Engineered by Simson for the sport motorcycle segment, the 1957 Simson 425 GS features a 247 cc (15.1 cu in) air-cooled single cylinder, four-stroke configuration. In factory specification, peak output is rated at 17.5 HP (12.8 kW) at 7,200 rpm, transferring power to the rear wheel through shaft drive (cardan) final drive. With a specific output of 70.9 HP per liter, the engine character is indicating a tractable, stress-free state of tune focused on everyday usability and broad torque delivery.
On the scales, the 425 GS measures 157 kg (346 lbs) dry, translating to a power-to-weight ratio of 0.11 HP/kg (8.97 kg per horsepower). The 16-liter (4.2 US gal) fuel tank paired with a rated consumption of 3.3 L/100 km provides an estimated theoretical range of roughly 485 km (301 miles) between fill-ups.
Within MotoLibrary's Simson archive, this model family spans 3 indexed model years from 1957 to 1959, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
70.9 HP/L
Power-to-Weight
0.11 HP/kg (8.97 kg/HP)
Theoretical Range
~485 km (301 mi)
Engine
Displacement247.0 ccm (15.07 cubic inches)
Engine TypeSingle cylinder, four-stroke
Engine DetailsSingle cylinder, four-stroke
Power17.5 HP (12.8 kW)) @ 7200 RPM
Bore x Stroke68.0 x 68.0 mm (2.7 x 2.7 inches)
Fuel SystemCarburettor
IgnitionMagneto
CoolingAir
Transmission
Final DriveShaft drive (cardan) (final drive)
Performance
Fuel Consumption3.30 litres/100 km (30.3 km/l or 71.28 mpg)
Greenhouse Gases76.6 CO2 g/km. (CO2 - Carbon dioxide emission)
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.
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.
