Triumph Bonneville - The Definitive Guide

One of the most iconic motorcycles ever has had a long and illustrious career

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Triumph’s Bonneville was introduced in 1959 and was produced up to 1988 in its original form. Then it was reintroduced by ’new’ Triumph in 2001 and started the ’Modern Classic’ movement.

History of the Triumph Bonneville

Triumph Bonneville - The Definitive Guide
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1938 - Parallel Twin 500cc Engine Introduced

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Back in 1938, Triumph Motorcycles, under the leadership of Edward Turner, introduced an engine that, up to the introduction of the Honda inline four-cylinder engine in 1969, became the default configuration for all performance motorcycles. This, by extension, means the British motorcycle industry.

The Triumph parallel-twin engine was barely dimensionally larger than the single-cylinder engines it would soon make obsolete, thus helping its acceptance among the notoriously tradition-bound motorcycle-buying public at the time.

In time, of course, the Triumph Twin was accepted and became one of the most adaptable engines ever. It powered everything from trials mud-pluggers to Daytona 200 and Isle of Man TT winners, not to mention, a bewildering array of road-going machines from 350cc to 750cc as well.

1959 - 650cc T120 Bonneville Launched

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But, it was in 1959 that Triumph introduced the motorcycle that was to become the defining model of that venerable and much-respected company. Taking its name from the venue for Johnny Allen’s record-breaking attempt in 1959, the new T120 Bonneville was to become the most popular model Triumph ever made, the Americans, in particular, appreciating its blend of style and performance.

In reality, the new Bonneville was a little different from the T110, which remained current after the T120 was introduced. The T110 was also 650cc, but had a single-carb cylinder head, although a twin-carb head was available as an option. The T120 had hotter camshafts and twin carbs and would reportedly do 120mph, hence the name.

1963 - Unit Construction of the 650cc Engine

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The first three years of production featured a separate crankcase and gearbox, But, for 1963, a new unit construction engine/gearbox was introduced, which improved rigidity considerably, although vibration increased because of it.

In this form, the T120 Bonneville continued with detail differences from year-to-year throughout the 1960s and well into the 1970s: each year heralded a new color for the tank and mudguards, and variations in frame construction - from twin-downtube to single downtube and back to twin downtube.

1971 - Oil-In-Frame Models

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1970 was the last of the ‘traditionally-styled’ Bonnevilles. For the 1971 model, a new frame was introduced which featured a large-diameter central spine tube that ran from the headstock backward over the engine and then turned downwards to meet the swing-arm pivot mounting. This carried the oil in place of the separate oil tank on pre-1971 models.

The problem with this frame was that it gave a very high seat, and, it has to be said that the looks of the bike suffered terribly, not helped by rather angular new petrol tanks for the home - U.K. - market.

By now, the Bonneville was looking very old-fashioned next to the Honda CB750 and Triumph’s own Trident 750. But, Triumph simply did not have the money to develop new models: even the Trident was a bit of a hash-up - a Triumph Twin-and-a-half, in effect.

1973 - 750cc and Front Disc brake

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In 1973, the engine was enlarged to 750cc which might have produced a lot more torque, but also, a lot more vibration. The name was changed to T140V to distinguish it from the 650cc models, the ‘V’ referring to a new five-speed gearbox. Styling returned to some of the attractiveness of the pre-1971 models, especially for the U.S.-bound bikes which had a shapely teardrop tank in place of the square-edged tank on the U.K. models. The seat height was also lowered by relocating the rear subframe tubes lower on the large spine tube.

1973 also saw the introduction of a Lockheed hydraulic disc front brake (which was joined by a rear disc brake in 1976).

1975 - 1983 - Workers Cooperative

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By this time, Triumph had been bought by a worker’s cooperative from the Norton-Villiers-Triumph concern, which, in the manner of the British automotive industry, had gradually gathered all the loose ends of the last of the British motorcycle industry under one roof, only for it to completely disappear a couple of years later, although Triumph soldiered on until 1983, when it was bought by property developer John Bloor.

Before that, however, Triumph had continued limited development of the T140 Bonneville. The emissions-compliant T140E arrived in 1978; the T140 ES Electro - with electric start - in 1980; the T140AV with anti-vibration rubber mounts for the engine in 1981; the T140 TSS with eight-valve cylinder head in 1982; the custom-styled T140 TSX, also in 1982, and the fairing, pannier and top-box-equipped T140 EX Executive in 1983.

1984 - 1988 - Les Harris-Built T140s

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In 1983, Bloor was attending the auction of the Meriden factory site, looking to buy it to turn into housing, and ended up buying the Triumph brand outright. He licensed the manufacture of the T140 Bonneville to Les Harris, who built 1,300 examples between 1984 and 1988. When the license expired, it was not renewed.

1991 - Launch of the New John Bloor-Era Triumph Motorcycles

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That was seemingly the end of the iconic Bonneville, as Bloor’s new Triumph concern developed a completely new and modern range of three- and four-cylinder models, introduced in 1991, designed to compete head-to-head with the world’s major manufacturers.

In this, they were ultimately successful and the motorcycles used names drawn from Triumph’s illustrious past - Daytona, Trophy, Thunderbird, and Trident. But, one name was missing from that list all the way through the 1990s and many wondered if ‘Bonneville’ would ever be seen on a motorcycle again. Speculation was rife that the name was reserved for a top-of-the-range sports bike but, in fact, the opposite was the case.

2001 - Triumph Bonneville Returns

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In 2001, the first ‘new’ Triumph Bonneville was launched. It was a pastiche of the original T120 Bonneville, complete with a parallel-twin engine of 790cc and ‘retro’ styling. However, while the engine strongly resembled the ‘old’ parallel-twin Triumph engine externally, it was thoroughly modern, with counter-balance shafts to damp out vibrations.

In one fell swoop, Hinckley Triumph (Hinckley was the name of the town where the new factory had been built; the old factory had been near a village called Meriden. Both are in the British Midlands) had invented the concept of the ‘modern classic’, a bandwagon that proved so popular that every other manufacturer jumped on eagerly in the coming years and decades.

2005 - 865cc Parallel-Twin Engine

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In 2005, the Bonneville’s engine was enlarged to 865cc and the T100 name was revived. From 2007, all models in the Bonneville range got the 865cc engine. Electronic fuel injection arrived in 2008 (U.K.) and 2009 (U.S.). Cleverly, and to retain its classic looks, the ‘carburetors’ were retained, now housing the throttle bodies for the EFI.

From 2008 to 2016, the range comprised Bonneville SE (two-tone paint, polished engine covers), T100 (top of the range model, with wire-spoked wheels), Thruxton (cafe racer style), Scrambler (copying the style of the original TR6C and Trophy Trail), America (semi-cruiser style) and Speedmaster (factory custom based on the America).

2016 - 1200cc Parallel Twin Introduced

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In 2016, Triumph moved the Modern Classics (now an official Triumph term) forward with a new 1200cc version of the engine. This came in two states of tune - High Power and High Torque - depending on the bike it was fitted into.

The 1200cc engine was fitted to the T120, T100, Thruxton, Speed Twin, and Bobber, while the 900cc engine was retained for the Scrambler, Street Twin, and Street Cup models. In 2019, Triumph released a brand new Scrambler 1200 which had the real off-road ability.

The ‘New Bonneville’ range has been massively successful for Triumph and gets better with every passing year. Despite the concept of modern engineered/retro-styled motorcycles having been copied by virtually every other manufacturer (with the notable exception of KTM which doesn’t actually have an old road model on which to base a modern classic) Triumph’s Bonnevilles and related models tap into a seam of nostalgia that still runs strongly through many motorcyclists the world over.

Important Dates

1938 - 500cc Triumph parallel-twin engine launched in the Speed Twin
1959 - Top-of-the-range Bonneville launched, with 650cc, twin-carb cylinder head and hot camshafts. Separate gearbox and crankcases. Named after the venue for Johnny Allen’s record-breaking attempt using Triumph engines.

1963 - Engine and gearbox built-in unit.

1971 - ‘Oil-in-frame’ chassis introduced, which gave an uncomfortably high seat.
1973 - T140V introduced, with the engine enlarged to 750cc and a five-speed gearbox fitted. Front disc brake fitted. Frame revised to give lower seating position.
1975 - after a year-long sit-in by the workforce, they buy out the management and form a cooperative to continue production
1976 - rear disc brake fitted
1978 - Emissions compliant T140E introduced

1980 - T140 ES Electro with electric start introduced
1981 - T140 AV with anti-vibration engine mounts
1982 - T140 TSS with an eight-valve cylinder head and T140 TSX with custom styling
1983 - T140 EX Executive, with fairing, panniers, and top box
1983 - Property developer John Bloor buys the rights to the Triumph name
1984 - 1988 - Bonnevilles produced under license by Les Harris. 1,300 bikes built

1991 - The first of the new ‘Hinckley’ Triumphs launched. Model range powered by three- and four-cylinder engines and reviving names such as Trident, Trophy, Daytona, and Thunderbird

2001 - The first of the ‘new’ Bonnevilles arrives, powered by a 790cc parallel-twin engine, this time with balancing shafts to cancel out vibrations.
2005 - 865cc engine introduced on the T100 model.
2007 - 865cc engine used across the Bonneville range.
2008/2009 - Electronic fuel injection introduced to the U.K./U.S. models respectively

2008 - 2016 - Range comprising Bonneville SE, T100, Thruxton, Scrambler, America and Speedmaster

2016 - 1200cc parallel-twin engine introduced, in High Torque and High Power versions. 900cc engine used in ‘Street’ models.
2019 - Scrambler 1200 introduced.

Harry Fisher
Harry Fisher
Motorcycling Contributor
Born and raised in England, he has lived in South Africa with his family since 2002. Harry has owned examples of Triumph, Norton, BSA, MV Agusta, Honda, BMW, Ducati, Harley Davidson, Kawasaki and Moto Morini motorcycles. He regrets selling all of them.  Read full bio
About the author

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