Ariel 4F Square Four 500 - Specifications & Review

4F Square Four 500

Article Complete Info

Articleid912954
CategoryAllround
MakeAriel
Model4F Square Four 500
Year1931

Chassis, Suspension, Brakes & Wheels

FrametypeTubular single loop
FrontbrakesExpanding brake (drum brake)
FrontsuspensionSpring girders
Fronttyre3.25-19
RearbrakesExpanding brake (drum brake)
RearsuspensionRigid
Reartyre3.25-19
WheelsWire spoked

Engine & Transmission

Borexstroke51.0 x 61.0 mm (2.0 x 2.4 inches)
Compression6.9:1
CoolingsystemAir
Displacement498.00 ccm (30.39 cubic inches)
DrivelineBurman gearbox
EnginedetailsSquare four cylinder
EnginetypeDouble twin - square 4 cylinder arrangement
Exhaustsystem2 x 1-into-1 pipes
FuelsystemCarburettor. Amal
Gearbox4-speed
LubricationsystemWet sump
Topspeed120.7 km/h (75.0 mph)
TransmissiontypefinaldriveChain
Valvespercylinder2

Other Specifications

ColoroptionsRed/beige
CommentsAlso called Squariel.
StarterKick

Physical Measures & Capacities

Dryweight193.0 kg (425.5 pounds)
Fuelcapacity13.25 litres (3.50 gallons)
Overalllength2,100 mm (82.7 inches)

About Ariel

Country of Origin: United Kingdom
Founder: James Starley & William Hillman (bicycles); later Ariel Motorcycles under Charles Sangster
Best Known For: Square Four tourers, Red Hunter singles, and innovative early designs

Company History

Ariel is among Britain’s most storied names, moving from bicycles to motorcycles in the brass era and innovating through several epochs. The Red Hunter singles set a standard for sporting roadsters, while Edward Turner’s Square Four delivered creamy long-distance power from a compact four-cylinder layout. Postwar Ariels carried commuters and enthusiasts alike, with alloy cylinders and tidy frames that showcased the firm’s engineering finesse. The two-stroke Leader/Arrow of the late 1950s pushed modernity—enclosed bodywork, pressed steel, unit construction—foreshadowing scooters and lightweight commuters. Industry headwinds and consolidation into BSA/Triumph eventually ended motorcycle production in the late 1960s. In the 21st century, the Ariel name returned on radical lightweight cars and a boutique V-4 motorcycle prototype, channeling the brand’s historic appetite for bold design. Historically, Ariel symbolizes British ingenuity: elegant solutions to packaging and power delivery, a willingness to try new materials and layouts, and an understanding that motorcycles could be both fast and refined. A well-sorted Square Four remains a bucket-list ride—silky midrange, dignified pace, and the sense of traveling with civilized authority.

Other Years

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