OK ca. 1927 349 cc OHV oil cooled Bradshaw frame# 7488 engine# 4082
OK motorcycles were manufactured by the firm of Humphries & Dawes in Birmingham from 1899 till 1939: from 1926, when one of the controlling partners left the firm, the company was renamed OK Supreme.
The motorcycles were built at the Hall Green Works in Birmingham.
The company had some success in racing in the twenties and was sufficiently well established to overcome the downturn in trade in the Depression years.
In the years before the Great War the company fitted among others “Precision” engines, in the early twenties Union and Villiers two stroke power units were fitted. In the mid-twenties the range consisted of two stroke models of 292 and 348 cc cc, the sports tourer OHV Bradshaw and sv and ohv Blackburne power units.
Plenty of choice in engines!
From the late twenties the company used mainly sv and ohv JAP engines, although there was also a model with OK ohc engine for some years.
Granville Bradshaw designed several oil cooled engines; the first was a 500 cc ohv flat twin which was used by Zenith in 1920.
In 1921 the range was extended with a 350 cc ohv single and a 1000 cc V-twin.
The engines were produced by James Walmsley & Co in Preston and marketed by Gilbert Campling.
From 1925 the engines were built by Dorman in Stafford.
The longstroke Bradshaw engine – used by OK from 1924 to 1928 – has bore and stroke dimensions of 68×96 mm and mechanical lubrication.
The machine has a 3 speed gearbox and Brown & Barlow carburettor.
It weighs about 200 lbs, so it’s a light and agile machine.