Triumph 6T Thunderbird (1963-66)

The Triumph 6T Thunderbird motorcycle was produced from 1963 to 1966 and featured a four stroke, vertical twin, OHV engine with a capacity of 649 cc. It had a 8.5:1 compression ratio, an Amal Monobloc induction system, and a kick-start. The motorcycle was capable of producing a maximum power of 31 kW or 42 hp at 6500 rpm. The clutch was wet and had multiple plates, while the transmission had four-speed constant mesh and the final drive was a chain. The gear ratios were 11.80:1 for first gear, 8.17:1 for second gear, 6.76:1 for third gear, and 5.84:1 for fourth gear. The frame of the motorcycle was brazed lug and the front suspension was telescopic fork with two-way hydraulic damping while the rear suspension was swingarm with two hydraulic dampers. The front brake was a SLS drum with an 8-inch diameter and the rear brake was a SLS drum with a 7-inch diameter. The front wheel was 3.25 x 19 while the rear wheel was 4.00 x 18. The wheelbase was 1384 mm or 54.5 inches and the seat height was 825.5 mm or 32.5 inches. The dry weight of the motorcycle was 165 kg or 363 lbs.

Technical specifications:

Make Model: Triumph 6T Thunderbird

Year: 1963 – 66
Engine: Four stroke, vertical twin, OHV
Capacity: 649 cc / 40.0 cu in
Bore x Stroke: 71 x 82 mm
Cooling System: Air cooled
Compression Ratio: 8.5:1
Exhaust: Two-into-two
Induction: Amal Monobloc
Starting: Kick
Max Power: 31 kW / 42 hp @ 6500 rpm
Clutch: Wet, multiplate
Transmission: 4-Speed constant mesh
Final Drive: Chain
Gear Ratios: 1st 11.80:1 / 2nd 8.17:1 / 3rd 6.76:1 / 4th 5.84:1
Frame: Brazed lug
Front Suspension: Telescopic fork, 2 way hydraulic damping
Rear Suspension: Swingarm, 2 hydraulic dampers
Front Brakes: SLS drum, 8 in
Rear Brakes: SLS drum, 7 in
Front Wheel: 3.25 x 19
Rear Wheel: 4.00 x 18
Wheelbase: 1384 mm / 54.5 in
Seat Height: 825.5 mm / 32.5 in
Ground Clearance: 127 mm / 5.0 in
Dry Weight: 165 kg / 363 lbs
Source: Classic British Motorcycles