Norvin Nirvana
John Surtees is recognised as the original Norvin creator, but many have since mated Norton’s Featherbed frame with Vincent’s formidable V-twin. After eight years perfecting the package, we try JMC’s example.
Evolution is inevitable, which is why modern bikes often look the same, feel the same and handle similarly. But back in the Fifties the British bike industry was still evolving, with some manufacturers better at chassis design, while others had more engine know-how, hence some great, and some not so great specials.
One of the poster bikes of these specials was the Norvin – a Norton Featherbed frame fitted with a Vincent V-twin engine. Creating such a beast was no easy task, as the Vincent engine was enormous and extremely heavy, so while the power was there, many examples were not the greatest at handling.
You can still buy a brandnew Norvin and with modern engineering techniques and a better understanding of chassis dynamics, they handle better now than ever. One man, John Mossey of JMC Classics, has spent eight years perfecting the design of his JMC Norvins.
“This bike has been built for a customer in Guernsey, who saw our website. He liked the design and had seen an example of our work, but wanted his own touches, like the magnesium racing brakes,” explains John. “The basis is a Burgess Featherbed frame, made to our design. This enables us to get the Vincent engine to sit more forward and lower than they used to for better handling. The ideal wheelbase is 55in; the same as a Ducati 900SS, so we mount the swingarm differently and fit the engine so the crankshaft is in line with the wheel axles.
“As standard, the engine is too high and they just feel like the front is falling into a corner. The top left frame rail also has a kink in it to clear the rear carb. It’s made from Reynolds 531 tubing and bronze-brazed – this allows more flex than welding so it’s less prone to cracking.”
The frame holds Minnovation racing yokes, which clamp 38mm Ceriani fully adjustable cartridge forks at a 26° rake, with an Öhlins steering damper. A Beriani WM 2.15 x 18in alloy rim and that beautiful 250mm, four-leading front racing drum sit beneath. That brake costs £2000. As standard, JMC uses a Robinson drum that John says “is just as good on the road and is £800 cheaper, but those mag drums do look amazing”.
At the rear a modern touch, again specified by the owner, are the Öhlins shocks. “Öhlins don’t make bespoke shocks, so these are Yamaha XJ1200 units, revalved and fitted with a lighter, 11kg spring and then we machine a preload spacer,” explains John. The wider, WM 2.50 x 18in Beriani wheel carries an Avon Roadrider tyre like the front and benefits from a magnesium drum, as opposed to the conical Manx Norton brake they would usually fit. The petrol and oil tanks, seat unit and mudguards are all alloy, while most of the fixings, bracketry and all those parts that make the difference between a nice bike and superb bike are made in-house. Thanks to the number of years building these, touches like the cable routing and wiring are sublime. The clocks are by Smiths, with a sender off the rear wheel for the speedo and rev counter off the ECU.