1959 Triumph Bonneville T120

1959 Triumph Bonneville T120

standard50sUnited Kingdom

The 1959 1959 Triumph Bonneville T120 packs a 649cc OHV twin engine with 46hp into a standard motorcycle package from Triumph.

Specifications

Engine

Type
OHV twin
Displacement
649 cc
Cylinders
2
Power
46 hp @ 6500 rpm
Torque
52.0 Nm
Compression
Bore × Stroke
71.0 × 82.0 mm
Cooling
Air-cooled
Fuel System
2x Amal carburetors

Chassis & Transmission

Frame
Steel single cradle
Front Suspension
Telescopic fork
Rear Suspension
Twin shock
Front Brake
Drum
Rear Brake
Drum
Front Tyre
Rear Tyre
Transmission
4-speed
Final Drive
Chain

Performance

Top Speed
177 km/h (110 mph)
¼ Mile

Dimensions & Weight

Dry Weight
172 kg (379 lbs)
Wet Weight
185 kg (408 lbs)
Seat Height
790 mm
Wheelbase
1400 mm
Ground Clearance
Fuel Capacity
14.0 L

History & Story

Triumph's 1959 Triumph Bonneville T120 arrived in 1959 as a standard motorcycle designed for the discerning rider. Produced in United Kingdom, it quickly earned recognition as a capable standard motorcycle from the 1950s.

At the heart of the 1959 Triumph Bonneville T120 sits a 649cc OHV twin engine producing 46 horsepower at 6500 rpm. The twin-cylinder powerplant features a twin-cylinder layout with air-cooled cooling, fed by 2x Amal carburetors. Power reaches the rear wheel through a 4-speed transmission and chain final drive.

The chassis employs a steel single cradle frame with telescopic fork up front and twin shock at the rear. Stopping power comes from drum front and drum rear brakes. Tipping the scales at 172 kg (379 lbs) dry, the 1959 Triumph Bonneville T120 offers a manageable riding experience with a 1400 mm wheelbase.

Performance-wise, the 1959 Triumph Bonneville T120 achieves a claimed top speed of 177 km/h (110 mph). With a fuel capacity of 14.0 liters, it offers reasonable range for standard motorcycle duties. The seat height of 790 mm makes it comfortable for most riders.

Today, the 1959 Triumph Bonneville T120 is considered a highly sought-after classic that commands strong prices among collectors worldwide. Parts availability is rated as good, making ownership relatively straightforward. It remains an icon of Triumph motorcycling from 1950s.

Known Issues

  • Oil leaks from primary chaincase
  • Lucas electrics (nicknamed Prince of Darkness)
  • Sludge trap cleaning essential
  • Amal carburettor wear and jetting issues
  • Period-correct fasteners and hardware hard to find

Fun Facts

  • Pristine examples of the 1959 Triumph Bonneville T120 can command six-figure prices at auction
  • The 1959 Triumph Bonneville T120 is considered one of the most collectible motorcycles from Triumph
  • The 1959 Triumph Bonneville T120 is widely regarded as a milestone in motorcycle history

Collector Information

Parts Availability
Good
Collector Rating
9/10

Resources & Parts