BSA A10/A65 SPECIAL
It looks like it just rolled off the production line at Small Heath in the ’50s – but look closer. Black arts have been employed here, to zap this plunger-framed BSA with some ’60s Lightning
Beautiful time-twister with an A65 twin engine in a plunger frame
Considering Robin Ludwell and his mates rent an industrial unit where they build bikes in their leisure time, they’re some of the most prolific classic bike builders we know, producing classy restorations and creating interestingly different specials, based mainly on old Triumph and BSA twins – and this is the latest one.
Robin explains how it came about: “Ian [Williets – Robin’s mate and the official tenant of the industrial unit] had restored a Triumph Blackbird, which I loved the look of. So, the idea was for me to build a BSA twin in a very similar 1950s style. Then we’d have two all-black British twins that, if anyone saw together, would assume they were very similar in age thanks to their styling.”
Initially, though, the intention was for the project to be an AJS. “I had an AJS single engine plus some gearbox stuff, but I didn’t have a frame or forks. So I was on the lookout at jumbles for a frame to build that engine into a complete bike,” Robin adds. “I started scouring the jumbles, but couldn’t find anything suitable, then I spotted a 1951 BSA A10 plunger rolling chassis – with forks, two wheels, rear mudguard, toolbox and petrol tank – all for £900. Well, it was too good to resist.”
While Robin continued chasing a frame for his AJS engine, he also needed a BSA engine for the A10 frame, and it was the BSA lump that came up first. He’d put the feelers out for a twin, and ended up buying a 1964 Us-spec A65 motor from an A65-2L Lightning Rocket – a twin-carb, tuned version for the US market with a 9:1 compression ratio, an optional close-ratio ’box, and twin 11/8in Amal Monoblocs to give it some extra oomph. There was just one issue – the frame was built to house an A10 pre-unit motor, not the later unit-construction twin. Never one to shirk a challenge, and egged on by his mate Ian, he decided to shoehorn the A65 engine into the A10 frame. Time to put the AJS project on hold, though initially Robin must have wondered if he had done the right thing. “While the BSA motor was a complete lump, it was in a right state,” he says. “It was seized – and once we’d removed the top end, we discovered that what had initially looked like two complete pistons sitting in the barrels was actually only one complete piston. The one in the other bore was just a piston crown. Underneath, it had broken up and all the bits were in the bottom of the engine. The rod was
bent and the barrels were cracked. The crankcases were full of water – there was so much in there, that the oil pump pick-up had literally rotted away. The crankshaft assembly was crusted with a horrible watery, rusty deposit.”
The Woodruff key slot for the alternator/stator was also damaged, although friend Trevor Norris managed to recut a slot and made a new key to fit. “Without him, we’d probably have ended up having to source a new crank,” adds Robin.
To appreciate just how bad things were, just take a look at the pictures (on the left here) of the corroded engine parts. But along with resurrecting the motor, there was another huge challenge – getting it to fit into the frame.
“Because the engine was in such a mess, I was pretty open-minded about what I was going to do with the bike,” he admits. “The biggest thing was to be sure it’d fit in the frame. We knew we could do it somehow, but when we offered the engine to the frame we quickly realised it wouldn’t fit between the tubes without major alterations, so Ian got the angle grinder out and attacked the bottom frame rails!
“There was this tense moment of truth. I remember Ian and I looking at each other in one of those ‘shall we, shan’t we’ indecisive moments, then Ian, with this evil grin on his face, just fired up the grinder and chopped the tubes out!
“We took the bottom rails out of the frame completely, six inches in total, and the way the engine sits now, it’s become a stressed member of the frame (where the engine forms a structural part of the frame rather than sitting within the frame). Ian also cut the top engine mounts off the downtubes and then rewelded them back in place, on the opposite sides to the original mountings, and lower than they were before.”
With that done, the engine could be fitted in the frame, so it was possible to work out where the rear engine mounts needed to be. Ian made them from scratch, then welded them in place to the seat post tubing.
Back on the engine, Robin managed to save the original
‘IAN, WITH THIS EVIL GRIN ON HIS FACE, JUST FIRED UP THE GRINDER AND CHOPPED THE FRAME TUBES OUT!’
crankcases and covers and Trevor rebored the barrels to +20 thou, which suggested the engine had not done too many miles since a rebuild when it seized up. The crankshaft was reground and replaced in the motor, with all new bearings fitted. The head only needed new valves and guides; the engine still has the original camshaft inside.
“The bloke I bought the engine off, Pete Dear, was pretty helpful when he realised just how bad it was internally,” Robin continues. “He replaced lots of the damaged parts, plus the oil feed – but after we got the motor back together we had a heck of a job getting the oil to circulate.
“We got oil to the bottom end, but we couldn’t get it to the top of the engine. We ended up going back in there [stripping the motor] and discovered an oilway blocked at the back of the pick-up. We had to remove the pick-up again and drill the oilway – that finally got it circulating properly. We’d already been through the oilways before we assembled it the first time, but must have missed a couple of blockages.
“The gearbox was missing teeth on two gears, so Pete gave me enough gears to put it right. Once we had them, the gearbox was completely rebuilt. When we took the primary case off, it all looked pretty new in there, so the only thing we replaced were the friction plates.”
Robin fitted a Boyer electronic ignition. The switch for the ignition and other electrics are under the right-side seat spring. He now wants to replace that with some smaller and better quality switchgear – probably relocated to under the fuel tank. Only thing is, all the wiring collects near that switch at the moment, so the loom needs to be modified.
An original Lightning Rocket, tested by American magazine Cycle World in June 1964, was revved to 7500rpm to produce a 14.3s standing quarter, with a top speed of 92mph, after the standard silencers had been replaced by a pair of open megaphones. They also achieved an indicated 109mph top speed after a half-mile run, although if there were what they described as ‘favourable conditions’ (a tailwind or going downhill) the Beeza would clock 127mph.
Robin, however, never built this bike with performance in mind, much preferring it to be used for lazy, sunny Sunday afternoon back-lane rides with Ian on his Blackbird and other mates on similar British iron.
Robin explains: “The barrels are stock BSA. There are also stock BSA rods with Hepolite pistons. I didn’t want a performance engine, I wanted a cruiser, so the compression is stock, too. We changed the twin-carb Lightning head to a single-carb Thunderbolt head, simply because I didn’t want the hassle of setting up twin carbs. I think the single carb is a much nicer set-up – and why do you need a twin carb set-up on a cruiser anyway?
“Saying that, it does pick up really well and has a fair turn of speed. But I like riding it at around 55mph – it just feels so comfy cruising along quiet back-roads at that sort of speed when we’re out on a Sunday ride.”
Back on the rolling chassis, Robin and Ian rebuilt the plunger units. “That was a first for me and Ian, but it was pretty straightforward,” Robin says. “The forks were rebuilt with new stanchions, seals, holders, etc. Ian sourced the front brake at the Shepton VMCC jumble; the original on the bike was worn out. The front mudguard, for which Ian made the brackets, is new old stock. He also did the
alterations to the frame and made a head steady. He did a bit of welding on the original rear mudguard to build it back up where it had rusted out, too. Otherwise it was in good order and looks perfect now. Ian’s modification of the standard chain guard for a lower, neater line, finished it off.
“The tank was in great condition – those are the original tank badges, repainted,” adds Robin. The bodywork was all done by Ace Classics, who also supplied the seat and refurbished the speedo and rev-counter.
The eight-inch headlamp came from Andy Rowett, a local mate. “Word got around that I was looking for something a bit different – I thought a big headlamp would give it a slightly different look, especially as I was keeping everything else pretty standard – and one day, this chap turned up at the workshop and said: ‘I heard you were looking for one of these...’”
The exhaust system features A10 plunger downpipes and silencers. Dropping the A65 engine to where it sits in the frame has put the pipes on a line that suits the rest of the bike. Robin admits it wasn’t planned – it’s a pleasant coincidence!
As far as the ‘bling bits’, as Robin calls them, they are all by CPC engineering in Cornwall; they include a steering damper knob with an adjustable BSA logo so it can always sit in the right position once the damper setting has been adjusted, plus fork top nuts with brass inserts that allow you to check the oil without taking the fork nut out completely. They also supplied the complete rear-wheel spindle kit with all the correct spacers, nuts and associated parts. With all the black paint on the bike, their parts really stand out.
The wheel rims and stainless spokes and nipples came from Ace Classics. Ray Hinton, another local who uses the workshop to build his own bikes, built the wheels. The tyres are Avon, with a Speedmaster front and SM rear.
“The bike’s turned out pretty much as I envisaged it,” says Robin. “You have to buy a lot of parts, then see how it all comes together. It’s like the AMC trail bike project I have on the go now – I’ve bought up lots of stuff I’ve seen over the years, telling myself: ‘It may come in useful one day for a project,’ as I handed over the cash!”
Now it’s finished, Robin is delighted – and rightly so. “I’m pleased with how the bike looks. Just small details like the gold-coloured coils matching the gold lining and badges on the tank give me satisfaction - even the exhausts have turned a nice golden colour to match!
“I like something different – but in a subtle way. I don’t like bikes that are overdone and in your face. I’d like to think that I could park this up at a bike meet and some people might not even notice that it’s got a much later, unit construction engine in it.
“And the best thing of all is that it’s a dream to ride. When I go out for a ride with Ian, I’d say the BSA has the edge in the speeds we like to do – my bike’s super comfy at 55mph in top gear, whereas Ian’s is more comfy in the 45-50mph range – his bike tends to hit a vibration patch at 55mph. I was quite surprised how little vibration there is with the A65. But there’s plenty of go in both engines when we need more. I’ve no idea what the top speed is on either bike and why worry about it anyway?” You said it, mate.
‘I’D LIKE TO THINK I COULD PARK IT UP AT A BIKE MEET AND SOME PEOPLE MIGHT NOT NOTICE THE MUCH LATER ENGINE’