1961 AJS Model 31 650 Swift Technical Analysis & Specification Breakdown
Built around AJS's allround motorcycle platform, the 1961 AJS Model 31 650 Swift pairs a 646 cc (39.4 cu in) air-cooled twin, four-stroke architecture with road-focused gearing. In factory specification, peak output is rated at 31.4 HP (22.9 kW) at 6,000 rpm, transferring power to the rear wheel through a 4-speed gearbox and chain final drive. With a specific output of 48.6 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 Model 31 650 Swift measures 176 kg (388 lbs) dry, translating to a power-to-weight ratio of 0.18 HP/kg (5.61 kg per horsepower). The 16-liter (4.2 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's AJS archive, this model family spans 8 indexed model years from 1959 to 1966, 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.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
