BSA C15
Encyclopedia
The BSA C15 was the first four-stroke unit construction
motorcycle
produced by the British company BSA
and manufactured between 1958 and 1967. At the time, the C15 was the largest capacity bike that a learner could ride on L-plate
s in the United Kingdom. The C15T Trials version also made the sport of motorcycle trials
accessible to a much wider range of riders but the lack of power and issues with reliability meant that BSA could not compete against emerging Japanese motorcycles such as the Honda C71 and CB72 which began arriving in the UK in the 1960s.
, itself coming from the 150cc Terrier. Edward Turner
became head of the BSA automotive division and in 1958 BSA introduced the concept of unit construction, where the engine and gearbox were combined in one piece rather than as separate components. The BSA C15 'Star' was the first unit construction model and proved more reliable and economical than its predecessor, the pre-unit BSA C11
.
The engine had an iron barrel and alloy head with overhead valves operated by pushrods which ran in a separate tube to fully enclosed rockers. The camshaft was geared directly to the crankshaft which had skew gears driving a shaft with the points at the top and the oil pump at the bottom. The alternator was to the left and the primary drive was via a duplex chain to a multi plate clutch. The four speed gearbox was at the rear of the vertically split crankcase. The frame was single loop with twin rails under the engine and pivoted fork rear suspension, and both wheels were 17 inch with full width cast iron hubs. An oil tank was under the seat on the right matched by a toolbox on the left. Between them was an ignition switch panel hiding the battery. The headlamp was fitted in a nacelle which also housed the instruments and switches as was fashionable at the time. Deeply valanced mudguards were fitted to the standard model, making it look heavier than it actually was.
The C15 also had a completely redesigned frame and the 250 cc C15 engine also exploited an advantage of being the biggest capacity motorcycle a learner rider in the UK could use before passing a motorcycle driving test.
The BSA C15 did, however, require careful maintenance and as well as oil leaks and electrical faults there were problems with the gearbox, failures of the valve gear, weak big-end and problems with the adjustment of the clutch. In 1965 the distributor was moved to the right on the whole range of BSA motorcycles.
During 1967 the 250 cc C15 was replaced by the BSA B25 'Starfire' and BSA C25 'Barracuda' models, which had a quickly detachable rear wheel and 12 volt lights. The engine was also increased in capacity to 441cc develop the BSA B44 Shooting Star
and the BSA Victor Special.
won the 500 cc World Moto-Cross Championship. This success led to the development of the 441 cc BSA Victor Scrambler.
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...
motorcycle
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...
produced by the British company BSA
Birmingham Small Arms Company
This article is not about Gamo subsidiary BSA Guns Limited of Armoury Road, Small Heath, Birmingham B11 2PP or BSA Company or its successors....
and manufactured between 1958 and 1967. At the time, the C15 was the largest capacity bike that a learner could ride on L-plate
L-plate
An L-plate is a square plate bearing a sans-serif letter L, for learner, which must be affixed to the front and back of a vehicle in many countries if its driver is a learner under instruction, or a motorcycle rider with provisional entitlement to ride restricted motorcycles.- Australia :In...
s in the United Kingdom. The C15T Trials version also made the sport of motorcycle trials
Motorcycle trials
Motorcycle trials, also termed observed trials, is a non-speed event on specialized motorcycles. The sport is most popular in the United Kingdom and Spain, though there are participants around the globe....
accessible to a much wider range of riders but the lack of power and issues with reliability meant that BSA could not compete against emerging Japanese motorcycles such as the Honda C71 and CB72 which began arriving in the UK in the 1960s.
Development
BSA acquired the Triumph marque at the start in 1936, and the BSA C15 250 cc four stroke was derived from the 200 cc Triumph Tiger CubTriumph Tiger Cub
The Triumph Tiger Cub is British motorcycle made by Triumph Motorcycles at their Meriden factory. Designed by Edward Turner and launched at the Earls Court show in November 1953 the Tiger Cub competed well against the other small capacity motorcycles of the time such as Villiers...
, itself coming from the 150cc Terrier. Edward Turner
Edward 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....
became head of the BSA automotive division and in 1958 BSA introduced the concept of unit construction, where the engine and gearbox were combined in one piece rather than as separate components. The BSA C15 'Star' was the first unit construction model and proved more reliable and economical than its predecessor, the pre-unit BSA C11
BSA C11
The BSA C11 is a British motorcycle manufactured by Birmingham Small Arms Company at their factory in Armoury Road, Small Heath, Birmingham, between 1939 and 1956. Actor Steve McQueen owned a 1951 BSA C11.-Development:...
.
The engine had an iron barrel and alloy head with overhead valves operated by pushrods which ran in a separate tube to fully enclosed rockers. The camshaft was geared directly to the crankshaft which had skew gears driving a shaft with the points at the top and the oil pump at the bottom. The alternator was to the left and the primary drive was via a duplex chain to a multi plate clutch. The four speed gearbox was at the rear of the vertically split crankcase. The frame was single loop with twin rails under the engine and pivoted fork rear suspension, and both wheels were 17 inch with full width cast iron hubs. An oil tank was under the seat on the right matched by a toolbox on the left. Between them was an ignition switch panel hiding the battery. The headlamp was fitted in a nacelle which also housed the instruments and switches as was fashionable at the time. Deeply valanced mudguards were fitted to the standard model, making it look heavier than it actually was.
The C15 also had a completely redesigned frame and the 250 cc C15 engine also exploited an advantage of being the biggest capacity motorcycle a learner rider in the UK could use before passing a motorcycle driving test.
The BSA C15 did, however, require careful maintenance and as well as oil leaks and electrical faults there were problems with the gearbox, failures of the valve gear, weak big-end and problems with the adjustment of the clutch. In 1965 the distributor was moved to the right on the whole range of BSA motorcycles.
During 1967 the 250 cc C15 was replaced by the BSA B25 'Starfire' and BSA C25 'Barracuda' models, which had a quickly detachable rear wheel and 12 volt lights. The engine was also increased in capacity to 441cc develop the BSA B44 Shooting Star
BSA B44 Shooting Star
The BSA B44 Shooting Star was a motorcycle made by BSA at their factory in Small Heath, Birmingham. Similar to the BSA C15 and sharing many of the same parts, the B44 had an uprated chassis....
and the BSA Victor Special.
BSA C15 'Sportsman' (SS80)
In 1961 the 'Super Sports' model (SS80) or C15 Sportsman joined the range, with a tuned engine, roller big-ends and lower handlebars. A faster 350 cc version, the BSA B40 was also added to the range but was not a big seller to the general public, as it was too big for learners and too small for those who had passed their motorcycle test - but it was ideal for military use and was popular with the British Armed Forces.BSA C15G
The BSA C15G was produced from 1966 to 1967 and was the last version of the C15 engine with the ball bearing timing side main bearing, roller drive side and strengthened crankcases, larger oil pump and needle roller gearbox layshaft bearings.BSA C15T
The BSA C15T was a trials version with a higher clearance frame fitted with a reinforced plate, special gear ratios suited to off-road use and a high level exhaust pipe. A special tank and optional lighting allowed it to be converted for legal road use. The all alloy engine had a number of modifications, including a special camshaft, and was specially tuned for off-road trials use, so proved to be competitive at club and national levels, so featured in the BSA range until 1965 unchanged.BSA C15T Trials Cat
In 1964 and 1965 the overbored 500 cc BSA C15T 'Trials Cat' ridden by Jeff SmithJeff Smith
Jeff Smith may refer to:*Jeff Smith , coach in the Minnesota Twins' organization*Jeff Smith , councillor in Manchester*Jeff Smith , creator of the comic book Bone...
won the 500 cc World Moto-Cross Championship. This success led to the development of the 441 cc BSA Victor Scrambler.