Retrospectove: BSA A65S Spitfire Mark II/III/IV Special: 1966-1968

1966 BSA A65S Spitfire Mark II Special
1966 BSA A65S Spitfire Mark II Special

Back in the early 1960s, many British bike companies were cheerfully warring with each other, paying no attention to the threat coming from the Orient. The major market for their 650 twins was the U.S., and Americans wanted horses—lots of horses. The more the better. Well-mannered commuter twins did not sell worth a damn to the power-crazed Yanks, who looked at quarter-mile times and top speeds as the main virtues of any motorcycle. Dependability? Who cared? The commute to work was done in a Ford or a Chevy.

1966 BSA A65S Spitfire Mark II Special
1966 BSA A65S Spitfire Mark II Special

Harry Sturgeon, BSA’s managing director, decided to give the ex-colonials exactly what they wanted, a hot-rodded, highly chromed, Royal Red 650 twin called the Spitfire that could blow off any hapless rider on a Triumph Bonneville or Royal Enfield Interceptor. The first rendition, in ’66, was labeled the Mark II, as BSA had previously used the name in the Spitfire Scrambler of 1957.

Claiming 55 horsepower and a top speed of 120 mph, the Mark II was the kind of kick-ass motorcycle that manly men chose to ride. As Cycle magazine’s road test warned, it was “… a full-fledged racing motorcycle disguised as a snarling street bike.” Another article described it as “tuned to the boiling point.” Moto-journalists have long been prone to mild exaggeration.

A little history is in order. What was happening was that the Brits did not have much in the way of R&D money to build new motorcycles, so they continued to pump more ponies out of 30-year-old technology. The blame for this can be laid on Edward Turner, who came up with the vertical twin design on the Triumph 5T Speed Twin in 1936. Apparently one could not patent such a thing as this engine configuration, so BSA immediately began developing its own version, which was delayed by the advent of World War II. But late in 1946, BSA’s A7 500 was presented to the public.

1966 BSA A65S Spitfire Mark II Special
1966 BSA A65S Spitfire Mark II Special

Turner upped the ante in 1949 by creating the 650cc Thunderbird, and came out with the famous dictum that 650cc and 6,500 rpm was as far as a vertical twin should go. This was long before any counterbalancing technology was in effect. BSA followed a year later with its own 650, the A10 Golden Flash, using a bore of 70mm, stroke of 84mm, equaling 646cc. Incidentally, in 1951 BSA bought the Triumph company, though the two brands were kept well apart.

Carbs, cams and compression ratios were the popular ways to make these bikes go faster. In the 1950s, dual carbs were popular as an option on these twins, but no stock bike had them until Triumph brought forth its Bonneville model in 1959. Bumpier camshafts were easily available, and compression was merely a matter of shaving heads.

BSA’s minor effort at modernity came with the unit-construction A65 Star for 1962. It maintained the 360-degree crankshaft, a single camshaft, and single Amal Monobloc carburetor of the non-unit A10, though it had an enlarged bore of 75mm and shortened stroke of 74mm for a total of 654cc. As well as 12-volt electrics, with an alternator and two coils.

1966 BSA A65S Spitfire Mark II Special
1966 BSA A65S Spitfire Mark II Special

Another change was a shortened chassis, 56 inches between the axles, though still the double-cradle design of old. The fork was two-way damped, and Girling provided the shock absorbers with spring preload adjustability. Weight was close to 400 pounds.

1966 BSA A65S Spitfire Mark II Special
1966 BSA A65S Spitfire Mark II Special

That first A65 was a pretty benign bike, having a modest compression ratio of 7.5:1 with an output rated at some 38 horses at 5,800 rpm. After a year or so, BSA realized that it was going to have to give the Yanks more power, and came out with hotter versions, the Rocket and the Lightning. Then Sturgeon said something to the effect of “Screw it! Pull out all the stops.” And the engineers did, pumping up the compression ratio to a heart-stopping 10.5:1, bolting on a pair of Amal GP carburetors, and claiming 55 ponies at 6,800 rpm. Sales for the Spitfire were helped by those ads claiming it to be a 120 mph machine—which it was, with a gentle tailwind helping.

Unfortunately, holding the throttle open at over 6,000 rpm meant the bike vibrated like a paint shaker. Also, if the engine was run at those speeds for any sizable amount of time, the crankshaft bearings might fail, as there was a bronze thrust pad on the timing side to deal with end float that was prone to wearing excessively and inhibiting lubrication.

1966 BSA A65S Spitfire Mark II Special
1966 BSA A65S Spitfire Mark II Special

Starting the bike, which had a central float bowl between the GP carbs with a hard-to-get-at tickler, could initiate some strong language from the rider. Especially with the 10.5 compression. As one critic wrote, it was barely civilized. But once the rider was barreling down the road at full tweet, all of that went away. The Spitfire demanded, and got, respect.

For the ’67 Mark III version, the GP carbs were tossed, replaced by a pair of new Amal Concentric 932s, and the compression ratio was lowered to 9:1. For ’68, the Mark IV sported a new twin-leading shoe front brake.
Then the Rocket III triple appeared in September of 1968, and BSA decided to drop the Spitfire and let the new machine take the role of fastest bike in the lineup, with the more modestly tuned Lightning filling the role of top twin. The spitter of fire was not much missed.

(This Retrospective article was published in the October 2014 issue of Rider magazine.)

10 COMMENTS

  1. Yawn, usual second hand rubbish.
    Stick with your antiquated Bavarian Motor Werke and leave us English riders to ride our English built motorcycles knowing what they are really like to ride.

  2. I bought a 1968 mk 4 in 1968,trading in a Suzuki x6 hustler. I ported and polished the head,bored it 20 over and 10.5-1 compression pistons.Installed better,stronger push rods,a pair of GP 2 carbs and a set of tuned larger straight pipes.When I tore it down,I knocked the crank apart and put the center ring in a lathe and lightened up to the point you could not use the timing -plug to set timing,taking off metal from the sides in an equal amount and turning the center down 3/16 “. I then took everything that would be on the crank to a very good balancing shop in town and told them”balance for high rpm. What a difference in performance,no Bonneville or Sportster could touch me. I rode this bike for 4 more years,trouble free and sold it so I could have some money for a house down payment. Wish I had it back!

  3. I am now the proud owner of the actual bike in this article….and what a beauty she is! And she runs “tuned to the boiling point”. She leaves both my Bonnevilles crying for help.

  4. Never ceases to amuse me how journalist’s put down Brit bikes for their antiquated engine designs then rave about BMW twins, when was the Beema engine designed? Weren’t they used by Germany at the start of WW2 which started in mid 1939! Ha Ha.

  5. I bought a MK IV in September 1968 after exiting the USAF. I had owned a Cyclone 500 while in the USAF out on the Mojave Desert.
    I would give the proverbial “left nut” to have that machine back today. I paid less than $2000.00 for it and the only problem I experienced was shift lever loosening requiring additional set-screws to resolve.
    I had a Triumph T120R Bonneville a couple of years later and it was a damned poor replacement for the BSA.

  6. I bought my Mk ll in September 1966, it was one of 3 new bikes in the showroom, they’d only just become available in Australia, I’d been racing my Honda CB72 for about 15 months, as well as a 1965 Triumph Trophy Special, the Triumph was pretty quick for a single carburettor bike but the Mk ll was infinitely quicker, I rode the bike to work through the week & went touring on the weekends, I entered in a 50 mile production race, held on a newly built track that no races had been held on, by the time the race came up, I’d been pushing it around on the road for 5 months & had become to feel ‘as one with it’. The race meeting finally came around, the race shortened from 50 miles to about 38 miles due to heavy rain, I led the race from the start & lapped some of the field up 4 or 5 times, only one bike finishing less than a lap behind me. I rode it in another 2 production races, winning both of those & cutting almost 1.5 seconds off Kel Carruthers’ lap record while also riding it in ‘open class’ races. Top recorded speeds were, 123, 125 & 128 mph, I ran it at a car drag meeting, timed at 12.36 or 12.39 seconds, 103 mph terminal speed. My first race win on it is on Wikipedia under Motorcycle Racing at Amaroo Park & / or Larry Simons. PS After winning 3 production races in a row, I became ineligible to compete in any more production races, they then cut it down to ‘two wins only’, apparently that rule was dropped a few years later & there was no limit to how many ‘proddie’ races a rider could win.

  7. The A 65.Spitfire was a death machine! It me over the cliff in gear many times . When the carburetors stuck wide open. In had many false neutrals , leaked gas from it’s fiber glass tank.

  8. Bought an A65 Lightning for a Christmas present to myself last year.
    I owned a Mk ll Spitfire towards the end of the 70’s and went mad on it.
    After it broke l rebuilt it and sold it.
    I love owning my fully restored Lightning and have calmed down a bit since the 70’s!
    The crank has been balanced and engine has extra strong lightweight con rods.
    When l ride it reminds me of my dad who bought a brand new A10 sidecar outfit in 1960.
    The A65 has that lovely crackling exhaust similar to the A10.
    Guys, 28psi front 30psi back.
    Ignore what it says in the manual.
    I shall cherish this lovely beeza until the end.
    Ride and stay safe everyone.
    Join MAG and ride free in the GB.

  9. I was a BSA Mechanic at a shop in Billings,Mt. I remember when the 66 Mark ll came out. We were impressed at seeing the Amal GP2 Carbs which were actally 29mm (not 30mm (1-3/16″) like the Monobloc/Concentric Amals used on other modela. Almost from the beginning this bike’s owner complained of constantly losing a Cylinder intermittely and then running normally again on both cylinders. Of course we blamed the GP2 Carbs, which are really a Race Carb and not really suited for Street use. We put on a set of new 1-3/16″ Monoblocs but didn’t cure the issue. We then did almost everything you could do ignition wise (new points,condensers, coils, rectifier,etc.) stiill no cure for going to one cylinder occasionally. Then sometime later I recieved a service bulletin from BSA West telling Dealers to remove the Points Cam Assembly and send it back to them in California. Apparently the Factory had made a number of defective Assemblies that showed up on Mark ll engines. Long Story short. BSA sent us a new Points Cam Assembly which I installed and timed at 34 degrees using a wheel verses the timing plug in the right main case. Problem solved, never dropped a Cylinder again. Not positive what the defect was in the assembly but I’m guessing the Breaker Lobe was ground wrong for the dwell period. Don’t know how many others had this problem but don’t blame the Carbs, although I would recommend Concentrics for Street use IMHO! S.M.

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