Built around Ariel's allround motorcycle platform, the 1939 Ariel 4G Square Four 1000 utilizes a 997 cc (60.8 cu in) air-cooled square four cylinder layout. In factory specification, peak output is rated at 35 HP (25.5 kW) at 5,500 rpm, transferring power to the rear wheel through a 4-speed gearbox and chain final drive. With a specific output of 35.1 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 4G Square Four 1000 measures 193 kg (425 lbs) dry, translating to a power-to-weight ratio of 0.18 HP/kg (5.51 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,422 mm (56 in) wheelbase engineered for balanced agility and highway composure. The 23-liter (6.1 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 140 km/h (87 mph).
Within MotoLibrary's Ariel archive, this model family spans 14 indexed model years from 1936 to 1949, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
35.1 HP/L
Power-to-Weight
0.18 HP/kg (5.51 kg/HP)
Engine
Displacement997.0 ccm (60.84 cubic inches)
Engine TypeSquare four cylinder
Engine DetailsDouble twin cylinder arranged as a square
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.
