TALES FROM THE SHED
Life in AMC Corner. Frank’s been riding a Bracebridge Street Norton while fiddling with Plumstead plodders. How creative, or something. Exhausting, maybe?
Life in AMC Corner. Frank’s been riding a Bracebridge Street Norton while fiddling with Plumstead plodders. How creative, or
something. Exhausting, maybe?
I’ve been enjoying such a good time hurling the spanners at the lightweight Matchless G5, one of the least over-rated motorcycles of all time, that as soon as I declared victory over the AMC gremlins I rolled the AJS 16 back onto the bench to replace the Matchless. The Ajay really does need to run better than it does, and I was flushed with something or other after a totally pleasant riding experience with the G5.
Have I improved the G5, after only a decade or so of fitful fiddling? Yes, I think so. And there is only one way to properly find out, so on with the gear and out into the roads again.
Although billed as being a lightweight – as opposed to a heavyweight like the AJS 16 – the G5 has a proper big bike riding position. The rider’s not cramped at all, the controls fall readily to foot (and indeed to hand) and it clips along really rather well. The new kickstart return spring does its stuff, the fresh oil and cleaned filter are plainly happy with their lot, and the ammeter shows a charge. What else? Love the handling. Chuff chuff chuff it goes, just like a proper bike. It’s even a little peppy, too, for which they are not famous. The brakes work fine, the engine is brisk (up to about 50) and it appears to be oil-tight as well! A bonus.
The AJS, however, that final incarnation of an engine design which started out in the 1930s, refuses to run properly. It’s really irritating, not least because I paid absolute top dollar for it. That has taught me an unwelcome lesson about buying unseen and trusting my fellow man. OK. Time to move on. Inside this badly running and unhappy machine there is a great bike. One of the many good things about being a marque anorak is that I’ve ridden enough other examples of most models to know how good (or otherwise) they can be. And they can be a lot better than this. The more I tried it, the more frustrated I became. Not least because it is a small truism that more use usually improves a machine. Not in this case, although it did provide some interesting detail about its misbehaviour.
Among its several unhappinesses is a reluctance to accept a decent handful of throttle. This was so bad at first that I diagnosed a sticking inlet vale and acquired everything I’d need to replace it. Serious spitting back through the carb and a total unwillingness to rev when under load and a bit of throttle. This is unhelpful when tackling Cornwall’s several hills. Maybe this was a Lincolnshire export model? Norfolk? Certainly not Devon or Cornwall.
Further experimentation (what else is a chap to do with empty roads and free time?) revealed that if I eased the throttle back, the engine fired less badly, and if I shut the choke a bit it actually pulled almost as well as a 350 AJS should. Much discussion followed, and several pals suggested that it was running weak, a common problem with modern fuels, so they said. A puzzle, then. The lightweight Matchless runs fine on modern fuels.
But there was more. The throttle cable was too tight – or something. When I put the bars on full lock the engine speeded up, and when it was hot the tickover was amazingly high. Destructively so in my opinion. So it needed a carb rebuild at least, as well as a new throttle cable, preferably routed properly. So of course I ordered a new exhaust. This is retail therapy, bike-style.
Exhausts are always an area where I can lose my mind for a little while, particularly
when considering bikes as unusual and indeed rare as the AJS 16. If I wanted to fit a new exhaust header pipe to the G5 lightweight, for example, I would have a few options to choose from – for both the 1966 AJS and the 1965 Matchless CSR, things are a little different. Both were originally fitted with the silly fat silencers which AMC inflicted upon their machines post-63. I like them. Other opinions are available. But until recently they were pretty much unavailable new and I’ve only seen one on ebay in the last decade. Of course I bought it. It’s wrapped up in oily rags and is destined to go onto the CSR at some point.
However, the CSR really needs a set of header pipes. Not just because they’re pretty unsavoury in appearance but also because the left-hand pipe blows like a steam whistle at its joint with the cylinder head. And I cannot actually budge it. I mean… of course I could apply great heat and hammer violence as well as the next artless bodger, but this is unhelpful if it results in the destruction of the pipe – and if the pipes are unavailable. Which they almost are. A conundrum.
However, the AJS 16 needs a new pipe, if only so that I could possibly have the tatty original rechromed, or something similarly bonkers. There is a company in Slovakia who supply new ones, and I know that their work is good because I bought one from Mike Partridge of Walridge Motors way back when I was rebuilding a 1965 Matchless G80. I was seriously stupid to sell that bike, too. I wondered whether the company who supplied Mike would supply another silencer to me? And as they’re in the EU and the UK is not, I wondered whether the endless online ranting about the impossibility of importing stuff from the EU was accurate or simply nonsense.
Email is a wonderful thing. I mailed Miloš at Buyak.sk and asked whether he could supply such a silencer. Of course he could. He offered one at a delivered price, inclusive of all taxes
– which was little more than buying a new silencer in the UK – and I sent him the money electronically. This was of course a risk, but you get nowhere without a sense of adventure.
The silencer arrived. It was utterly excellent. It was also a left-hand silencer for a twin, not a right-side silencer for a single. I mailed Miloš. He was profoundly embarrassed and put a correct item in to the post immediately, asking only that I return the original, which I did. No fuss, no argument. A simple mistake, easily corrected. We returned the wrong silencer – this is no more difficult than sending a parcel within the UK – and were surprised at how little it cost, including EU taxes. Ah, said the online experts; just wait until the huge tax / VAT demand arrived, you’ll not be so smug them.
I’m still waiting. The replacement silencer arrived, complete with a small envelope marked up ‘Post’, which contained a decent sum in Euros to cover the cost of sending the wrong one back. It was far too much. I’ll deal with Miloš at Buyak again. Inevitably.
But a new silencer would make the Ajay’s original tatty header look strange, so I decided to replace that as well. Life is filled with excitement, no?
As soon as I mentioned my intention on the RC Facebook page, the most excellent David Manuell got in touch to reveal that he had a late model AJS 350 exhaust header – and even more amazingly he simply stuck it into the post! And it arrived, and was indeed marked up with a note saying what it was and it was even in decent condition. Who could ask for more?
And now, stumbling only a little, we enter the Strange But True department. I offered David’s pipe up to the Ajay’s exhaust port and instantly observed that it was rather too slender. I am a Noted Expert: I can spot these things. Expertise is its own reward: trust me on this. But! How come the right pipe didn’t fit the right bike? Time for deep thought and actual research. Are you ready? Can you cope with this excitement? OK then…
In 1964 for no reason I can understand, AMC changed the outside diameter of their exhaust pipe, increasing it to 1 5/8”. So while you’ll see pipes listed for 1962-on, they may be 1/8” smaller in diameter than is required for the 64-66 machines. Happily, Armours list the exact right pipe – and I mailed them to confirm this, as you should – and indeed they supplied it, PDQ, too. It was the correct size, and fit the bike when I offered it up. How can this be? If things fit, what can an earnest scribbler complain about? Happily…
…the pipe was about a half-inch too long, which mean that it stopped the most excellent silencer fitting where it should. Phew. But the
silencer’s intake fit the pipe exactly, and I am a man with a hacksaw and the skill to operate it! Although it took me two attempts, caution being what it is. On went both pipe and silencer, and don’t they look good! They sound good too, which is always a bonus.
Now then gentle reader: remember the research that I just did, because it solved another forthcoming minor mystery. This time concerning the carb. Which should be a 276 on a 350, right? Wrong. In 1964 AMC changed the carb to a 389 with a bigger throat than the previous 276. How is this important? Because a previous owner did not know this and had plainly had the carb apart. Do you remember the misfire? Read on, grid your lions.
It is my view – often expressed – that the old factories knew how to build their bikes. My logic has always been that if I return the functional parts of a motorcycle to pretty
much as the factory built it, then it should run fine. Cosmetics? They’re up to the owner, probably. So after I actually managed to make the AJS rideable, more or less, I found myself puzzling over why the revs rose rapidly when the handlebars reached either lock. This can only be the result of a cable which is too short, and is curable by adjusting the cable so that there’s sufficient play to allow the bars to move through their full range. Easy.
Except that there was no free play at the twistgrip and the inner was so short relative to the outer that the carb’s slide never actually seated – hence the wild tickover. And the adjuster was already screwed fully home into the top of the carb, so there was no adjustment left. Easy. Dig into The Shed’s many big boxes of potentially useful bits and find another cable. None of them was an improvement – most had such a difference in the relative lengths of the inner and outer that it was impossible to adjust them properly, even if the cable had an adjuster as well as that in the top of the carb.
So I bought two new cables, from different suppliers, claimed to be dimensionally identical and with the right size of nipple for the bike’s original Amal twistgrip. Both arrived. Only one was the correct length, inner and outer. That one had the wrong sized nipple. The cable with the correctly sized nipple was far too short. By this point I was beyond getting grumpy!
Out with the file and into the vice. After almost no time at all the nipple worked perfectly in the twistgrip and as if by magic the carb’s slide now touches down as it was intended to.
Chats with a pal about the bike’s serious spitting and missing when under load suggested that it was running weak on modern fuel. It was certainly running hot; the new chrome exhaust header went blue within five minutes of starting the engine. The cure? New main jet and raising the needle a notch. I bought the new jet and … hang on, the old jet is a 230 and should be a 260. Has someone been here before me? They surely had: not only was the jet too small for real fuel, but it also had small witness marks, suggesting that it had not been fitted by an Amal fitter. Happily I had a new jet … but it was a bigger jump in size than I felt comfortable making. Back to that big box of bits and unearth a new
(how? why?) 260, which I fitted. Meanwhile, I discovered another sign of the earlier fiddler – the carb’s needle was visibly bent. Not a small bend, either. How … remarkable. And I didn’t have a spare. Oh well, they’re not expensive and are freely available.
This is what I mean when I talk about putting a bike back to as close to its original spec as possible. I do this not because I am a Noted Expert, but because I am not. In my long experience of these things, a bike is almost always considerably improved by putting the carb and exhaust back as close to stock as possible, setting the ignition timing by the book, and generally undoing the ‘improvements’ which previous owners have inflicted on it down the years.
Proof. Pudding. Carb back together, tank back on. Time to… hang on. The choke cable’s route is a mess: it’s the work of seconds to put it right, so…
Have a look at the pics which should be nearby. Someone had broken the original choke lever – easily done, usually by trying to free the cable by levering its guide with a screwdriver. I’ve done this. Of course I have. And then I’ve bought a replacement lever and gone on my way. Not the Ajay’s previous owner. He’d somehow repaired the lever! I’ve never seen that before, but it works, so I’ve left it. And ordered a replacement lever, just in case.
Proof. Pudding. Try again. First kick, and off it goes. That was a surprise.
I was so surprised at the steady and relaxed tickover than I pedalled hotfoot out of The Shed and dragged the Better Third in from her relentless antibamboo campaign to stare in wonder and admiration. Which she did. And then – while it sat there ticking over like a relaxed steam engine – I pedalled hotfoot back to collect hat and coat and set out for a reasonable ride. Five miles, in the end, and apart from being oddly gutless – at least after the G5, which is unusual – it ran well. No misfire, no spitting back. Huge hurrahs, then. A little vindication of my cautious original-is-best philosophy.
Remind myself on the first decent lefthand bend that I really do need to replace the bent centrestand because it seriously ruins the cornering.
Rolled cheerily into The Shed, clicked neatly into neutral and the engine showed its delight with its new bits by proceeding to spit back through the carb a couple of times and then stall. What! I kicked it up again and it started instantly, but would no longer tick over. Turned it off, then on again; same result. How very strange. I find myself wondering whether the automatic advance mechanism is failing to automatically retard when hot? Hmmm.
More irritating however is the puddle of oil which forms beneath the gearbox. The box was empty when I acquired the bike, so I’d filled it, like you do. And it doesn’t drip at all when standing for a week or several. Does this mean that the gearbox leak isn’t a gearbox leak at all? If so, and because the leak only happens while the engine’s running and immediately afterwards, does this mean that pressure somewhere is forcing out the oil? Could the culprit be a leaking oil return pipe? I hope not, because there are none spare in the whole world…