A Triumph Bonneville T120 with pre-unit engine on display at the Deutsches Zweirad- und NSU-Museum.
Triumph Motorcycles Ltd
|Production||1959–1983, 1985–1988, 2001–|
|Engine||Four-stroke parallel twin|
|Transmission||4-speed (later 5-speed)|
The Triumph Bonnevilles are a range of standard motorcycles made in three different production runs beginning in 1959. The first two, by the defunct Triumph Engineering in Meriden, West Midlands, England were 1959 to 1983 and 1985 to 1988. The third run, by Triumph Motorcycles in Hinckley, Leicestershire began in 2001. It is named after the Bonneville Salt Flats, Utah, where Triumph and other motorcycle companies made attempts on motorcycle speed records. All share a parallel-twin four-stroke engine configuration. The current version, produced since 2001 by the modern successor of the original company, is a completely redesigned and re-engineered evolution of the original design.
Development history 
The original Triumph Bonneville was popular, particularly in its early years, for its performance compared with other available bikes. Although its engine was later enlarged to 750 cc, in the late 1970s and early 1980s sales abroad greatly suffered in competition with more modern Japanese motorbikes from Honda and other manufacturers. Domestically, however, the T140 remained the best-selling 750 cc motorcycle against more sophisticated Japanese and Italian opposition, picking up the prestigious Motor Cycle News Machine Of The Year award in 1979.
T120 Bonneville 
The original Triumph Bonneville was a 650 cc parallel-twin motorcycle manufactured by Triumph Engineering and later by Norton Villiers Triumph between 1959 and 1974. It was based on the company's 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. Initially it was produced with a pre-unit construction engine which enabled the bike to comfortably achieve 115 mph without further modification, but later in 1963 a unit construction model was introduced which was stiffer and more compact, including additional bracing at the steering head and swing 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 Bonnevilles used a new frame which contained the engine oil instead of using a separate tank; this became known as the oil in frame version. The T120 engine, both in standard configuration and especially when tuned for increased performance, was popular in café racers such as Tribsas and particularly Tritons.
T140 Bonneville 
The early 650 cc capacity production T120 Bonneville, often known as the duplex frame model, was replaced in the early 1970s by the T140 Bonneville, the same basic machine but with a 750 cc engine. Refined from the later 'oil in frame' version of the T120, the first few T140s, designated T140V, featured a larger-capacity engine of 724 cc, a five-speed gearbox option and indicators, but still retaining drum brakes and kick-start. Shortly after, the engine was further bored out to 744 cc and front disc brakes were fitted using single discs until 1982. In 1975, along with engine modifications, the gearchange lever was moved from right to left to comply with new regulations mandated for the American market and a rear disc brake fitted. Several T140 models followed featuring various modifications and refinements including electric starting from 1980 until production ceased with the closure of the Meriden works in 1983.
Although this should have been the end of the Bonneville, as it turned out it was not. Triumph Motorcycles was acquired by businessman John Bloor, who licensed a company called Racing Spares in Devon, run by Les Harris to manufacture the T140 Bonneville. These continuation bikes are known as the 'Devon Bonnevilles', which did not reach the market until 1985, and were not sold in the U.S. Production ended in 1988.
New Bonneville 
A completely new Triumph Bonneville 790 was debuted in 2001 by Bloor's Triumph Motorcycles Ltd. Originally built exclusively in Hinckley, England, some models are now produced at the company's Thailand manufacturing facility, which also makes components and accessories for various Triumph bikes. The new "Bonnie" strongly resembles the earlier models in style and basic configuration, but with entirely modern engineering. At the debut the new version was given a 790 cc parallel-twin engine, with the up-spec T100 receiving a 865 cc engine. From 2007 on, all Bonnevilles received the 865 cc engine. Until 2007, all engines had carburettors; electronic fuel injection (EFI) was then introduced to the 2008 models in Britain and to United States models in the 2009 model year, in both cases to comply with increasingly stringent emissions requirements. Dummy carburettors, which are actually redesigned throttle bodies made to resemble carburettors, have been added to the 2009 models to retain the original vintage styling of previous years.
From 2008, all models received a bigger and reshaped tank. This tank is a bit larger in order to accommodate the EFI pump, but does not offer greater capacity. The enlarged tank was fitted to the US 2008 model, though these were not EFI. The bigger tank served no purpose in the US 2008 model, but did mean that they had the same tank as the EFI European models.
In 2006, Triumph launched the "Sixty-8" line of Bonneville accessories, offering vintage and modern-style items including seats, seat covers, cam covers, sprocket covers, petrol tank covers, tank badges, panniers, and other items to allow Bonneville owners the opportunity to customise their bikes for considerably less cost than traditional customisations. The adoption of the EFI engine in 2008 rendered many of these accessories obsolete, since tank covers, tank badges etc. would not fit the redesigned tank.
Many different versions of the original Bonneville were produced; suffix letters were given to denote the exact model. Listed below in chronological order are the main types and their features:
T120 Bonneville 
- T120 – Home and general export model.
- T120R – Export model for the United States of America.
- T120C – Export COMPETITION model with high-level exhaust pipes.
- T120TT – 1964 export Dirt Track Racing model of the T120C for the U.S. East Coast. 'Thruxton' models were Factory Homlogated Road Racing models.To special order.
- T120RV – Five-speed transmission.
- T120V – Five-speed transmission with front disk brake.
T140 Bonneville 
- T140V – The initial model of the T140, the 'V' stood for five-speed transmission. Produced between 1972 and 1978.
- T140RV – Export version of T140V.
- T140J – Limited edition of 1,000 each (plus 400 for Commonwealth export) of the T140V in USA and UK specification, produced to commemorate the 1977 Silver Jubilee of Elizabeth II.
- T140E – The letter 'E' stood for emissions, enabling export to the USA market. This model featured redesigned Amal carburettors soon joined by, Lucas electronic ignition to meet emission regulations.
- T140D – Limited edition T140D offered with Lester,later Morris, cast wheels in black/gold scheme only. The US version had a special siamesed exhaust system unique to this model. The 'D' stood for Daytona, USA, where the model was conceived.
- T140ES – Electric start or 'Electro' Bonneville.
- T140AV – Anti-Vibration engine mountings.
- T140LE – Limited Edition, 250 Royal Bonnevilles were built to commemorate the 1981 marriage of Lady Diana Spencer and Prince Charles.
- T140W TSS – The Triumph T140W TSS, revealed in 1982, featured an eight-valve cylinder head and a revised crankshaft designed to reduce vibration. The TSS stood for Triumph Super Sports.
- T140TSX – A custom-styled T140, the Triumph T140 TSX featured Morris cast wheels, the rear being 16-inch diameter, stepped seat and special finish.
- Harris T140 - Built under licence 1985-88 by Les Harris after the Meriden factory closed and featuring significantly more Italian and German component parts.
Hinckley Bonneville 
- Bonneville 790 – Original 790 cc model
- Bonneville – Designation for current baseline model. In 2009 the baseline model gained cast alloy wheels, tank badge in decal form, black engine covers and upswept megaphone exhaust silencers
- Bonneville Black – 2007-2008 variation on baseline model with black paint and introducing the black engine covers subsequently used across the family from 2009, except on the Speedmaster, SE and T100.
- Bonneville SE – Designation for uprated model introduced in 2009 still with black engine, cast alloy wheels and upswept megaphone exhaust silencers, but with traditional metal tank badge, polished alloy engine covers and ‘shortie’ mudguards. Available with two-tone colour scheme
- T100 – Top-of-the-range model with spoked wire wheels, fork gaiters, two-tone tank colour scheme, twin ‘peashooter’ exhausts, chromed engine covers, Triumph logo on seat,
- Thruxton – Redesigned Bonneville with 60s café racer styling, introduced 2003, first model with the 865 cc engine.
- Scrambler – Redesigned Bonneville with off-road styling apeing the T100C version of the Triumph Tiger 100, the TR6C and the Triumph Trophy Trail (TR5T). Introduced in 2006.
- America – Semi-cruiser styled model primarily intended for the United States of America with lengthened wheelbase, lowered saddle .
- Speedmaster – 'factory custom' cruiser based on the Triumph Bonneville America.
See also 
- Nelson, 2001. p.28.
- The History of British Motoring, 2007. pp.166 – 167.
- Gaylin, 1997. p.44.
- "Triumph's Last Days" Motorcycle Classics magazine, Sept/Oct 2008
- Nelson, 2001. p.59.
- The History of British Motoring, 2007. pp.180 – 181.
- Bacon, Roy (1990). Triumph T140 Bonneville and Derivatives, 1973-1988. Niton Publishing. ISBN 1-85648-305-3.
- Bacon, Roy (1995). Triumph Twins and Triples. Niton Publishing. ISBN 1-85579-026-2.
- Davies, Ivor (1991). Triumph-The Complete Story. The Crowood Press. ISBN 1-86126-149-7.
- Gaylin, David (1997). Triumph Motorcycle Restoration Guide-Bonneville and TR6, 1956-1983. MBI Publishing Company. ISBN 0-7603-0183-2.
- McDiarmid, Mac (1997). Triumph-The Legend. Parragon Publishing. ISBN 0-7525-2080-6.
- Nelson, John (2001). Bonnie - The Development History of the Triumph Bonneville. Haynes Publishing. ISBN 0-85429-957-2.
- Author, not given (2007). The History of British Motoring. Abbeydale Press. ISBN 978-1-86147-197-0.
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