BSA A10 Golden Flash

RUSHING A PRODUCT into production is always a risky expedient. Matchless did it in the late 1920s/early 1930s with the Silver Arrow and Silver Hawk and fell flat on its face with a temperamental motorcycle, poor sales and a bleeding reputation.

The Ford Motor Company did it in 1957 with the Edsel and got its quality control fingers burned all the way up to the shoulder.

Norton did it the following year with the Jubilee and reaped a bitter harvest of technical problems that sent most of its potential buyers running for the hills.

And Triumph did it in 1982 with the T140W TSS souring what little was left of the last of the Meriden wine.

All these machines could have been wonderful had a few extra months, or even weeks, been spent sorting out the various developmental and production bugs (and the Edsel was wonderful, or at least good, once Ford finally cracked the assembly line issues and … well, totally revamped the design—which was way too late for its customers who had moved on elsewhere).

But at the time, for various commercial reasons, all these products were rushed onto and off the drawing board, hurried through the prototype stage, cosseted through the trade shows and pretty much dumped into the showrooms with the designers and company executives crossing their fingers and hoping that the deus was safely in the machina.

▲ Herbert Perkins and David Munro were the men behind the 495cc BSA A7 Star Twin. Solid, surefooted, reliable and a smooth ride. This example is from 1950. You might want to try one of these before straddling an A10.

BSA A7 and A10: Bert Hopwood, Herbert Perkins

So it was with BSA in October 1949 when the firm announced the 650cc (actually 646cc) A10 Golden Flash which would be on sale for the 1950 season.

Triumph was at the root of BSA’s panic—or, at least, haste. Edward Turner’s pre-war 500cc 5T Speed Twin had, way back in 1937, set the pace for a new era of parallel twin motorcycling—a pace that was about to be reset with the imminent launch of the 1949, 34bhp, 650cc 6T Thunderbird.

 Not that BSA had been entirely caught napping. For three years, the company had been marketing a rival parallel—and not-quite-so-speedy—twin in the shape of the 62mm x 82mm 500cc A7 (66mm x 72.6mm from 1951 taking the capacity from 495cc to 497cc).

Launched in 1946 (from what was essentially a 1939 design), the A7 was a robust and attractive rigid-framed bike designed and developed essentially by Herbert Perkins and David Munro, but with engineering cues from Val Page who had masterminded the (arguable) predecessor of the A7, the 1933 Triumph 6/1.

And then there was Edward Turner himself. Bombed out of Triumph’s Priory Street factory following the infamous raid on Coventry (14th November 1940), and with time on his hands before the new Meriden factory near Allesley, Warwickshire was up and running, Turner spent some time at BSA’s Armoury Road site at Small Heath, Birmingham and injected one or two of his own pet design devices—notably detachable rocker boxes in the now familiar Triumph twin style.

By 1949, the 500cc A7, with its iron head and barrels, bolt-up crankshaft, bolt-on gearbox (à la Triumph 6/1) and telescopic front fork had firmly established itself in the marketplace. What made the engine substantially different to the Speed Twin was its single camshaft (also à la Triumph 6/1) located at the rear of the cylinder block (as opposed to the Triumph’s twin camshafts mounted fore and aft).

Triumph’s design required two pushrod tubes (also installed fore and aft), while BSA’s design carried the four pushrods within a tunnel in the cylinder block casting, thereby reducing the risk of oil leaks and allowing for an increased airflow over the barrels.

Both designs had their advantages and disadvantages, but the Speed Twin, with its svelte styling and evocative name (and oil leaks) always had the edge both in terms of sales and performance. It was a true 90mph machine, with maybe even a few extra mph on tap under the right circumstances. While the A7, meanwhile, was happy to lope along at around 80-85mph in the solid and dependable BSA tradition.

But the arrival of the new 650cc (649cc) Thunderbird was about to up the Speed Twin’s ante, thereby forcing BSA to also think bigger. And faster.

Enter Bert Hopwood, another of the great British motorcycle designers who had worked at Ariel (on the Square Four), at Triumph (on the Speed Twin and Tiger 100) and Norton (on the Dominator) before moving to BSA in May 1949. And it was Hopwood who took the seeds of Perkins' A7 and grew them into a bike of his own making.

 Commonly—and erroneously—referred to as a Gold Flash, the Golden Flash was never intended to take on the Thunderbird head-to-head. That wasn’t BSA’s style; a company that broadly preferred to cater to the needs of the everyday rider as opposed to the more sporting/hooligan element. But the 650cc engine had come of age— although the nation’s major motorcycle factories would build and sell half litre machines for many years after.

The 500cc A7 and 650cc Golden Flash

At first glance, the A10 was nothing other than a bigger A7, and certainly had all the big lumps in usual places. But there were many detail changes, most notably revised castings for the cylinder head and rocker box, plus a cast-in carburettor manifold (as opposed to bolt-on for the A7).

From the start, the A10 was available with BSA’s new plunger frame (although rigid frames would be an option until 1952). The A10 also came with an 8-inch front brake (as opposed to 7-inch for the A7).

 The A10 engine featured a 360-degree bolt-up crank with a roller drive-side main bearing and a corresponding white metal plain bush on the timing side. The big ends were shell type on split con-rods. A single Amal Type 276 carburettor metered the fuel at around 55-65mpg.

A crucial point regarding the A7/A10 crank (as Sumpster Bob Bradley has reminded us) is the need to thoroughly flush the sludge trap every time the engine case is split. As with the Triumph T140, the sludge trap design is very efficient, but only up to a point. Unwanted matter in the oil passes through the spinning crankshaft and is thrown (by ordinary inertia) through a crude filter and trapped inside the crank's central tunnel.

It takes a while for the sediment/sludge to build to a dangerous level, but if ignored, it will eventually restrict normal oil flow, and will finally cut off that flow entirely.

The solution is simple. Clean the sludge trap every time you strip the motor. No ifs. Not buts. It's a simple job and should take about 30 minutes, or less. Maybe an hour if you're inexperienced.

Meanwhile, the cylinder block and cylinder head was cast iron, but later sporting models ran with light aluminium alloy heads. The primary chaincase was always aluminium alloy, and reasonably oil tight.

The ignition was by magneto located at the rear of the engine and driven via a train of gears. The dynamo was located at the front of the crankcases and driven by a chain. Lubrication was via a gear driven pump inside the right side timing chest.

The clutch was a dry multi-plate unit driven by a duplex primary chain and tensioned with a Weller-type adjuster (later A10 clutches were of a slightly different design and configuration, and swinging arm models had a single row chain). The bolt-on 4-speed gearbox was modified in 1954 to a more conventional design, with the primary chain being tensioned by sliding the entire gearbox back; a move made necessary by the introduction of the swinging arm frame.

Golden Flash, Road Rocket and Super Rocket

But all this was of secondary appeal when faced with the brilliant gold livery of the A10, from which it drew its name. This new honey-coloured piece of Small Heath hardware certainly kicked Triumph’s (slightly dowdy) amaranth red Speed Twin into touch, and also upstaged the new 6T Thunderbird which arrived in an uninspiring blue-grey—which was revised the following year into the now classic polychromatic blue.

For those who wanted the A10, but were too conservative to be seen in public in the company of that much colour, BSA offered the bike in basic black and chrome. But it was the gold that set the standard, driven largely by the real or perceived expectations of the US market which was where 80-90% of the A10s of that era were headed.

The A7, meanwhile, continued in production, and both bikes were steadily improved and upgraded.

In 1954,  the sporting A10 Road Rocket appeared. Two years on, aluminium alloy brake drums were fitted as standard which both reduced unsprung weight and increased stopping power.

In 1957, the 40bhp Super Rocket—with its Amal TT carburettor and high lift cam—appeared, thereby taking the A10 to the penultimate level of BSA parallel twin enlightenment—and more than once giving rival Triumph a bloody nose on the street.

The final and greatest A10 incarnation (in terms of power and performance) was the famed Rocket Gold Star which appeared in 1962, by which time the new unit-construction (combined engine/gearbox) A50s and A65s were ready for launch.

The 500cc A7 and 650cc A10 was discontinued—but the A10 derived Super Rocket and Rocket Gold Star remained in production until 1963.

▲ There's the proof. Men ride hulking Golden Flashes, and women ride diminutive Bantams. At least, that was how BSA's marketing people saw it. .

Riding the BSA A10 Golden Flash

The best all round, all purpose BSA? Could be.

When BSA road tested these bikes in the frantic rush to clip Triumph's sales of the Thunderbird, 100mph-plus was the goal, and that was exactly what the testers reported back.

Ton plus.

No problem.

Job done.

Of course, those pre-production bikes were in top tune and built from parts that were not merely plus or minus whatever manufacturing tolerance BSA dialled in, but machined to precise specifications. All the same, the product as sold to the public was, in most cases, a true 100mph performer.

But the big numbers were really for the marketing people, because the BSA engineers were aiming squarely at the aforementioned middle ground of riders loyal to the famous "piled arms" logo and looking to make the move up from sidevalve to OHV. And these guys, by tradition if not genetics, were the more staid and sober types who were in it for the long haul rather than a fast fix of fun.

You won't been hustling along at breakneck speed. On a BSA A10, you probably won't want to. You won't exactly be bimbling along either. Instead, you'll be somewhere between the two and just making steady progress.

Yes, you can swing them around a little. Nothing too exciting is likely to happen. It's just that the A10 vibe is different. As with, say, Ariel twins, you'll rise above any urges to get your knee down. These bikes are more gentlemanly. Not dull, note. Just ... easy going.

Starting a BSA A10

Starting an A10 is usually a one or two kick affair. Immediately the engine should settle into a slow, methodical, solid, chuff-chuff-chuff with less top-end clatter than, say, a 650cc Triumph, and usually less piston slap. There is generally some cam noise. But nothing really intrusive; just a soft background whine interspersed by the backbeat of the pushrod cluster at the rear of the cylinder.

Naturally, each A10 wants a peculiar variation on the starting theme to get those pistons pumping. But there's no mystique here. No insider information. And if you haven't got it started in half a dozen or so manly swing-throughs, check the fuel level and then start pulling plug caps.

BSA A10 clutches and gearboxes

The clutch is reasonably light and engages progressively taking up any driveline slack and raking up the horsepower which is delivered without fuss or fervour—except when the clutch warms up in heavy traffic where you can expect a little drag, especially with respect to worn clutch hubs. Many owners prefer bikes fitted with the later 4-spring clutch units to the earlier 6-spring items. But when properly adjusted and maintained, there's not a lot in it.

That said, the 4-spring units do have the edge. SRM in Wales can supply an alloy clutch pressure plate to improve feel and grip, and they can also supply a radial needle roller bearing to keep that pressure plate square to the mainshaft.

Whenever practicable, owners are advised to check the alignment of the clutch sprocket and engine sprocket. Various clutches from across the BSA-Triumph range can be coaxed into an A10, and often have been. But mainshafts across the models are of different length, and different spacers and hub adapters are needed to get the primary chain running straight and smooth.

Beware.

The gears are reasonably quick (by Old Brit standards) and engage faster than a couple of teenagers on a hot date. There's the usual first gear clunk, and occasionally you experience a hint of vagueness between ratios. But nothing significant. BSA designed well and built well, and as the miles roll by you soon get into the rhythm and leave your right foot to do what it wants to do in its own good time.

Rebuilding an A10 gearbox isn't particularly difficult. But time would quite probably have taken its toll, so take nothing for granted. Check everything. Measure everything. Question everything. Fix everything. When sorted, these gearboxes will cover tens of thousands of miles without problems.

BSA A10 rigid frames and plunger frame problems

Handling is solid and predictable—unless the rear plungers are badly worn. You'll know (or will at least suspect) straight away that there's a problem there if you corner hard. The bike will wallow quite alarmingly (depending on the state of wear), and on really bad examples you can feel a distinct "notchiness" sometimes accompanied by a soft clunk. But if it's that bad, you can feel it slop about from the starting line, especially if you suddenly turn on the power.

The remedy is a complete plunger strip and rebuild, and it will transform your sloppy mule into something more akin to a racehorse. Or, at least, a trusty carthorse.

Arguably, a rigid framed Golden Flash is a much better ride. Yes, it will be a little harder at the rear, especially when two up and loaded, but that's a small price to pay for cornering predictability—and at the speeds you're likely to be riding, you'll be gaining more than you'll lose.

If you want to sharpen the feel of the steering, you can fit taper roller bearings available from most large BSA parts suppliers. But most of this "sharpening" is nothing other than the act of replacing worn ball bearings and races for new rollers. In other words, the original equipment is adequate as long as it's in good repair.

▲ 1962 BSA Rocket Gold Star (RGS) £18,450. This bike, which marries the highly competitive BSA DBD Gold Star 500cc single looks with an uprated 650cc A10 engine, was sold by H&H auctions in October 2013.

BSA A10 electrics and vibration issues

Upgrading the electrics to a 12-volt system might be wise if you're riding a lot of miles at night. But 12-volt bulbs have finer filaments than 6-volt bulbs, so expect to have the vibes knock out a few every couple of thousand miles or so.

And these bikes do vibrate. Good ones generally start to get uncomfortable after the first few hundred miles—assuming a constant cruising speed of 55-60mph. In which case, you'll want to stop, fill up and stretch your pins for the next leg of your journey (no pun intended) which will impact over the ensuing hours depending on your personal endurance threshold. But you should be able to put in 400 miles in a day on an A10 without needing spinal traction.

But bad A10s are a modern torture inside fifty miles. That said, you'll know a bad one on the test ride because it will feel rough throughout the rev range and may even skip a little on the centre stand when you twist the throttle.

If you've got a bad one, the only fix is to get the engine out, split the crankcase and have that crank dynamically balanced. But a rough engine, note, can be due to many other factors including mismatched spark plugs, a weak HT lead, a weak coil, a sticky valve, a weak valve spring—and numerous other factors. So rule these out first before dissecting the motor.

▲ 1963 BSA A10 Spitfire Scrambler. Bonhams sold this one for £7,510 in January 2012 at their Las Vegas Sale. Click the image for more information and a larger view.

BSA A10 brakes and fork

The single-leading-shoe brakes are merely adequate, and less than adequate for heavy work in town where you can expect a significant amount of fade. Which is why you need to adjust the brakes regularly and clean them out every few thousand miles if you want to stop the bike before something unforgiving stops you. If you're riding two-up and are covering a lot of hard miles, upgrade the front brake to a twin leading shoe item from a later BSA. It will cost you a few bob (maybe a couple of hundred quid or so), but the difference will be worth it.

The front fork, meanwhile, is a decent instrument and soaks up all but the worst of the road violence. You might have to try a few sets of fork springs to get the best ones for your own style and temperament, but cherry picking the right bits can make a real difference. Just keep in mind that many fork springs on the second hand market are well past their sell by date and fit only for scrap. So if you're particularly fussy or sensitive, invest in a modern set of progressive springs—and even then, you may not get a good balance.

If all else fails, knock a couple of PSI from the tyres. But go easy and never run fast and hard on under-inflated tyres.

BSA A10 Prices and spares

Overall, BSA A10s are one of the best all-round British classic bikes you can buy. Fuel economy is good. Maintenance is easy, and fairly light. And they have plenty of all-important presence on the road. In short, people like 'em. We do too.

It's true that the more basic A10s rarely get the heart racing or the eyes popping, but these motorcycles soldier on and on and on with almost—but not quite—wearying monotony. If you want to go touring on a Brit twin and are more interested in the scenery than what's between your legs, you can do much worse than choose an A10.

Prices are still relatively low, with BSA A10s generally on par with Triumph T140s, which makes them usually significantly cheaper than Norton Commandos (assuming the same general condition).

The more exotic variants such as the Rocket Gold Stars (RGS) and the Super Flash will generally fetch anything from two, three or even four times the price of a standard A10. But up-to-the-minute pricing information is beyond the scope of this feature, so you'll have to do some homework.

Spares availability is good, and there is quite a lot of remanufactured items on the market from petrol tanks to chainguards to general engine components and performance goodies. But watch the stuff from India (in particular) which has varying degrees of quality from not too bad to ugly and downright dangerous. Expect to make a few fitting adjustments with re-made parts, and unfortunately that includes some of the items manufactured right here in the UK.

Quite simply, BSA hit all the right notes when they built these wonderful machines. Get to grips with one, and you've got a decent, all-round practical classic that will hold its value and earn its keep.

BSA A10 specialists

SRM Engineering

www.srm-engineering.com

Phil Pearson

Telephone: 01493 780055

www.bsagoldstar.co.uk