Triumph Bonneville T120
Encyclopedia
The Triumph Bonneville T120 is a British motorcycle
that was designed and built by Triumph Engineering between 1959 and 1975, when the engine size was increased to 46 cu in (0.0007544 m³).
's last production design at Triumph (in retirement Turner designed the Triumph Bandit/BSA Fury which did not pass the prototype stage before BSA went under). The new motorcycle was conceived and developed by Doug Hele
and Brian Jones
so quickly that it wasn't even included in the 1959 Triumph catalogue. With a 649 cc parallel-twin (two-cylinder) engine the T120 was based on the Triumph Tiger T110
and was fitted with the Tiger's optional twin 1 3/16 in Amal
monobloc carburettors as standard, along with that model's high-performance inlet camshaft. Launched in 1959 by Triumph as "The Best Motorcycle in the World", the Bonneville T120 was aimed mainly at the lucrative US market where enthusiasts were demanding extra performance.
Initially produced with a pre-unit construction
engine which enabled the bike to achieve 115 mph (185.1 km/h) without further modification, the power tended to induce high speed wobbles from the single downtube frame, so in 1963 a unit construction
model was introduced which was stiffer and more compact, including additional bracing at the steering head and swinging arm. The steering angle was altered and improved forks were fitted a couple of years later, which, together with the increased stiffness enabled overall performance to match that of the Bonneville's rivals.
Later T120 models used a new frame which contained the engine oil instead of using a separate tank; this became known as the oil in frame version. In 1968 the T120 gained a new and more reliable ignition system. In 1967, Triumph posted its most successful year in the United States with an estimated 28,000 T120s sold, but by 1972, competition from larger capacity motorcycles led to the T120 being replaced by the 750 cc Bonneville T140
. Production of the 650 carried on until 1973 at which point Meriden went on strike. In 1974, less than 1000 of the 650cc assembled machines were released. With only 38 650's released in 1975.
T120V 650cc Oil-in-frame model with 5-speed gearbox and front disc brake.
in 1967 and 1969. The re-introduction of the Production TT had just taken place in 1967 when John Hartle
took first place on his Bonneville. Three years later Triumph set a new landmark in TT history when Malcolm Uphill
averaged 100 mph (160.9 km/h) around the Mountain Course on a Bonneville. Uphill’s achievement was the first time that a production motorcycle had ever passed the three-figure mark from a standing start. Following Uphill's record the Dunlop
K81 tyres he was using were renamed 'TT100's.
In 1962 Tony Godfrey and John Holder rode T120 Bonnevilles to victory in the Thruxton 500 mile endurance race
, and an article in The Motor Cycle entitled "Thruxton Triumph by Bonneville" led to the development of the Triumph T120R 'Thruxton', which was hand-built by a team of Triumph technicians using specially picked components and precision-machined cylinder heads and crankcases. Peak power was increased and each 'Thruxton' engine was bench tested to deliver around 53 bhp at 6,800 rpm with a safe rev ceiling of 7,200 rpm. Only around 55 Thruxton T120Rs were built and surviving examples are rare.
In 1969, Bonneville T120 bikes achieved the first three places in the Thruxton 500.
Percy Tait
and Malcolm Uphill finished first in the Thruxton 500, ahead of two other Triumph T120Rs.
racer Johnny Allen on the Bonneville Salt Flats in Utah
. In September 1955, Allen had achieved a two-way average speed of 193.3 mph (311 km/h) on his special motorcycle the "Devil's Arrow", a 650 cc twin-cylinder Triumph engine fuelled by methanol
in a unique 'streamliner' fairing. Allen's speed was ratified as a record by the American Motorcycle Association but not by the world authority, the FIM
, as no official observers were present. German motorcycle firm NSU
took the record the following year, so Allen and his team returned to Bonneville in September 1956 and won it back with an average speed of 214.17 mph (344 km/h). The FIM also refused to accept this as a world record but Triumph gained much needed publicity from the legal dispute that followed. After the Bonneville T120 had been named in recognition of Allen's records, other Triumph-engined motorcycles went faster still on the Salt Flats. In 1962 Bill Johnson set a two-way average of 230.269 mph (370.5 km/h) over a measured mile, riding a 667 cc 'streamliner' whose design was based on the American X-15 rocket plane
. In 1966 Detroit Triumph dealer Bob Leppan raised the record to 245.66 mph (395.3 km/h) with his 'Gyronaut X-1', powered by two 650 cc Triumph engines. For the next few years, Triumph fitted Bonneville roadsters with "World's Fastest Motorcycle" stickers.
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
that was designed and built by Triumph Engineering between 1959 and 1975, when the engine size was increased to 46 cu in (0.0007544 m³).
Development
The Bonneville T120 was Edward TurnerEdward Turner
Edward Turner was a British motorcycle designer. He was born in Camberwell in the London Borough of Southwark, on the day King Edward VII was proclaimed King....
's last production design at Triumph (in retirement Turner designed the Triumph Bandit/BSA Fury which did not pass the prototype stage before BSA went under). The new motorcycle was conceived and developed by Doug Hele
Doug Hele
Douglas Lionel Hele was a pioneering British motorcycle engineer with Triumph and other firms: BSA, Douglas and Norton. He was born in Birmingham in 1919 and died in Hagley, Worcestershire on the 2 November 2001.-Career:...
and Brian Jones
Brian Jones (motorcycle designer)
Brian Jones was a motorcycle designer and engineer born in Gloucester, UK in 1928. Notable for his contribution to the original design of the Triumph Bonneville, he died in Coventry, on 4 March 2001.-Career:...
so quickly that it wasn't even included in the 1959 Triumph catalogue. With a 649 cc parallel-twin (two-cylinder) engine the T120 was based on the Triumph Tiger T110
Triumph Tiger T110
The Triumph Tiger 110 was a British sports motorcycle first made by Triumph at their Coventry factory between 1953 and 1961. Developed from the Triumph Thunderbird the T100 first appeared in 1954...
and was fitted with the Tiger's optional twin 1 3/16 in Amal
Amal (motorcycle)
AMAL is a British carburettor trademark. AMAL were the suppliers of carburettors to the British motorcycle industry and their products were present on the products of the largest British motorcycle manufacturers such as BSA and AMC...
monobloc carburettors as standard, along with that model's high-performance inlet camshaft. Launched in 1959 by Triumph as "The Best Motorcycle in the World", the Bonneville T120 was aimed mainly at the lucrative US market where enthusiasts were demanding extra performance.
Initially produced with a pre-unit construction
Pre-unit construction
Pre-unit construction, also called separate construction, is a motorcycle engine architecture where the engine and gearbox are separate casings, with their own oil reservoirs, and usually attached to parallel plates that also attach to the frame...
engine which enabled the bike to achieve 115 mph (185.1 km/h) without further modification, the power tended to induce high speed wobbles from the single downtube frame, so in 1963 a unit construction
Unit construction
Unit construction is a term used to describe the design of larger motorcycles where the engine and gearbox components share a single casing. The term is sometimes applied to the design of automobile engines and was often loosely applied to motorcycles with rather different internal layouts such as...
model was introduced which was stiffer and more compact, including additional bracing at the steering head and swinging arm. The steering angle was altered and improved forks were fitted a couple of years later, which, together with the increased stiffness enabled overall performance to match that of the Bonneville's rivals.
Later T120 models used a new frame which contained the engine oil instead of using a separate tank; this became known as the oil in frame version. In 1968 the T120 gained a new and more reliable ignition system. In 1967, Triumph posted its most successful year in the United States with an estimated 28,000 T120s sold, but by 1972, competition from larger capacity motorcycles led to the T120 being replaced by the 750 cc Bonneville T140
Triumph Bonneville T140
The Triumph Bonneville T140 is a British motorcycle with a capacity engine that was designed and built by Triumph Engineering at Meriden near Coventry....
. Production of the 650 carried on until 1973 at which point Meriden went on strike. In 1974, less than 1000 of the 650cc assembled machines were released. With only 38 650's released in 1975.
T120 Export models
- T120R – export model intended for the US market with higher-rise handlebars and a smaller fuel tank.
- T120C – 'competition' model with high-level exhaust pipes.
- T120TT – 1964 model of the T120C for the US East Coast. In 1968 Evel KnievelEvel KnievelEvel Knievel , born Robert Craig Knievel, was an American daredevil and entertainer. In his career he attempted over 75 ramp-to-ramp motorcycle jumps between 1965 and 1980, and in 1974, a failed jump across Snake River Canyon in the Skycycle X-2, a steam-powered rocket...
jumped the Caesar's Palace CasinoCaesars PalaceCaesars Palace is a luxury hotel and casino located on the Las Vegas Strip in Paradise, Nevada, an unincorporated township in Clark County, Nevada, United States in the Las Vegas metropolitan area. Caesars Palace is owned and operated by Caesars Entertainment Corp....
fountains on a Bonneville T120TT, and was seriously injured breaking many bones after losing control on landing. - T120RT – a special 750 cc model manufactured by Triumph's American arm to permit them to be used in American Motorcycle Association production-based racing events. To qualify, motorcycles had to be made and sold to the public in the same form as they would be raced. Triumph had to produce and sell at least 200 of them before they qualified, and although the exact number sold is not recorded they did meet the requirement.
T120V 650cc Oil-in-frame model with 5-speed gearbox and front disc brake.
Racing success
The T120 won the Production Isle of Man TTIsle of Man TT
The International Isle of Man TT Race is a motorcycle racing event held on the Isle of Man and was for many years the most prestigious motorcycle race in the world...
in 1967 and 1969. The re-introduction of the Production TT had just taken place in 1967 when John Hartle
John Hartle
John Hartle was a British Grand Prix motorcycle road racer.Hartle began racing in 1954 and in 1956 he signed for Norton to ride for them in what would be the last year for the factory team. MV Agusta signed him in 1958 at the urging of John Surtees...
took first place on his Bonneville. Three years later Triumph set a new landmark in TT history when Malcolm Uphill
Malcolm Uphill
Malcolm Uphill was a former Grand Prix motorcycle road racer. His best season was in 1968 when he finished in ninth place in the 250cc world championship. In 1969, he teamed with Percy Tait to win the Thruxton 500 endurance race. At the 1969 and 1970 Isle of Man TT, Uphill won the 750 Production...
averaged 100 mph (160.9 km/h) around the Mountain Course on a Bonneville. Uphill’s achievement was the first time that a production motorcycle had ever passed the three-figure mark from a standing start. Following Uphill's record the Dunlop
Dunlop Rubber
Dunlop Rubber was a company based in the United Kingdom which manufactured tyres and other rubber products for most of the 20th century. It was acquired by BTR plc in 1985. Since then, ownership of the Dunlop trade-names has been fragmented.-Early history:...
K81 tyres he was using were renamed 'TT100's.
In 1962 Tony Godfrey and John Holder rode T120 Bonnevilles to victory in the Thruxton 500 mile endurance race
Thruxton 500
The Thruxton 500 is a 500 mile motorcycle endurance race held at Thruxton Circuit, near Andover in Hampshire, United Kingdom, which is the fastest racetrack in the country...
, and an article in The Motor Cycle entitled "Thruxton Triumph by Bonneville" led to the development of the Triumph T120R 'Thruxton', which was hand-built by a team of Triumph technicians using specially picked components and precision-machined cylinder heads and crankcases. Peak power was increased and each 'Thruxton' engine was bench tested to deliver around 53 bhp at 6,800 rpm with a safe rev ceiling of 7,200 rpm. Only around 55 Thruxton T120Rs were built and surviving examples are rare.
In 1969, Bonneville T120 bikes achieved the first three places in the Thruxton 500.
Percy Tait
Percy Tait
Percy Tait is a former professional motorcycle road racer and senior road tester for Triumph motorcycles, where he was estimated to have clocked over a million miles of road testing...
and Malcolm Uphill finished first in the Thruxton 500, ahead of two other Triumph T120Rs.
The Bonneville name
The Bonneville name came from the achievements of TexasTexas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
racer Johnny Allen on the Bonneville Salt Flats in Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
. In September 1955, Allen had achieved a two-way average speed of 193.3 mph (311 km/h) on his special motorcycle the "Devil's Arrow", a 650 cc twin-cylinder Triumph engine fuelled by methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
in a unique 'streamliner' fairing. Allen's speed was ratified as a record by the American Motorcycle Association but not by the world authority, the FIM
Fédération Internationale de Motocyclisme
The Fédération Internationale de Motocyclisme is the governing body of motorcycle racing. It represents 103 national motorcycle federations that are divided into six regional continental unions....
, as no official observers were present. German motorcycle firm NSU
NSU Motorenwerke AG
NSU Motorenwerke AG, normally just NSU, was a German manufacturer of automobiles, motorcycles and pedal cycles, founded in 1873. It was acquired by Volkswagen Group in 1969...
took the record the following year, so Allen and his team returned to Bonneville in September 1956 and won it back with an average speed of 214.17 mph (344 km/h). The FIM also refused to accept this as a world record but Triumph gained much needed publicity from the legal dispute that followed. After the Bonneville T120 had been named in recognition of Allen's records, other Triumph-engined motorcycles went faster still on the Salt Flats. In 1962 Bill Johnson set a two-way average of 230.269 mph (370.5 km/h) over a measured mile, riding a 667 cc 'streamliner' whose design was based on the American X-15 rocket plane
North American X-15
The North American X-15 rocket-powered aircraft/spaceplane was part of the X-series of experimental aircraft, initiated with the Bell X-1, that were made for the USAAF/USAF, NACA/NASA, and the USN. The X-15 set speed and altitude records in the early 1960s, reaching the edge of outer space and...
. In 1966 Detroit Triumph dealer Bob Leppan raised the record to 245.66 mph (395.3 km/h) with his 'Gyronaut X-1', powered by two 650 cc Triumph engines. For the next few years, Triumph fitted Bonneville roadsters with "World's Fastest Motorcycle" stickers.