BSA Unit - construction singles

Further information: BSA Unit construction singles
BSA C15
The BSA C15 was a 250 cc single-cylinder ohv motorcycle manufactured by the British company BSA between 1958 and 1967, and was BSA's first four-stroke unit-construction bike. At that period, a 250cc was the largest capacity bike that a learner could ride on L-plates in the United Kingdom, the C15 was attractive to riders with provisional licences. An off-road version, the C15T Trials, gave riders access to the sport of motorcycle trials.
Producing only 15 bhp (11 kW), the C15's lack of power and issues with reliability[citation needed] meant that it was hard for the BSA to compete with the more sophisticated 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 Cub, 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.
Originally, the distributor sprouted from above the R/H side of the gearbox; but in 1965 the distributor was moved to the right side of the engine.
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.

Models:
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 special camshaft, and was specially tuned for off-road trials use. The C15T proved to be competitive at club and national levels, and it remained unchanged in the BSA range until 1965.
BSA C15T Trials Cat
In 1964 and 1965 the overbored 500 cc BSA C15T 'Trials Cat' ridden by Jeff Smith won the 500 cc World Moto-Cross Championship. This success led to the development of the 441 cc BSA Victor Scrambler.
BSA C15S
The BSA C15S was the motorcross competition version of the 250 cc Star produced between 1959 and 1965. As with the trials version, the C15S saved the weight of a battery through an 'energy transfer' electrical system which was notoriously unreliable. The problem was that the timing and points gap required far too much careful setting for a rugged competition motorcycle. The scrambler C15 was unsilenced and had special tyres and strengthened fork springs with rubber fork gaiters to protect the seals.
BSA C15 Starfire
The BSA C15 Starfire Roadster was produced between 1968 and 1970 with chrome mudguards and tank side panels.
BSA C15P
The BSA C15P was a police model produced between 1963 and 1967.

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.

History:
In 1965 an off road motocross BSA B44 named the ‘’Victor’’ was launched at the Earls Court Show. Developed from scramblers used by Jeff Smith to win the 1964 and 1965 500cc World Championships, the model proved so popular that Victor Grand Prix and Victor Enduro models were developed, as well as a road-going version, the 1967 Victor Roadster. The Victor Grand Prix Scrambler had a displacement of 441cc, and the Enduro model was known as the 441 Victor in the United States. BSA began offering a road version, the B44VR Victor Roadster, in 1967. When that model was exported to U.S. dealers in 1968, the name was changed to the B44SS Shooting Star. The B44VS Victor Special was also successfully exported to the US between 1968 and 1970.
In 1968 the B44 became BSA's top export model. The good availability of spare parts and the relative simplicity of the single-cylinder engine meant that the surviving examples are easily restored to as-new condition.
On the original 1969 footage of the Woodstock Concert, producer Michael Lang is seen riding a BSA Victor motorcycle across the pastures.
Features:
The Victor Roadster (or Shooting Star, a name borrowed from a 1950s-era BSA twin), had a top speed of around 90 mph (the same speed as the 250 BSA Barracuda - a.k.a. B25 Starfire) and was designed with a focus on easy riding over speed. It came with high-rise handlebars and reflectors both beneath the tank and on either side of the taillight. In 1969 the Shooting Star was updated with a steel gas tank and a twin-leading-shoe brake.
Victors had impressive power-to-weight ratios that made them ideal for hill climbs. The 11:1 compression ratio required a compression release lever for kick starting.

All Type Of Construction Single Unit BSA Motorcycles

Model	Engine	First year	Last year	Notes
C15	250 cc	1958	1967
C15T	250 cc	1959	1965
C15S	250 cc	1959	1965
SS80	250 cc	1961	1966	High-performance version of C15
B40	350 cc	1960	1965
SS90	350 cc	1962	1965	High-performance version of B40
B44 GP	441 cc	1965	1967	(Chrome lined barrel, a two-piece exhaust where the rear section was a tuned megaphone rather than a silencer, plastic bung for a fuel cap, the first unit single with oil-bearing frame differing from later oil bearing frames as it used super strong/lightweight Reynolds 531 tubing aimed at competition use)
B44 VE "Victor Enduro"	441 cc	1966	1970
B44 "Victor Roadster"	441 cc	1966	1970	From 1968 to 1970, called "441 Shooting Star"
B40WD	350 cc	1967	1967	2,000 for Ministry of Defence
C25 Barracuda	250 cc	1967	1967	Short-lived high-compression model
B25 Starfire	250 cc	1968	1970	Similar to the C25 but with slightly reduced compression
B25FS Fleetstar	250 cc	1968	1971	Made with low-compression engine to increase reliability and fuel economy for police and civilian fleet use
B25SS Shooting Star	250 cc	1971	1971
B25ST	250 cc	1971	1971
B50SS Gold Star	500 cc	1971	1972
B50T Trail	500 cc	1971	1972
B50MX Motorcross	500 cc	1971	1972	In 1974 sold as Triumph TR5MX for US