BSA A65 GUIDE
Compared to its pre-unit counterpart, BSA’S A65 accumulated something of a suspect reputation over time. Paul Henshaw has built and ridden most of the range, and reckons their infamy is undeserved…
Compared to its pre-unit counterpart, BSA’S A65 accumulated something of a suspect reputation over time. Paul Henshaw has built and ridden most of the range, and reckons their infamy is undeserved…
Although I’ve never actually owned an A65, that situation could be subject to change at any time as I greatly admire them. On the very day I started writing this, I was offered a pre-oif Thunderbolt, so the information here is much to advise myself as it is for anyone else. Despite not (yet) owning a 650 unit Beezer, I have worked on a dozen or more during the last ten years, work which included several partial or full engine rebuilds. Before these bikes go back to their owners I typically cover 50 to 200 miles on each, to ensure all is well. So I have a fair idea of how most of the various types of A65 perform, handle and generally ride around the Welsh hills, bends and straights, giving a good, overall impression of them. My first encounter with an A65 was when I was about 10 years old. Our neighbour bought a mid/late 1960 Lightning fitted with a single-carb head, long megaphone silencers and the massive fibreglass Spitfire tank.
It cost him £50 and inspired my father to buy his 350 Norton Navigator for £35! I bought my first bike less than a year later, so this A65 and its owner have a lot to answer for. When dad and Doug rode together I would hop on the back of the BSA, which evened out the difference between the two somewhat.
Even then, it struck me how effortless everything was with the BSA. It never sounded flustered or strained and it felt safe and planted. When idling, the BSA would fall to a ridiculously slow tickover. After suitable refreshments, it nearly always fired up first kick and went straight back into that almost mesmerising tickover. I never saw it stall even though I often expected it.
Forty years later I had an enquiry about doing some work on an OIF Thunderbolt. I’d seen this machine 20 odd years previously, in a cow shed on a farm, looking rather sorry
for itself. Apparently, some deft work
with a telehandler boom and a chain hoist was required to lift the A65 out of that shed! It looked even more sorry for itself when it finally turned up…
I had inevitably heard many of the horror stories about these 650s and how they will chew themselves to pieces in a flash if you so much as dare to start their engines. This one had the dreaded crankshaft end float after a previous rebuild, many moons ago. A full engine strip it would be, then. It turned out that most of what was inside was in good shape, but there were no shims present inside to take up the end float: none had been fitted!
Shims were soon fitted, the sludge trap was stripped and cleaned, gaskets, seals and various other consumables (valves, guides, piston rings, etc) replaced. Then it all went back together, minus the end float, into a tidied-up dove-grey frame. There was some non-factory weld at the lower end of the main frame tube, near the swinging arm pivot. This can be a bit of a weak spot on such frames and obviously it had cracked at some stage on this machine. It held its oil so must have been OK.
This was not a restoration, not by any means, so the bike still looked quite sad but the engine was a cracker. As soon as it started, I was transported back in time by that incredible slow and steady tickover, just like a beating heart. Badumff, badumff, badumff, badumff: lovely, and pretty amazing for such an over-square, short-stroke engine design.
Let’s get one thing straight right away; the timing side bush is not the best or strongest bearing in the world but it is adequate. Proper servicing at the correct intervals, with good oils, will go a long way towards prolonging the life of the bush and the engine in general. Neglect will have the opposite effect! These machines are only as good as the care and maintenance they receive, but they needn’t be wrapped in cotton wool, either and can be given a bit of stick without falling apart. They are not, as some would have you believe (even now) ‘bad bikes’.
I have worked on some real dogs, but this was never anything to do with how they were designed or put together at the factory. For instance, there was a ‘rebuilt’ mid-60s Lightning which came back from the USA. The owner asked me to ‘just give it a service, the tappets are a bit noisy’. It needed a full engine rebuild because, although the engine had obviously been apart and lots of new bits were found inside, someone had forgotten to cross the oil pipes between the engine and oil tank. So the engine had only been splashlubricated by the half pint or so of oil that had been put into the crankcase at some stage and was trapped in there. Meanwhile the oil pump scavenge side just pumped random bubbles of air into the oil held captive in the tank via the feed pipe connecting the bottom of the tank to the oil pump!
The ‘noisy tappets’ turned out to be play in the big ends. The cylinders had been rebored and new pistons fitted. The bores were way too tight, and needed honing to fit the pistons, which had survived thanks to the big ends getting noisy before the pistons ran out of splash lubrication. The valves and guides needed attention; the wheels were buckled with flat spots in the rims (possibly in a crash when it hit a kerb hard while on its side); the forks didn’t damp very well with water in one leg and dry, powdered rust in the other one; there were electrical gremlins, carb gremlins, the clocks needed repair, the fuel tank leaked and the handlebars were bent. The only things I didn’t touch were the seat and the swinging arm!
I found other engines with crank end float issues, again because they’d been assembled minus vital components or using incorrect ones. The worst A65 I’ve encountered was a truly stunning-looking machine. The new owner bought it after a very expensive ‘professional restoration’ for not far off £8000. The motor was knocking and rumbling loudly and within minutes of its arrival, I had measured some 1.5mm (0.060”) crankshaft end float: only 20x the maximum permissible! The owner started it to demonstrate the noises and he suggested I might take it for a ride. Thankfully, I had found the end float already via the removable inspection plate for checking the ignition timing, on later models.
When I took the crank to be inspected with a view to having it polished or reground, John at Aeron Engine Services was quite intrigued
by the timing side big end journal and the lop-sided measurements he was seeing. This turned out to be caused by a crack running two-thirds of the way through the big end journal: a broken crankshaft, which would have probably destroyed pretty much the entire engine. Glad I didn’t accept the owner’s offer of a preliminary test ride…
There’s a pattern emerging here. None of these problems were down to how the machines were designed or put together or the materials they were made from originally. But it’s possible to spend a lot of money and effort and still produce a ‘bad BSA’ which would cost considerably more to put right!
UPGRADES & IMPROVEMENTS
One engine I rebuilt already had the timing side bearing conversion. It still needed a crank regrind, new big ends and the sludge trap cleaned out. Personal preference obviously applies, but magnetic sump plugs and remote oil filters are a wise move. If your oil pump is getting tired, then new and improved ones are available and not hard to fit.
Electronic ignitions are popular and I would choose one without hesitation if the original points set-up was missing or worn out. However, I’ve had several A65s that ran nicely with points ignitions and their original carbs. If you’re considering binning carbs and points in good condition – well, my bin is just at the end of my lane! Please feel free…
MUST-DO MAINTENANCE
Let’s assume that we have a correctly assembled, well maintained example of a pre-oif A65. Carefully ridden and never thrashed, it could still be in mortal danger. The oil tank design isn’t very user-friendly. It’s virtually impossible to remove, even with the seat and rear mudguard out of the way. Few are removed for thorough cleaning. If you have ever drained the oil tank and poked a finger into the oil feed strainer hole / drain plug hole (don’t get stuck in there!), then the chances are you will find a fine residue, a bit like grinding paste, about an inch deep. It’s usually right at the bottom and just below the filter gauze, so could go straight back into the engine immediately after an oil change, when it gets churned up with that six pints or so of lovely fresh oil just poured in.
Much of this stuff may well have been in there for most of a machine’s life, slowly causing unnecessary wear and accumulating steadily. Time spent getting the oil tank spotlessly clean inside will pay dividends – the oil tank really should be considered a part of the engine itself and treated as such. It’ll extend the working life of the oil pump, timing side bush, sludge trap and big ends if it is kept clean.
Removing the crankcase sump plate permits removal of those last oily dregs. The scavenge suction strainer can also be examined, cleaned and checked for any nasties. Any metallic flakes found here will probably not herald great news.
One not-so-nice aspect of the OIF models is removing and refitting the cylinder head. There isn’t a lot of room beneath the fat top frame tube. It’s best to leave some of the inner head bolts loosely in place. I once got a head on, fitted some outer bolts and then
found a couple of inners wouldn’t go past the fat top tube. The cylinder head had to be lifted part way off again and tilted to get them in.
Let’s not forget a nasty little bolt at the rear engine mounting, one of the smaller of the four. It’s very nearly too long to fit when offered up from the gearbox sprocket side, but only just long enough when the nut is fitted and tightened at the other end. Unpleasant on pre-oif models, it is out-andout nasty on the OIF bikes!
There is also a fiddly steel cover, held by three screws to the inner drive side of the engine, which is often missing for obvious reasons. In either frame type, the oil pipe fitting to the underside of the engine needs to be in place, with a good gasket fitted, before the engine is bolted in. You probably won’t get it off with the engine in place in the frame.
Over the years, many small changes were made even to bolt and thread sizes, as well as minor changes to the main bearings, the timing side bush, the thrust washers and shims, the conrods. It’s a good idea to know what you have, and take care when ordering parts. ‘I want a full set of main bearings for an A65,’ could get you a variety of things which might all fit, but won’t necessarily work out too well. Study the parts lists and ask questions if you have doubts. Give engine and frame numbers and even email pictures when ordering parts. Burton Bike Bits, Draganfly and Kidderminster Motorcycles have all been very useful and helpful, and some of the SRM upgrades can be helpful when rebuilding, too.
I find it best during the engine build to get the cylinder barrels on before putting the engine into the frame, but leave the head off until the engine is in place. The barrels are heavy and add considerably to the weight of the engine. I’ve found it easier to fit the barrels with the engine moveable and at eye level on the bench, than when in the frame, but the engine is easier to get hold of and put into the frame and jiggle about as required before the head goes on. Personal preference again, perhaps, but it works for me.
MODEL CITIZENS
Many changes and improvements were made during the A65’s ten year lifespan. Some of the hotter / later models certainly ask more of that timing side bush when pressed, no doubt about that. But are today’s owners constantly wringing a classic roadster’s neck? I doubt it.
The Thunderbolt is one of the more gentle variants, with its single carb and fairly low state of tune. It should be easy to kick over and start and can be a pleasant machine, capable of comfortably maintaining A-road speeds and occasional overtaking. It’s notably less powerful than the Lightning and Firebird variants. With either frame, the Thunderbolt is a relatively low stressed machine and should return good fuel economy – its hotter counterparts can consume far more fuel if their extra performance is often enjoyed. The Thunderbolt’s low state of tune will of course be less demanding on the various engine components.
With only one carburettor to worry about, an A65T might appeal to anyone who is not too comfortable with setting up a pair of old Amals. From a financial point of view an OIF Thunderbolt can be a very attractive proposition. It will be nowhere near as soughtafter nor expensive as a pre-oif Spitfire.
The Lightning and Firebird versions have two carburettors, more compression, more noise and more speed. I’m drawn to the higher performance models in the A65 range; BSA’S answer to the Bonneville. They can certainly go a bit when asked, especially
compared with the tamer Thunderbolt. I prefer either type of Firebird and the pre-oif Lightning in US spec, but that is a personal thing. Each to their own!
Finally we have the fire-breathing monsters which were all pre-oif as far as I am aware: the Spitfire and Spitfire Hornet. The Spitfire came in UK and US specs and developed something in the region of 54bhp. Not to be sniffed at! That ‘adequate’ timing side bush really had its work cut out with that lot going at full chat. Twin GP carbs were fitted to some and these might be more tricky to set up than a pair of Monoblocs or Concentrics, with a remote float chamber and no tickover adjuster screws.
I did some work on a Spitfire Hornet scrambler, a version made for export for just one year, and I had the chance to ride it. I believe it had a compression ratio of some 10:1 or more and it showed, both with an angry snarl from the straight-through highlevel pipes and by lifting the front wheel as I let the clutch out in first gear! I am pretty sure it lifted the front wheel again as I opened up in second gear. What an animal.
TAKEN FOR A RIDE
Handling and braking should be fine on all variants. The riding position on earlier bikes mean you sit ‘in’ rather than ‘on’ and this is accentuated on the US versions with high handlebars. The OIF models handle well but are taller by a small margin. There are at least three or four different front brakes used over the years and they should be adequate at the very least. A well set-up conical front brake can lock a wheel – you don’t need more than that (at least, I don’t.)
The A65s are a good tourer, and despite being a short-stroke type engine, they pull well from very low revs even in high gears. This is where they come into their own. Where a Bonneville might urge you to go faster and faster using the revs and gears, a Lightning excels at a more relaxed, high speed cruise. It romps around corners and pulls effortlessly out of them with a twist of the throttle instead of frantic and frequent gear changes.
Contrary to this rather laid-back nature, we have what must have been one of the closest ratio gearboxes on the planet in its day, certainly between third and top gear. It can feel as if you have changed into another third
ratio, there is so little change in engine note and not much of a fall on the tacho. Presumably this was to help keep that pesky Bonneville within sight! The biggest gap is between second and third, and I suspect that the five-speed conversion probably addresses this.
However, the standard four-speed gearbox is one of the most pleasant in the business. It’s a much enlarged version of a Triumph Terrier / Tiger Cub design, believe it or not. Very smooth, precise and strong. Neutral should be very easy to find at a standstill.
I wouldn’t describe any of the various A65s as ‘light’ but they are fairly manageable. Apart from when you need to haul an OIF variant onto its centrestand. This really is an unbelievable struggle, even if you’re a fairly strong 15 stone chap.
BEST BUY?
So back to my possible acquisition of an A65T. The Thunderbolt is not the most exciting of the bunch, but the one being offered to me is pre-oif. It looks quite presentable, runs and might be ok… but it might not, and there’s the crux. I would rather buy a tired example or a basketcase for much less money and sort it out myself. Then I’d know it’s good, rather than gamble on a tidy-looking one which will cost more but could still need money and time spent on it.
Once you (or even I) have found a good one we shouldn’t need to remove / rebuild the engine every other weekend: they really aren’t that bad. The A65’s worst enemies are not their design ‘shortcomings’, but people who don’t realise the importance of some of the little bits are that are supposed to be inside. Cleanliness of the lubrication system and proper routine maintenance will go a long way towards helping your A65 go a long way.
They really are not such bad bikes!