Author Topic: A Two Stroke Douglas  (Read 4513 times)

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Offline Chris

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A Two Stroke Douglas
« on: 24 Nov 2005 at 08:56 »
Mention the Name Douglas to almost anybody and they will invariably respond with Douglas Dragonfly? Perhaps it is the alliteration of the name that appealed because the machine did not. It signalled the end of the Bristol maker in 1957 after 50 years of motorcycle manufacture. What is truly surprising is that although this model is so universally known, Douglas Motors and Pride and Clark combined only sold 1,510 of this model. It was however, the last in the line of machines that followed a very consistent pattern started in 1907 with a horizontally opposed twin cylinder engine giving excellent balance and smoothness. Those more familiar with the marque will know that in the main the engines were fore and aft pre-1939 and transverse post 1945. The only exception to this was the shaft drive Endeavour of 1934/1936, which experimented with a transverse engine.
It was about the same time that Douglas, obviously feeling more adventurous than usual, decided to break with tradition and produce a single cylinder two stroke. Two models were initially designated Model X and X1 but later given the name Bantam The difference between the two options was provision of a dynamo and battery in the luxury model as opposed to flywheel lighting coils in the cooking version.
Intended as a cheap commuter model, unfortunately, like some other Douglas ventures, it did not meet the intended specification nor provide the universal appeal needed to make it a winner. It was too well engineered with a heavy frame made of tubes bolted up with shock absorbing buffers. A very large petrol tank, incorporating a separate compartment for storing oil to mix with the petrol, added unnecessary weight. Large leg/foot-shields sweeping back underneath the footrests combined with sheet steel full engine enclosure panels gave excellent protection from the elements and the oily bits but further added weight. Other features provided in the interests of standardisation and hence economies of scale, (or to use up bits left over from other models) was the use of massive 8" brakes front and rear. Motive power selected was a 148cc Villiers engine. Needless to say, the performance with all this over-specification and weight was pretty pathetic with a top speed, under favourable conditions, of about 42 mph. At £27-10s-0d and £25-0s-0d respectively they were not particularly cheap either.
A feature unusual at the time was the horizontal disposition of the engine giving a lower centre of gravity and excellent access to the sparking plug without removing the engine panels. However, this caused a problem with overheating as this engine with radial fins was designed to run in the vertical position to provide cooling airflow to the cylinder. A three-speed Albion gearbox, (hand change), and cork lined clutch transferred the power, (or lack of it), to the rear wheel.
After about a year, Douglas decided to introduce an engine of their design. It has been suggested that this was forced upon them by credit having run out with Villiers, not unlikely, as Douglas were suffering particularly difficult financial problems in the mid 30s. Unashamedly, the Douglas engine is almost a carbon copy of the Villiers engine with two exceptions. The fins on the cylinder became axially disposed to improve cooling together with revised transfer porting to both balance flow and further improve cooling.
The later models with the Douglas engine also usually have a modified frame with a large U section middle frame element replacing a tubular steel assembly.
Modifications did not stop there however and over its production life from its introduction in 1933 to the last sales in 1935, three versions of front forks were used, (two pressed steel and one tubular girder), two completely different designs of cast aluminium exhaust waffle boxes feeding two types of twin silencers, two versions of the leg/foot-shields, two different saddles, (one rubber top, one mattress), two shapes of petrol tank, two designs of engine enclosure panels and no doubt many other not so obvious changes. One particularly interesting item was the use of the polished wood tram handle knobs to secure the engine panels. These were obviously left over from the gear change levers of the 2.3/4 hp models, which finished production in 1926.
Although in the above I have not been particularly kind in my description of this interesting, if not commercially successful venture of a manufacturer of some outstanding machinery over the years, the final verdict, I think you will agree, is that it is very attractive motorcycle. With a bit more thought and experience in this particular field, it could have been the success that Douglas sought. They tried again in 1938 with the CL38, but prototypes produced did not go into production so the Bantam remains the only two-stroke motorcycle to enter series production by Douglas Motors Ltd. Some 13 or 14 are known to exist with only about half of these in running order.
My machine, pictured below, was restored in 2002/03 from a very incomplete set of components. Most of the missing parts, including some castings, were manufactured from scratch. See a more complete story of its restoration and before and after restoration pictures in Members Gallery HERE
A phoenix is arising from the ashes in Australia where restoration of another example is now nearing completion.

« Last Edit: 11 Sep 2006 at 18:33 by Chris »

Offline Dave

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Re: A Two Stroke Douglas
« Reply #1 on: 24 Nov 2005 at 09:29 »
Thanks for this Chris - I'm enjoying reading your interesting posts.