Douglas 1931 500 cc OHV twin “ F 31 “ frame# FD 212 engine # ET 136
The 1931 overhead valve models were derived from the innovative S5 (500 cc ) and S6 ( 600 cc ) sports machines designed by Freddy Dixon that were presented at Olympia for the 1930 season.
They were silent, flexible and turned out to be very reliable.
The 1931 500cc and 600 cc OHV models had fully enclosed valve gear, completely enclosed carburettor and dry sump lubrication.
The wheels had big 8 inch brakes and tapered roller bearings.
The place of the gearbox above the engine was reminiscent of earlier Douglas racing practice.
This machine lacks the original mudguards and is need of restoration.