The beauty of building a bitsa is that inspiration can be unleashed by an engineer’s expertise and ingenuity. Harley Richards reveals a Velo MAC which blends the best of pre-war style and 21st century technology…
The beauty of building a bitsa is that inspiration can be unleashed by an engineer’s expertise and ingenuity. Harley Richards reveals a Velo MAC which blends the best of pre-war style and 21st century technology…
MikeH, the builder and owner of this fine Velocette, is by no means a purist. He is however a very talented machinist, which means that when he decided it was time to dip his toe into the world of bobbers, his first thoughts weren’t of small Honda twins or air-cooled BMWs, but rather a 1930s Velo.
It’s perhaps worth noting that Mike has something of a track record where Velos are concerned. He’s rebuilt and restored dozens of Hall Green’s finest over the years, so utilising a Velo from the era when bobbing first took place wasn’t quite the odd choice it might appear. Mike’s objective was simple: build a light machine with some modern touches like decent brakes; lose the electrics except for the mag; fit large diameter, skinny wheels, and extract enough poke from the engine to keep life interesting – all with the external appearance of a period machine… to the casual observer at least.
Before any Velo fanatics start penning abusive letters about ruining a perfectly good classic, rest assured that what you see is a collection of parts from any number of bikes. Surely it’s better to have one running machine out on the road than to have random parts quietly rusting away in dark corners? Anyway, with a 350 MAC motor already lurking under his workbench, the build proper got underway with the arrival of a frame. With all unnecessary lugs removed and rearset footrest lugs welded on, Mike contacted the Velocette Owners’ Club for a dating certificate.
He found that the original bike had been bought some four days after leaving the factory on 21st September 1938, from the agents Jordon of Hull by a Mr J McDonald of 3 The Grove, Garden Village. One can visualise a young man, perhaps with a few savings, seeing the forthcoming world war on the horizon and thinking: ‘Sod it, I may never come back’, then heading down to his local Velocette dealer to buy some two-wheeled fun before it was too late. Whatever his reasons, Mr McDonald made a wise choice.
The design of Velocette’s high camshaft engine, which first saw the light of day in 1933, can trace its roots back to the 250cc MOV model. Blessed with nearly square dimensions of 68 x 68.25mm bore and stroke, the initial rigid framed, girder fork single was gradually stroked and bored; given Dowty Oleomatic front suspension, an alloy engine and swinging arm rear suspension, and garnered fame and fortune in Viper, Venom and Thruxton forms. Although the original 250 was very well received by the motorcyclists of the day, and tuned to reach over 100mph by some privateer racers both in UK and Australia, a 350 was demanded. Thus was born the MAC, of which over 22,000 were produced.
Due to the small bore of the 250 MOV, and the subsequent placement of the barrel retaining bolts, Velocette weren’t able to simply bore the barrel out to create
a 350. Instead they increased the stroke, significantly, to 96mm. Despite these design constraints, Mike felt that there was still room for improvement inside the motor and set to in search of some extra power. After a period of careful measuring and head scratching, the MAC’s engine underwent some serious surgery. The barrel was bored out to 73.5mm to take the capacity up to 400cc which, along with polished Thruxton bottom rockers, an M17/4 cam, a lip seal on the drive side main bearing and a positive pressure oil feed, provided the sort of additional oomph that Mike was after.
That oomph finds its way from the engine to the gearbox via a very discrete modern upgrade in the shape of a Kevin Thurston belt primary drive, which allows Mike to run a dry clutch. This was important because a previous accident means that Mike finds it difficult to change gear with his right foot. The belt drive removes any need for fluid in the primary case, so he could reverse the gearchange linkage and route it through the middle of the primary chaincase. It’s one of those little touches that’s easy to miss on first inspection but is so well executed that you find yourself wondering if it was a factory installation.
Velocette was a small family business and would use whatever was on the shelf for their latest designs, a rather curious mix of Germanic efficiency and Yorkshire canniness! As an example, cranks and rods from earlier models would often find their way into new models, bringing endless opportunities to those who think outside the box. In Mike’s case, because Velo stuck to the same gearbox bearings for many years, it enabled him to take the wider close ratio gears from a later Type 12 model and narrow them down to fit the earlier MAC shell – giving him the gearing of a Mk8 KTT. This exercise, for the avoidance of any doubt, was a lot more complex than it sounds…
If any Velo purists are consoling themselves that at least the bike uses predominantly Velo parts, they might want to look away now. With a left hand gearchange it made sense to use a rear wheel which has its sprocket on the left side and its brake on the other – thus only needing a simple rod to hook up the brake pedal to the brake actuating arm. A quick internet search suggested a unit from a Yamaha XT250 would fit the bill perfectly and, sticking with the Japanese theme, Mike sourced a similar sized front hub from a Yamaha SR250. Powder coated black and laced to black 21” x 1.60” alloy rims, you would really have to know your classic British machinery to realise they weren’t factory stock.
Of course, the Yamaha wheels and brakes provide more appropriate stopping power for today’s roads. That increase in stopping power led Mike to reinforce the spindle lugs and brake support plates on the forks (1938 mid-weight Webb girders) as a precautionary measure. Finishing off the front end are a set of 5” rise Renthal bars and a Chronometric speedo shell which contains the workings from the same Yamaha SR250 that gave up its front hub – waste not, want not!
The rest of the rolling chassis follows the
same theme of period Velo bits (petrol tank, pipe and silencer) mixed with modern parts (alloy mudguards, selfcontained LED brake and horn) to give it the spindly, yet purposeful, look that Mike set out to achieve. With over 30bhp on tap, good brakes and weighing just 100kg, this is a feisty machine which has fulfilled all his expectations.
Ah yes; the name. ‘Sixpence’. Mike had been given the five digit registration CMN 6D and had already made up a pressed alloy plate in anticipation of the build when a visiting friend saw the plate and said ‘sixpence!’ The Velo was officially christened. For our younger and overseas readers, ‘6D’ is a throwback to the days of pre-decimal currency in the UK when prices were fixed in pounds, shillings and pence (or ‘LSD’ for short – I know, it’s confusing and based in Latin derivations but we built an empire on such stuff ). Hence, six pennies would be written as 6D and, if you look closely, a 1938 sixpenny piece has been sunk into the top cross piece of the forks, a neat touch.
And that would probably be the end of the story were it not for the fact that Mike is, by his own admission, a serial builder and is now thinking about the next project. Garage space constraints mean a sale may soon be on the cards so, for the right person offering the right price, Mike might be prepared to let Sixpence go to a new home. Serious enquiries through RCHQ please.