Just one of over 160 makers of powered two-wheelers once present in the city of Coventry, the Sparkbrook Company, like so many others, began life as a maker of bicycles, based at 14, Holborn Viaduct and 5, Lisle Street at the top of Leicester Square. Having introduced their first powered two-wheeler in 1912 (it was actually a 3-wheeler, a sidecar outfit with a choice of either 746 or 980 cc V-twin JAP engines), bicycle manufacture continued. Their first solo motorcycle was announced in 1914, powered by the just-introduced (and immediately popular) 21/2 h.p. Villiers 269 cc 2-stroke engine, early versions having a traditional, front-mounted, chain-driven magneto while later ones, from the 1921 Mk. 1V onwards, incorporated the revolutionary, designed-in-house, self-contained and cheap-to-produce, Villiers flywheel magneto. The origins of the latter device lay in the impossibility of obtaining, during WW1, supplies of the German Bosch magneto - Villiers' solution (granted a patent in January, 1917) was to reach production form in 1920, too late to assist the war effort, but a great boon to the Villiers Company that allowed hundreds of thousands of their motorcycle and industrial engines to avoid having to mount a separate (and expensive) Bosch or other make of magneto - as well as bringing in substantial licence fees from other engine makers who used the Villiers' system.Pictures below are very high resolution and take time to load
As a smaller concern - they made just 3,000 machines during a 10-year period - Sparkbrook's range of motorcycles was necessarily limited, but did eventually stretch from a little Villiers' powered, single-speed and direct-drive run-about, the bare-bones "Spark", to the previously-mentioned JAP powered V-twin sidecar outfit (a machine discontinued in 1915). Although various other engine options were offered, including Bradshaw oil-cooled and Bar & Stroud sleeve-valves types, judging by the numbers surviving (though even these are rare) the most popular model was the Villiers-powered Type A "Touring". This version was originally made in two forms and, upon its introduction in 1919, was available with either direct belt drive from the engine sprocket or fitted with a built-in-house, 2-speed gearbox that could be had with or without a clutch. By 1922 (though possibly earlier) and listed at £46, the "A" was equipped with a Sturmey-Archer 2-speed gearbox and direct drive or, for £2 more (£100 in today's money), equipped with a clutch - while a further £2 brought the convenience of a kick-starter. All these "A" models, until around 1922, employed what was known as a chain-cum-belt transmission system (chain from engine to gearbox and belt drive to the rear wheel) and were powered by the 269 cc Villiers engine first manufactured in 1913. This simple engine, with its deflector piston in cast iron, had bronze main and little-end bearings with a roller big end; there were no seals to retain crankcase compression, the engine relying upon the close fit of the long main bearings to achieve this.
According to the records (and confirmed by an experienced rebuilder of these units), the 269 cc engine was built in several slightly modified forms and obviously by using that well-known method of development, the customer…. Alterations included the exhaust system (a cheaper steel instead of aluminium unit), a new design of decompression valve, alternations to the crankcase, main bearing bushes and drive shaft and a flywheel with a separate centre section that allowed a choice to be made between either belt or chain drive. On the engine with a separate magneto, its drive was altered so that bike builders could arrange for it to be mounted either in front or behind the cylinder. However, despite the changes, the external appearance remained substantially unchanged until the Mk. 4 and its flywheel magneto.
Carrying the Type Letter "O", the first engine was built from 1913 to 1916, this being followed by a number of regular improvements categorised as: the Mk. 2 "A" from 1916 to 1820; the Mk. 3 "B" from 1920 to 1921. The completely new flywheel-magneto Mk. 4 "C" was made in just 1921 and the Mk. 5 "D" in 1922. However, registration dates and year specifications do not always match, some bikes remaining with dealers for up to three years before being sold..
Lubrication was not by a petrol-oil mix (though this could be used), but by a drip-feed pump with oil drawn from a compartment in the bike's fuel tank through a pipe connected to a drilled crankcase bolt (crankcase compression being denied access to the pump by a one-way valve built into its outlet pipe).
After 1922 a range of new, improved Villiers engines was introduced where, generally, both exhaust and carburettor faced to the front. The first three types, that spanned 1922 to 1924, being the Mk. 6C of 147 cc (prefix H); the Mk. 5A of 247 cc (prefix A) and the Mk. 6B of 342 cc (prefix K). It is possible to tell, at a glance, which engines are the earlier and which the later type: all 269 cc versions had parallel cylinder finning from top to bottom, while to give better cooling the 247 cc and 342 cc (as offered on Sparkbrook machines from 1923 onwards) had radial "star-burst" fins where the cylinder head would have been - the barrel being cast "blind ended". The 247 cc engine was a substantial improvement and gave some 25% more power than the 269 cc - though as the brakes on all lightweight motorcycles of the time were hopelessly weak, that might not have been the improvement most riders sought. After 1924 Villiers engines were once again heavily revised but, as Sparkbrook motorcycle production ended in that year, these are out of our remit
One additional advantage of the flywheel magneto was the facility to fit extra coils to run a lighting system, the Mk. 5 engine being the first designed to take these with Villiers offering, for £4 : 10s : 0d, a complete, bolt-on kit that included a small dry-cell battery for parking lights and the necessary wiring and switchgear. However, although a seemingly attractive system, as there was no regulator, high engine revs caused the voltage to rise and, unless you were prepared to take it steadily, bulbs would burn out with depressing frequency
Sparkbrook materials and build quality were both exceptionally good and the bikes - though differing little in design from those of many competitors - of neat appearance. Interestingly, if you compare prices now with those in the early 1920s they are, model-for-model, much the same. For example, the amount asked for a Sparkbrook "Model A" with 2-speed gearbox, clutch and kick-starter at £50 : 0s : 0d would, in 2018 money, be £2550, this being around the price of a typical 125 cc bike or scooter from a Japanese maker and intended to sell into much the same ride-to-work market segment. However, the 1920s were a time of fierce competition in a largely hard-up market and, by 1930, Triumph were offering something of a bargain: a 173 cc single-cylinder two-stroke with a two-speed gearbox, lighting from its flywheel magneto and all-chain drive for just £24 : 17s : 6d - half the price of a similar model from ten years previously.
How do you ride a motorcycle with a 2-speed gear and no clutch? Well, even on the comparatively deserted roads of the 1920s this would have exercised the owner's judgement and fitness as it required the rider to first operate the cylinder decompressor by pulling a lever on the left-hand side of the handlebar, then run with the bike in gear (the engine "chuffing" unresponsively) until, with sufficient speed up, the lever was released to restore compression and an attempt made to jump aboard. With luck, ignition would take place and away you went - killing the engine with the decompressor lever to change gear, giving a stroke to the tank-mounted Best and Lloyd oil pump and setting the drip rate (visible through a sight-glass) at 30 to the minute. However, if the ignition system and carburetion were spot on, or the engine warmed up, it was often possible to paddle the machine off while sitting down, a slightly easier process. If a stop should be forced, the whole pantomime had to be performed again - an especially annoying occurrence if it occurred going up a hill for that involved running back down to start the engine and finding somewhere wide enough to turn round….. With these disadvantages in mind, one would have thought that few bikes without a clutch would have been sold but, in the writer's experience, most surviving examples are indeed to that specification - with the "deluxe" clutch and kickstarter versions being very much harder to find. Copyright Tony Griffiths
If you have a Sparkbrook, the writer, Tony Griffiths, would be delighted to hear from you by email or phone: 01298-872874