Ariel Square Four

Ariel Square Four
ManufacturerAriel Motors Ltd, Bournbrook, Birmingham
Also called'Squariel'[1][2]
Production1931–1959
Engine997 cc (60.8 cu in), 4-stroke, square four, air-cooled, OHV, 8-valve, SU MC2 carburettor[3]
Power40 bhp (30 kW) @ 5,800 rpm[1]
Transmission4-speed manual gearbox to chain final drive
Frame typeTubular single loop[4]
BrakesDrums, 7 inch front, 8 inch rear
Tyres3.25 x 19 inch front, 4.00 x 18 inch rear
Wheelbase1.422 m (4 ft 8.0 in)
DimensionsL: 82 in (2,100 mm)
Weight425 lb (193 kg)[1] (dry)
Fuel capacity5 imp gal (23 L; 6.0 US gal)
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The Square Four is a motorcycle produced by Ariel between 1931 and 1959, designed by Edward Turner, who devised the Square Four engine in 1928. At this time he was looking for work, showing drawings of his engine design to motorcycle manufacturers.[5] The early engine with "two transverse crankshafts"[2] was essentially a pair of 'across frame' OHC parallel twins joined by their geared central flywheels, with a four-cylinder block (or Monobloc) and single head.[6] The idea for the engine was rejected by BSA, but adopted by Ariel. Thus it became the Ariel Square Four.

In 1966 Phil Vincent wrote in Motor Cycle: "Alas, in 1959 the Square Four went out of production, a victim of the modern trend towards small, high-revving modern power units. The demand had tailed off a bit, and with reduced output, the price would have had to be hoisted excessively high. At the time it was approaching £350—out of reach of all but a few of the potential buyers."[2]

A further development was the Healey 1000/4 based on an updated Square Four, produced between 1971 and 1977.

  1. ^ a b c Wilson, Hugo. (1993) The Ultimate Motor-Cycle Book p.85 1955 Ariel Square Four. Dorling Kindersley ISBN 0751300438 Accessed and added 2014-07-08
  2. ^ a b c Motor Cycle 1 December 1966 pp.728–731 Glamour-Puss by Phil Vincent Accessed 4 May 2015
  3. ^ Cite error: The named reference Newnes was invoked but never defined (see the help page).
  4. ^ McDiarmid, Mac (1998). Classic Superbikes From Around the World. Paragon. p. 25. ISBN 978-1405427166.
  5. ^ "1955 Ariel Motorcycle". Mathews Collection. Archived from the original on 9 November 2006. Retrieved 10 November 2006.
  6. ^ "Ariel Square Four – The Real Classic Bike Guide". RealClassic.co.uk. Archived from the original on 3 January 2007. Retrieved 10 November 2006.