The ultimate cafe-racer Norvin
FOR SPEED-CRAZY, CAFE-RACING motorcyclists in the 1950s and 1960s, mixed-make hybrids were an inevitable result of the quest to top anything on the road.
A popular choice of the time was the Triton: a tuned Triumph parallel-Twin bolted into a Norton Featherbed frame.
But as soon as the Triton was established as the ultimate burn-up tool, a few bold individuals looked for someth ing more powerful, even more intimidating.
They sought the absolute in the Norvin, a Vincent-engined Norton.
The Stevenage V-Twin had obvious advantages-more cubes for a start, lOOOcc against Triumph’s 650. It was the biggest, fastest lump available, even 10 years after its manufacture ended in 1955. In turned form, it promised a significant advance on the best parallelTwin’s 45-odd horsepower. And the Vincent engine/gearbox stuffed the engine bay of the Featherbed to splendid fullness.
There were racetrack precedents for this, including the Norton-Vincent British roadracer John Surtees built when working at Vincent in 1953.
But there were problems too. Squeezing the biggest, fastest British engine available into the Norton frame proved tricky, especially if top-heaviness was to be avoided. Also the complexity of Vincent's high cam, 50-degree Twin contrasted with a Triumph's stark simplicity.
As a consequence, Non ins were rare beasts, and not all such hybrids succeeded in becoming much more than a sum of their parts. Building a successful Norvin was, and still is, an ultimate challenge for the home engineer.
That didn’t stop collector Peter Fox (owner of the pristine example featured in this article) from his quest. When he saw a Norvin on a visit to the Isle of ManTT festival in the early '70s, he simply knew he would someday ride one of his own.
That day came three years ago, and the machine Fox owns is a classic example of the Norvin at its best.
As such, it has an engine, originally from a 1954 Rapide Series C tourer, with a lug sawed off the rear of its inunit four-speed gearbox. Needless to say, irreversible surgery of this sort to cram an engine into the frame doesn’t endear Norvin builders to Vincent purists. But otherwise, the installation looks deceptively straightforward, with four alloy mounting plates and a cylinder head stay.
Fox commissioned former Vincent factory men Alf Furness and Jack Searle to rebuild the engine, and their expertise is readily evident. Compression is up from the 6.5:1 standard ratio to nearly 9:1, and 30mm Amal Concentric carburetors replace less reliable separate-float Amal originals. Ignition is by an ultra-rare Lucas KVFTT racing m a g n e t o m a d e speci f i c a 11 y f o r Vincent Twins.
The most special components in this motor are the racing cams, as specified for Vincent’s full-house 70-horsepower Black Lightning. To make the most of them, a 2-into-l straight-through pipe was fabricated. It’s a copy of a system first developed for “Gunga Din,” the famous Vincent tweaked by factory sprinter and roadracer George Brown. Fox has acknowledged this historic link with the sign-written “Spirit of Gunga Din” on the Norvin’s Manx-style front number plate cowling.
A Norvin’s engine, however, is only part of the story. This bike’s frame started life on a 1955 500ec Dominator Twin, but Fox has installed a Manx swingarm and rear hub. The conical
mag-alloy hub and its single-leading shoe brake are reversed to suit Vincent’s right-side final drive chain.
The front stopper is a British-made Seeley two-sided single-leading shoe drum. Fender-stay lugs were shaved off the Norton fork's alloy sliders to give them a smooth racer look. Manxstyle alloy fenders complete the track profile, with a registration plate screwed on for legality.
Cosmetically, the genuine Manx gas tank is this Norvin’s crowning glory. Elegance continues in the single seat, with a cutaway to allow access to the specially-made oil tank.
Like all the best cafe-racers, this half-tamed beast takes some mastering. Starting calls for juggling the manual spark-advancing lever, temporarily tucking a hinged portion of the gearchange pedal out of the way, and giving the kickstart lever a determined, unflinching swing.
The raucous, irregular explosions of tickover can be smoothed with more nudging of the timing lever and a tweak of the twistgrip. A high-ish first gear in the Vincent close-ratio gearbox demands a force ful-and deafeningtake-off.
Once the Norvin is coaxed up to its deceptively lazy and unfussed gait, you realize what it’s really all about: torque, masses of solid, surging torque.
The remote-linkage gearshift and crude-feeling changes inhibit carefree cog-swapping. But who cares when the chuntering engine will pull out of almost any hole? Getting caught in the wrong ratio is no big deal.
As the revs are steadily stoked up, the Norvin forges forward effortlessly. The Smiths tachometer barely needs to show 5000 between shifts to jerk the speedo needle past 100 mph, before notching top. Owner Fox says he once caught a reading of 140 mph on an airfield, albeit with even higher gearing than the Norvin carries now. A realistic maximum is thought to be 125 mph.
But this king of the old-style cafe racers isn't merely about flat-out straight-line velocity, and it's certainly no t about 1ow -usefulness. What it excels at, apart from being dcvastatingly handsome, 1 o u d a n d uncomfortable, is easy, fuss-free midrange flexibility, lovely for prolovely prolonged bend-swinging.
On 19-inch Dunlop racing tires, the Norton frame lives up to its reputation as the best roadholder of the time. Changes of direction can be as nimble as with a stock Norton roadster, belying the bulk of the Vincent engine.
It's no wonder that rockers and other cafe-racers yearned for a bike as powerful and handsome as this. The Norv in is an ultimate machine combining the best of Vincent and the finest of Norton-a tough blend to beat. Not only would a Norvin scream past other homemade hybrids to reach the next cafe first, it would turn heads while doing so. Mick Duckworth
