First ride: British-built Metisse prototype

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This 997cc Metisse parallel twin could eclipse Norton’s long-awaited production plans with the first machines set to hit the road within 18 months.

The British company, based near Oxford, has already built a working prototype parallel twin engine of its own design and bolted it into an existing chassis.

MCN was granted a first ride, and we were pleasantly surprised by the ‘rough cut’ powerplant. The 997cc (98 x 66mm) engine is an 8-valve, air-cooled, parallel twin with a 360° firing order. Even at this early stage of development, dyno testing has shown the engine to produce 95bhp at 8000rpm, with a linear spread of torque that peaks at 70ftlb at 7000rpm. This is significantly more performance than Metisse owner Gerry Lisi expected.

Plans are also on the drawing board to produce a 1200cc version using the 997cc engine’s crankcases and minimal modifications.

As it is, the twin-cylinder lump carries a heady amount of low down torque coupled with high rpm power. It sounds furiously fast because the Metisse exhaust is free-breathing and exits from the middle of the rear fender. At least you get to hear the metallic ringing noise of the barrel fins before 70mph exhaust rasp drowns it out.

Vibration is minimal. A slight buzz up to 4000rpm can just be felt through the frame, but after that the two gear-driven counter-balancers ensure mirrors, bars and pegs are vibe-free.

The gearbox was originally a Kawasaki design and the five gears are short spaced so the bike runs out of revs very quickly. For testing purposes, the AER (Advanced Engine Research) ECU limits revs to 7500rpm. A six-speed Metisse gearbox is currently being manufactured.

Bolted within the donor Metisse Mk5  chassis – a sorted dual-purpose machine – the prototype shows exciting potential. Motec data acquisition is fitted to learn, store and give feedback on engine and exhaust temp and the dual fuel injection.

Development work of riding and component evaluation is ongoing. Small niggles like the overrun fuelling producing loud backfires are in hand.

Lisi has started work on building engine number two, which will be the basis for customer machines, along with three new rolling chassis; an updated dual-purpose bike, roadster and tourer.

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Trevor Franklin

By Trevor Franklin