Sunbeam 1917 3 ½ HP side valve frame 4829 engine 4924
The Wolverhampton based firm of John Marston Ltd. earned fame for their superb bicycles at the end of the 19th and beginning of the 20th century.
In 1912 their first motorcycle was presented. It was equipped with a 2 ¾ hp engine designed by Harry Stevens, one of the talented family of Stevenses later to found their own company not far from Sunbeamland.
Stevens acted as a consultant to Marstons and designed a conventional 349 cc side valve single, with two-speed transmission and forward placed magneto.
Further development of engine and cycle parts was then taken over by John Greenwood, a highly competent engineer and rider, who came with the firm in 1912 and remained at Sunbeamland for the rest of his working life, designing almost every Sunbeam motorcycle.
Greenwood ( who had previously designed the Rover3 ½ HP engine) altered the Stevens design in that he moved the magneto to the position behind the cylinder.
In general motorcycle design and manufacture was carried out according to the standards set for the Sunbeam bicycles: elegance, silence in operation, reliability and impeccable finish were the keywords.
At the end of 1913 a 3 ½ HP model ( 85x88mm) was launched, a model that would make the Sunbeam name world famous.
Nickel plating on Sunbeams was kept to a minimum, almost all parts were enamelled black.
The enamel was of outstanding quality, as witnessed by many vintage Sunbeams still having their first finish… The whole machine followed John Marston’s dictum of the best possible quality allied to the best possible specification.
Some of these outstanding features are the aluminium “ Little Oil Bath “ alloy primary chaincase and the enclosed rear chaincase.