• Restored by Tennant-Eyles in the 1980s
• Engine rebuilt by Draganfly Motorcycles
• Numerous modern upgrades
Designed by the legendary Edward Turner, the Ariel Square Four was first shown at Olympia in 1930. Unique at the time of its introduction, the 'Squariel', as it was swiftly dubbed, featured a single block of four cylinders and twin geared-together crankshafts with pistons phased at 180 degrees. The crankcase was split horizontally, unusually for a motorcycle engine of the period, while the vertical valves were operated by a single overhead camshaft.
Although launched as a '500', the 'Squariel' was soon enlarged to 601cc with an eye on the important sidecar market, this bigger version being made available for the 1932 model year. In 1937 a total redesign saw it re-emerge as the Model 4G, with 995cc overhead-valve engine, making the Squariel an even more enticing prospect for sidecarists. Anstey-link plunger rear suspension became an option in 1939 but would not be offered again until 1946 when a telescopic front fork replaced the previous girder type. An exercise in weight shedding saw the cast-iron cylinder head and barrel replaced by alloy components for 1949, the revised model, now capable of 90mph-plus, being known as the Mark I. Introduced in 1953, the 'four pipe' Mark II with redesigned cylinder head elevated the Square Four into the league of genuine 100mph motorcycles. Square Four production, along with that of all other Ariel four-strokes, ceased in 1959. To date, the innovative Ariel Square Four remains unique in motorcycling history; a true 'gentleman's motorcycle, this refined yet charismatic machine retains an enthusiastic and loyal following, and is highly prized by discerning enthusiasts.
This Ariel Square Four was restored during the mid-1980s by the well-known restorer J W Tennant-Eyles, as evidenced by bills on file totalling circa £9,000, which was followed by an engine rebuild undertaken by marque specialists Draganfly Motorcycles in December 1988. The current vendor acquired the Ariel in July 2007 (purchase receipt on file), since when it has been upgraded with an Iron Horse alternator, electronic voltage regulator, electronic ignition points module, Morgo oil pump, modern oil filter, and flashing indicators. The machine has seen little use since acquisition, and although the tyres were renewed nine years ago, the rear at least will require replacement due to age. Described as in generally good condition, this sensibly upgraded Square Four is offered with an old-style logbook, some expired MoTs, old/current V5/V5C registration documents, and the aforementioned invoices/bills.