10/28/08

A Norton International History

# Engine - 490cc, single ovh-cam single-cylinder four-stroke
# Bore x Stroke - 79 x 100mm
# Power - 29bhp
# Top Speed - 93 mph
# Carburettor - 1 5/32 in Amal TT
# Wheelbase - 54.75in
# Launched - 1931-1939



The Norton Inter story started as far back as 1927, when Walter Moore (formerly the Douglas chief designer) created the first Norton overhead camshaft engine with bore and stroke dimensions of 79x100 mm, giving 490 cc capacity. Straight from the drawing board it provided Alec Bennett with a TT victory in 1927. Known as the CS 1 (Camshaft Senior one) it was listed as a production machine for the 1928 season. The smaller 348 cc version ( 71x85 mm) was known as the CJ (Camshaft Junior). By 1930 Moore had left to work for NSU in Germany and for the TT that year Arthur Carroll , his successor at Bracebridge Street, redesigned the camshaft engine. With this design Norton started its incredible run of success in road racing. For the 1932 season a sort of road going race replica was listed as the International and was equipped with TT Amal carburettor, racing magneto and close ratio four speed gearbox. Later in the thirties the Inter got hairpin valve springs and after the war Roadholder telescopics and plunger rear suspension were added.
Thanks to the Motorbike search engine

The Internationals, the larger Model 30 and the smaller Model 40 are a story in themselves. From the early machines were developed some road bikes and more famously the racers, culminating later in the Manx.


Thanks to : George Cohen

The second generation Norton OHC engine was designed by Arthur Carroll in 1929/30 and made its first appearance at the end of the latter year in the existing Models CS1 and CJ. Quickly adopted for competition use, the new engine soon proved its potential when Bill Lacey improved the world hour record to 110.80 m.p.h. at Montlhéry in France.

The International itself was listed for 1932 in both 490cc and 350cc engine sizes. The specification was a mixture of racing and road features, with racing cams and options on the gearbox internals along with quickly detachable wheels and optional lights for use on the road. Engine tune was usually one step behind the works racers and cycle parts were regularly updated. A Norton manufactured clutch was used from 1934 onwards, and the Norton/Burman gearbox from the following year. As the Manx took over from the Inter for racing purposes, the engine of the latter sadly received virtually no development beyond 1936. Nothing was done to improve its poor reputation for oil leaks either; owners had to seek their own remedy. The 29 b.h.p. output would move it along at just about 100 m.p.h. under favourable conditions. The plunger rear end frame was an optional extra for 1938, having been previously used only on the works racers from 1936. The handling qualities of the plunger and girder Norton were reckoned to be good for the type. The 1938 works bikes went over from the long stroke engine to a short stroke one with a bigger bore; typically, the works bikes design was kept a couple of years ahead of the production models.



Post-war production of the International started again in 1947, but fitted with an iron head and barrel as on the pre-war CS1 and CJ machines.

Although the frame was the regular 'garden gate', with plunger rear springing, the front end was adorned with Roadholder telescopic forks instead of girders. The late '40s was perhaps the last great era of clubmans' racing and many Inters were stripped of silencers and lights for racing use.

Some notable successes were recorded, but the BSA Gold Stars had a distinct performance advantage so it all had to be hard won.


Close ratios were used in the gearbox from 1947, but that was the last significant change before the all alloy engine was restored in 1953, along with the adoption of the Featherbed frame, an 8" front brake and the laid down gearbox. Frames used for singles can be identified easily because the right hand side top tube of the frame was flattened to clear the large nut on the end of the cam box. Quantity production ceased in 1955 and the International was no longer featured in the Norton catalogue, but small numbers were built to special order for two or three years after.

Many thanks to the norton owners club