Britain's First Production Racing 50cc Machines.
The basis for this page is taken from a number of sources, Dave Brearley's Scrap Book, in an article written for a magazine, and from my archives.
A CHANCE telephone call led a journalist, of the motorcycle media, to a back street in the peaceful Hertfordshire town of Stevenage, and to the inconspicuous shop beneath which a blow is being struck for the British motorcycle industry. It is here that work has going on since last October on the designing and manufacture of Britain's ﬁrst production racing 50cc machines. I say machines advisedly because there will be three types of machines available, an ohv, a single and a twin cylinder two-stroke.
The men behind this bold adventure are a rare combination, a Scot, Duncan Mitchell and an Irishman, Shaun Mooney. both with national brogues you could cut with a knife. Unusual too in that both are tea-total and only Duncan smokes. Duncan is in charge of design while Shaun looks after the technical side.
I asked Duncan what led them to enter this field in competition with the already established imports from Italy and Japan. We have both raced 50s for quite some time , I began in Blandford in 1956, and after experimenting with the various machines available, felt that we ought to put our own ideas into practice.
I asked them was it easy? Shaun told me: “We approached many British component manufacturers and asked if they would supply us with specialised items. Many did not even answer, a few answered and said they were too busy to disrupt production for what would only be a small item while others took the trouble to come round and see us. We have naturally favoured their parts. We could not find anyone to produce an engine of our design for us, the castings being the problem, so we had to go to Italy for this, as we did the brake hubs.
I looked at the ohv machine, the ﬁrst on the assembly bench. It looks quite functional. It has a duplex frame with single-leg telescopic forks, but an optional extra will be an Earles-type leading link pattern. The 18 inch wheels have Avon WMO18 racing rims around the 5-inch full width die-cast alloy Forni brake hubs and are fitted with Avon 2.00 inch and 2.25-inch tyres,
The 3/4-inch, 14 gauge duplex frame has a rear swinging arm controlled by Girling units as are the Earles type forks and the three-gallon TT tank is in fibreglass styling made especially for them and has a single centre ‘bolt fitting and a Monza quick-filler cap. Clip-on bars are fitted with rev. counter and steering damper unit and Doherty control levers.
The Engine has a clean appearance. being of unit construction. The cylinder inclines forward at 10 degrees and has the pushrods enclosed in the fining. Barrel and head are alloy. ﬁtted with liner with a bore oi 40 mm and a stroke of 39mm. giving a capacity of 49 cc. Operating on a compression ratio of 10:1, it develops 4.2 bhp at 7.200 rpm. although it is envisaged that this will improved upon after tests and development with lightened fly-wheels.
A battery (Varley 3 IN 5) ignition. is used to supply current to the 14 mm plug. The two valves are inclined at eighty degrees and have a single coil operation. A 15UAS Dell’Orto carburettor is ﬁtted, though Duncan said he would like an Amal, type 274, to fit on to the tuned induction.
A 3-speed foot-change gear- box is ﬁtted at. present, but they are now looking for some one to cut their own pattern 4-speed close ratio cluster that fits into the existing shell. A multi-plate clutch operates in oil. The engine has a sump lubrication. The unit is the first of a batch made expressly for them by Daldi and Matteucci, and has needle caged roller main bearings.
Refinements such as the extensive use of Allan-cap screws and the snail-cam chain adjustment show the thought that has gone into the design, which includes a fibreglass padded racing seat moulded by Nickri of Goodmayes, Essex, who also were responsible for the neat Dolphin-type fairing with which every machine will be sold. Aluminium guards are ﬁtted front and rear. made by Speedwell.
The overall weight is under 85 lbs, and the cost, in kit form is anticipated to be about £160 complete ready to race. Finish is in black, “Traditional Stevenage colours.” said Duncan. Two hours should sufﬁce to construct the machine from the kit parts with the complete tool kit supplied.
The two-stroke engine unit has a Mitchell designed two-plug head with the plugs in the specially ported position. A flat headed piston is used, giving a compression ratio of 17:1 and 7.5 bhp at 9.000 rpm. An Amal GP2 down draught carburettor with rubber mounted remote float is used. Other speciﬁcations are similar to the ohv model. The price being £150 complete in kit form.
I saw also the twin cylinder two-stroke engine, each cylinder of witch uses a 32mm bore and 30.5 mm stroke, giving 24.9 cc, or jointly, 49.7cc. The inclined barrels are separate, united Scott-style by a double sprocket gear to the 5-speed gearbox with dry clutch. Again the other features remain the same as the other models. The price of this is anticipated to be around £200.
Under a bench I spotted a 50 cc four cylinder two-stroke the boys have been experimenting with, but put aside for the moment, to await further development. This unit sits across the frame. MV style. (Editor: This unit was the four cylinder unit developed by Maurice Raby and F. Eric Fitz-Hugh. For the full story click on the picture.)
Wheelbase for all models is 45ins. Saddle height 25 ins and overall height 32 ins. The boys were still looking for someone who would be prepared to bend the tubes, pipes and fashion the megaphone exhaust systems.
"It was at one of the 'New 50 ERA' club's monthly race meetings that Duncan approached Brian Cockell, a 50cc racer, after seeing the frames that he and Ian Ager had made for their engines. They had built three of frames with Ian using one for building his bike and the two others being used by Ray “Jasper” Smith and Brian Cockell himself. Duncan asked if they would build a batch of frames for MOTO DECLA Ltd".
The team was also contemplating producing a Moto-Cross machine before the end of season depending how production of these interesting 50 cc racers progresses.
Duncan and Shaun, with two “sleeping partner” directors, aim to provide ready-to-race 50 cc machines at a reasonable rice for the enthusiast, who, like themselves. have found the need to improve the out-dated imports available at similar costs. Their product is neat, work-manlike and certainly functional looking. With the tremendous interest in this class this year, they could well strike the jackpot, I hope they do.
Unfortunately the company was unable to remain stable and closed for business around 1963/64.
Return to Racing Hardware