The Ariel square four’s original design by Edward Turner is said to have been a masterpiece, but it proved too costly to produce commercially and so Chief designer Val Page was instructed by the Ariel Board to cut its costs by making any alterations that were necessary.
Page went to work and the production version of the redesigned Four was presented to the public at the London Olympia Show in November 1930. The machine was heavier than the original design and didn’t have the integrated gearbox. Frame and cycle parts were common to those of the existing 500 cc Sloper Model. But it created a sensation, nevertheless. The 1931 model had a cubic capacity of 498 cc; in 1932 a 601 cc version became available. The engine is an air cooled square four with chain driven overhead camshaft.
The two crankshaft are coupled by gears. The mixture is fed to the engine through a single, front-mounted Amal carb and the lubrication is of the wet-sump type with a gear pump ( from 1933 onwards this became a plunger pump). There is a four speed hand change gearbox on board. Dry weight is 181 kilograms , max power is 24 HP @ 6,000 and top speed a comfortable 75 mph.
A fascinating design and a pleasant motorcycle to look at and to ride!
Report by yesterdays.nl