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.

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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