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BSA Bantam - History.

1948

The BSA D1 125cc. engine unit began production in 1948 for export only. The design had been taken from the German firm DKW as part of the war reperations. The engine proved itself, and with small motorcycles becomming ever more popular in Britain, BSA decided to build a complete motorcycle around the D1 engine. In October 1948 the BSA Bantam was released, the bike had telescopic forks, a rigid rear end, direct electrics, shovel front-mudguard and fishtail silencer. She had three gears, a maximum speed of around 50 mph, good brakes for the time and fuel economy of over 100 miles to a gallon of fuel, interesting when compared to the lower effeciency of similar modern bikes. The lighting was supplied by a 27 Watt Wico-Pacy Geni-mag generator, direct electrics meant no battery, and that the engine would have to be running for the main lights to work. A small battery was included to operate a smaller pilot bulb in the headlamp when parked. Ignition was supplied from the same unit, in the form of a simple Magneto, this also eliminated the need for a battery. Although the bike had its fair share of faults, it sold well and became a common sight on the Roads of Britain. One thing BSA had not expected, was its introduction into competition events. Owners modified their bantams, fitting non-standard sprockets and wider handlebars. The Bantam was one of the first bikes to be used in this way, trials before that had been more professional events run by substantially larger bikes.

D1 advert by BSA. "Where do I sit?"

1949

1949 Rigid belonging to Tony in Australia.

1950

Some of these deficiencies in the design were tackled in 1950. The D1 was now offered with plunger rear-springing, a welcome relief to the backsides of Bantam owners, this was a major change to the frame, and altered many of the asscoiated parts. A newer non-valenced mudguard was fitted, as was a shorter stem rear carrier and mudguard stays. The use of bantams in the competition events had not gone unnoticed by BSA, and they released both rigid and plunger bikes as specific competition models. Many changes were made to these models, the most noticeable fitting the silencer in an upswept position. The cylinder head had a second hole for a decompressor to be fitted and a folding-kickstart. The 27 Watt Geni-Mag was replaced by two options, a wico-pacy Series 55 30 Watt generator, and a Lucas IA45 45 Watt Alternator. The Series 55 was the next development of the Geni-mag, more powerful, more reliable, while the Lucas was completely new. The system incorporated a external ignition coil, powered by a battery. Being a DC system it also used a Selinium rectifier and was electrically much more complex than the Series 55. Rubber Gaiters were added to the front forks to prevent debris from interfering with the motion of the forks. The exhaust pipe was routed above the footrests, giving an overall more pleasant line to the bike.

1950 Plunger D1 Wico-Pacy electrics, fitted with optional crash bars, looks like they have too.

1951

1951 D1 rigid competition with Wipac AC electrics.

1952

Wipac Light switch moved from handlebars to top of headlamp unit.

1952 D1 plunger with Lucas Battery/coil Electrics.

1953

The shovel front mudguard was never the pinnacle of style, and was replaced by a much more sedate unvalenced unit, complete with the then standard "pedestrian slicer" front numberplate. Evidently the Bantam was being used more for commuting because a dual-seat option was offered, naturally rear footrest lugs were added to the frame. Chrome also hit the scene, with plated wheel rims and fuel tank seam covers. The Black Bantam also came into being, offering another paint than the standard mist- grey.

1953 D1. Not all Bantams look as good as this.

1954

The DC Geni-Mag Series 55 replaced the Lucas for the battery models, elimating the remote coil for a bit. Post 1954 Bikes are immediately recgonisable by their larger finned cylinder barrels and heads, improving cooling. The rather flimsy Headlamp bracket was replaced by a steel pressing gusset, improving the look of the bike if rendering it a little more difficult to get at. There was another reason for enlargening the cylinder head and barrel. The cylinder was able to be safely bored out, increasing capacity to 150cc. This change was listed as another model, the D3 Bantam Major. Asides from the boring-out little changed, stronger front forks were fitted to the D3 as was a beefier front brake. The bike was painted a pleasant grey colour, which is the easiest way to spot a D3. The larger capacity rocketed power from 4 to 4.9 horse power, sacrificing a little economy in the process.

D1 showing off the girlfriend- friendly dual seat option.

1955

Plunger frame competition models dropped.

1955 D3 competition plunger.

1956

The D3's suspension was replaced by a more modern swing-arm type, while the D1 continued to use plunger. Rigid suspension production was stopped, as was all the range's competition models. Swing arm models had a longer silencer and shorter exhaust, necessiated by no longer being able to support the end of the silencer by the frame. Pratically the whole rear end was new, a dual seat was now standard for the D3.

1956 Swinging Arm D3.

1957

1957 Swinging Arm D3.

1958

This year the 150 c.c. D3 was replaced by the 175 c.c. D5. The 1954 cylinder wasn't big enough for this bore-out, so a new one was produced, the engine now produced a whopping 7.4 horse-power! It is recognisable by the slanted monobloc carburetter protruding from its rear. A larger 2 gallon tank was bolted to the frame, as the D5 could otherwise not hope to compete with the range of the D1. Asides from other minor engine alterations, the D5 was identical to the D3, sporting the same hap-hazard rear framework. This model was built only in this year, making it one of the rarest and most valuable of Bantams.

A 1958 D5 in New Zealand.

1959

The D3 was superceeded by the same capacity D7 Super. The redesign mainly considered the cycle parts, the swing-arm was all new, with cleaner lines and fewer parts, the front forks were new, and smaller wheels were added. The main visual change to the engine was the addition of an outer cover to the nearside, enclosing the generator. Overall the design has much smoother lines, a design trait typical of the 60s, fortunately the Bantam was never to succumb to the "bath-tub".

1959 D7.

1960

Late D1s can be recognised by a black frame and forks, which was introduced this year, the colouring remained on the fuel tank, mudguards etc.

1960 D7 showing the extra engine side-cover.

1961

1961 D7.

1962

The use of smaller wheels in 1959 had the effect of lowering the effective gearing, great for trials, but not so hot for fast running. The gears ratios were altered to combat this problem, giving the engine an easier time.

1962 D7.

1963

1963 marked the end for the D1, 15 years after it's introduction.

Late D1 (I think the wheel rims should be chrome).

1964

The civilian D1 may have ended production the previous year, but the GPO model seems to have been produced into 1965. This is a shady area at best so please don't quote me one it.
D7 de luxe released. All battery models fitted with the 2-switch electric system.

1965

1965 D7 in lovely condition.

1966

'66 seems to be another year of a change in direction. The de luxe remained, but was supplemented with the cheaper D7 silver. This is more common of modern practice, to merely re-package the same thing in a different finish and charge you more for the privilege, saving the company producing two sets of engines etc. The models are distinctive for they were fitted with a new 1¾ gallon tank, with cut-aways for one's knees. Apart from the obvious decrease in range, this had the effect of making the Bantam look slightly lanky, when it was never a particularly muscular bike in the first place. Also the 50's "fishtail" dissapeared from the end of the silencer. 
Then came the second re-think, the D10
The capacity of the engine had got as big as it would go, so the only way to increase power was to increase the compression ratio. It was increased from 7.4 to 8.65, and the addition of a larger concentric carburetter increased power to 10 h.p. A new Wico-Pacy alternator, the 1G.1768, replaced the old series 55, after 16 years of service. This change of generator caused the points to be evicted to the other side of the engine. The 3 speed Supreme (De Luxe) and Silver models remained, but were complemented by two further models, the 4-Speed Bushman and Sports models. Apart from the obvious internal changes to the crankcase to accomodate the new gearbox assembly, it is almost impossible to tell a 4-speed engine without looking at the engine number. Both the latter models had high-level exhaust pipes, and other quite major changes to the cycle parts. Only the Bushman retained the direct lighting, with all other models utilising a coil driven battery lighting system.

1966 D7 De Luxe.

1967

1967 D10.

1968

BSA was far from finished with altering the Bantam, and introduced the D14 range. Production began late in 1967, and early engine prefixes were listed as D13, though this was never a model. BSA dropped the Silver leaving the other three models to attract the market. The Supreme was now also fitted with the 4-speed box, ending the Bantam's relationship with 3 speeds. The old exhaust pipe bore was found too restrictive for the new tune up, so a larger one was fitted. On the ever diminishing market for British motorcycles, BSA sought to make the Bantam yet more powerful. They increased the compression ratio to 10:1, resulting in a power increase to 13 h.p. The bike would now shift along at the best part of 70 m.p.h, the market had changed from wanting the fuel-efficient three speed D1, to the speedy D14/4. Asides from the diminished fuel efficiency, the high compression ratio made the bike notorious for difficult starting, as is normal with high performance engines. The Supreme and Sports models changed the style of air filter, but the Bushman kept the pretty D10 pancake type. The D14 was another one year only model, the D13 prefixed engines and frames are therefore probably rarer than the D5s.

1968 D14/4 Supreme.

1969

For one reason or another, the D14 became the D175, the final Bantam model. The Sports model, in my opinion the best looking of the swing-arms was dropped, leaving the Supreme and Bushman to stand it alone. The D175 is often referred to as the B175, but to me it was always part of the "D" group. The most striking difference is the axially-mounted spark-plug, this would be a welcome relief for anyone who has ever tried to measure TDC on a Bantam!

1969 D175 Bantam.

1970

Last Model of Bantam.

1971

This was the last year in which the Bantam was built, BSA was going under, along with all the other British motorcycling firms due to the Japenese invasion of the '60s. The Japenese bikes offered less engine life, slower top speeds, less fuel efficiency. They included indicators and every mod con that was going, and they were most importantly cheaper. This was probably the single most factor that caused the revolution, the change in attitudes towards manufacturing. The British bikes were built to last forever, the Japenese bikes were not. From a classic owners point of view in latter days however, that is a godsend. The Bantam is easy to work on, most parts are able to be simply replaced by the lay-man, requiring little specialist skill save for wheel building and cylinder boring. Apart from being the most numerous of classic motorcycles, the long lifetime of the model (23 years), its simplicity and general good looks make it the epitomy of the classic British motorcycle.

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