AJW Motorcycles :: History
Chapter 5

Two Strokes

A.J.W. ended 1929 with the introduction, at the Olympia Motor Cycle Show, of a range of five two-stroke Villiers engined lightweights with Albion three-speed gearboxes.

The design of the frame is of particular interest announced Motor Cycling in November 1929.  The main portion of the frame is made from two malleable castings which run from the rear spindle to the front of the engine, one on either side. These are of D section until they reach the gearbox, where they get very much deeper and form a solid mounting for the crankcase and gearbox. These components serve as distance pieces between the two castings. The gearbox can be detached through a suitably sized square hole in the side of the casting and is held in position by two cross bolts running through longitudinal slots. A draw bolt is provided.

Silver Fox frame 1931

Two stroke frame

The rest of the frame is built up of ordinary tubes, tapered and using bolts instead of brazed lugs.  A pair of long tubes run from the rear spindle to the top of the steering head, tapering all the way. Another pair run from a wide cross lug at the base of the head to the front of the main frame, getting nearer to one another towards the base. There are also twin seat tubes and a single rail connection from the bottom of the steering head to the cross lug under the saddle.

The frame of the saddle is attached in the ordinary way to a rearward extension of this under the tank rail. The steering head is long and has large triangular side webs, which support the cross lug at the base and in conjunction with the tapering down tubes, help to make the frame particularly free from whip.

The latest pattern Druid central spring fork is used with a steering damper and shock absorbers. The same forks are fitted on the cheapest utility model, but minus the damper and absorbers.

The petrol tanks hold both petrol and oil.  They also have a Villiers sight feed mounted centrally between the two filler caps, and there is also a route card or map holder frame. As it is difficult to see the oil level through the filler cap a dip-stick is provided.  On the 250cc and 350cc Silver Fox models the tank is 2ins wider than on the smaller Black Fox and Utility machines.

Foot rests are fully adjustable and mounted on a shaft running through the casting just behind the crankcase.

Hand adjustment is provided for both brakes. The drum sizes on the Utility are 5ins front and 6ins rear: all have water excluding flanges. The tyre size is 25inx3in. The Silver Fox models have Dunlop tyres. D-section 5in mudguards are used, and both chains have guards fitted.

On the Black Fox and Utility models the standard tank finish is nickel with a black side panel edged with a narrow red line. The Silver Fox models are similar but use chromium plating throughout.

For an extra charge of £3 these models can be supplied ready for competition work with upswept pipes, Petroflex tubing, sports tyres, number boards and non-inverted levers covered with rubber. The ground clearance is 5 ½ in. The top of the A.J.W. five model Two-Stroke range was the 346cc Silver Fox. It cost £39.

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(Taken from an A.J.W. brochure)

This model had been specially introduced to meet the demand for a high class motor cycle fitted with new Villiers 346cc long-stroke engine.  This was a particularly fine piece of work, and undoubtedly the best two-stroke unit on the market at the time.  There was little doubt that such an excellent engine deserved be housed in a well-built and soundly constructed frame.

We have therefore built the new 346cc Silver Fox up to the same standard of perfection

Silver Fox 2 STROKE 328

Silver Fox

as the engine. The price, although very reasonable, has not in any way been considered when this model was designed, and the machine is sold fully equipped and ready for the road. Chromium plating is a standard finish, while electric lighting, air cleaner, license holder, etc, are all included in the price, thus saving the purchaser all these costly but necessary extras which must be procured before the machine can be used on the road.

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The Villiers 346cc long-stroke engine was fitted with a patented inertia ring, which was one of the most important improvements made in two-stroke engine design for many years. The object of the inertia ring was to prevent the gumming up of the ordinary piston rings, and it achieved this object in a very simple manner. In practice, it was found that a film of oil formed above the piston rings gradually became burnt and carboned, eventually fixing the rings solid in their grooves. The inertia ring, which was fitted above the top piston ring, was designed so that it could not touch the cylinder walls. It was permitted to have a slight up and down movement and to rotate freely. This movement prevented any film of oil forming above the piston ring and so kept the rings quite free.

The cylinder of this engine had been designed scientifically to prevent distortion and over heating. The fins were arranged so as to give the maximum cooling effect, and the position of the sparking plug had been carefully determined to avoid pre-ignition and give cool running. The sparking plug fitted as standard equipment was not be changed to any other type, because it had been found to be the most satisfactory one for all round running in this engine.

Lubrication to the engine was by the Villiers Automatic System, which had no moving parts and required no separate pump. The sight feed and oil regulator of the lubricator fitted neatly into the tank. By this method oil was fed to the engine under pressure from the crankcase, and the supply of oil was increased automatically as the load of the engine became greater.  This gave a very accurate lubrication and, in practice it was most efficient and reliable.

Villiers 346 c.c.Long-Stroke Engine.1931

Villiers 346cc engine

The Villiers flywheel magneto had many advantages over other forms of ignition. It simplified the construction of the engine, reduced weight and required no separate driving chain or platform. The only rotating part of the magneto was the flywheel itself, in which there were the pole shoes and magnets. All other parts were stationary and, therefore, no carbon brush, slip ring or delicate bearings were necessary. The space available in the construction of the flywheel magneto enabled coils and magnets to be used which gave an intense spark and so ensured easy starting and perfectly regular running at low speeds. In the flywheel magneto the intensity of the spark remained unaltered however far the ignition may have been retarded. The flywheel magneto was encased in a water tight cover and no parts were exposed.

The Villiers carburettor which was fitted, had a compensating action which automatically regulated the strength of the mixture to suit varying engine conditions. There was no jet to become choked in the carburettor, because the taper needle working in the jet kept it free from obstruction.  A Villiers air cleaner was fitted to prevent dust and grit being drawn through the carburettor into the engine, an accessory proved to prolong considerably the life of an engine,

All the A.J.W. two-strokes were fitted with Terry’s silencers.  Their brochure states, “Here we have the world’s finest silencer a wonderful model which actually gives a power increase over an open exhaust of up to 3,000 rpm.  There is positively no power loss.”

Silencer

Terry’s Silencer

The Terry’s highly polished cast aluminium silencer was unusual in that it had a long spring attached to its inside that held a baffle against the input end, so it only opened as the revolutions increased. The back pressure must have been tremendous.

The 196 cc Utility was the base model of the five model range of Two Strokes. The main differences were its smaller engine and the tank was nickel plated instead of chromium  plated.

Utility 196cc

Utility 196cc

The Motor Cycle road tested a Silver Fox in April 1931 and reported

For two reasons the 346 cc A J.W. Silver Fox is a machine of particular interest, first it has an original type of frame, and secondly, it is fitted with the new 346cc long-stroke Villiers engine.

The frame of the Silver Fox is of bolted construction built up on one malleable iron channel-section casting which houses both the engine and gear box, besides forming the rear chain stays. From the steering head the two down tubes are set wide apart, but converge to a point in front of the engine, while two tubes run from the steering head straight to the rear fork ends, a combination which reduces whip to a minimum.

After the carburettor had been flooded generously the engine never failed to start at the second kick, and for a two-stroke its tick-over was excellent.

Siler Fox control plan

Silver Fox controls

On the model tested a foot-operated gear lever was fitted with the rear brake pedal on the same side, a rather awkward arrangement, however, the position of the pedal, is optional. An upward flick of the pedal and bottom gear was engaged, while a light downward pressure brought second into operation, and a further downward movement engaged top. The knack of finding the gears was very soon acquired and owing to the ease with which the control could be operated, the     arrangement appeared to have the advantages of a positive change, with the added feature that only one movement of the foot was required to change from top to bottom. At no time was it necessary to accelerate or slow the engine to select a gear, while the gear-box itself was absolutely silent in operation.

The engine proved somewhat of an eye-opener to many riders of ohv models encountered during the course of a 600-mile test, for it could easily hold average machines of its own capacity, and even larger, both on acceleration and speed while its pulling on hills was astounding. Under slightly adverse conditions a speed of 62 mph was reached, while 45 mph was touched in second gear, a remarkable figure considering the ratio of 8.6 to 1. Actually the most comfortable touring speed was in the neighbourhood of 40 mph.

The carburettor, with the control set at “weak” appeared to provide an excessively rich mixture.  This no doubt, accounted for the petrol consumption figure of 55.8 mph at a maintained speed of 30 mph.  Owing to the engine being new a generous oil setting was given, the consumption being in the neighbourhood of 800 mph.

Although enhancing the racing lines of the Silver Fox, the exhaust system was unsatisfactory, the machine being far too noisy and gas escaping from the various joints. Also the exhaust pipes were so arranged that they were liable to foul the road if a bend was taken really fast.

The 6inch brakes were both smooth and effective, being capable of pulling the machine up dead with the minimum of effort.

With the fork action slightly damped, the steering of the machine at speed was exemplary, but like the majority of light machines, the A.J.W. was a trifle lively on rough going. This however did not mean that over rocky surfaces it was bad, far from it. While in mud, its behaviour was all that could be desired, in spite of the rather “road burner” type handlebars.

Gradients of 1 in 6 could be taken comfortably in second gear which speaks volumes for the pulling power of the new Villiers engine, while the low bottom gear gave the feeling that the machine would climb the proverbial side of a house.

Rear chain adjustment was a simple operation and, thanks to the fact that the rear wheel was pushed forward for removal, the chain need not be disturbed.

Throughout the test the direct lighting system never gave one moment’s trouble. The beam at 40 mph, although not so good as many modern dynamo-cum-accumulator sets, was amply sufficient, while the parking light battery gave no sign of fading out even after several hours continuous use.

As a machine for the rider who requires a practically fool proof motor cycle, with simplicity as its key note and with the power and performance of an ohv 350cc model, the 346cc two-stroke A.J.W. Silver Fox amply justifies itself.

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The target output for 1930 was eight machines per week. If achieved they had done well.

John Wheaton was prepared to build anything on two wheels and to anybody’s specification.  The machine (below) was built for a Naval officer as a special order using the Two Stroke Silver Fox frame but this time fitting a J.A.P. 172cc engine. It was also fitted with a Maglita lighting set.

Special with a J.A.P engine

Special with a J.A.P engine

The picture (below left) is believed to be an A.J.W. speedway machine, probably built in 1930. How many were built is not known as no records of their construction survive.

A.J.W. speedway machine,

It is believed that Noel Johnson, an Australian, rode a prototype A.J.W. dirt track machine at an Exeter speedway meeting in 1930.  Later, probably in 1932, he was killed riding at Pennycross Stadium in Plymouth, but it is not known which machine he was riding.

The A.J.W. factory asked Fred Jolly, who was then the main agent for A.J.W. motorcycles in Adelaide, South Australia, if he would be interested in having a speedway machine to promote the A.J.W. road going machines. Fred jumped at the chance. The machine duly arrived and Fred asked an Adelaide rider called Jack Young to ride it. Young was little known then and had not ridden on a genuine speedway machine before, but that did not stop him taking the lap record at Rowley Park first time out.  He was later picked to ride for Australia and beat the legendary Jack Parker. Young became the first rider that Fred sponsored but not the only World Champion.  Later he supplied machines for Ivan Mauger in Australia before he came to Britain.

Fred Jolly went on to sell Czechoslovakian ESO machines and later he built his own SR60 speedway machines.

At the time of writing no Two- Strokes are known to have survived.

Jack Young and Fred Jolly (right) with Emu Bird.

Jack Young and Fred Jolly (right) with Emu Bird.

 

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