TALES FROM THE SHED
There’s life in AMC Central! FW has been adventures… enjoying some singular
If your memory is less unreliable than my own, you may recall that last month I finished off the story with the AJS 16 sitting on the bench poised to receive its rear wheel, complete with a new tyre of mysterious manufacture, a new battery and indeed some new oil for the forks. Phew. In a moment of optimism, or madness, which may of course be the same thing, I also included a photo of the entire bike, complete and ready to roll. Which it did. So! My plan for this episode was to triumphantly reveal how my masterful skills had overcome the strange mechanical mischief wrought upon an otherwise exemplary AJS by some anonymous maniac, and to share with you that delightful riding off into the sunset moment. However.
The fork oil. Even SAE20 takes its time winding amusingly down the fork springs – and that’s telling you nothing about my impossible
inability to remove the fork top nuts to actually pour in that very oil. I was forced to seek advice from the Profound Sages of the Realclassic Facebook group, which is a sure sign of deep terror and indeed frustration.
The problem? I could unscrew the fork nut on the first (right) leg so far but it simply refused to detach from the stanchion and come free. This has never happened to me before, so I was bewildered.
The answer? It’s completely obvious. Undo the other fork top nut completely and lean on the handlebars, so compressing the forks a little. Both nuts promptly released, and I could savour the relaxing moments – many moments – as the measured amount of the right oil wended its way down the spring and into the leg. And then it’s a simple matter to tighten up the nuts and smile a smile of accomplishment. Or something. Amusing how a simple and obvious answer to a simple and obvious dilemma could have eluded me, no?
Refitting the rear wheel was easy. It went straight in, and spinning it around by hand revealed that the odometer at least was actually working. Hurrah. I’d cleaned and
greased the replacement speedo drive too, and it appeared to be working properly. Even the new (and horribly expensive) battery was the right one and fitted perfectly after I’d first introduced a fuse into the circuit before fitting the battery itself. If you recall, when the new cell arrived, I’d started to connect it, but had been rewarded by flashing sparks and a full-scale deflection on the ammeter. Fitting the old, dead battery and connecting the charger across its terminals produced no electrical unhappiness, so I dug out a nice new fuse holder, connected it all up and tried again with the new battery.
It worked perfectly.
Next! The engine had spit back unbearably, last time I rode it. It also ran a very fast tickover when hot, so I backed off the tickover, checked that fuel was flowing through the replacement replacement tap (it is impossible to have too many replacement taps) and fired it up. It started at once. Well, it did when I remembered to switch on the ignition. Every little helps.
It sounded very well. Oil was returning to the tank. The ammeter was showing a charge, the new battery’s vigour was obvious. The sun was shining. I grabbed a crash helmet and a jacket, and ventured out into the wilds of the Cornish lane along which we live. I scanned the horizons anxiously for signs of invaders – there were none in view. Off we go!
These late 350 singles are quite quick, but a chap’s natural exuberance needs to be tempered with cautious resolve if elderly bearings are to survive being put back into regular use after a long rest. The speedo’s neat red needle swung to a heady 40mph, at which point I hefted the gear lever to select top gear. Boom, went the exhaust; chatter went the valvegear; whoopee sang the rider, who should have known better.
About a half-mile from RCHQ there is a wide farm gate, and I decided to turn around there, head back to the ranch, then repeat. One of the many joys of having no nearby neighbours is that it is possible to chug, rattle and bang up and down the lanes as much as a chap might wish, irritating only sheep. The only hazards are ambulances speeding to the nearby care home, and our neighbour out on his quad bike, seeking refuge from sheep and ambulances. I saw neither.
Pulled up, observed that the tickover was
still at an unrelaxingly elevated engine rpm, but otherwise all sounded well enough, the odo had recorded a half-mile, so might even be a bit accurate, and we headed back to the res. Turn around: repeat. A chap may not get to experience the thrill of adventurous exploration riding up and down the same stretch of lane, but everything has its moment. After exactly two miles the speedo stopped working.
And the misfire returned. I may have cursed a little. The wind roar was quite loud, so I probably wasn’t offended by my own profanity. In any case, I could understand my reasons for swearing. Tolerance in all things is important.
The misfire was more of an irritation than the speedo’s demise. It was less percussive than previously, so I carried on my reciprocating voyage of discovery to investigate further. It’s throttle related. Opening the throttle wide in the top two gears produces a sudden aggressive misfire and spitting back through the carb. When this first happened I had convinced myself that the inlet valve was sticking and had indeed acquired all the parts to perform a top end overhaul. They’re safely in storage.
As soon as the spitting back starts, easing the throttle a little cures it at once. So it’s not a sticky valve. Snag is that it’s too spitty-back to actually pull top gear up a hill, so that’s a little annoying. More annoying than that. I rode back to The Shed and parked up the AJS, leaving it running at what may more accurately be described as a fast idle than a tickover. There was a large and growing pool of oil beneath the gearbox. You’re unlikely to recall that I had filled the box because it was empty. Now I know why. Switched off. Removed the fuse. Parked the bike.
For a very long time now – several years, indeed – I have been intending to replace the kickstart spring on the Matchless G5 which was parked shyly next to the AJS. It’s a job I’d never done, so when the Matchless first arrived in The Shed I ordered the bits to do the job, read it up, and determined there and then that it was a job for an experienced mechanic. Recognition of such uncomfortable facts is one reason that I am internationally recognised as a Noted Expert.
However. Understanding for once that if I vented my spleen (which means what, exactly?) on the AJS then I would just break things, make it worse, and render the old tub even less valuable than the idiotic price I’d paid for it. Do not mention this to the Better Third, who might lose her towering respect for my unerring ability to spot a bargain. So instead I decided to work off my grump with a little spannering on a bike which everyone says is rubbish, so I cannot possibly hurt it. Correct? Good. Glad you agree. Have a lollipop.
Whenever I acquire a new … another motorcycle I typically waste even more money by buying handbooks and parts lists. I surely do know how to have a good time. So of course I have an assortment of instruction books and spares lists for AMC’S light singles. Replacing the kickstart spring is obviously such a simple task that it gets mentioned only in passing. This is a good sign. I venture into the misinformational morass which is the internet and promptly wish I hadn’t. The easiest way to replace the spring, revealed several noted experts, some with video, is to remove the gearbox first. This involves a lot of dismantling, as you know and… and…
I ask those of my few remaining friends who will admit to working on these machines for advice. These are prompt arriving and contain a common theme: take it to Kenny at Ace Mosickles. Leave bike there until it’s fixed. Pay the bill with a wide smile and without question. Then sell the bike or throw it from a high cliff. This is encouraging stuff.
There are many good reasons for owning and riding a bike which is unfashionable, which everyone hates and which is therefore inexpensive. Relatively inexpensive. I am emboldened. Up onto the bench. Gird loins. Wipe down the amusingly vast alloy cover which in the eyes of some pretends that the engine is pretending to be unit construction. In fact, I think it’s just a cover, and that if AMC had
wanted to build a unit single engine that is exactly what they would have built. They didn’t, so they didn’t, but they did want it to look smoother and more modern than their trad big bangers – which it does. To my eyes at least. Other views are inevitably incorrect.
Of course, this being a fine representative of classic British motorcycle engineering, to remove the cover to get at the other cover so you can remove it to get at the broken spring, a chap must first remove a footrest. Also the exhaust. The former is easy enough, as you might expect, while the exhaust pipe is a very tight – some might say immoveable – fit in the cylinder head. I’ve worked / played with AMC machinery for over half a century and have often wondered why other, plainly lesser manufacturers went to all those big threads into the cylinder head performances. The Norton Commando? I mean…
Just two nuts release the pipe and silencer from the frame – and these were not the original nuts, either. Grasping my comfort anorak for safety, I observed that these two nuts are actually brass pillar nuts, and although of noble Cycle threads they take AF spanners. What nonsense is this? As my sanity stabilised itself with a promise of an imminent glass or two of strong cider, I worked out that the nuts were car exhaust manifold nuts, usually fitted as brass rarely welds itself to steel. That’s OK then.
Thor, King of Hammers, made short work of removing the exhaust pipe from the exhaust port. Delicacy in all things is important.
The shapely, handsome outer cover is retained by four screws, which just … unscrew. That wasn’t very dramatic. I am further encouraged. I am also considerably amazed at the condition of everything inside the cover. It looks new. I hope the pics do it justice.
Given the bike’s mileage, the internal condition is remarkable. The only fastenings which bear visible witness marks are the six screws holding the gearbox’s outer covers together. The rest look untouched. I wonder how this can possibly be? But I don’t wonder for long. Gift horse, mouth, that kind of thing.
Online experts and owners’ club forums suggest that the best way to remove those six screws holding on the cover under which lives the kickstart spring is to shear off the heads and then use a set of Molegrips to remove the broken screws themselves. This seems extreme, even to me. I cautiously insert the tip of my big screwdriver (an ancient Draper) into the topmost screw, and rotate! The screw turns. Just like that. So much for online experts. Huh, etc.
Two of the others also unscrew without much effort. That’s half of them, then. The others are resolute. They are determined to stay where they are. They are not, we might say, for turning. I consult the assembled brilliance and technical excellence with is the RC Facebook group. There are many, many suggestions, most of them amusing. I dig out my elderly impact driver and a harder hammer. The impact driver has never ever succeeded in freeing off a stuck screw,
but there is always a first time.
This is not that first time.
However, the impact driver and a few of the comments from The Reader reminded me that sometimes counter-intuitive counterturning works. In order to loosen the screw it is sometimes an idea to tighten it further first. I do this. The remaining screws unscrew without fuss. This technique was first suggested to me by a seriously gruff fitter when I worked (briefly, mercifully for all) as a plant fitter in the early 1970s. I thought he was insane. But it worked. Sometimes. The outer cover came free with just a little encouragement from Thor, King of Hammers, and the anticipated flood of oil from the opened gearbox failed to pour forth. Of course I had already removed the drain plug, but that only released a few spoonsful of oil; clean oil, but little of it.
Oil is a contentious subject with these gearboxes. As in fact are the boxes themselves. This is all down to the engine’s interesting design, and the idea that AMC were trying to make their new powerplants look as though they were unit construction. I can’t see that this is the case. If they had wanted to build a cheap engine, then they could have built their own version of the BSA C15, a seriously cheap piece of engineering, typical of Edward Turner. Anyone who struggles with the mysterious belief that AMC were incapable of designing a unit-construction engine needs to take a look at the light Norton twins. Amusingly, the internals of the gearbox used by Norton’s light twin engines are pretty much the same as those in the AJS / Matchless light singles, although the Nortons adjust their primary chains using a slipper tensioner rather than by moving the clutch and its chainwheel rearwards.
Matchless decided to stick with the non-unit approach. I once read a long interview with – I think – Phil Walker, who – I think – was the engine’s designer. Of course I can no longer find that feature. This of course means that I can’t pass on his explanation for this curious choice of engine construction, which must have cost a huge load more to manufacture than the simpler unit approach. Whatever, that’s what they did. Where the lightweight box differs from the heavy singles is in the way it’s moved to adjust the primary chain. It’s rotated, rather than pivoted rearwards. The box’s castings aren’t bolted up to the crankcase. Rather they’re clamped to it by a pair of strong steel straps, which when loosened allow the entire box to be rotated, and as the output shaft isn’t concentric with the box casting, this rotation adjusts the primary chain tension. It takes longer to write it down than it does to perform a chain adjustment.
A strange feature of this otherwise mostly rational arrangement is that the gearbox’s two shafts are mounted high up, presumably to suit the geometry required to achieve that very same chain adjustment. In turn, mounting the shafts high up in the box means that they are a long way from the bottom of the shell, which means that there needs to be a lot – a big lot – of oil inside to keep the gears lubricated. These boxes have a reputation – justified – for wearing and whining, especially in the intermediate gears. They also leak, mainly around the output shaft. So I was a tad sad to observe how little oil came out of the box.
Oil is for later. I observe that the kickstart spring is indeed broken. Hurrah. That’s easy to fix, and I have at least a few spare springs. I’ve been intending to do this little job for most of a decade and every time I decide to do it I acquire another spring. This is a fine example of hope springing eternal.
The spring fits into two holes, one in the gearbox centre casting, the other in the kickstart shaft. No problem! Except that I am too feeble to be able to stretch the spring to fit properly so that it exerts enough tension to return the kickstart lever to a fine upstanding position. I try levers, screwdrivers, hammers and drifts. My fingers and thumbs are raw. Screaming only slightly, I consult the inevitable online resources to read about replacing the spring. Remove the gearbox, suggest some, remove the inner casting, insist others – going on to say that the best way to do this is to remove the gearbox. I ask the RC Facebook team. There are almost no sensible suggestions (which is not entirely unusual!). I repair to the house to consider the problem, wondering how profound would be the mockery from Ace Mosickles when I ask them to take the thing away and fix it. This is worrying. I fall asleep worrying.
Then wake up again. I have An Idea…