BSA Spitfire by Roland Brown

Naming a high performance motorcycle after a high performance aeroplane should have been a good idea. Roland Brown tests the motorcycle.

The blast from south London down to the site of the old World War II airfield at Biggin Hill didn’t take long, but it was one of those memorable rides that stays in the memory for months afterwards. The Spitfire was running perfectly, its torquey engine and easy-handling chassis blending to give lively performance on the narrow Kentish lanes and faster A-roads alike.

When I reached Biggin Hill and parked the Spitfire in the shadow of a replica of its famous winged namesake, it was easy to understand how BSA’s bosses had thought the plane’s name ideal for their hot new roadster back in the mid ‘60s. With its bright red paintwork, and a tuned engine producing over 50bhp, the Spitfire was BSA’s top-of-the-range sports model. Comparisons with the fast and stylish fighter ‘plane were natural, if not strictly relevant.

Riding this nicely restored Spitfire had done little to alter that impression, either, at least when plenty of allowance was made for the bike’s 30-something years of age. As well as having a fair turn of straight-line speed, the Spitfire handled well, and stopped with unusual enthusiasm for a bike from the ‘60s, thanks to its big twin-leading-shoe front drum brake.
But if this nicely restored MKIV was a fine example of the last and best model of BSA’s Spitfire series, there can be no denying that the two-wheeler of that name failed to match the impact of the flying machine that inspired it. While the fighter plane’s legend lives on, the bike’s reputation is for fragility as much as performance. The Spitfire MKIV deserves to be remembered, though, for in terms of pure sprinting speed this was arguably as good as BSA’s parallel twins ever got.

Ace designer Bert Hopwood can surely not have imagined this end result when he penned BSA’s original 646cc twin engine for the 1950 model A10 Golden Flash. That 35bhp machine had been launched to compete with Triumph’s new 650cc Thunderbird, and Hopwood’s basic engine layout was unchanged. Performance had increased steadily during the ‘50s, with models such as the Super Flash and Super Rocket bringing peak output above 40bhp by the end of the decade, by which time top speed had risen past the ton mark.
Interest in BSA’s twins was boosted in 1964 with the introduction of the first sports model, the A65 Rocket, whose 105mph top speed and aggressive looks proved popular. The twin-carburettor A65 Lightning of the following year was even faster, and was also available in Lightning Clubman trim with clip-ons, rearsets, tuned and bench-tested engine and humped racing seat.

The Spitfire replaced the Lightning Clubman as BSA’s highest-performance machine in 1966, when curiously it was called the Spitfire MkII Special although there had been no MkI version in the past. BSA had used the Spitfire name a couple of years earlier for the Spitfire Hornet, but this was an off-road model with open exhaust and no lights, created for the American export market, so was far from the new model’s predecessor.
BSA had clearly decided that the Spitfire name was worthy of greater exposure, and the MkII machine was certainly an outstanding motorbike – at least on paper. To the already racy spec of the Lightning Clubman, which had high compression pistons plus a close-ratio gearbox, it added a pair of Amal GP2 carbs that brought peak power output to 54bhp – quite a figure in the year that England won the World Cup, the Beatles and Rolling Stones were battling in the charts, and London’s King’s Road was the centre of the Swinging Sixties.

The Spitfire also benefited from the 12v electrics and the chassis changes that BSA introduced across all its twins in 1966. The chassis mods included a revised, twin-downtube steel frame, new front forks developed through the Birmingham firm’s scrambles team (featuring rebound damping for the first time) plus new Girling shocks. In addition the Spitfire boasted the 190mm front drum brake and full-width alloy hub that had previously been an option on the Clubman, and lightweight alloy rims that helped bring weight down slightly to 174kg.
Finished in red, the Spitfire came with a tiny fibreglass fuel tank that held only eight litres (there was an 18 litre option) and looked very handsome. For a time it went every bit as well as it looked, too. The hotted-up engine gave lively acceleration plus a top speed of 120mph. Handling from the new chassis was more than acceptable, and the Spitfire had the performance to match any standard production machine on the road. But sadly for the proud owners of a new Spitfire MkII, this happy state of affairs normally did not last very long at all, because the model’s introduction coincided with a disastrous engine revision across all BSA’s twins.

Changing the crankshaft main bearings from ball to roller design was an ill-conceived engineering solution that did not hold the crank sufficiently securely. The roller bearing allowed sideways movement in the crank, which soon generated wear. Coupled with the BSA twin’s dated and barely adequate lubrication system, the factory’s poor level of crankshaft balancing, and the inevitable parallel-twin vibration, the result was potentially nasty. The right main bearing bush wore, turned in its housing, cut off the oil supply to the bearings — and BANG!

Naturally the most vulnerable engine of all was the high-revving, high-compression unit in the Spitfire — which soon developed a terrible reputation for unreliability, as many hard-riding owners found themselves examining their conrods through holes in the crankcases. BSA’s response was not exactly swift, typically of a firm, which by the late Sixties was already in serious financial trouble, along with the rest of the British bike industry. The main change for the Spitfire MkIII of 1967 was that Amal Concentric carburettors replaced the racing GP2s. The engine also gained a finned top for its rocker box, plus an access cover to the rotor in the chaincase.
Predictably this did nothing to shed the Spitfire’s deserved reputation for unreliability if its performance was used to the full. And the same was true of this model, the MkIV of 1968, whose significant changes were to cycle parts: the introduction of a big eight-inch twin-leading-shoe front brake, plus exposed springs for the rear shocks. At least, by now, Spitfire owners knew that the motor must be treated with care, and examined regularly for wear, if expensive problems were to be avoided.

Luckily for present day BSA enthusiasts, these weaknesses can be cured fairly easily and cheaply. A new and more rigid oil pump, plus the substitution of the vulnerable crankshaft bush with a ball and roller bearing that holds the crankshaft more securely, goes a long way to making the Spitfire MkIV the bike it should always have been. And fortunately those modifications had been made during the rebuild of this very sweet example, which was on sale at south London classic specialist Planet Motorcycles.

This Spitfire started first or second kick with a healthy bark from its pipes, didn’t leak oil and was running just as smoothly and strongly at the end of my ride as at the beginning. Slightly more smoothly, in fact, because after I’d headed away from the shop, it was clear that the Beesa’s gearchange was not all it should have been. Changing down was no problem, but second and third gears were very hard to find going up through the four-speed box.

After a couple of miles I was debating whether I should head back to Planet to get it checked out, when I realised that the problem had disappeared and the Spitfire was shifting cleanly, presumably because the gearbox had warmed up. The odd teething problem was not surprising because this was the first serious run-out the bike had been given since being rebuilt, when it was converted from an American spec model with higher bars, tiny fuel tank, upswept exhaust pipes and a fatter rear tyre. A large percentage of BSA’s output went to the States in the Sixties, but this home market version is more popular elsewhere.

Mindful of the Spitfire’s reputation as well as its recent rebuild, I kept the revs down and didn’t get near that genuine 120mph top speed that so impressed testers and tempted owners in the Sixties. At lower revs the BSA was very pleasant, its delivery seemingly unaffected by the Spitfire motor’s relatively high state of tune. The Concentric carbs gave a crisp response, and the bike pulled so strongly at about 50mph in top gear that once out of town the by-now sweet-shifting gearbox was rarely needed.