Ariel 1931 Model “4F.31” 497 cc OHC four cylinder frame# R 787 engine # R229
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.
The frame and cycle parts were common to those of the existing 500 cc Sloper Model.
But it created a sensation, nevertheless.
The engine is an air cooled square four with chain driven overhead camshaft and bore x stroke dimensions of 51x61 mm.
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 two gear pumps.
There is a four speed hand change Burman gearbox on board.
This “ first year” Ariel Four is a fascinating design and a pleasant motorcycle to look at and to ride!