BSA Bantam
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The Bantam was a two-stroke unit construction motorcycle produced by BSA from 1948 to 1971. Over 250,000 were sold - some estimates place the number closer to half a million.
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[edit] History
The original design of the Bantam came from a German design, the DKW RT 125 (de) that was received as part of war reparations. This fact was not made widely known until long after the demise of BSA and for many years the Bantam was thought by many to be a 'truly British' lightweight motorcycle despite the original DKW design being taken up by two other manufacturers - Harley Davidson for one. The BSA designers converted the design to meet British conventions - creating a mirror image - and into Imperial measurements for manufacture in Birmingham. This original Bantam, the D1, would continue to be produced for several years. Subsequent members of the Bantam range differed markedly in frame but their engine was a development of the original.
The first Bantams were available only in all-over "mist green", and sold for £60 plus tax. Later models changed distinctly from the original; over the years it gained improved suspension including a rear swinging arm, electrics and the engine size increased from 125 to 175 cc.
[edit] Engine
The engine is a unit construction (engine and gearbox of one piece) single cylinder 2 stroke. The barrel is cast iron while the head is alloy. The gearbox was initially three speeds, later versions went to four, fed through a "wet" clutch. Ignition was of two types a Lucas battery powered coil in earlier machines or a magneto by Wipac. The magneto was on a composite assembly sitting within the flywheel with its magnet inserts; windings gave power either directly to the lights (with a dry cell for when the engine was stopped) or through a rectifier into a lead acid battery. The early D1s had a flattened fish tail style exhaust. This was replaced with a more convention round tube exhaust which ran at a higher level on trials and off-road models such as the "Bushman"
[edit] Models
Main variants listed, most models were also available in competition form or with extra refinements. Nominal engine sizes given. BSA used the letter system for their range of motorcycles.
[edit] D1
- 1948-1963
- 125cc, 4 bhp single-cylinder engine.
- Three gears, foot operated
- Top speed 45 mph
- Telescopic spring front suspension, rigid or plunger rear suspension.
- 19 inch wheels with 5 inch brakes front and rear
[edit] BD1
same as D1 exept:
- black
- chrome tank strips
- leg guards
- limited edition
- chrome wheels
[edit] D3
- "Major"
- 1954-1957
- 150cc, 5.3 bhp
- Telescopic front suspension, plunger rear suspension (changed to swing arm from 1956)
- The D3 Major represented the next step in development of the Bantam, although the D1 would be produced for many years to come. With the increased power from the larger engine a twin seat was fitted; this had been an option on the D1 which otherwise had a parcel carrier behind the sprung "saddle" seat.
[edit] D5
- "Super"
- 1958
- 175cc, 7.4 bhp
- Telescopic front suspension, swinging arm rear.
[edit] D7
- 1959-1966
- 175cc, 7.4 bhp
- Telescopic front suspension, swinging arm rear.
[edit] D10
- 1966-1967
- 175cc, 10 bhp
- Telescopic front suspension, swinging arm rear.
[edit] D14/4
- 1968-1969
- 175cc, 12.6 bhp
- Four speed gearbox
- Telescopic front suspension, swinging arm rear
[edit] D175
- 1969-1971
Also known as B175. A minor reworking of the D14/4. The spark plug sits in line with the cylinder head and the front forks are stronger.
- Bushman model available
