ARIEL Square Four Models/Series Timeline, Specifications & Photos

The first Ariel Square Four 4F was presented in 1930, having an engine of 500cc. In 1931, the engine grew to 601cc. The year 1937 came for the Square Four with a changed engine with a displacement of 995cc, whose production lasted till 1949. At the beginning of the '50's, a Square Four I with 35 hp ( 26.09 Kw) at 5500rpm was produced. This bike was able of running with 90mph. Its brother, the Square Four Mark II, built from 1953 to 1959 had the same 997cc engine and its speed was of 160 Km (100 mph). In 1954 there was a Mk3 prototype which, unfortunately, never saw the roads. After this experiment, the Square Four production ceased in 1959.

The 1932 Ariel Square Four 600 4F has, at its heart, an air-cooled, four-stroke, 601cc, double vertical twin cylinder engine paired to a four-speed manual transmission, and can also produce a claimed 23 horsepwoer at 5600 rpm. In addition, it comes with a hardtail rear suspension, a sprung single seat, a large luggage rack, a parallelogram front fork, full fenders, a large headlight, a drum braking system, laced wheels, a dual exhaust system, and a blacked-out frame.