Built around Harley-Davidson's allround motorcycle platform, the 1948 Harley-Davidson S-125 pairs a 125 cc (7.6 cu in) air-cooled single cylinder, two-stroke architecture with road-focused gearing. In factory specification, peak output is rated at 3 HP (2.2 kW), transferring power to the rear wheel through a 3-speed gearbox and chain final drive. With a specific output of 24 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 S-125 measures 90.7 kg (200 lbs) dry. The 6.62-liter (1.7 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 72 km/h (45 mph).
Within MotoLibrary's Harley-Davidson archive, this model family spans 12 indexed model years from 1948 to 1959, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
24 HP/L
Engine
Displacement125.0 ccm (7.63 cubic inches)
Engine TypeSingle cylinder, two-stroke
Engine DetailsSingle cylinder, two-stroke
Power3.0 HP (2.2 kW))
Compression6.6:1
Bore x Stroke52.0 x 58.0 mm (2.0 x 2.3 inches)
Fuel SystemCarburettor. Single Langsenkamp-Linkert
CoolingAir
Transmission
Gearbox3-speed
Final DriveChain (final drive)
Performance
Top Speed72.4 km/h (45.0 mph)
Chassis
Frame TypeSingle downtube steel cradle
Front SuspensionGirder fork coil spring
Rear SuspensionRigid-
Wheels & Brakes
Front Tyre3.25-19
Rear Tyre3.25-19
Front BrakesExpanding brake (drum brake). SLS drum front and rear
Front Brake Ø127 mm (5.0 inches)
Rear BrakesExpanding brake (drum brake). SLS drum front and rear
Rear Brake Ø127 mm (5.0 inches)
Dimensions & Weight
Dry Weight90.7 kg (200.0 pounds)
Power/Weight0.0331 HP/kg
Fuel Capacity6.62 litres (1.75 US gallons)
Other
StarterKick
Notes
Made in Germany in 1948 following Germany’s defeat in World War II.
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.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
