Triumph Bonneville 790
Encyclopedia
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.
Motorcycle Show in September 2000, with a 790 cc, 360-degree crank, parallel-twin
engine. Triumph's development team had originally designed a prototype they called the 9O8MD project in April 1997, an 'entry-level' medium displacement motorcycle for the export market. Market research indicated that Triumph's heritage was an important factor for overseas buyers, so Export Manager Ross Clifford decided to develop a parallel engine layout that could combine the latest technology with classic engine architecture. By the Summer of 1997 the concept had been agreed and the chassis and engine design teams began development work. The styling of the new bike had to link the heritage look to a modern handling frame. The team began with a fully restored 1969 Bonneville T120
and worked on the design throughout 1998. By August 1998, the first styling review of a full size three-dimensional model was completed by sales and marketing as well as engineering departments. The first 'Bonneville' engine was tested on 15 December 1998. The prototype engines were run for extended periods of time before committing to tooling production. By the end of 1998, the chassis team had completed their work on the styling prototype. In March 1999, the new engine was run in the prototype chassis for the first time and full scale road testing began, with the first six development bikes are built in July 1999. Four were mainly used for engine testing and the remaining two for chassis development work. By September 1999, the final review of the production Bonneville's styling and specification was completed by Triumph's sales and marketing teams and final testing was completed in July 2000, well in time for the dealership launch.
of 750 cc and even the original 650 cc were considered before 790 cc was chosen. The 86 mm bore size worked well with the four-valves per cylinder layout, while the 68 mm stroke allowed a long conrod that helps to minimise secondary vibration, although Triumph engineers also altered the bar weights to restore a little 'character' vibration. Designer David Stride was able to add details that retained the look of the original, such as a finned cylinder and dummy pushrod tube (which functions as a cylinder head oil breather) and internal oil lines to create a clean appearance. As well as the desired low and midrange performance, the engine is capable of 115 mph (185.1 km/h) and produces a respectable peak power output of 61 bhp @ 7400 rpm, with maximum torque of 44 ft.lbf @ 3500 rpm, with 90% of the engine's torque output available from 2750 rpm all the way to the rev limit
. The engine was air-cooled like the original, but had twin overhead camshafts instead of the old model's pushrod valve operation. A frame mounted oil cooler ensured consistent running temperatures and camshaft drive is by chain between the cylinders and incorporates an idler gear that allowed the cylinder head to be kept very compact.
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 in Hinckley
Hinckley
Hinckley is a town in southwest Leicestershire, England. It has a population of 43,246 . It is administered by Hinckley and Bosworth Borough Council...
, Leicestershire
Leicestershire
Leicestershire is a landlocked county in the English Midlands. It takes its name from the heavily populated City of Leicester, traditionally its administrative centre, although the City of Leicester unitary authority is today administered separately from the rest of Leicestershire...
by Triumph Motorcycles Ltd
Triumph Motorcycles Ltd
Triumph Motorcycles Ltd is the largest surviving British motorcycle manufacturer, which was established in 1984 by John Bloor after the original manufacturer Triumph Engineering went into receivership...
between 2001 and 2007, when the engine size was increased to 865 cc.
Development
Triumph launched the first new Bonneville for 15 years at the MunichMunich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...
Motorcycle Show in September 2000, with a 790 cc, 360-degree crank, parallel-twin
Straight-two
A straight-two engine, is a two-cylinder piston engine that has its cylinders arranged side by side....
engine. Triumph's development team had originally designed a prototype they called the 9O8MD project in April 1997, an 'entry-level' medium displacement motorcycle for the export market. Market research indicated that Triumph's heritage was an important factor for overseas buyers, so Export Manager Ross Clifford decided to develop a parallel engine layout that could combine the latest technology with classic engine architecture. By the Summer of 1997 the concept had been agreed and the chassis and engine design teams began development work. The styling of the new bike had to link the heritage look to a modern handling frame. The team began with a fully restored 1969 Bonneville T120
Triumph Bonneville T120
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 .-Development:...
and worked on the design throughout 1998. By August 1998, the first styling review of a full size three-dimensional model was completed by sales and marketing as well as engineering departments. The first 'Bonneville' engine was tested on 15 December 1998. The prototype engines were run for extended periods of time before committing to tooling production. By the end of 1998, the chassis team had completed their work on the styling prototype. In March 1999, the new engine was run in the prototype chassis for the first time and full scale road testing began, with the first six development bikes are built in July 1999. Four were mainly used for engine testing and the remaining two for chassis development work. By September 1999, the final review of the production Bonneville's styling and specification was completed by Triumph's sales and marketing teams and final testing was completed in July 2000, well in time for the dealership launch.
Engine design
'Traditional' engine capacitiesEngine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...
of 750 cc and even the original 650 cc were considered before 790 cc was chosen. The 86 mm bore size worked well with the four-valves per cylinder layout, while the 68 mm stroke allowed a long conrod that helps to minimise secondary vibration, although Triumph engineers also altered the bar weights to restore a little 'character' vibration. Designer David Stride was able to add details that retained the look of the original, such as a finned cylinder and dummy pushrod tube (which functions as a cylinder head oil breather) and internal oil lines to create a clean appearance. As well as the desired low and midrange performance, the engine is capable of 115 mph (185.1 km/h) and produces a respectable peak power output of 61 bhp @ 7400 rpm, with maximum torque of 44 ft.lbf @ 3500 rpm, with 90% of the engine's torque output available from 2750 rpm all the way to the rev limit
Redline
Redline refers to the maximum engine speed at which an internal combustion engine or traction motor and its components are designed to operate without causing damage to the components themselves or other parts of the engine...
. The engine was air-cooled like the original, but had twin overhead camshafts instead of the old model's pushrod valve operation. A frame mounted oil cooler ensured consistent running temperatures and camshaft drive is by chain between the cylinders and incorporates an idler gear that allowed the cylinder head to be kept very compact.