251 SS

1927 NSU 251 SS Technical Analysis & Specification Breakdown

Engineered by NSU for the sport motorcycle segment, the 1927 NSU 251 SS utilizes a 247 cc (15.1 cu in) air-cooled single cylinder, four-stroke layout. In factory specification, peak output is rated at 10 HP (7.3 kW) at 4,400 rpm, transferring power to the rear wheel through a 3-speed gearbox and chain final drive. With a specific output of 40.5 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 251 SS measures 110 kg (243 lbs) dry, translating to a power-to-weight ratio of 0.09 HP/kg (11 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,330 mm (52.4 in) wheelbase engineered for quick, flickable steering geometry. The 7.75-liter (2 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 100 km/h (62 mph).

Within MotoLibrary's NSU archive, this model family spans 3 indexed model years from 1927 to 1929, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.