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 Norton - CS 1 first OHC
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Norton D2-492-38-02
Photo ou archives : F-M. Dumas

Capacity : 500
Model : CS 1 first OHC
Production : 1928 - 1939
Category : (R) Racing


500 CSl -1928

First of the cammy Nortons

Norton's new overhead-cam 500 made its racing debut in the 1927 Senior TI, a famous

victory because Alex Bennett won the race while Stanley Woods, the chief works rider, made the fastest lap (71 mph) before retiring with clutch trouble. Scarcely six months later, the works announced a client version, the CS1 (for "Cam Shaft One").

The Fastest 500 on the Market

Norton claimed the CS1 was the fastest production machine ava ilable in its category. It was a faithful copy of the works bike, which had been clocked at 93.7 mph in the Isle of Man. Designed by Walter Moore (who designed a similar power unit for NSU), the single-cylinder CS1 engine was a long-stroke unit with a single shaft-and-bevel-driven overhead-camshaft. Primary transmission was by chain to a Sturmey Archer racing gearbox.

New Cradle Frame

The powertrain was housed in a new cradle frame instead of the diamond frame used with the previous Norton pushrod engine. The CSl could be supplied with a touring gearbox, fitted with a kick-starter and solo or sidecar gear ratios as well as with a closeratio box and no kick-starter. The generous drum brakes were reputedly copied from those of the 1926 version of the Ford Model T. The dry-sump lubrication was supplied by a gear pump mounted beneath the lower driving bevels of the camshaft drive. The CS1 remained in production in this form until 1932, when it was replaced by a road-going version of the famous International (which, while it retained the CS1 designation, had an entirely different engine).


Engine: 490cc (79xl00mm) air-cooled singlecylinder four-stroke; dry-sump lubrication; magneto ignition

Power Rating: 28 hp @ 5200 rpm

Valves: shaft-driven overhead-camshaft

Fuel System: carburetor

Transmission: 3-speed, chain final drive

Suspension: girder forks (front); rigid (rear)

Brakes: 7.9 inch drum (front & rea r)

Wheels: 20 inch wire (front & rea r)

Weight: 348 lb

Maximum Speed: 90 mph


The Norton 500cc CSJ was incontestably one of the greatest sport bikes oft be 1920s.

Motorcycle encyclopedia Moto Passion, realised by François-Marie Dumas, include almost 2000 photos presented with an exhaustive history of the motorcycles exhibited.

This unique collection has been realised with the participation of many specialists. With many thanks in particular to Yves Campion, Michael Dregni, Didier Ganneau, Jean Goyard, Helmut Krackowizer, Michel Montange, Christian Rey, Bernard Salvat, Mick Woollett, etc

One can order here

  • Original cards on paper (in french)
  • High resolution scans or original documents presented and signed with my name.

Please contact me at for conditions and copyright.

© Tous droits réservés
François-Marie Dumas

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