{{short description|Motorcycle}} {{Use dmy dates|date=April 2022}} {{Infobox motorcycle | name = BSA A10 series | image = frameless | alt = | caption = Swinging arm BSA Golden Flash | aka = | manufacturer = BSA | parent_company = | production = 1950 - 1963 | assembly = Small Heath, Birmingham, UK | predecessor = None | successor = BSA A65 | class = | engine = {{Convert|646|cc|abbr=on}} air cooled twin | bore_stroke = {{convert|70|x|84|mm|abbr=on}}<ref name="classic-british-motorcyclesA10" /> | compression = | top_speed = | power = | torque = | ignition = Magneto | transmission = 4 speed chain drive | frame = Rigid<br />Plunger<br />Swinging Arm | suspension = Telescopic fork (front) | brakes = Drum brakes | tires = | rake_trail = | wheelbase = | length = | width = | height = | seat_height = | dry_weight = | wet_weight = | fuel_capacity = | oil_capacity = | fuel_consumption = | turning_radius = | range = | related = | sp = | footnotes = }} The '''BSA A10 series''' was a range of {{Convert|646|cc|abbr=on}} air-cooled parallel twin motorcycles designed by Bert Hopwood and produced by Birmingham Small Arms Company at Small Heath, Birmingham from 1950 to 1963. The series was succeeded by the A65 unit construction models.
==Background== BSA, then the largest UK motorcycle manufacturer, was falling behind in the parallel-twin race after the introduction of the 650cc Triumph Thunderbird. Although BSA had a 500cc parallel-twin, the BSA A7, they needed to develop a 650 to remain competitive.
Bert Hopwood served an apprenticeship under designer Val Page at Ariel. In 1936, Hopwood moved to Triumph, where he worked under Edward Turner to develop the 1937 Triumph Speed Twin. The innovative Speed Twin became the exemplar of the parallel twin engine layout for British motorcycles in the 1950s and 1960s. In April 1947 Hopwood joined Norton to design the Norton Dominator engine.
In May 1948, the factory enticed Hopwood after only a year at Norton,<ref name="Classicbike">{{cite web|url=http://www.classicbike.co.uk/pdf/506/197882.pdf |title=Norton Dominator |access-date=2008-12-20 |url-status=dead |archive-url=https://web.archive.org/web/20110728093000/http://www.classicbike.co.uk/pdf/506/197882.pdf |archive-date=28 July 2011 }}</ref> and he was commissioned to create a competitive BSA 650cc parallel-twin.<ref>{{cite web|url=http://www.bsaoc.demon.co.uk/earlya7.htm |title=The BSA Owners' Club Library archives |access-date=2008-12-20 |url-status=dead |archive-url=https://web.archive.org/web/20080611181957/http://www.bsaoc.demon.co.uk/earlya7.htm |archive-date=11 June 2008 }}</ref><ref name="hagerty.">{{cite web |title=1954 bsa a10sf super flash Values - Hagerty Valuation Tool® |url=https://www.hagerty.com/apps/valuationtools/1954-bsa-a10sf_super_flash |website=www.hagerty.com |access-date=9 July 2018}}</ref>
==Development== ===Engine=== thumb|250px|A10 engine (1958 Golden Flash) Launched in October 1949, Hopwood's A10 Golden Flash drew heavily from the A7 design by Page and Bert Perkins.<ref name="classic moto">{{cite book |last=Kemp |first=Andrew |year=2001 |title=Classic British Bikes |publisher=Bookmart Ltd |pages=[https://archive.org/details/encyclopediaofcl0000unse_q3v0/page/120 120–121] |isbn=978-1-86147-058-4 |url=https://archive.org/details/encyclopediaofcl0000unse_q3v0/page/120 }}</ref> The A10 was increased to {{Convert|650|cc|abbr=on}} by using a 70mm bore and 84mm stroke.<ref name="classic-british-motorcyclesA10" /> It had a revised alloy rocker box and cast-iron cylinder head, plus an integral manifold for the single Amal carburettor. A single camshaft behind the cylinders operated the valves via pushrods passing through a tunnel in the cast iron block. A magneto was located behind the cylinders, driven by a train of gears, to provide ignition. A dynamo was positioned in front of the cylinders, driven by a chain. Lubrication was dry sump with oil being distributed by a mechanical pump located inside the timing cover.<ref name="sump-publishing">{{cite web |title=BSA A10 Golden Flash Buyers guide |url=http://sump-publishing.co.uk/bsa%20golden%20flash.htm |website=Sump |access-date=8 July 2018}}</ref>
The crankshaft was a bolt-up 360-degree item (both pistons went up and down at the same time). Main bearings were roller drive-side and a white metal plain bush on the timing side. The conrods were of the split type with shell type big ends. The crank-cases were vertically split.<ref name="sump-publishing" />
A semi-unit gearbox meant the duplex primary chain was adjustable via a slipper tensioner within the primary chain case. The A10 was so closely based on the A7 that it used many of its well-proven components, and this large carry-over of parts from the A7 promised greater reliability, with minimal risk of new technical problems.<ref name="classic moto"/>
With the introduction of a swinging arm frame in 1954, the semi-unit gearbox was abandoned for a separate "pre-unit" item. The new design had a modified clutch, new gearbox internals and a single row primary chain. The primary chain was adjusted by moving the gearbox, which caused the rear chain to requiring re-tensioning.<ref name="sump-publishing" />
An alloy head was introduced with the Road Rocket in 1955. The RR also featured a thicker cylinder base flange (1/2" instead of 3/8") and these cylinders became known as "thick flange".<ref name="draganfly_head" /> The big end was increased in diameter from 1.46" to 1.68". Crankshafts and conrods with the bigger bid ends became known as "big journal".<ref name="bigend" /> These changes continued on subsequent sports models. "Thick flange" cylinders and "big journal" big ends were fitted to the Gold Flash in 1958.<ref name="draganfly_head" /><ref name="bigend" />
In 1957 an improved clutch was introduced on all models, using 4 springs instead of six<ref name="sump-publishing" /> and improved friction material.<ref name="AmericanMotorcyclist57">{{cite book |title=American Motorcyclist |date=1957 |publisher=American Motorcyclist Association |url=https://books.google.com/books?id=YvgDAAAAMBAJ&q=Laconia+Bend+handlebars&pg=PA12 |language=en}}</ref>
====Camshafts====
Three different camshafts were used on the production models, with another available as an accessory for racing only.
* '''334 "standard"''' - fitted to the Golden Flash from 1950 - 1959.<ref name="camshafts">{{cite web |title=Pre-Unit A Group |url=https://www.draganfly.co.uk/index.php/a65anda50/category/886-pre-unit-a-group |website=www.draganfly.co.uk |access-date=7 July 2018 |language=en-gb }}{{Dead link|date=October 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> * '''356 "sports"''' - Fitted to the Road Rocket, to the Super Rocket until 1959 and The Golden Flash from 1960. Originally fitted to the A7 Star Twin.<ref name="camshafts" /> * '''357 "race"''' - Fitted to the Super Flash, Spitfire Scrambler and Rocket Gold Star. Also fitted to the Super Rocket from 1960.<ref name="camshafts" /> Also known as ''Spitfire cam.'' * '''358 "acceleration"''' - ''"Gives maximum 'dig-out' power. For racing use - not recommended for road use."''<ref>{{cite web |title=Extract from BSA accessories catalogue |url=https://www.a7a10.net/forum/index.php?action=dlattach;topic=2758.0;attach=7430;image |website=A7 A10 Net |access-date=7 July 2018}}</ref>
====Carburettors====
Five different Amal carburettors were fitted to the range.
* '''76/276''' (1 1/16" bore) - Rigid and plunger framed Golden Flash, also swinging arm Golden Flash in 1954.<ref name="draganfly_carbs">{{cite web |title=Carburettor Settings – B.S.A |url=https://www.draganfly.co.uk/data/pdf/Carb%20settings.pdf |website=Draganfly Motorcycles |access-date=7 July 2018 |archive-date=1 August 2014 |archive-url=https://web.archive.org/web/20140801103742/http://www.draganfly.co.uk/data/pdf/Carb%20settings.pdf |url-status=dead }}</ref> * '''10TT9''' (1 1/16" bore) - Super Flash and Road Rocket,<ref name="draganfly_carbs" /> also Super Road until 1961.<ref name="amalcarb">{{cite web |title=List Vehicles - The AMAL Carburetter Company |url=http://amalcarb.co.uk/cf/vehicle/list/?manufacturer=B.S.A&vehicle=A10+Super+Rocket+%28Export%29 |website=amalcarb.co.uk |access-date=7 July 2018 |language=en |archive-date=27 February 2019 |archive-url=https://web.archive.org/web/20190227060211/http://amalcarb.co.uk/cf/vehicle/list/?manufacturer=B.S.A&vehicle=A10+Super+Rocket+(Export) |url-status=dead }}</ref> * '''376 Monobloc''' (1 1/16" bore) - Golden flash swinging arm frame 1955 to 1959<ref name="draganfly_carbs" /> and Spitfire Scrambler (1956 - 1959).<ref name="amalcarb_spitfire_small">{{cite web |title=Parts for 376/89 for B.S.A A10 Spitfire Scrambler 646cc O.H.V. - The AMAL Carburetter Company - The AMAL Carburetter Company |url=http://amalcarb.co.uk/carbspec/carburettor/spares/id/4758/ |website=amalcarb.co.uk |access-date=7 July 2018 |language=en}}</ref> * '''389 Monobloc''' (1 1/8" bore) - Golden flash 1960 on.<ref name="draganfly_carbs" /> * '''389 Monobloc''' (1 5/32" bore) - Spitfire Scrambler (1960 on),<ref name="V_spitfire_big">{{cite web |title=List Vehicles - The AMAL Carburetter Company |url=http://amalcarb.co.uk/cf/vehicle/list/?manufacturer=B.S.A&vehicle=A10+Spitfire+Scrambler+%28Export%29 |website=amalcarb.co.uk |access-date=7 July 2018 |language=en |archive-date=27 February 2019 |archive-url=https://web.archive.org/web/20190227060151/http://amalcarb.co.uk/cf/vehicle/list/?manufacturer=B.S.A&vehicle=A10+Spitfire+Scrambler+(Export) |url-status=dead }}</ref> Super Rocket (1962 on) and Rocket Gold Star.<ref name="amalcarb" />
===Cycle Parts=== thumb|250px|Early Golden Flash A10s had frames with either no rear suspension, or plungers, and had a semi-unit engine and gearbox, with the gearbox bolted to the rear of the engine The frame was available in rear rigid format, but the more common option was plunger suspension, adopted for the export market.<ref name="motorbase">{{cite web |url=http://www.motorbase.com/auctionlot/by-id/1189789635/ |website=Motorbase |title=Lot 031: 1950 BSA A10 Golden Flash |access-date=2008-05-13 |archive-date=15 March 2012 |archive-url=https://web.archive.org/web/20120315223346/http://www.motorbase.com/auctionlot/by-id/1189789635/ |url-status=dead }}</ref> The A10 featured a hinged rear mudguard to ease rear wheel removal.
BSA were concerned that wear in the plunger suspension was leading to uncertain handling. In 1954 the factory adopted a swinging arm,<ref name="classic">{{cite book |last=Brown |first=Roland |title=Classic Motorcycles |publisher=Anness Publishing |year=2002 |pages=120–123 |isbn=978-1-84038-433-8}}</ref> and the hinged mudguard was deleted. Plunger frames remained an option on the Gold Flash until 1957.<ref name="bsaownersclub" />
Brakes were initially an 8" single side front brake and a 7" rear.<ref name="classic-british-motorcyclesA10">{{cite web |title=BSA A10 |url=http://www.classic-british-motorcycles.com/bsa-a10.html |website=Classic-British-Motorcycles.com |access-date=8 July 2018}}</ref> Full width brake of the same size were fitted to the higher performance models from 1958.<ref name="pressreader." /> Some of the Spitfire Scramblers and the Rocket Gold Star used a Gold Star 190mm front brake.
The Rocket Gold Star used Gold Star cycle parts<ref name="silodrome" /> (Frame numbers beginning with A10, all other A10 models had frames starting with A7) Spitfire Scramblers also used Gold Star Catalina cycle parts in 1957<ref name="Bike-urious57spitfire" /> and 1963.<ref name="hailwoodSpitfire" />
==Models== ===Overview of models===
All models are swinging arm frame unless otherwise indicated.
{| class="wikitable" style="text-align: center;" |- ! {{vert header|1950}} !! {{vert header|1951}} !! {{vert header|1952}} !! {{vert header|1953}} !! {{vert header|1954}} !! {{vert header|1955}} !! {{vert header|1956}} !! {{vert header|1957}} !! {{vert header|1958}} !! {{vert header|1959}} !! {{vert header|1960}} !! {{vert header|1961}} !! {{vert header|1962}} !! {{vert header|1963}} |- | colspan="4" style="background: #DDFBFF;" |A10 Golden Flash (Rigid)<ref name="bsaownersclub">{{cite web |last1=Jones |first1=Rob |last2=Trigwell |first2=Ray |title=BSAOC Year Listing |url=https://www.bsaownersclub.co.uk/yearlisting.html |website=www.bsaownersclub.co.uk |access-date=28 June 2018 |language=en-gb|archive-url=https://web.archive.org/web/20191007184757/https://www.bsaownersclub.co.uk/yearlisting.html|archive-date=7 October 2019}}</ref> || || || || || || || || || || |- | colspan="8" style="background: #DDFBFF;" |A10 Golden Flash (Plunger) <ref name="bsaownersclub" /> || || || || || || |- | || || || || colspan="10" style="background: #DDFBFF;" |A10 Golden Flash<ref name="bsaownersclub" /> {{refn|group=note|Also known as "Royal Tourist" in the US from 1960.<ref name="American_Motorcyclist_1959">{{cite book |title=American Motorcyclist |date=1959 |publisher=American Motorcyclist Assoc |url=https://books.google.com/books?id=UfoDAAAAMBAJ&q=BSA+royal+tourist&pg=PA14 |language=en}}</ref>}} |- | || || || || || || || || || || || colspan="3" style="background: #DDFBFF;" |A10 Golden Flash (Alternator)<ref name="bsaownersclub" /> |- | || || || colspan="2" style="background: #DDFBFF;" |A10SF Super Flash (Plunger) <ref name="bsaownersclub" /> || || || || || || || || || |- | || || || || style="background: #DDFBFF;" |A10SF Super Flash <ref name="bsaownersclub" /> || || || || || || || || || |- | || || || || || colspan="3" style="background: #DDFBFF;" |A10R Road Rocket <ref name="bsaownersclub" /> || || || || || || |- | || || || || || || || colspan="7" style="background: #DDFBFF;" |A10S Spitfire Scrambler <ref name="bsaownersclub" />{{refn|group=note| Also known as "Gold Star Spitfire Scrambler" and "Rocket Gold Star Scrambler"<ref name="bsa.hailwood">{{cite web |title=1963 BSA Gold Star Spitfire Scrambler A10 Literature |url=http://www.bsa.hailwood.com/goldstarspitfirescrambler.html |website=www.bsa.hailwood.com |access-date=29 June 2018}}</ref>}} |- | || || || || || || || || colspan="6" style="background: #DDFBFF;" |A10R Super Rocket<ref name="bsaownersclub" /> |- | || || || || || || || || || || || || colspan="2" style="background: #DDFBFF;" |A10RGS Rocket Gold Star<ref name="bsaownersclub" /> {{refn|group=note| Also known as "Gold Star Twin"<ref name="bsa.hailwood" />}} |}
'''Notes''' {{reflist|group=note}}
===Golden Flash=== {{main|BSA Golden Flash}} thumb|250px|1960 Golden Flash The BSA Golden Flash, commonly referred to as the Gold Flash,<ref name="sump-publishing" /> was the first of the series to be launched in 1950. Painted in a new gold colour, 80% of production was destined for the United States. This resulted in long delivery times for British customers, who were offered the model only in black.<ref>{{Cite news |title=BSA Golden Flash on test |newspaper=Classic Bike Guide |date=May 2008}}</ref>
Although never designed as a sport motorcycle, the Golden Flash was nonetheless fast for its time and competitive with the Triumph Tiger 100, achieving over {{convert|100|mph|km/h}} in tests in 1950, and covering a standing quarter mile (400 m) in under 16 seconds.<ref>{{cite web|url=http://www.realclassic.co.uk/bsaa10a7.html|title=RealClassic.co.uk: BSA A10 / A7|website=www.realclassic.co.uk|access-date=2018-07-07|archive-date=2017-05-12|archive-url=https://web.archive.org/web/20170512081657/http://www.realclassic.co.uk/bsaa10a7.html|url-status=dead}}</ref> Its gold colour proved a marketing success, outselling Triumph's Speed Twin and 6T Thunderbird.
It received updates throughout its model life. In 1960 it was renamed the "Royal Tourist" in the US.<ref name="American_Motorcyclist_1959" /> An alternator was offered as an alternative to the dynamo from 1961 to 1963, the last three years of production.
===Super Flash===
In 1951, BSA Chief designer, Bert Hopwood, went on a fact-finding tour to America and talked to dealers and riders. The feedback he got from the tour was that a more powerful motorcycle would sell well in America. The swinging arm frame and alloy head Road Rocket were planning stages but some way off production.<ref name="beezagent">{{cite web |title=The BSA Super Flash Story |url=http://beezagent.blogspot.com/2009/02/ |website=The Beezagent |access-date=7 July 2018 |date=16 February 2009}}</ref>
The BSA competitions department had experience of tuning the existing models. They had tuned versions of the 500 for the Daytona 200 race. Works rider Fred Rist has an A10 desert racer capable of 140 mph, and Gene Thiessen set an AMA class 'B' record at the Bonneville salt flats of 151 mph in October 1951. Hopwood decided to make a faster model by bolting on performance parts to the existing model.<ref name="beezagent" />
Engine modifications included a 356 race camshaft<ref name="motos-anglaises">{{cite web |title=Pas Golden.... mais SUPER Flash !!! BSA Super Flash 650cc 1953 |url=http://www.motos-anglaises.com/motos/bsa/superflash-1953.html?reload_coolmenus |website=Motos Anglaises |access-date=7 July 2018 |language=Fr}}</ref> and an Amal TT carburettor.<ref name="draganfly_carbs" /> Power output was {{convert|40|bhp|abbr=on}}.<ref name="huntsmaster" /> The TT carburettor required a kink to be put in the frame's seat post for clearance.<ref name="beezagent" /> The frame also had welded on lugs for rearset footrests.<ref name="motos-anglaises" /> A 2.5 gallon Gold Star tank was fitted and chrome mudguards and stays.<ref name="beezagent" />
The first Super Flash was shipped to America in February 1953 and American Motorcycling magazine give it 'Motor of the Month'. The bike was in American showrooms in April that year. Most of the production went to the US, but later in the year models were shipped to Europe, Africa and Australia..
Production continued into 1954, and some swinging arm versions were made in that year.<ref name="bsaownersclub" /> The price was $975 in the US<ref name="beezagent" /> and £325 in Australia.<ref>{{cite web |title=BSA 1954 Prices A7, A10, JGM Sidecars |url=https://cybermotorcycle.com/gallery/bsa-1954/BSA-1954-Price-List-Australia-4.htm |website=Classic Motorcycles by Sheldon's Emu |access-date=7 July 2018}}</ref> Production stopped in 1954 with the Road Rocket about to go into production. In total about 700 machines were made.<ref name="beezagent" /><ref name="motos-anglaises" />
The engine from the Super Flash later powered the Ariel Cyclone.<ref name="huntsmaster" />
===Road Rocket=== {{main|BSA Road Rocket}} thumb|250px|1954 Road Rocket The Road Rocket was a sports motorcycle developed from the Golden Flash.
Launched as the top of BSA's range in 1954 the BSA Road Rocket was the first A10 engine with an alloy cylinder head.<ref name="realclassic" /> Unlike the Golden Flash, the inlet manifold was separate to the cylinder head<ref name="draganfly_head">{{cite web |title=Pre-Unit A Group |url=https://www.draganfly.co.uk/index.php/a65anda50/category/859-pre-unit-a-group |website=www.draganfly.co.uk |access-date=7 July 2018 |language=en-gb }}{{Dead link|date=October 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> enabling twin carburettors to be fitted if required.<ref name="BSA Twins" /> Standard fitment was an Amal TT carburettor.<ref name="draganfly_carbs" /> New "thick flange" cylinders were introduced. (The bottom flange was increased from 3/8" to 1/2" for improved rigidity and reliability.).<ref name="draganfly_head" /> Big end size was increased from 1.48" to 1.68".<ref name="bigend">{{cite web |title=Pre-Unit A Group |url=https://draganfly.co.uk/index.php/a65anda50/category/871-pre-unit-a-group |website=draganfly.co.uk |access-date=8 July 2018 |language=en-gb }}{{Dead link|date=October 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> High compression pistons and a higher lift camshaft, the 356 "sports" profile,<ref name="camshafts" /> were also fitted. These engine modifications raised the power output to {{convert|40|bhp|abbr=on}}<ref name="realclassic">{{cite web |last1=Hoseason |first1=Rowena |title=BSA A10 Classic Motorcycle Buying Guide |url=http://www.realclassic.co.uk/bsa_a10_auction_buying_guide.html |website=Real Classic |access-date=7 July 2018 |archive-date=25 April 2018 |archive-url=https://web.archive.org/web/20180425155346/http://www.realclassic.co.uk/bsa_a10_auction_buying_guide.html |url-status=dead }}</ref> and a top speed of {{convert|109|mph|abbr=on}}.<ref name="Bike-urious">{{cite web |title=1954 BSA A10 Road Rocket |url=https://www.bike-urious.com/1954-bsa-a10-road-rocket/ |website=Bike-urious |access-date=7 July 2018 |date=18 December 2017}}</ref>
The model was launched with chrome mudguards and stays and a half-chrome petrol tank. A tachometer was an optional extra.<ref name="Bike-urious" />
The Road Rocket was discontinued in 1958 when it was replaced by the Super Rocket.<ref name="BSA Twins">{{cite web |title=Cylinder Heads |url=http://beezanet.com/twincarb/history.htm |website=BSA Twincarb Site |access-date=7 July 2018 |archive-url=https://web.archive.org/web/20131105015537/http://beezanet.com/twincarb/history.htm |archive-date=5 November 2013}}</ref>
===Super Rocket=== {{main|BSA Super Rocket}} thumb|250px|1963 Super Rocket The Super Rocket was an improved sports model that replaced the Road Rocket in 1958.<ref name="bsaownersclub" /> It retained the Amal TT carburettor and 356 sports cam of the Road Rocket. Compression ratio was raised to 8.5:1 and a new alloy cylinder head fitted.<ref name="realclassicSR">{{cite web |title=1960 BSA Super Rocket - Classic Motorcycle Review |url=http://www.realclassic.co.uk/bsa04013000.html |website=Real Classic |access-date=7 July 2018 |archive-date=19 September 2015 |archive-url=https://web.archive.org/web/20150919210224/http://www.realclassic.co.uk/bsa04013000.html |url-status=dead }}</ref> The cylinder head had a cast in inlet manifold<ref name="BSA Twins" /> and larger ports and valves. The inlet valve was increased from 1.455" to 1.5".<ref name="pressreader.">{{cite web |title=BSA Super Rocket |url=https://www.pressreader.com/australia/old-bike-australasia/20180301/283025465118959 |via=PressReader |publisher=Old Bike Australia |access-date=8 July 2018 |date=1 March 2018}}</ref> The crankshaft was stiffened compared to the previous models. These modifications increased power output to 43 bhp.<ref name="pressreader." /> A lower 1st gear ratio gave increased acceleration off the line.<ref name="realclassicSR" />
New brakes were fitted to the model, full width hubs instead of the previous half width items. The front brake was 8" and the rear 7". Both were operated by cables.<ref name="pressreader." />
The 357 race camshaft was fitted in 1960<ref name="camshafts" /> and the clutch was improved.<ref>{{cite web |title=Model changes each year for USA Super Rocket Models |url=http://www.geocities.com/MotorCity/Downs/9472/a10years.html |archive-url=https://web.archive.org/web/20091023134403/http://geocities.com/MotorCity/Downs/9472/a10years.html |url-status=dead |archive-date=23 October 2009 |website=www.webcitation.org |access-date=10 July 2018 |language=en}}</ref> A larger 1 5/32" bore Monobloc carburettor fitted in 1962.<ref name="draganfly_carbs" /> These raised the power output to {{convert|46|bhp|abbr=on}}.<ref name="pressreader." />
===Rocket Gold Star=== {{main|BSA Rocket Gold Star}} thumb|250px|1962 Rocket Gold Star The Rocket Gold Star was introduced in 1962, using a tuned Super Rocket engine a Gold Star frame.<ref>''Motor Cycle'' 15 June 1967, Diamond TT number, p.831. Help Club. ''Gold Star applies only to singles...there was a 646 cc twin called the Rocket Gold Star which featured a Super Rocket engine in a Gold Star-type frame. This model was included in BSA's 1962 and 1963 ranges''. Accessed 21 June 2015</ref> Gold Star tuner and dealer, Eddie Dow, had a customer that wanted to be supplied with a Gold Star fitted with a Super Rocket engine. BSA supplied a Gold Star less engine and a separate Super Rocket engine. Dow assembled the special. The special was well received and the BSA management decided to put the concept into limited production.<ref name="silodrome">{{cite web |title=1962 BSA Rocket Gold Star Scrambler |url=https://silodrome.com/bsa-a10-rocket-gold-star-scrambler/ |website=Silodrome |access-date=8 July 2018 |date=8 May 2017}}</ref>
The later (1961–1963) 9:1 compression Super Rocket engine was used with a 357 ''Spitfire'' camshaft and a 1 5/32" bore Amal Monobloc carburettor which gave {{convert|46|bhp|abbr=on}} as standard. Options such as an Amal GP2 carburettor, ''siamesed'' exhaust pipes and a close-ratio RRT2 gearbox could increase this to {{convert|50|bhp|abbr=on}} – and add 30% to the price.<ref>{{Cite web|last=Ker |first=Rod |title=Rocket Gold Star |url=http://www.classicbikeguide.com/archive/oct05/ft1.htm |access-date=2008-05-16 |url-status=dead |archive-url=https://web.archive.org/web/20061103055857/http://www.classicbikeguide.com/archive/oct05/ft1.htm |archive-date=3 November 2006 }}</ref> The model was also known as the Gold Star Twin.<ref name="bsa.hailwood" /> Rocket Gold Star production ended in 1963.
===Spitfire Scrambler=== thumb|250px|1963 Spitfire Scrambler The Spitfire Scrambler was introduced in 1957 at the request of BSA's West Coast distributor, Hap Alzina, to meet a need in US desert racing to beat the dominant Triumph twins.<ref name="CycleWorldSpitfire">{{cite book |title=Cycle World Magazine |date=2003 |page=10 |url=https://books.google.com/books?id=wHSDST9VvU8C&q=hap+alzina+spitfire+scrambler&pg=RA8-PA10 |language=en}}</ref> The engine was a modified Road Rocket unit. The head was modified to allow a 1 1/16" Amal Monoblock carburettor to be fitted. Compression was raised to 9:1 and a 357 "race" camshaft was fitted. Initially it was thought a special scrambles cam would need to be developed, but the race cam proved to be suitable.<ref name="Bike-urious57spitfire" /> The gearbox had wider, scrambles ratios.<ref name="AmericanMotorcyclist57spitfire" /> The frame, forks and wheels initially used were from the Gold Star Catalina,<ref name="Bike-urious57spitfire">{{cite web |title=1957 BSA Spitfire Scrambler |url=https://www.bike-urious.com/1957-bsa-spitfire-scrambler-2/ |website=Bike-urious |access-date=9 July 2018 |date=2 December 2017}}</ref> but halfway through 1957 this was changed to an A10 frame.<ref name="Bike-uriousSpitfire">{{cite web |title=1957 BSA Spitfire Scrambler |url=https://www.bike-urious.com/1957-bsa-spitfire-scrambler/ |website=Bike-urious |access-date=8 July 2018 |date=28 January 2016}}</ref> A skid-plate and 2 US gallon petrol tank were fitted. No lights were fitted and the exhausts had no silencers.<ref name="AmericanMotorcyclist57spitfire">{{cite book |title=American Motorcyclist |date=1957 |publisher=American Motorcyclist Assoc |page=32 |url=https://books.google.com/books?id=3_UDAAAAMBAJ&q=bsa+spitfire+scrambler+pistons&pg=PA32 |language=en}}</ref> A Lucas competition magneto was used on this model.<ref name="sumpSpitfire">{{cite web |title=BSA-A10-Spitfire-Scrambler |url=http://sumpmagazine.com/bsa-a10-golden-flash/bsa-a10-spitfire-scrambler.htm |website=sumpmagazine.com |access-date=8 July 2018}}</ref>
In 1958 the engine gained the 'big valve' head which was also fitted to the newly launched Super Rocket.<ref name="marquis">{{cite web |title=1958 BSA Spitfire Scrambler |url=https://themarquisblogger.wordpress.com/2015/11/05/1958-bsa-spitfire-scrambler/ |website=The Marquis |access-date=8 July 2018 |date=5 November 2015}}</ref>
A shorter seat was fitted in 1959 and the exhausts were high level on the left hand side. This configuration continued until production ended in 1963.<ref name="suprememotos">{{cite web |title=1957 BSA A10 Spitfire Scrambler, Correct Concourse Restoration |url=http://suprememotos.com/bsa/99361-1957-bsa-a10-spitfire-scrambler-correct-concourse-restoration.html |website=suprememotos.com |access-date=9 July 2018 |language=en}}</ref> In 1963 the model again used the Gold Star cycle parts after being merged with the Road Gold Star Scrambler<ref name="hailwoodSpitfire">{{cite web |title=1963 BSA Gold Star Spitfire Scrambler A10 Literature |url=http://bsa.hailwood.com/goldstarspitfirescrambler.html |website=bsa.hailwood.com |access-date=9 July 2018}}</ref> and renamed the Gold Star Spitfire Scrambler.<ref name="hailwoodSpitfire" />
===Other models=== ====Ariel Huntmaster==== thumb|250px|1955 Ariel Huntmaster Ariel Motorcycles became a subsidiary of BSA in 1951.<ref>{{cite book |last= Reynolds|first= Jim|year= 1990|title= Best of British bikes|url= https://books.google.com/books?id=X9Xb0YOEXOEC&q=Huntmaster+A10+sidecar|publisher= Patrick Stephens|page= 31|isbn= 978-1-8526-0033-4|access-date= 2014-04-21}}</ref> Although they already had a 500cc twin, the Val Page designed model KH500,<ref name="mcs">{{cite web |title=Ariel KH 500 Fieldmaster |url=http://www.motorcyclespecs.co.za/model/Arial/Ariel%20KH500%20Fieldmaster.htm |website=MCS |access-date=9 July 2018}}</ref> the management did not want the expense of developing a 650cc machine. In 1954 an A10 Golden Flash enginge, with different outer casings, was fitted to the Ariel frame to create the Ariel Huntmaster.<ref name="huntsmaster">{{cite web |title=Almost Famous: The 1958 Ariel Cyclone - Classic American Motorcycles - Motorcycle Classics |url=https://www.motorcycleclassics.com/classic-american-motorcycles/1958-ariel-cyclone-zmmz15sozhur |website=Motorcycle Classics |access-date=9 July 2018 |language=en}}</ref> The machine continued until 1959 when all 4-stroke Ariel motorcycles were discontinued.<ref name="AOMCC">{{cite web |title=History |url=http://www.arielownersmcc.co.uk/history.html |website=Ariel Owners Motor Cycle Club |access-date=9 July 2018 |archive-date=30 October 2017 |archive-url=https://web.archive.org/web/20171030023859/http://www.arielownersmcc.co.uk/history.html |url-status=dead }}</ref>
====Ariel Cyclone==== A sporting version of the Huntmaster, the Cyclone was also produced. This used the {{convert|40|bhp|abbr=on}} Super Flash engine, albeit with an Amal Monobloc carburettor fitted instead of the Super Flash's Amal TT version.<ref name="huntsmaster" />
==Further reading== * {{cite book |last1=Bacon |first1=Roy |title=BSA A7/A10 Twins, All Models, 1946-1963 |date=1989 |publisher=Niton Publishing |isbn=9780951420454 |language=en|id= {{ASIN|0951420453|country=uk}} }} * {{cite book |last1=Bacon |first1=Roy H. |title=BSA Twins and Triples |date=2007 |publisher=Mercian Manuals Ltd |isbn=9781903088364 |edition=First |language=en|id= {{ASIN|1903088364|country=uk}} }} * {{cite book |last1=Henshaw |first1=Peter |title=BSA 500 & 650 Twins: The Essential Buyer's Guide |date=2008 |publisher=Veloce Publishing |isbn=9781845841362 |language=en}} * {{cite book |last1=Kemp |first1=Andrew |title=Classic British Bikes |date=2004 |publisher=Abbeydale Press |isbn=9781861471369 |url=https://www.abebooks.co.uk/9781861471369/Classic-British-Bikes-Andrew-Kemp-186147136X/plp}} * {{cite book |last1=Wright |first1=Professor Owen |title=BSA A7 & A10 Twins Super Profile |date=1984 |publisher=G T Foulis & Co Ltd |isbn=9780854294466 |edition=First |language=en|id= {{ASIN|0854294465|country=uk}} }} * {{cite book |title=BSA Twins A7 & A10 1946-1962: Road Test Book |date=1996 |publisher=Brooklands Books |isbn=9781855203365 |edition=First |language=en|id= {{ASIN|1855203367|country=uk}} }}
==References== {{reflist}}
{{BSA motorcycles|state=collapsed}}
A10 series Category:Motorcycles introduced in 1950 Category:Motorcycles powered by straight-twin engines