At the heart of the 1951 Hercules 313 Starr sport motorcycle, Hercules relies on a 123 cc (7.5 cu in) air-cooled single cylinder, two-stroke powerplant. In factory specification, peak output is rated at 6.5 HP (4.7 kW) at 4,700 rpm, transferring power to the rear wheel through chain final drive. With a specific output of 52.8 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 313 Starr measures 90 kg (198 lbs) dry, translating to a power-to-weight ratio of 0.07 HP/kg (13.85 kg per horsepower). The 11-liter (2.9 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 85 km/h (53 mph).
Within MotoLibrary's Hercules archive, this model family spans 7 indexed model years from 1951 to 1957, 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.
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.
