The model range from 1930 was severely pared down for 1931. Sunbeam was
attempting to weather the Great Depression in the world's economy. The
catalogue emphasised 'Sunbeam value' with lower cost machines (the Lion
and new Model 10) replacing longstanding designs. It even provided details
of a Sunbeam hire purchase agreement through the factory or recognised
Other than the 596cc 'Model 7' flat-tank machine
(unaltered since 1928 and still available to order) the side-valve range
was reduced to one machine: the cut-price 'Lion' introduced mid-season the
previous year. Gone were the longstanding Marston side-valves: the
347cc 'Model 1' and 'Model 2' plus the 'Model 5' and 'Model 6' versions of
the 492cc Longstroke.
The 347cc OHV 'Model 8' was also lost. However, it
was replaced by a new introduction to the range; a John Greenwood and
George Stephenson designed 344cc OHV machine named the
'Model 10'. This machine had a distinctive crankcase, holding a wet sump -
a design only previously seen in the 1925 OHC racing machines.
Its design did not allow for the use of Sunbeam's trademark enclosed rear chaincase. Roy Bacon also refers to Sunbeam offering a tuned
version of the 'Model 10' for the mid-season in July 1931.
Mid-season, in July 1931, a 599cc version of the side-valve Lion
was also added to the range. Designated the 'Model 7A', it introduced a
side-valve engine with a detachable head and 'boxed-in' valve springs
which became the standard side-valve design for 1932 and thereafter.
The 493cc OHV Model 9 in its standard and 'Model 90'
sporting varieties continued to be available but it was now provided with
the chrome tank and Webb-style forks of the newer models. 'Model 9' was
available with both single and twin-port cylinder options; 'Model 90' only
as a twin-port. The 'Model 90' was offered in both road racing and 'fast
Druid forks are replaced by centrally sprung Webb-style front forks, made at
Chrome-plated, welded tanks were introduced - the petrol tank finished in chrome
plate with black panels. Needless to say, it did not go down well and an
all-black colour scheme returned in 1932.
Engine and gearbox
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* John Marston Ltd, 1931, 'Sunbeam Motor Cycles 1931'.
* Robert Cordon Champ, 1980, 'The Sunbeam Motorcycle'. Haynes Publishing.
*Robert Cordon Champ, 1989, 'The Illustrated History of Sunbeam Bicycles and
Motorcycles'. Haynes Publishing.
* Roy Bacon, 1986, 'British Motorcycles of the 30s'. Osprey Publishing