Norton Big Four
This model (Model 1) was launched in
1908, and was the first Norton machine to incorporate
a Norton manufactured engine, previous ones having
been bought in from other sources such as Peugeot.
The engine was a side-valve one, with a characteristic
cylindrical silencer which lay across the front of
the engine.
It started out as a belt drive machine but gained
a chain in 1915. There were various modifications
to the design, particularly for 1931 when, amongst
other things, dry sump lubrication was introduced
and the front mounted magneto was moved to the rear.
The right hand side exhaust system was adopted in
1932 and a four speed gearbox was optional for the
following year.
The Big 4 was a particular favourite of James Norton
himself and in the early '30s he toured South Africa
on a Big 4 combination, covering several thousand
miles and hoping that the fresh air away from the
industrial grime of Birmingham would improve his ailing
health. Ideas for machine improvements were incorporated
on his return to England.
Like the 16H, these machines were also used in the
war and both there and in civilian use could frequently
be seen with a sidecar attached. From 1948, the original
82mm x 120mm engine dimensions (633cc) were reduced
to 82mm x 113mm (596cc). Developments ran side by
side with the 16H, both machines having the laid down
gearbox from 1950; better brakes and a petrol tank
increased in capacity from 2.75 gallons to 3.5 gallons
in 1951; a long awaited change from a saddle to a
dual seat in 1953; and an 8" front brake in the
following year. Power output from the later versions
reached 14 b.h.p., from a machine weighing 413 lbs.
In 1954, production of the Big 4 (and its 490cc counterpart,
the Model 16H) ceased as the popularity of side valve
machines waned rapidly. It had been manufactured for
over 40 years unbroken by wartime, albeit in a number
of quite different forms.
Norton Big Four
- 633cc side-valve - 1908-1947
- 596cc side-valve - 1948-1954
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