Ariel 1952 model 4G 1000cc Square Four MK 1 frame SV 211 engine TM 224
Ariel unveiled the all new SQ 4 to the motorcycle world at the Olympia show in 1930.
It was a brainchild of design genius Edward Turner and was powered by an OHC engine with 2 parallel crankshafts, mounted in a crankcase transversely across the frame.
The two cranks were geared together in the center uf the unit, so in effect there were two vertical twin engines running in opposite directions. The result was a silky, smooth power output with instant response to the throttle.
In 1932 the capacity was increased to 600 cc and in 1937 a new 4 appeared, this time of 1000 cc and with pushrods instead of the chain-driven overhead cam.
This new model was labelled the mark I. Roller conrod bearings were also dropped in favour of plain bearings and the coupling gears were moved from the center of the engine and placed in a case on the left side.
Power output was about 38 HP, top rpm approx. 5500.
In 1939 a new spring frame was added, and after WW2 a new telescopic front fork .
The engine was also considerably lightenend by the use of a new alloy cylinder barrel and head. Additional finning was used to improve heat dissipation.
Lucas coil ingintion was fitted in place of magneto ignition for better starting and less weight.
The Mark I was a popular machine, a strong seller and exceptionally smooth runner. It is a quiet, comfortable machine with fantastic acceleration and surprising top end performance.