Speedway Workshop


Scattered throughout the "Workshop" pages, you will see various engines that are 2V, 4V and even 5V. But there are also engines that use 3 Valves (2 Inlet and 1 Exhaust), and one such engine is the "JWS" DOHC 3 Valve conversion for the JAWA. Built in the Netherlands by Jeroen Woudenberg (the name JWS deriving from his initials + "special") between 1984/85, the JWS came in two versions, the Mk1 and the Mk2.

On the Mk1 (Prototype), the camdrive is driven by 2 toothed belts, whilst on the Mk2 Production model, the camdrive is driven by a combination of gears and a normal chain.
The differences can be seen in the diagram (Right) and in the series of photographs pictured below (courtesy of Ben Ludolphy). Also listed are the Technical Specifications for the Mk2 Engine.


Volume: 493 ccm
Bore/Stroke: 88/81 mm
Compression: 15:1
Max Speed RPM: 10000 RPM
Piston: Corworth
Inlet Valve: 35mm (Angle 15deg)
Exhaust Valve: 40mm (Angle 15deg)
Valvelift: 12mm
Valvesprings: 2 at 130-140kg
SparkPlug: Champion G 56 R
Carb: Modified 34mm Mikuni
Weight: 28.5 kg
Methanol Pump: Volvo Penta

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Phil Aynsley Photography
Phil Aynsley Photography
Thousands of quality photographs featuring Ducati, Moto Guzzi, MV Agusta and numerous other marques. An index to many of the amazing galleries on his site is available here:
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