BSA LIGHTNING ROCKET
What could be faster than a speeding Rocket? A Lightning Rocket! Frank Westworth went out to play…
What could be faster than a speeding Rocket? A Lightning Rocket! Frank Westworth went out to play…
It’s rather a long time since the great repatriation of ancient British motorcycles from far away began in earnest. From far-flung outposts of the two-wheeled world, back they came; loads and loads of them. Most were mainstream models and entirely familiar to us Brits, but among all the Bonnevilles and Tigers was a selection of TT Bonnevilles and a few TR6C machines; among the Gold Stars was the odd Catalina, and mixed in with all the Lightnings and Rockets was an occasional handful of Lightning Rockets, Hornets – even a Spitfire Hornet or two. Do you remember standing and staring at the unfamiliar machinery? I certainly do. To an eye familiar only with the home market offerings they appeared … strange.
Back in the early 1990s I borrowed several of these reimported ‘export specials’ from a friend in the trade – some things never change. Some were great, some were appalling, but the opportunities for anorak overload were immense – and indeed compelling. I should hold my hand up straight away and reveal that I wasn’t personally wildly excited by the mainstream marques’ overseas offerings, but was more than a little fascinated by the AJS and Matchless equivalents, of which there were several. Matchless Pinto, anyone? Maybe a Tomahawk?
After clambering off an almost entirely original, low mileage and seriously rorty TT Bonneville (a kind of US market open-pipe Triumph, nothing to do with the Isle of Man, in case you wondered), I asked my friend, who we’ll call Gavin, because he was called Gavin, whether folk were queuing up to stuff his pockets with folding money in return for vigorous machines like this one – loud, very loud, and in fact loud.
Also a lot of fun over a very short distance. You’d be deaf after five miles and probably locked up after ten.
He just grinned at me and revealed that no one bought them so he converted them to UK or a less extreme US spec. I wasn’t surprised. At the time, that is. Now of course I am both amazed and appalled. Time works in mysterious ways indeed. Apparently no one knew BSA nomenclature sufficiently well to spot the ‘A65D’ engine number prefix, the ‘D’ in this case being a subtle clue, rather than labelling the engines A65LR, which would have been too easy, plainly. And at the time few folk appeared to care.
So when I was offered a ride on a rather intimidatingly yellow BSA Lightning Rocket I was a little bit ho-hum about the idea. Until I saw the photos and read the specs. This could easily have been the Lightning Rocket BSA had built had they not been a staid British company based mainly in Birmingham. Not only is this particular bike a fine and flashy yellow (my opinions of colour options are variable, as you can see) but it also has a seriously beefed-up engine. The sun was shining, the roads were dry and pleasantly clear of traffic, the lockdown being in force at the time, and it have been churlish to decline a generous offer, so – without much enthusiasm – off I pottered.
That was a joke, in case you missed it. What actually happened was that as soon as I arrived, made pleasant small talk and admired some dull old Vincent or Velocette (or something, they’re hard to tell apart), I just stood there, slack-jawed, staring at the vivid yellow beastie and trying to think of something sensible to say. Apart from, that is, various unoriginal expressions of wonder. In the end I just asked whether it was a total pig to start in view of the engine mods that had been carried out. More on those later. And sometimes it’s not easy to appear intelligent.
Chris just smiled in that easy relaxed way I’ve come to recognise with a steadily sinking heart. He walked over to it, switched it on and kicked it. He was of course wearing moccasins rather than the hefty Caterpillar boots I prefer when anywhere near a motorcycle. Of course it started first kick. Of course it sat there ticking over in a bored and consistent kind of way. I shook my head sadly.
‘Mikuni,’ said Chris, still smiling, like it was a magic word. No choke, no tickling, no fuss, no fun. These things will never catch on.
You already know what a BSA A65 is, but I’ll tell you anyway. Think 1962. The Beatles were yet to happen, Honda were mainly a distant mystery and BSA had decided to replace their popular 500 and 650 twins with new ones, basically very similar motorcycles but for the engines, which were a considerable departure from their earlier models. Although several core features of the engine were carried over – ohv 2-valve top ends operated by a single camshaft carried behind the cylinder block, robust gear-type oil pumps lubricating a crankshaft carried in a ball race (which had of course replaced the earlier roller bearing) on the drive side and a bronze bush on the timing side. That would be the allegedly weak timing side bush which as well as supporting the crankshaft also fed oil under pump pressure to the big ends.
The gearbox was also pretty similar. It still contained just four ratios and still shifted them by application of the right foot. The great big shiny difference was that the gearbox casing was cast in one with the crankcase – the fabled unit construction, as you know.
Fixing the gearbox centre line meant that primary chain adjustment needed to be carried out by tensioning the chain rather than by swivelling the gearbox in its mountings, and BSA did the job properly by employing a triplex chain bathed in oil and resting on the rubber face of a slipper tensioner. No chain could ask for more.
Many, many folk will tell you that BSA (and indeed their Triumph stablemates) made the shift to unit construction as a way of saving money, which may of course be true. However, their big time competitors like Royal Enfield, Norton and AJS / Matchless could also do sums
and presumably weighed the tooling costs of a new engine with the savings involved in building the things. However… it’s also likely that BSA were encouraged by Lucas, suppliers of electrical wossnames various, discontinuing the mighty magneto in favour of cheaper coil ignition systems, while the alternator was already in common use and could be tucked away inside an engine, improving its smoothness and modern image. Whatever, unit construction was hailed as a great leap forward.
Pretty much as soon as BSA introduced their new powerplant, riders demanded that it grow large and provide more power. Twin carbs, higher compression ratios, humpy cams also followed, producing engines which were more pokey but arguably less loveable. I’ve always preferred the relatively gentle charm of the single-carb Thunderbolt to the vigorous harshness of the Firebird Scrambler, for example, but love the latter’s styling, which is – in my view – what a bike should look like, pretty much.
By the time Norton had stretched their 650 to 750 to produce the Atlas, and RE had unleashed their own 750, the Interceptor, lots of riders expected BSA (and Triumph, of course) to follow suit. Which of course they did, and in fine style, with their own 750s – which were triples rather than twins. The Rocket 3 is
another story, and weighty with it. When it launched – and indeed throughout its production run – many were those who felt that the beef of a 750 twin in a light bicycle would more than compensate for the extra horses alive in the triple, hobbled by its extra weight. So – enter the A70, BSA’S biggest twin. A chorus of hurrahs? No. Not exactly.
Once the classic surge was under way, loads of history emerged, blinking, from the ruins of the old industry. A fine example of this was BSA’S own 750 twin, the A70 Lightning 75, which they’d built as an homologation special to allow the company to provide engines for American dirt track racers. The story goes that BSA built 200 of these machines, all of which were sold in the USA – or were at least shipped there – along with a few extra engines. The surprising feature of these particular engines is that BSA opted not to simply over-bore their existing block, but instead stretched the stroke to 85mm (from 74mm) resulting in a device which surely must have pumped out some truly stump-pulling torque!
This bike is not one of those. This is an SRM engine, fitted with that company’s big bore kit. And I can reveal at this point that it is not a big bore at all. In fact, it is considerably exciting.
Rather than go to all the grief and expense inevitable with fitting a longer stroke crank, the SRM (née Devimead) conversion takes the bore out from 75mm to 79mm. This is a proper job, too, involving not only bigger holes in the cylinder block with pistons to match, but an entirely new block casting, complete with fittings and fasteners rather more substantial than original (and now elderly) BSA parts.
This particular example of SRM art includes the company’s well-known bottom end conversion, whereby the original timing side main bearing – a simple bronze bush – has been replaced by a rather more complex device featuring a combined roller and ball bearing to take the stresses, and a total revision of the oiling system. This latter is as important as the bearing, not least because in the original BSA way oil from the pump is fed to the big ends via the bush. Removing the bush… You get the picture. The new feed involves taking oil from the pump and sending it down a ‘quill’ fitted into the end of the crankshaft directly to the big ends. It works well,
too, and was originally developed for racing engines back in the latter years of the BSA factory when chaps really did race A65s, particularly in sidecars, oddly.
There is also a rather improved SRM oil pump to maintain flow and pressure. This is, as you can tell, not a simple cheap job, but if a chap intends to extract rather more performance than Small Heath intended, then every little helps, as we say.
I should also say that although I’ve run a few BSA twins down the years, none of them has had the bottom end conversion, although I ran a Lightning with a Devimead over-bore for a year or so in the 1970s. It was very fast but scarily vibratory and used the original BSA barrels bored to match the bigger pistons. A proper SRM job it was not!
It might seem strange that having gone to the considerable trouble and expense of decently major engineering to get a decently major improvement in the engine’s performance, that the previous owner then chose to fit a single Mikuni carb rather than a pair of mighty fuel-swilling Amals. But they did, and guess what…
Starting is easy enough, as I’ve already said. Hot or cold, whichever ignition system is fitted to the BSA works very well. I can’t find out what kind of compression ratio the engine is running – more than one was offered – but it turns over smoothly, and simply fires up in a way which will be familiar to riders who’ve converted their own bikes to run a Mikuni rather than an Amal Monobloc or two. It pays to remember that the ‘choke’ lever actually opens a cold-start jet rather than dropping a slide into the intake side of things to enrich the mixture, so the handlebar lever works in the opposite way to the Amal way. I needed to be reminded of this. Ahem.
And the engine is quiet and civilised. No no, it really is. Mechanically quiet, I mean. Time for a ride.
The clutch is a delight. It’s always a pleasure to borrow a bike which has genuinely benefitted from the time, effort and expense expended on making it better. Click into first, treading down on the short-throw right-foot lever. And then it’s the familiar routine of working out where the clutch bite point is, balancing that against the imperative to neither stall the engine nor scare the proud owner with the bellowing revs which result from too clumsy throttle control. Happily, this is light, easy, and everything is where it should be and works as it should. I even like the riding position, which is relaxed and quite tall, suitable for a stout chap in full March riding kit. I enjoy being comfortable – I’ve always felt that comfort is all part of being in control, which is why I don’t borrow bikes with clip-ons and rearsets – or indeed apehangers.
Two good things: the roads were almost entirely empty, and this is a great riding position, with the bars holding my hands in a relaxed relationship with both my feet and backside. Even the seat is comfortable, and roomy too. But you don’t care about that. You want to know how well it all works.
First gear is short if you want it to be; rather longer if you want to go rapidly, which is easy enough. Once the engine’s nice and warm it’s comfortable shifting up at a relaxed 30 or so, then into third at 50… and third is a very long
gear, relaxed in a way that 5-speed boxes often lose, for some reason. It would be easier to compare the way the engine works to a 4-speed Commando than to a 5-speed Bonneville, for example. Similar long-legged feel. The shift is very short too, and once on the move it’s not actually necessary to use the clutch.
This BSA rides more like a scrambler than a trad Brit BSA twin. Its riding position and engine characteristics respond well to flicking into a corner, rather than swinging the bend Brit-style, and the wide gearing means that you’re on the power almost as soon as you’ve stopped braking. Which sounds a little frantic, but isn’t. Not at all. Steering is as good as the handling, with the forks and Koni shocks working very well together. Even the brakes are excellent, which is a worry, as this story is sounding rather less than objective. The bike must have some flaws, surely, otherwise the whole world and her dog would be riding A65s.
It is too loud. This is plainly affected by the high level pipes, which look superb, but make too much noise. And if you are riding slowly, in traffic, for example, the heat shields get very warm indeed. Warm enough, for example, to do serious injury to plastic overtrousers. And the bike is limited to what its original design engineers wanted it to do. The Lightning Rocket was never intended to cruise lengthy dual carriageways at 80 or so, and although the modified machinery might be willing, the rider’s spirit would be weak. It is also quite hard, almost harsh – a soft woofly giant this is not, despite the single carb. It is in fact considerably sporting – you would likely be the fastest rider on a Brit bike on a VMCC run, for example. Although such is the softer side of the engine you would be able to trickle along with Bantams if needs must. And without too much clutch slipping.
But basically we find ourselves with a decently self-contradictory machine. On the one hand it has a seriously well-developed power package with altogether brisk performance, but with none of the synch irritations which can so easily plague twin carbs. It’s not fussy, but it is sometimes abrupt. In some ways it could be viewed as just a stretched Lightning Rocket, but on the other hand it’s actually more like a supertuned Thunderbolt. There is little single-purpose about it. It’s both frantic and relaxed, hard or soft depending on how the rider’s feeling that day.
I liked it. I liked it rather more than the oilyframe A65T project bike which grew in The Shed a couple of years back. A faintly sad irony is that this machine’s improvements were built around ideas which were already rolling around the workshop areas of BSA in the late 1960s. Instead, we Brits were offered the increasingly fraught Spitfires, and this is a better bike than any of those I’ve ridden.
And it is yellow, also…