Sunbeam S8 (1949-56)

The Sunbeam S8 was a motorcycle produced from 1949 to 1956. Around 8,530 units were produced during its run. The engine was a 487 cc parallel twin with SOHC, capable of producing a maximum power of 18.6 kW/25 hp at 6000 rpm. The compression ratio was 6.5:1, and the cooling system was air/oil cooled with lubrication via wet sump. The starting system was a kick-start and the electrical system was 6V. The clutch was a single plate, dry type, and the transmission had four speeds. The final drive was via shaft. The frame consisted of a twin cradle made of steel. The front suspension was telescopic with one-way damping while the rear suspension was plunger with a spring-loaded saddle. The front and rear brakes were drum, leading shoe type with a diameter of 203 mm or 8 inches. The front and rear wheels were 4.50 x 16 inches and 4.75 x 16 inches, respectively, while the front and rear tyres were 4JA x 16 inches and 43A x 16 inches, respectively. The wheelbase was around 1400 mm or 57 inches, and the dry weight was 187 kg or 413 lbs. The top speed was 121 km/h or 75 mph.

---

Technical specifications:

Make Model: Sunbeam S8 500

Year: 1949 – 56

Production: 8 530 units

Engine: Parallel twin, SOHC

Capacity: 487 cc / 29.7 cu in

Bore x Stroke: 70 x 63.5 mm

Compression Ratio: 6.5:1

Cooling System: Air/Oil cooled

Lubrication: Wet sump

Starting: Kick

Electrical system: 6V

Max Power: 18.6 kW / 25 hp @ 6000 rpm

Clutch: Single plate, dry

Transmission: 4-Speed

Final Drive: Shaft

Frame: Twin cradle, steel

Front Suspension: Telescopic, one way damped

Rear Suspension: Plunger, spring loaded saddle

Front Brakes: Drum, leading shoe, 203 mm / 8″

Rear Brakes: Drum, leading shoe, 203 mm / 8″

Wheel, Front: 4.50 x 16″

Wheel, Rear: 4.75 x 16″

Tyres, Front: 4JA x 16″

Tyres, Rear: 43A x 16″

Wheelbase: 1400 mm / 57″

Dry Weight: 187 kg / 413 lbs

Top Speed: 121 km/h / 75 mph

Source: Sump Publishing