Triton motorcycle

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Pre-unit construction 650 cc Triumph twin-cylinder engine in a Norton 'wideline' Featherbed frame Triton.jpg
Pre-unit construction 650 cc Triumph twin-cylinder engine in a Norton 'wideline' Featherbed frame

Triton motorcycles were hybrid motor cycles built from the 1950s to the 1970s[ citation needed ] that involved fitting Triumph engines into Norton frames. Because no factory offered Triton motorcycles, they were typically privately constructed. However, some UK dealers offered complete bikes.[ citation needed ] The aim was to combine the best elements of each marque and thus gain a bike superior to either. The name 'Triton' is a contraction of Triumph and Norton; 'Triton' was the name of a mythological Greek God.


During the period in which Triton motorcycles were constructed, the Norton Featherbed frame was regarded as the best handling frame. [1] [2] Triton bikes aimed to combine the "best engine" with the "best frame" by replacing the standard Norton engine with a Triumph parallel-twin engine. Although "best" is subjective, a popular engine choice was the Triumph Bonneville unit with twin carburettors and twin camshafts. This pushrod engine gave good performance and reliability and could be more easily tuned for greater power using high-profile camshafts, high compression pistons and twin carburettors. In due course, a Weslake 8-valve head became available for the Triumph motor.

The Triumph engine was seen as an upgrade because the Norton 650 and 750 vertical twin engines were known to have reliability problems.[ citation needed ] At about 7000 rpm the piston exceeds the engineering limit for piston speed, so over-revving soon destroys the engines. The BSA 650 had a bronze bush main bearing on the right hand side, doubling as the crank oil feed, with a lack of effective crankshaft end play control, that all had difficulty staying together when ridden hard, even though the rest of the design was possibly more robust than the Triumph. The Triumph vertical twin used a ball on the timing side, and a roller on the other, with the oil feeding through a separate bronze bush in the outer right hand engine side cover.

650 cc Triumph twin-cylinder engine in a Norton 'slimline' Featherbed frame Triton Peter Ritzen.jpg
650 cc Triumph twin-cylinder engine in a Norton 'slimline' Featherbed frame

Whereas the Norton 650SS 646.44 cc had a bore and stroke of 68 x 89 mm giving 49 bhp (37 kW) @ 6,800 rpm, the Triumph T120 Bonneville 649.31 cc had a bore and stroke of 71 x 82 mm giving 46 bhp (34 kW) @ 6,500 rpm. However the mean piston speed of the Norton was 3,971 ft/min (almost at the, then accepted, limit of 4,000 ft/min). The Triumph, with its shorter stroke, had a mean piston speed of only 3,497 ft/min, had much less vibration and was much stronger and reliable. Road tests showed that the Norton had a higher top speed due to its 3 bhp (2.2 kW) advantage. In spite of this, the Triumph was the much preferred engine. The Norton featherbed was the preferred frame, hence the Triton.

Tritons with a pre-unit Triumph motor sometimes retained the post-1960 Norton AMC gearbox, which was thought superior to the equivalent Triumph gearbox. A Quaife five speed gearbox was sometimes used. More modern Tritons use a Triumph unit construction twin in a Featherbed frame.

Several motorcycle dealers made equipment for Triton conversions, some would do the complete job for customers while others sold complete Tritons. The most important part required are the engine mounting plates and several different designs exist that can affect the engine placement and therefore the handling. The lower the engine is mounted the better the handling achieved from the Norton frame.

Other hybrids

The Triton was probably the most common hybrid motorcycle, but another was the Tribsa, with a Triumph engine in a BSA frame. Other frame/engine combinations included the 'Norbsa' which had a BSA engine in the Norton featherbed frame. Vincent V-twin motors have on occasion been fitted into Featherbed frames to make a hybrid called a Norvin. [3]

Related Research Articles

Norton Motorcycle Company British Motorcycle Manufacturer

The Norton Motorcycle Company is a brand of motorcycles, originally based in Birmingham, England. For some years around 1990, the rights to use the name on motorcycles was owned by North American financiers.

Triumph Engineering Co Ltd was a British motorcycle manufacturing company, based originally in Coventry and then in Meriden. A new company, Triumph Motorcycles Ltd, based in Hinckley, gained the name rights after the end of the company in the 1980s and is now one of the world's major motorcycle manufacturers.

Tribsa British motorcycle

The Tribsa, or Tri-B.S.A., was a custom built café racer or off road motorcycle of the 1960s and 1970s. Its name was an amalgamation of Triumph and BSA. The purpose was to combine the best elements of each marque to give a superior bike to either.

Triumph Bonneville

The Triumph Bonneville is a standard motorcycle featuring a parallel-twin four-stroke engine and manufactured in three generations over three separate production runs.

Geoff Monty British motorcycle racer

Geoff Monty was an English professional motorcycle racer, constructor, rider-sponsor and retail dealer, initially based in Kingston on Thames and later – under the name Monty and Ward – Twickenham areas, near London, with a move to Edenbridge, Kent by 1968.

Norton-Villiers was a British motorcycle manufacturer formed in the 1960s following the collapse of AMC. With the general decline of the British motorcycle industry, under a British Government initiative it was later combined with the remnants of BSA Triumph to form Norton-Villiers-Triumph.

Doug Hele British motorcycle engineer

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 2 November 2001.

BSA Golden Flash

The BSA Golden Flash, commonly referred to as the Gold Flash, was a 646 cc (39.4 cu in) air-cooled parallel twin motorcycle designed by Bert Hopwood and produced by Birmingham Small Arms Company (BSA) at Small Heath, Birmingham. The Golden Flash was the first model in the BSA A10 series. It was available in black and chrome; but it was the distinctive golden paint scheme that gave The Golden Flash its name. Production continued until 1963, when it was superseded by the BSA A65 Star.

Norton Dominator

The Dominator is a twin cylinder motorcycle developed by Norton to compete against the Triumph Speed Twin. The original Dominator was designed in 1947 and 1948 by Bert Hopwood, who had been on the Speed Twin design team at Triumph. Available for sale from mid 1949, this design set the pattern for Norton twins for the next 30 years.

Norton Atlas

The Norton Atlas was a Norton motorcycle made between 1962 and 1968, until it was replaced by the Norton Commando.

Featherbed frame Motorcycle frame

The featherbed frame was a motorcycle frame invented by the McCandless brothers and offered to the British Norton motorcycle company to improve the performance of their racing motorcycles in 1950. It was considered revolutionary at the time, and the best handling frame that a racer could have. Later adopted for Norton production motorcycles, it was also widely used by builders of custom hybrids such as the Triton, becoming legendary and remaining influential to this day.

BSA Road Rocket

The BSA Road Rocket was a 1950s 646 cc (39.4 cu in) air-cooled parallel twin motorcycle designed by Bert Hopwood and produced by Birmingham Small Arms Company (BSA) at Small Heath, Birmingham. Developed from the A10 Golden Flash it was the first sports bike in the BSA A10 series. The A10 had a reputation for reliability but was struggling to compete against the Triumph engines and the Norton Featherbed frames. Advertised by BSA in 1956 as 'undoubtedly the world's greatest motor cycle' the Road Rocket was discontinued in 1958 when it was replaced by the BSA Super Rocket.


The BSA A7 was a 500cc motorcycle model range made by Birmingham Small Arms Company (BSA) at their factory in Armoury Road, Small Heath, Birmingham. The range was launched in 1946 using a 495 cc (30.2 cu in) long stroke engine. An improved 497 cc (30.3 cu in) version based on the BSA A10 engine was launched in 1950. The various A7 models continued in production with minor modifications until 1961/2 when they were superseded by the unit-construction A50 model.

Triumph Bonneville 790 British motorcycle

The Triumph Bonneville 790 cc is a British motorcycle that was designed and built in Hinckley, Leicestershire by Triumph Motorcycles Ltd between 2001 and 2007, when the engine size was increased to 865 cc.

Norton Isolastic frame

The isolastic frame, designated by Norton as GlideRide, used a system of engine-to-frame mountings incorporating rubber bushes to isolate the vibration of the vertical twin engine from the frame and rider. The isolastic frame was developed for use with the Commando inclined engine, whilst the Featherbed frame continued in production for the Mercury with a softer-specification 650 cc vertical-engine until 1970.

BSA A10 series Motorcycle

The BSA A10 series was a range of 646 cc (39.4 cu in) air-cooled parallel twin motorcycles designed by Bert Hopwood and produced by Birmingham Small Arms Company at Small Heath, Birmingham from 1950 to 1963. The series was succeeded by the A65 unit construction models.

Norton Model 7 Dominator

The Norton Model 7 Dominator was a 500 cc vertical twin motorcycle manufactured by the Norton Motorcycle Company from 1949 to 1955. It was the first of Norton's Dominator range of motorcycles. The engine was designed by Bert Hopwood and was a departure from Norton's previous practice of producing single-cylinder machines. The Model 7 was used in Japan as a police motorcycle.

Norton Model 88 Dominator

The Norton Model 88 Dominator, also originally known as the Dominator De Luxe was a 500 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company from 1952 to 1966. It was the first of Norton's motorcycles to use the featherbed frame, which established Norton's reputation of producing fine handling machines. The 88 used the Bert Hopwood designed engine that was first fitted to the Model 7 and was initially for export only. It became available on the home market in 1953. Norton were a small manufacturer at the time and without the economies of scale the model was expensive compared to other manufacturer's equivalent machines. The 88 retailed for 20% more than the contemporary Triumph Speed Twin and was dearer than the 650 cc Triumph Thunderbird.

Norton Model 99 Dominator

The Norton Model 99 Dominator was a 600 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company at their Bracebridge St, Birmingham factory from 1956 to 1962. The 99 was based on the 500 cc Model 88 Dominator with an enlarged engine. The model was superseded by the 650SS.

The Norton Manxman was a 650 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company at their Bracebridge St, Birmingham factory for export. It was first shown at the November 1960 Earls Court Motorcycle Show and listed by the American importer, Berliner, in their catalogue from 1961 to 1963. Berliner had asked for the model to be named Manxman although the twin had never been raced at the Isle of Man.


  1. Foale, Tony (2006). Motorcycle Handling and Chassis Design: The Art and Science. Tony Foale. ISBN   9788493328634.
  2. Walker, Alastair (2009). The Cafe Racer Phenomenon. Veloce Publishing Ltd. ISBN   9781845842642.
  3. Norvin technical section (retrieved 18 November 2007)