer, four-stroke powerplant. In factory specification, peak output is rated at 24.1 HP (17.6 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 48.8 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 R51 2 measures 185 kg (408 lbs) wet (curb), translating to a power-to-weight ratio of 0.13 HP/kg (7.68 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,400 mm (55.1 in) wheelbase engineered for quick, flickable steering geometry. The 14-liter (3.7 US gal) fuel tank paired with a rated consumption of 4.1 L/100 km provides an estimated theoretical range of roughly 341 km (212 miles) between fill-ups, while factory top speed is listed at 135 km/h (84 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.
Specific Output
48.8 HP/L
Power-to-Weight
0.13 HP/kg (7.68 kg/HP)
Theoretical Range
~341 km (212 mi)
Engine
Displacement494.0 ccm (30.14 cubic inches)
Engine TypeTwo cylinder boxer, four-stroke
Power24.1 HP (17.6 kW)) @ 5600 RPM
Compression6.4:1
Bore x Stroke68.0 x 68.0 mm (2.7 x 2.7 inches)
Fuel SystemCarburettor. Bing 22mm
Fuel ControlOverhead Valves (OHV)
IgnitionBattery
LubricationWet sump
CoolingAir
Transmission
Gearbox4-speed
Final DriveShaft drive (cardan) (final drive)
ClutchDry-single plate-cable operated
Performance
Top Speed135.0 km/h (83.9 mph)
Fuel Consumption4.10 litres/100 km (24.4 km/l or 57.37 mpg)
Greenhouse Gases95.1 CO2 g/km. (CO2 - Carbon dioxide emission)
Chassis
Frame TypeSteel single cradle
Front SuspensionCartridge
Rear SuspensionTwin shock-Swingarm
Wheelbase1400 mm (55.1 inches)
Ground Clearance120 mm (4.7 inches)
Wheels & Brakes
Front Tyre3.50-19.00
Rear Tyre3.50-19.00
Front BrakesExpanding brake (drum brake). Half hub
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.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
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.