Triumph T 120 Bonneville (1959-60)

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The Triumph T120 Bonneville 650 was produced in 1959-1960 and had a four-stroke, parallel-twin, OHV engine with a capacity of 649cc. It had a compression ratio of 8.5:1 and was air-cooled. The motorcycle had 2 Amal 1-1/6″ carburetors and a Lucas magneto ignition, with a starting system that required kicking. The max power was 34 kW or 46 hp at 6700 rpm, and it had a wet, multi-plate clutch and a 4-speed constant mesh transmission with a chain final drive of 101 links. The gear ratios were 1st 11.90/2nd 8.25/3rd 5.81/4th 4.88:1. The frame was made of twin-steel downtubes, and it had a telescopic fork front suspension and a swingarm rear suspension with twin Girling dampers. The front brakes had an 8″ SLS drum, and the rear had a 7″ SLS drum. The front tire had a size of 3.25 x 19 Dunlop, and the rear had 4.00 x 18 Dunlop. The wheelbase was 1400mm or 55.25 inches, with a seat height of 770mm or 30.5 inches, and ground clearance of 127mm or 5.0 inches. The dry weight was 183kg or 403lbs, and the fuel capacity was 13.6L or 3.6 US gallons for the US and 18L or 4.8 US gallons for export to the UK and other countries.

Technical specifications:

Make Model: Triumph T120 Bonneville 650

Year: 1959 – 60


Engine: Four stroke, parallel twin, OHV
Capacity: 649 cc / 39.6 cu in
Bore x Stroke: 71 x 82 mm
Compression Ratio: 8.5:1
Cooling System: Air cooled
Induction: 2 x Amal 1 – 1/6″ carburetors
Ignition: Lucas magneto
Starting: Kick
Max Power: 34 kW / 46 hp @ 6700 rpm
Clutch: Wet, multiplate
Transmission: 4 Speed, constant mesh
Final Drive: Chain, 101 links
Gear Ratios: 1st 11.90 / 2nd 8.25 / 3rd 5.81 / 4th 4.88:1
Frame: Twin steel downtubes
Front Suspension: Telescopic forks, hydraulic damping

Rear Suspension: Swingarm, twin Girling dampers
Front Brakes: 8″ SLS drum
Rear Brakes: 7″ SLS drum
Front Tyre: 3.25 x 19, Dunlop
Rear Tyre: 4.00 x 18, Dunlop
Wheelbase: 1400 mm / 55.25 in
Seat Height: 770 mm / 30.5 in
Ground Clearance: 127 mm / 5.0 in
Dry Weight: 183 kg / 403 lbs
Fuel Capacity: US: 13.6 L / 3.6 US gal / 3 Imp gal / UK and other Export: 18 L / 4.8 US gal / 4 Imp gal

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