The BSA Gold Star is a

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

made by BSA from 1938 to 1963. They were 350 cc and 500 cc

single-cylinder A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery ( ...

four-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...

production motorcycles known for being among the fastest bikes of the 1950s. Being hand built and with many optional performance modifications available, each motorcycle came from the factory with documented

dynamometer A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed (RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the ...

test results, allowing the new owner to see the

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...

(bhp) produced. The Gold Star was almost continuously developed over its lifetime by BSA's engineers and riders, who improved its capabilities and increased output from its essentially simple

push-rod An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located be ...

petrol engine than had been thought possible. It was highly successful across almost all areas of motorcycle sport for well over a decade and is still regarded as a design icon of its era.

Origin

In 1937,

Wal Handley Walter Leslie Handley (5 April 1902 – 15 November 1941) born in Aston, Birmingham,
Kolumbus.fi Walter Leslie Han ...

lapped the

Brooklands Brooklands was a motor racing circuit and aerodrome built near Weybridge in Surrey, England, United Kingdom. It opened in 1907 and was the world's first purpose-built 'banked' motor racing circuit as well as one of Britain's first airfields, ...

circuit at over on a

BSA Empire Star The Empire Star was a standard motorcycle made by BSA at their factory in Small Heath, Birmingham. Named to commemorate the Silver Jubilee of King George V of the United Kingdom and advertised as ''The Masterpiece of the Industry'', the Empi ...

, and was awarded one of the traditional Gold Star badges. That inspired BSA to produce the BSA Gold Star. The first Gold Star was an M24 model. It had an all alloy bore and stroke,

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

, with a separate rocker box bolted to the aluminium head, pushrod valve actuation, an Elektron (magnesium alloy) gearbox with close ratio option, and a rigid frame made of light tubes devoid of

sidecar A sidecar is a one-wheeled device attached to the side of a motorcycle, scooter, or bicycle, making the whole a three-wheeled vehicle. A motorcycle with a sidecar is sometimes called a ''combination'', an ''outfit'', a ''rig'' or a ''hack''. ...

attachment lugs. This model continued up to the start of World War II. There were two variants of the M24; 1938, JM24 and 1939, KM24. Several modifications were made to the design during its lifespan. The 1939 KM model used a redesigned crank and crankcase with timing gears on fixed shafts, supported by a strong steel "outrigger" plate (a feature carried on throughout the Gold Star's entire production period.) The earlier JM model had cams that ran directly in the timing cover, with the potential for premature wear, hence the re-design. Power outputs were around 30bhp. The cast Elektron gearbox was dropped in 1939 to use the side-valve M20's cast aluminium shell but with close gear ratios as an option. Some KM's were used by the military at the start of WW2. Very few of either model were produced, with numbers in the low hundreds for each.

1948 ZB32GS introduced

After the war, in 1945-46, BSA had introduced the iron engine B31 and subsequent B33. In preparation for the 1949 model season, and to attract sporting buyers, the bore and stroke, all alloy 348 cc ZB32 type Gold Star was first shown at the

Earls Court Earl's Court is a district of Kensington in the Royal Borough of Kensington and Chelsea in West London, bordering the rail tracks of the West London line and District line that separate it from the ancient borough of Fulham to the west, the ...

motorcycle show at the end of 1948, with a very large list of optional components. Unlike the pre-war M24 engine the cylinder head was a strong one-piece casting, with the rockers incorporated into the unit. The all new spring frame had so-called

plunger A plunger, force cup, plumber's friend or plumber's helper is a tool used to clear blockages in drains and pipes. It consists of a rubber suction cup attached to a stick (''shaft'') usually made of wood or plastic. A different bellows-like des ...

suspension, half-way between the earlier rigid and later swingarm types. These used undamped springs mounted on shafts and forgings either side of the rear wheel spindle and although they were an improvement over a rigid frame for the average road rider, they came in time to be regarded by competition riders and racers as too heavy and poor handling. Once ordered the bike was assembled by hand, and the engine bench tested and not released unless an acceptable power output was achieved, which was around , depending on specification. They were lighter than the comparable cast-iron barrel and head B series single. They were almost immediately successful, winning the

Manx Grand Prix The Manx Grand Prix motorcycle races are held on the Isle of Man TT Course (or 'Snaefell Mountain Course, Mountain Circuit') every year for a two-week period, usually spanning the end of August and early September. New for 2022 is a period re ...

Clubman's 350 class from 1949 and remained so until 1956 when the class was discontinued. They could be specified in tourer,

trials In law, a trial is a coming together of parties to a dispute, to present information (in the form of evidence) in a tribunal, a formal setting with the authority to adjudicate claims or disputes. One form of tribunal is a court. The tribunal, w ...

ISDT The International Six Days Enduro (ISDE), formerly known as the International Six Days Trial (ISDT), is the oldest 'off-road' motorcycle event on the FIM Calendar. The ISDT was first held in 1913 at Carlisle, England. It has occurred annually, a ...

scrambles ''Scrambles'' is the fifth studio album by Bomb the Music Industry!, released digitally and physically on February 15th, 2009. The album was released a year and a half after Get Warmer, making it the longest gap between the release of two chrono ...

, racing or "Clubman's" trim. Racing models used the well established

Amal TT AMAL was a British engineering company servicing the motorcycle and other light-engineering motor industries between 1927 and 1993 All genuine bench-tested Gold Stars had the addition of "GS" after the year and range letters; thus ZB32GS, followed by the actual engine number. A standard YB32 or subsequent years competition machine was not a Gold Star as it did not have a bench-tested engine or the full "GS" engine number. In subsequent years BSA produced competition machines delineated with a stamped "A" to signify an aluminium engine. They were not bench-tested Gold Star engines, despite the physical similarities and use of some of the same parts.

1949 ZB32GS and ZB34GS

In 1949 the B32 Gold Star was in full production. The 499 cc B34 Gold Star was introduced, with a modified heavier

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

, stronger drive side crankcase, larger diameter drive-side main-shaft and a different design main bearing. The 350 cc continued as before. Spring

frames were most commonly used, along with a standard B type rigid option for trials competition use. In 1950 both received larger 8" front

brakes A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Background ...

. In late 1951 the 500 gained a new barrel and

Bert Hopwood Herbert Hopwood (1908 – 17 October 1996) was a British motorcycle designer. He was, at least, partly responsible for some of the most influential designs for the British motorcycle industry and worked for Ariel, Norton, BSA and Triumph. ...

design head with separate rocker box, and the 350 had a new barrel and head of that design the following year The earlier connecting rod was shortened by , which with other improvements gave a useful increase in power. This engine redesign initially used sand-cast heads and barrels, still designated as ZB. After engine number ZB32GS-6001 production moved to die castings which allowed a more accurate and cleaner finish.

1953 BB34GS and BB32GS

In 1953, a

swingarm A swingarm, or "swinging arm" (UK), originally known as a swing fork or pivoted fork, is a single or double sided mechanical device which attaches the rear wheel of a motorcycle to its body, allowing it to pivot vertically. The main component of ...

duplex (twin front downtube) frame was introduced, although rigid and plunger frames were still available, along with a much improved gearbox for the new frames, with a choice of gear ratios These frames and all later GS and pre-unit B series swingarm frames had a distinctive kink in the lower offside rail, to accommodate and protect the oil-pump casting on the lower timing-side crankcase. A small number of the early swingarm frames had a separate cast steel kink welded or brazed in place. Some modifications were also made to the general design so later frames are somewhat different from the BB type. In all later frames the frame rail was pressed out to form the kink. Some machines specified for lighter-weight competition use had no rear loops that normally held the pillion footrests. Due to the new frame a new larger and distinctive chrome plated fuel tank was introduced. The engines maintained the same die-cast barrel and head with separate rocker box design as with the late ZB models. The BB models remained in production for touring and trials competition use into 1954.

1954 CB34GS and CB32GS

The new CB engine was introduced, (subsequently known as the Big Fin engine), given deeper and squarer finning, a 5 bolt head, quite soon changed to 8 bolts, a stronger crankshaft, an even shorter connecting rod at , oval flywheels (500), improved valve gear with eccentric adjustment, and an

Amal GP AMAL was a British engineering company servicing the motorcycle and other light-engineering motor industries between 1927 and 1993 Power outputs were once again increased to around respectively.

1955 DB32GS and DB34GS

The DB Gold Star had an improved oil feed to the crankshaft, and finned front brakes. DB32 models had smaller exhaust valve than the CB32 and power increased slightly to over . Power outputs of the 499 cc engines were developed to about over the next few years. The Clubman cam and timing option included a special silencer. At the end of this year the BB and CB models were discontinued. The last batch of 350 cc DB32 machines left the factory in 1963.

1956 DBD34

The 500 cc DBD34 was introduced in 1956, with clip-on handlebars, the same big finned alloy engine with a newly designed head, 38 mm ( 1 1/2" ) bell-mouth Amal carburettor and swept-back exhaust. The DBD34 had a top speed.Wilson, Hugo. (1993) ''The Ultimate Motor-Cycle Book'' p.69 ''1960 BSA Gold Star DBD34''. Dorling Kindersley Accessed and added 2014-08-24 The Gold Star dominated the

Isle of Man ) , anthem = "O Land of Our Birth" , image = Isle of Man by Sentinel-2.jpg , image_map = Europe-Isle_of_Man.svg , mapsize = , map_alt = Location of the Isle of Man in Europe , map_caption = Location of the Isle of Man (green) in Europe ...

Clubmans TT that year. Later models had an ultra close-ratio gearbox (RRT2) with a very high first gear, enabling plus before changing up to second. Amongst the options available were a tachometer and a 190mm full width front brake that gave a larger lining area than the standard 8" single sided unit. A scrambles version was also offered. Many of the machines were exported to the USA where there was high demand for them. A series of special models were made for this lucrative market. Production ended in 1963.

Gold Star Daytona

In 1954, BSA wanted to win the prestigious United States

Daytona 200 The Daytona 200 is an annual motorcycle road racing competition held in early spring at the Daytona International Speedway in Daytona Beach, Florida. The race was founded in 1937 when it was sanctioned by the American Motorcyclist Associati ...

race. During the 1950s, the race was run partly on asphalt and partly on the beach at

Daytona Daytona refers to the city of Daytona Beach, Florida, or things named after it. Daytona may also refer to: Locations * Daytona Beach Shores, Florida * South Daytona, Florida * The Daytona Beach metropolitan area * Halifax area, also known as Da ...

. A team of works prepared Gold Stars and A7 Shooting Stars were entered. The race was won by a Shooting Star with a Gold Star in 3rd place. A replica of the works Gold Star was offered to the public. The specification included a rigid frame, which saved over the swinging-arm frame. Engine modifications included using a 350cc head, which had a better downdraught angle, machined to 500cc dimensions and fitted with a large inlet valve. The engine produced 44bhp. The model was also offered in subsequent years. Rigid framed machines became successful on the USA "Flat Track" scene in the hands of riders such as Dick Mann and tuners like CR Axtell. Special lightweight rigid frames such as the "Trackmaster" were also produced by American makers specifically for this purpose. A swinging arm version, known by the factory as "USA Short Circuit" was also produced in 1956 and 1957.

Gold Star Catalina

In 1956, Chuck Minert won the Catalina Grand Prix on a modified Gold Star. (The Catalina Grand Prix was a popular 100-mile race on the island of Santa Catalina off the coast of

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...

. In 1956 more than 1,000 bikes started the race.) Modifications included a larger fuel tank, an air scoop on the front brake and a 19" front wheel.

US west coast The West Coast of the United States, also known as the Pacific Coast, Pacific states, and the western seaboard, is the coastline along which the Western United States meets the North Pacific Ocean. The term typically refers to the contiguous U.S ...

BSA distributor, Hap Alzina, persuaded the factory to produce a replica named after the race. The Gold Star Catalina was manufactured from 1959 to 1963.

End of production

Towards the end the Gold Star was only offered in scrambles, or Clubmans trim. In 1963 Lucas ceased to produce the magneto used in the B series, and that line of singles was ended. The demise of the Lucas magneto was a prime reason that BSA and Triumph reconfigured their pre-unit-construction parallel twins into engines with integral gearboxes, simultaneously converting the ignition system from magneto to battery and coil. The Gold Star was not considered for progression to unit-construction, and instead the 250 cc

BSA C15 The BSA C15 was a 250 cc single-cylinder ohv motorcycle manufactured by the British company BSA from September 1958 until 1967, and was BSA's first four-stroke unit-construction bike. For most of that period, after the introduction of 'L ...

was developed (via the B40) into the 500 cc B50. Although the B50 never attained the kudos of the DBD34, a B50 fielded by Mead & Tomkinson once held the class lap record in the Production TT, as well as gaining a class 2nd at the 24-hour endurance races the Le Mans

Bol d'Or The Bol d’Or is a 24-hour endurance race for motorcycles, held annually in France. The riding of each bike is now shared by a team of three riders. History The Bol d’Or, first organized by Eugene Mauve, in 1922, was a race for motorcycles ...

and a class win at the

Montjuïc circuit The Montjuïc circuit is a former street circuit located on the Montjuïc mountain in Barcelona, Catalonia, Spain. The circuit was also the venue for the Spanish motorcycle Grand Prix from 1950 to 1968, and then hosted the event on even-numbered ...

Barcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second most populous municipality of Spain. With a population of 1.6 million within ci ...

. CCM used

BSA B50 The BSA B50 was a single-cylinder ohv motorcycle, produced by BSA at their factory in Small Heath, Birmingham. The last of the big capacity unit-construction singles from the Birmingham Small Arms company, it had an alloy engine with a bore ...

bottom ends in their early specials.

New ownership

In 2021, the Mahindra Group, the new owners of the BSA marque, announced the return of the Gold Star into production. The first units were shipped to the UK from their manufacturing base in India in October 2022 and expected to go on sale shortly thereafter through UK dealers.

Isle of Man TT wins

BSA Gold Stars won the following

Isle of Man TT The Isle of Man TT or Tourist Trophy races are an annual motorcycle racing event run on the Isle of Man in May/June of most years since its inaugural race in 1907. The event is often called one of the most dangerous racing events in the world ...

races.

Notes

Sources

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