Built around NSU's sport motorcycle platform, the 1939 NSU 351 OSL features a 346 cc (21.1 cu in) air-cooled single cylinder, four-stroke configuration. In factory specification, peak output is rated at 18 HP (13.1 kW) at 5,020 rpm, transferring power to the rear wheel through a 4-speed gearbox and chain final drive. With a specific output of 52 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 351 OSL measures 110 kg (243 lbs) dry, translating to a power-to-weight ratio of 0.16 HP/kg (6.11 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,420 mm (55.9 in) wheelbase engineered for balanced agility and highway composure.
Within MotoLibrary's NSU archive, this model family spans 7 indexed model years from 1934 to 1940, 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.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
