Classic and Classy Motorcycles Ltd

Historical Context

The 1972 Triumph T120R Bonneville 650cc marks the final year of full production for the legendary 650 twin, which began in 1959. Named after the Bonneville Salt Flats, the T120R was Triumph's performance icon through the 1960s and became a symbol of British motorcycling worldwide. The 1972 model represents the culmination of the 650's development, just before Triumph fully transitioned to the larger 750cc T140. Built at Meriden during a time of industrial unrest and market pressure from Japan, the 650 Bonneville still delivered the classic look, sound, and feel that had made it famous—and is now considered a true collector's piece.

Technical Specifications and Performance

• Year: 1972
• Make: Triumph
• Model: T120R Bonneville
• Engine Displacement: 649cc
• Engine Type: Air-cooled OHV parallel twin
• Compression Ratio: 9.0:1
• Carburetion: Twin Amal concentric carburetors
• Ignition System: Points ignition
• Transmission Type: 4-speed manual
• Final Drive: Chain
• Cooling System: Air-cooled
• Fuel Capacity: Approx. 2.5 gallons
• Braking System: Drum front and rear
• Dry Weight: Approx. 395 lbs
• Top Speed: Around 105 mph

Technical Advancements

While the 1972 T120R retained much of the traditional Bonneville formula, it featured several important updates. The frame was revised to the oil-in-frame (OIF) design shared with the newer T140 models—this improved stability but raised the seat height and changed the bike’s proportions. The Amal concentric carbs made tuning easier than earlier Monoblocs. Though still using a 4-speed gearbox and drum brakes, the T120R delivered sharp throttle response and lively midrange torque, making it one of the best British twins of its time to ride in real-world conditions.

Evolution of the Model

The Bonneville 650 went through many updates since its launch in 1959. From pre-unit to unit construction, from 6V to 12V electrics, the T120 evolved to keep pace with changing markets. The final 1972 model was built during a time of upheaval at Meriden, just before the factory was taken over by the workers’ cooperative. While Triumph focused future efforts on the 750cc T140, the T120R’s lighter weight and revvier feel made it a favorite among purists. As the last of the 650s, the 1972 model holds special historical significance.

Competitors in the Market

By 1972, the T120R was competing with advanced bikes like the Honda CB750, Yamaha XS650, and Kawasaki H1 Mach III. While those bikes boasted electric start, disc brakes, and more power, the Bonneville still appealed to riders who valued hands-on ownership, British style, and a visceral riding experience. It remained a strong seller in the UK and U.S. markets, especially among enthusiasts who wanted a motorcycle they could tune and maintain themselves.

Legacy and Appeal

As a barn find or restoration project, the 1972 Triumph T120R Bonneville 650cc is a high-value classic. It’s the last true version of the 650 twin and features the best refinements of the model’s run. With its slim frame, iconic tank, and instantly recognizable exhaust note, the T120R remains one of the most collectible and beloved British motorcycles ever made. Whether restored to original spec or lightly customized, it offers a satisfying ownership experience steeped in history and charm.