Classic Dirtbike

Know the alphabet

Velocette are not the only manufactur­e to use letters to describe a particular model.

- Words: Tim Britton Media Ltd

Well at least the Velocette alphabet, where Movand Macmean quite a bit.

It is a curious thing, to me anyway, that using names seems to fit in with some manufactur­ers, while for other marques it is the letters and numbers thing which seems to be the way.

For instance, Amcused letter and number combinatio­ns for years - G80CSAS an example - then when their marketing department came up with the 'Southerner' for AJS' 18Csand 'Marksman' for the G80csmatch­less it just didn't seem right and was changed back pdq.

Most of us will manage to work out, if we didn't know, BSNS sporting 500 Gold Star has a designatio­n of DB34GS TO describe it as a 500cc sporting single with alloy barrel and special assembly, and before you Db34gser swrite in, it's one simple sentence covering a complicate­d numbering sequence which

'A Galland' took a full book to do - and anyway this is about Velocettes.

The point is, talk about a Gold Star or Goldie and it's likely most enthusiast­s will know what you're on about, chip in with 'Marksman' and Ibet there'll be a lot of blank stares and maybe those that do recognise the name have lots of room at the buffet.

It is the same with MAC,MOVAND any other letter combinatio­ns associated with Velocettes, chuck them out there and the assembled crowd will know basically what you're on about.

Last year in the one sunny day we had before the weather turned chilly, a slack handful of Huddersfie­ld Falcon members strong-armed me into a multi-velo test at their regular venue. First bike we featured from that shoot was Chris Haigh's superb MSSIN issue 51, now it's time to do the othervelos there on the day. Ones belonging to the ingenuous Paul Jackson. Why ingenuous? Well in common with many other highly skilled engineer types what seems a simple and obvious way to work to them is awe-inspiring to the rest ofus.

Paul is well known in the classic world as 'someone who can .. .' and his problem-solving is legendary. Take

the SSDTFOR instance, he rode a Cub in the Seventies, its four-speed 'box needed lower gears for the sections and on the road its top speed was er...lacking. Paul's answer? A dual rear sprocket. Bigfor sections, small for the road.

Okay,he's suffered enough with the praise so onto the bikes. Often the main reasons to use a particular machine as a basis for a Pre-65 trials bike are because you can, or maybe to see if you can, or even because the bits were there.

Using a Velocette engine isn't the easiest option in a build as they are quite a tall engine even in 250 MOVOR 350 Macform, with the Macbeing the taller of the two. It is fitting both Movand Macare in this one feature as the 350 Macwas derived from the 250 Movand I hope Velocette enthusiast­s won't get too offended if I restrict saying the difference­s amount to a longer stroke on the 350. Naturally there are slightly more details, but for this feature ...

Initially this 250 had been prepped for racing but the owner felt ajawa engine would be better suited to the Seeley chassis and the race circuit, so the Movwas surplus to requiremen­ts.

In any motorcycle sport the lighter the bike the easier time it and the rider has and in order to save a bit of weight a pre-second World War alloy Mactop end is fitted and a Triumph piston runs in the bore.

"I think it will be a 5TAORTLO0 piston," Paul says before adding "it was about the right size and available." One of the many points Velos are known for is the stiffness and narrowness of their bottom ends. This is because the company wanted such stiffness for its race bikes and the rest followed suit. Paul does his own big-end bearing modificati­ons which brings the cost of crank rebuilds - once converted - into the realms of normality. Once modified, it is a simple matter of buying an off-the-shelf bearing from a bearing factor and pressing it in. So,bottom end sorted, new bearings and ready to go.

There are trials cams and that sort of thing available

for Velocettes but this Movhas a Macroad cam in the timing chest and Macroad valves in the head.

These days with sticky trials tyres the need for soft power is less vital than in the old days when tyres were made from a harder compound. Ignition too is much more modem and thanks to the Velocette's primary drive arrangemen­t there is enough room for the Electrex World electronic ignition to fit behind the drive. But we're jumping ahead here as the Velo is a non-unit constructi­on engine the gearbox is a separate item and can be dealt with on its own.

Velocette had their own gearbox and the company were at the forefront of technology when the newfangled idea of changing gear with one's foot rather than hand arrived. Their patented positive stop gear change method modernised motorcycli­ng instantly. That said, there is no need to use a Velocette gearbox and neither 250 nor 350 does in this case as Burman's B52trials gearbox is regarded as the market leader. Contained within its cases are the trials gears. "Do you know about the Burman trials gearing?" Paul asked. I had to admit to not really knowing as there's always been the archive to check these things in. "The trials cluster is basically a lower second gear and a 1:1 top ratio."

A Burman clutch is fitted to the shaft and has a shock absorber inside to smooth out the snatch in transmissi­on and the whole lot goes inside a neat cast alloy primary case. "Afriend of ours called Jim Wiggleswor­th developed these cases about 20years ago and casts them up now and again."

Both 250 and 350 are housed in Htariel type frames which Paul builds, though has vowed he'll never do another one ... a vow similar to Scott Trial riders who vow never to do another as they reach the finish ... then the regs come out for the next year. "There's nothing fancy about the frames, I make them from Cdssteel tube so I can weld it." Paul continues with "the forks are built up from Kawasaki Kdxstanchi­ons and internals and fitted to Amcsliders," which again are nothing too fancy. The Jackson workshop also turns out the billet yokes the forks sit in.

Wheels are a speciality of Paul's and the back of his workshop has a rack with lots of the things in, some waiting for rebuilding, others already done and awaiting collection with still others part way through the process. It can be assumed the wheels were built in- house and for the 250 there is a Max Heyes cast Tiger Cub replica front one laced into an alloy rim and at the rear is a widened steel Cub type. It's widened because the standard Cub width needs a large spacer at the nonsprocke­t side if it's not going into a Cub swinging arm.

This is fairly common practice and indeed my own B40 had this mod done a million years ago. Rear wheel also has an alloy rim and it is a standard one with a tube type Irctyre.

Building each engine in to a frame is done with engine plates Paul cut from sheet alloy and bolted everything in with stainless steel bolts.

Also stainless steel is the exhaust system on both bikes. Paul buys stainless steel tube bends used in the dairy industry which just happens to have the same dimensions he prefers for exhaust pipes, then it's a 'simple' matter of fitting them to the bike and welding them up. Using this method is a good way to become creative and Paul routed the Movpipe routes over the primary case and the Macgoes over the timing side, both end in alloy silencers fabricated by the lad himself.

As the HT frames Paul makes are oil-bearing

there's no need for an oil tank on either one as all the lubricant is carried inside the frame tubes. There is a need for a petrol tank though and again they're made by Paul from thinner alloy sheet than the engine plates.

Finishing the cycle parts off are plastic Stilmotor mudguards in classic dark grey which might not be strictly period but look the part. As Paul's bikes tend to be used in the Pre-65 Scottish - an event which has its own eligibilit­y rules - the Velos wear Amal Premier Mk.1 Concentric carburetto­rs which are popular fitments on a lot of British Pre-65 trials bikes. Suspension too is an area where advances have been made and the choice is vast. Also improved is the travel from the stroke of the units ... Okay, these units are Trikshox.

The days of rigid footrests on trials bikes are long gone, once the introducti­on of folding footrests made life a lot easier for us in the feet-up world all sorts of footrests were used ... These ones are Raptors and grab the sole of a rider's boot with the tenacity of the dinosaur of the same name. There's a lot of choice too in handlebars, most, though not all, riders use high tensile alloy bars and the ones of choice on here are Protaper.

Paul adds Domino controls and Venhill cables to finish the bike off. As Paul and I chatted we were mostly discussing the 250, after looking at a few things in his workshop I had the pen poised ready for the scoop on the 350. So... Paul, the MACIS...? "Exactly the same at the 250 Tim, except it's a 350." Eh? Exactly? Paul thought for a bit, "It's got a steel hub on the front ..." he grins. Is that all? "Yes, oh the seat is different. On the 250 Tony Archer upholstere­d it, I think the one on the MACIS just as found."

What I did know is the 350 was fettled for Richard Allen - Allen's Used Trials Spares - because he likes a challenge and fancied riding something different in last year's (2019)Pre-65. Richard took the Velo round the two days for a loss of 18 marks. Ah roll on 2021.

 ??  ??
 ??  ?? O Takeyour choice, 250 at the rear or 350 at the front.
O Takeyour choice, 250 at the rear or 350 at the front.
 ??  ?? 5: Plenty of ground clearance for gliding over rocks though there isaschool of thought which claims one can have too much ground clearance.
5: Plenty of ground clearance for gliding over rocks though there isaschool of thought which claims one can have too much ground clearance.
 ??  ?? 6: Evenfrom this angle it's a nice, slim profile.
6: Evenfrom this angle it's a nice, slim profile.
 ??  ?? 4: Amal Premier carbs are the modern incarnatio­n of the Mk.l Concentric.
4: Amal Premier carbs are the modern incarnatio­n of the Mk.l Concentric.
 ??  ?? 2: Virtually the only difference between the 250 and 350 engine is the length of the stroke.
2: Virtually the only difference between the 250 and 350 engine is the length of the stroke.
 ??  ?? 1:Jim Wiggleswor­th is the man responsibl­e for this fine bit of casting work.
1:Jim Wiggleswor­th is the man responsibl­e for this fine bit of casting work.
 ??  ?? 3: Trickshox take care of rear suspension.
3: Trickshox take care of rear suspension.
 ??  ??
 ??  ?? 0 Bluesky,some rocks, a couple of decent trialsbike­s,what more do you need? Oh,a beer... well,we did have a sip later...
0 Bluesky,some rocks, a couple of decent trialsbike­s,what more do you need? Oh,a beer... well,we did have a sip later...
 ??  ?? 1: What d'you want me to stand like this for? Forthe owner pie of course Paul.
1: What d'you want me to stand like this for? Forthe owner pie of course Paul.
 ??  ?? 3: At the front are slab alloy yokes which were milled in Paul's workshop.
3: At the front are slab alloy yokes which were milled in Paul's workshop.
 ??  ?? 2: An airbox- well two of them really,one for each bike -were fabricated; afoam filter is inside.
2: An airbox- well two of them really,one for each bike -were fabricated; afoam filter is inside.

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