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.
Bore/Stroke: 88/81 mm
Max Speed RPM: 10000 RPM
Inlet Valve: 35mm (Angle 15deg)
Exhaust Valve: 40mm (Angle 15deg)
Valve lift: 12mm
Valve springs: 2 at 130-140kg
SparkPlug: Champion G 56 R
Carb: Modified 34mm Mikuni
Weight: 28.5 kg
Methanol Pump: Volvo Penta
About the Speedway Workshop Archive