July 2, 2011
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Cive Tomkinson.

Clive Tomkinson bought Norton-Villiers about 20 years to supply vintage motocross parts for classic bikes (those powered by the infamous Norton-Villiers Starmaker engine). Clive specializes in vintage 6-8e, 9e-37A and Starmaker engines (at So, it comes as a surprise that the Salford, England, engineer has come up with a totally new design for a two-stroke engine that could put the two-smokes back on the motocross map again.

Tomkinson’s new two-stroke engine is currently going through the patent application process, so it can’t be shown, but Tomkinson says that his two-stroke engine would cost up to 60 per cent less to manufacture than equivalent four-stroke engines. Not only is a two-stroke engine cheaper to produce than a four-stroke engine, but it produces 30-40 per cent more power. Tomkinson has worked with experts from universities in Salford, Lancaster and Belfast (decades ago there was collaborative engineering effort began between Greeves and Dr. Gordon Blair of Queen’s University, Belfast. This collaboration resulted in the last significant bike to be sold by Greeves, the Griffon 380 QUB (Queen’s University Belfast)).

Starmaker-equipped AJS Stormer 250.

Clive says, that the two-stroke has “fallen out of favor over the years because it uses an oil/petrol mix as fuel, so it is smelly and it doesn’t comply with modern emissions regulations. The potential applications for my new design are enormous, from small generators that could be carried in a backpack for use in disaster zones, to engines that could power container ships or even Formula 1 cars. A car engine size of, say 1000cc, could be reduced to around 600cc using this design, resulting in lower fuel costs, lower insurance and so on.”

Mr. Tomkinson’s new engine can be powered by petrol, diesel or most bio-fuels and uses a completely different process to reduce friction in the engine. The engine is lubricated by a Norton Villiers controlled spray system, designed to give a minuscule level of drag on the engine and surfaces (thus it does not require pre-mix).

Classic Greeves Starmaker 24ME.

Norton Villiers was a well-known British motorcycle manufacturer (famous for its street bikes, like the Norton Commando), but its two-stroke engines were used in Greeves, Cotton and AJS motocross bikes.


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