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Norvin single

Feature build - one-off Norvin

(originally published in MT #337, July 2019, posted May 2020)

Ed's note: Tthis bike is now for sale - see the end of the story for details.

Norvin single

Flash Build

by Guy 'Guido' Allen

It’s one thing to restore a bike and make a few changes along the way. But to build a one-off? That’s a whole other nest of vipers

Say ‘Norvin’ to most folk, and you get a visual image of one of the legendary V-twin Vincent powerplants shoe-horned into a Norton Featherbed frame. To some eyes it’s not actually a natural fit as the Vincent unit looks huge compared to the powerplants that Norton bolted into the same space. But there’s no denying the end result looks muscular.


Done right, you end up with a bike with a more contemporary look and improved handling.
The machine you see here, however, is a very different and more ‘natural’ variant – a single-pot Vincent Comet engine (in Grey Flash-plus spec) squeezed into the plot. Now that, for some purists, is potentially a match made in heaven. The Featherbed frame was after all made famous by the single cylinder Manx racers.


Meet Mick McCrudden, the owner and builder of this stunner. During the day, Mick runs a workshop called Glenlyon Motors, which has en enviable reputation among owners of classic and special interest cars. He builds all sorts of interesting specials and restomods, so a visit to the palatial shed is never dull.

Norvin single


However he’s also been a bike nut for decades. “At one stage I had 13 old British bikes packed in the back yard, until my Mum got the shits with it,” he laughs. His tastes are eclectic and lean towards British and European machinery, preferably with one of two cylinders. That doesn’t stop him from having a crack at just about anything when the opportunity arises.


He also recalls a time when old British motorcycles were cheap: “You could get a Beeza Bantam for $20,” he explains, shaking his head. And that was a time when he owned a string of desirable machinery, including Featherbed-framed Nortons and a series of Vincents. “Back then they were cheap, but of course now they’re worth a fortune!”


Which kind of begs the question of why Mick went down the path of a scratch-built racer, rather than a resto that might arguably offer greater financial rewards for the same effort. The answer is simple: he was building something to please himself – no-one else.


This is one of those machines where you see lots of familiar-looking components but some aren’t that easy to place. Or there’s some nagging doubt about its origins. The reason is this thing has an extraordinary high custom-build factor.

Norvin single

As anyone who has tried it themselves, scratch-built components are a massive challenge, or pain in the arse, depending on your point of view. You’re tackling several times the workload of simply restoring an existing piece and there’s no guarantee the end result will wrok.


Let’s start with the frame as an example. It’s a Norton Featherbed, Manx-style frame, yes? Well, yes and no. While brothers Rex and Cromie McCandless – who came up with the original as a race frame in the late 1940s – would recognise the hugely influential twin loop design made from Reynolds tubing, it’s not factory-built. Nope, it’s a one-off, done with the assistance of notable Brit classic bike builder Bob Johnson.


A former Repco and Ansett engineer, Bob guided Mick through the process, which had plenty of challenges. “We started with a jig based on the drawings,” explained Mick, “But I reckon I had about 47 false starts and a lot of written-off chrome-moly steel before I was happy!” The whole plot features nickel-bronzed joins.


Norvin single

And then there’s the engine. Now you would have thought a Manx powerplant would have been appropriate, but Mick had a thing for Vincents and there is a proud history of Comet-engined Nortons. For some the Comet single is a sweeter motor than its flamboyant twin-pot sibling. In any case, Mick managed to get the motor from local Vincent enthusiast Phil Pilgrim, of Union Jack Motorcycles.


A real Grey Flash is ultra-rare. Essentially it’s a tuned and often stripped-down race version of the Comet single road bike, claiming a modest 35 horses and capable of an impressive 115mph (185km/h). Remember this is back in 1949, about the same time Norton started playing with the Featherbed.


However we’re not talking about a stock Vincent engine – not any more. Mick decided it needed a capacity boost from the stock 499cc and bumped it out to around 620 with the aid of a Yamaha piston fitted with Jawa rings, matched to a Carillo rod originally intended for a small-block Chevrolet engine. The bottom end, by the way, has been engineered to run on ball race bearings instead of bushes. It’s also running a performance cam and big valves.

Norvin single


As if that wasn’t enough, the whole thing is set up to run on alcohol, fed via a hand-made remote reservoir carburettor.


So how powerful is it? That’s yet to be measured and the bike hasn’t so far fired a shot in anger on a racetrack. Maybe soon. In the meantime the best estimate is it should be producing around 75 horses. If it’s anywhere within cooee of that, it should have an impressive top speed.

Norvin single


Of course you need a gearbox and standard these were a four-speed. Albion is thought to have produced a compatible five-speed when these things were new, and Mick undertook to do his own version, using the existing cases. That’s complemented by a custom belt-driven diaphragm clutch.

Norvin single


Think about the speed potential of this tiny narrow package and you might start to wonder what’s been done to finish off the chassis, assuming you have an interest in surviving the experience. Again, Mick has gone for ‘age appropriate’ gear, albeit up-dated and refined.

 

Norvin single


The giant quad leading shoe drum brakes seem to have a vaguely familiar appearance. But don’t feel bad if you can’t quite place where they came from. It is in fact a clean-sheet design, where the patterns were done locally, as was the casting and machining. It certainly looks the part, with a substantial swept area and giant air scoops, all nicely finished.

Norvin single


Out back, there’s a more familiar-looking bit of kit – a Triumph twin-leading shoe conical hub. This and the front are laced to Akront rims.


As for suspension, the crew has gone fairly conventional, with Norton Roadholder forks up front and Manx rear shocks.


The slick bodywork is typical of the much of the project, with the entire thing hand-laid in fibreglass - that includes the fuel tank.


For heaven’s sake, why not just buy some of the reasonably plentiful off-the-shelf options out there? “I had a bee in my bonnet about hand-building everything and not just assembling parts,” admits Mick.
Fair enough, so how long did that take? “Ten years.” After all that effort Mick has decided to sell this bike and move on to the next project. We can’t wait to see what that is…

Ed's note: Mick McCrudden owns a classic and contemporary vehicle workshop in Melbourne, AUstralia, called Glenlyon Motors. He can be contacted via kthow@glenlyonmotors.com.au or at tel 61 3 9381 1666 during business hours. He can assist with international shipping.

Norvin single

Norvin single

Norvin single

Norvin single

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