Scott Motorcycles: The Origin Story of the Two-Stroke Motorcycle

Reading time: 4 min | Word count: ≈ 800

1. 1901 – A Marine Engine on a Bicycle: The Very First Spark

Alfred Angas Scott, a 25-year-old engineer from Shipley, Yorkshire, had grown up around high-speed marine steam engines.

In 1901 he bolted a home-made twin-cylinder 2¼-inch bore two-stroke into a Premier bicycle frame.

The crankshaft drove the front wheel by friction directly onto the tyre—"useless in the wet" Scott later admitted, but it proved the engine's punchy torque and mechanical simplicity.

He ran the contraption up and down the Leeds-Liverpool canal tow-path, collecting data on port timing and piston temperature that would feed every future Scott design.

2. 1904 Patent – The World's First Purpose-Built Two-Stroke Motorcycle Engine

While rivals adapted industrial four-strokes, Scott filed British Patent 7,803 on 3 April 1904 for a vertical-twin, water-cooled two-stroke specifically intended for motorcycles.

Key claims:

• Over-hung crank-pins for twin cylinders on a single throw.
• Curved-top deflector piston to improve scavenge without complex valves.
• Thermo-syphon cooling – hot coolant rises into a high-mounted radiator, cools, falls back; no water-pump needed.

The patent examiner scribbled "elegant but daring"; rival makers called it "unnecessary". They stopped laughing when the prototype climbed Sutton Bank in top gear with a pillion passenger.

3. 1908 Production Model – Water-Cooled, Twin-Cylinder, Kick-Start

With financial help from Jowett Cars of Bradford, Scott unveiled the 1908 Scott at the Stanley Show, London.

Numbers that stunned Edwardian England:

Feature	Scott 450 cc Twin	Typical 4-Stroke Single
Power	6 bhp @ 3,000 rpm	3.5 bhp @ 1,800 rpm
Weight	120 lb (54 kg) dry	140 lb (64 kg)
Cooling	Water-cooled	Air-cooled
Gears	2-speed, foot-rocker	Single-speed, belt
Starter	Patented kick-start	Push-and-hop

Every bike left the factory with a toolbox, a tyre-pump and a brass hand-pump for the radiator—luxury unheard of in 1908.

4. Racing Shock-Waves – Hill-Climb, TT Records and the 1.32 Handicap

• 1908 Wass Bank Hill-Climb – Scott beats 500 cc four-strokes by 14 seconds.
• Auto-Cycle Union retaliates – multiplies Scott's capacity by 1.32× for race classes (a 450 cc Scott races as 594 cc).
• 1910 Isle of Man TT – Frank Phillip rides a Scott to become the first two-stroke ever to finish the Mountain Course.
• 1911 TT – 50.11 mph lap record (80.64 km/h), fastest machine of the meeting; handicap lifted in 1912 after rivals complain it's free advertising.

Between 1912-1914 Scotts were fastest bikes at TT every single year—a two-stroke dynasty before the term "dynasty" existed.

5. Engineering Firsts That Became Industry Standards

1. Rotary inlet valve – disc cut into crank-web, timed by gear-train; precursor to modern reed-valves.
2. Half-compression lever – handle-bar lever opens secondary exhaust port, dropping compression for push-start; doubles as engine brake downhill.
3. Two-speed counter-shaft gearbox – dog-clutch selection, no sliding gears; idea copied by BSA, Triumph in the 1920s.
4. Over-hung crank – allows narrow crank-case, short wheel-base; still used in today's 250 cc Moto3 two-strokes.

6. World War I – Machine-Gun Sidecars and Military Contracts

The British War Office ordered 18 Scott 552 cc specials (1914) configured as mobile machine-gun batteries:

• One bike carried Vickers .303, second carried ammo, third served spare.
• Water-cooling meant no overheating during continuous fire retreats in Flanders mud.

Post-war, surplus Scotts flooded civilian market—ex-servicemen became brand evangelists, fuelling 1920s export boom to Australia and India.

7. The Inter-War Decline – Luxurious Squirrels and a 1,000 cc Triple Dream

• 1926 Flying Squirrel – 596 cc, 70 mph, £135 (nearly twice a Triumph 500).
• Great Depression – sales collapse; £70 budget "Touring" model (1929) too late.
• 1934 prototype – inline water-cooled 1,000 cc triple, 120° crank, elektron crank-case; shown at Olympia but WWII and bankruptcy kill the project.

Production limped until 1950; rights passed through Silk Engineering (1970s) but Scott Motorcycle Company itself never fully recovered.

8. Quick-Fire Spec Sheet – 1908 Scott vs 1908 Four-Stroke Singles

Metric	1908 Scott 450 cc Twin	1908 Triumph 475 cc Single
Cycle	Two-stroke	Four-stroke
Cooling	Water (thermo-syphon)	Air
Power	6 bhp @ 3,000 rpm	3.2 bhp @ 1,800 rpm
Weight	120 lb	140 lb
Top Speed	65 mph (105 km/h)	45 mph (72 km/h)
Fuel	Petrol + 2% oil (pre-mix)	Petrol only
Price	£60	£45

9. Quick-Fire FAQ – Water-Pumps, Rotary Valves, Oil-in-Fuel

Q1. Did early Scott have a water-pump?

No – thermo-syphon convection loop; pump added only on post-1929 racers.

Q2. What was the half-compression lever for?

Drops effective compression for easy push-start and doubles as engine brake on downhill runs.

Q3. Why rotary valves on TT bikes?

1911-1914 racers used rotary disc for inlet timing; gave crisper throttle before reed-valves existed.

Q4. Oil ratio in 1908?

½ pint castor oil per gallon – roughly 1:30 pre-mix; riders carried measuring cup under seat.

Q5. Can you still buy a Scott today?

≈150 rideable bikes worldwide; good 1926 Flying Squirrel fetches £18k-22k at UK auctions.

Bottom Line

Alfred Scott didn't just build a motorcycle—he legitimised the two-stroke cycle, terrified four-stroke rivals and wrote the blueprint for every pinging, oil-sweating, high-revving two-stroke that followed.

From canal-tow-path experiments to TT lap records, Scott proved that twice the power-strokes could mean twice the fun—a lesson the motorcycle world is still inhaling with every blue-clouded breath.