Historic Motorcycle Brands

The Scott Motorcycle Company was a manufacturer of innovative motorcycles and light engines, founded by Alfred Angas Scott in 1908. Scott and Scott-origin Silk motorcycles were produced until 1979.

Scott two-cylinder two-stroke motorcycle engine – Rankine Kennedy

Alfred Scott’s brother had developed a two-stroke engine that he used to drive machinery in his experimental workshop. Alfred admired the efficiency of the two-stroke, in comparison with the ‘one-power-stroke-in-four’ of the Otto cycle. 

Scott’s first experiments with a two-stroke were in a motor boat, which led to an engine of his own design being fitted into a Premier bicycle, in 1901. This twin-cylinder engine had steel cylinders with shrunk-on aluminium radiator ‘flanges’ and drove the front wheel via friction, directly onto the tyre. 

He described the drive system as ‘useless in the wet’ and he could not prevent the cylinders from scoring. 

His next engine had cast iron cylinders of 2 1/4-inch bore, with belt drive to a clutch countershaft and then chain to the rear wheel. Ignition arrangements included a link made by a pin placed mid-way along the connecting rod. 

In parallel with this he continued work on a four-inch bore, four-inch stroke marine engine that developed 10bhp at 800rpm. He attached a large water-cooled brake wheel – effectively a dynamometer – that allowed him to experiment with port designs and piston shapes.

The outcome was a ‘curved top’, deflector piston that gave effective cylinder scavenging, albeit with a less than ideal combustion chamber shape.

Scott designed and patented a vertical-twin, two-stroke engine design in 1904 and patented the Scott motorcycle frame in 1908. The two designs were complementary in achieving a low centre of gravity. 

The resulting motorcycle was launched in 1908, powered by a Scott 450cc two-stroke, twin-cylinder, water-cooled engine. Obvious in the patent drawing is Item 49 – a high-mounted radiator for the thermo-siphon cooling system. Coolant heated by the engine dropped in density and rose up a hose into the top of the radiator, from where it sank down the radiator core as it cooled and returned via a hose into the bottom of the engine. There was no need for a water pump.

Innovative features included a patented two-speed chain transmission, in which the ratios were selected by clutches, operated by a rocking foot pedal. This bike also had a patented kick-starter. 

1913 Scott 550cc – Midnightbird

The first few machines were produced by Bradford-based car firm, Jowett, but Scott soon became a manufacturer in his own right.

Scott’s production machines were aimed at the typical well-heeled Edwardian gentleman and he knew there was valuable publicity to be had from competition success.  Scott’s victory at the 1908 Wass Bank hill-climb showed that his early Scott motorcycles were powerful enough to beat four-stroke motorcycles of the same capacity with ease. 

The outcome was that the Auto-Cycle Union handicapped Scott motorcycles, by multiplying their cubic capacity by 1.32, for competitive purposes.

That consoled his competitors, but resulted in free, positive advertising for Scott. The handicap was lifted three years later.

Scott bikes made several appearances at the Isle of Man TT Races between 1910 and 1914 with specially-built racing machines. 

Scott Squirrel 486cc – Yesterdays Antique Motorcycles

In 1910, a Scott was the first two-stroke motorcycle to complete a full TT course under race conditions. In 1911 a Scott ridden by Frank Phillip recorded a TT lap record of 50.11mph average speed.

Scotts were also the fastest machines in 1912, 1913 and 1914.

From 1911 to 1914 Scott’s Tourist Trophy racers used rotary valves to control the inlet and scavenge phases of the two-stroke cycle. In 1911 the engine was controlled by advancing or retarding the valve timing and not by the throttle. 

From 1912 Scott used fixed-gear rotary valves, with engine speed regulated by throttle control.

Three months after the outbreak of the First World War in 1914, Scott received a Government contract and had to postpone the launch of its planned 1915 civilian models until the end of the War. 

Scott WW1 mobile machine-gun battery

The British army requirement in 1914 was for single-cylinder 3.5hp models, or opposed twins. In order to manage its spare parts inventory the British Army rationalised its motorised vehicle purchases and Scott was not on that engine list. However,  Scott was asked to produce motorcycle and sidecar machine-gun vehicles. 

Each mobile machine-gun group comprised three Scott 552cc machines: one with a Vickers gun; one carrying ammunition and one as a spare. Eighteen bikes – six groups of three – were sent to the front for testing at the end of 1914.

Alfred Scott also developed a wheel-steered, three-wheeled, machine-gun carriage that was not taken up by the military.

After the War, Alfred Scott left the company he had founded, to develop his three-wheeled vehicle design for civilian use. The resulting vehicle was marketed as the Scott Sociable, from 1921 until 1924, but wasn’t successful.

After the War, the Scott Company production restarted with the 532cc Standard Tourer.

Scott Sociable – Bradford Industrial Museum

In 1922, Scott introduced the first of the famous ‘Squirrel’ sporting models. Engine displacement was reduced slightly, to 486cc that brought it below the 500cc competition-class upper limit, but lighter aluminium pistons and some tweaking saw it produce more power. 

Also, heavy touring-bike accessories, including foot boards and leg shields were dispensed with, making the Squirrel a very light and competitive motorcycle. 

1927 Scott Super Squirrel 596cc twin

It was followed by the Super Squirrel, with revised engine capacity of 498cc or 596cc and those bikes were the mainstay of production in the mid-1920s.

Scott racing bikes didn’t regain their pre-War status, but competed successfully in sporting events, scoring third and fourth places in the 1922 TT and a third spot in 1924. 

A three-speed gearbox with conventional clutch was offered from 1923 and in this form the machine had some success as a trials motorcycle.

1930 Scott Flying Squirrel National Motorcycle Museum Iowa

Development of the three-speed, Scott Flying Squirrel began in 1922 but, as the company was in severe debt and faced receivership, it wasn’t launched until the 1926 Earls Court motorcycle show.

The Flying Squirrel was nearly twice the price of a sporting four-stroke motorcycle of the time, but it did incorporate a redesigned three-speed gearbox, multi-plate clutch and repositioned magneto that were seen as significant improvements.

In 1929 Scott achieved third place in the Isle of Man TT and launched a road going TT Replica Flying Squirrel. Following cost cutting in 1929, the factory also launched a basic touring model for under £70. 

Financial problems continued, however and in 1931 Scott was unable to enter the TT or the Earls Court show. 

1938 Scott 1000cc – Thruxton

In 1935, the Scott three-cylinder motorcycle was launched as a water-cooled, 750cc in-line machine that exhibited more innovative engineering by the Scott Company. It was followed by a 1000cc version, but neither bike made it into quantity production, due to financial constraints and then the outbreak of the Second World War.

In 1946, after the Second World War, Scott relaunched the Flying Squirrel, powered by 500cc or 600cc engines, but these updated bikes were heavier than the pre-War versions and expensive for the performance offered. Sales were disappointing.

Scott Squirrel – Thruxton

In 1950, the company went into liquidation and was acquired by Scott enthusiast Matt Holder. His Aerco Jig and Tool Company in Birmingham continued to build the same models, from surplus parts and these ‘Birmingham Scotts’ remained available into the 1960s. 

In 1956, Holder began development of a 596cc model, with a duplex frame and telescopic fork front. In 1958 the Birmingham Scott was updated with a swing-arm frame and the dynamo was replaced by an alternator. 

A new 493cc motorcycle, called the Scott Swift, was announced but never went into production. However, Holder continued to produce one-off Scott motorcycles.

Silk

Dual-branded Silk-Scott motorcycle

The Silk motorcycle brand was founded in the late 1960s by George Silk, a Scott motorcycle enthusiast, who worked for Derbyshire Scott specialist Tom Ward. George Silk had developed a racing motorcycle, combining a Scott engine with a Spondon frame. 

Following some success with his ‘Silk Special’ at the Barbon Hill Climb in 1970, George Silk began planning a road-going prototype with his business partner Maurice Patey. 

They set up Silk Engineering and began providing a spares and repair service for Scott motorcycle owners. They also offered a range of modifications to improve the reliability and performance of Scotts, as well as improving the lubrication and gas flow. 

Silk exhibited the Silk-Scott prototype at the Racing and Sporting Motorcycle Show in London in 1971. Orders exceeded the company’s capability to produce them, so only 21 Silk-Scott Specials were sold between 1971 and 1975.

Matt Holder, who retained the rights to Scott engines, then disputed the use of the Scott trademark and prevented Silk from making Scott engines under licence, so Silk had to develop a replacement. A new 653cc two-stroke, 48bhp engine was developed by David Midgelow (ex Rolls Royce engineering) and George Silk, with assistance from two-stroke expert Gordon Blair of Queen University, Belfast, who optimised the porting.

Silk 700S engine. Note the electric cooling fan.

The Silk 700S was launched in 1975 and featured the new engine in a specially designed steel tubular frame made by Spondon, who also made the forks.

Output was quite competitive for the time, especially when coupled with good mid-range torque and a dry weight of around 140kg, so performance was excellent. However, at a cost of Stg£1355 it was more expensive than any other production motorcycle of the time. 

The 700S continued to be developed at the Darley Abbey works in Derbyshire, along with the SPR Production Racing version. Production was slow, with just two motorcycles a week coming off the production line. 

Customers could select from five colour schemes – British Racing Green, metallic blue or green, black with gold coachlines or plain red. There was also a Scott special edition in purple and cream – and a special scheme similar to Silk Cut cigarettes, which were popular at the time.

In 1976, Silk Engineering was taken over by the Kendal-based Furmanite International Group, which continued production of the Silk 700S that was upgraded to the 700S Mk2, in 1977 and named ‘Sabre’. 

Improvements from the Mk 1 included increased output to 54bhp, finned cylinder barrels and a redesigned seat, instruments and rear light nacelle. 

In 1978 the 100th Silk motorcycle was built and production continued until December 1979, when it dawned on the company that it was losing Stg£200 on every motorcycle sold!

Silk 700S – Mike Schinkel

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