313 Starr

1955 Hercules 313 Starr Technical Analysis & Specification Breakdown

Engineered by Hercules for the sport motorcycle segment, the 1955 Hercules 313 Starr 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).

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.