TALES FROMTHE SHED
Frank discovers a complex, slow way to darken the afternoon sunlight…
Frank discovers a complex, slow way to darken the afternoon sunlight
The excitement of an afternoon in The Shed is almost beyond description. I hardly know where to start this month’s magnificent octopus, things have been so entertaining. Do I continue with the increasingly illuminating headlamp saga, whereby I can almost find the almost correct bits and almost fit them? Or do I dive straight into the gritty nitty and dazzle you with the sparkling brilliance of my magneto refitting skills? Not an easy call, I’m sure you’ll agree.
You may recall reading Jacqueline PUB’s excellent piece last time about how she received the CSR’s magneto, gave it a serious dose of technical looking-at and decided that only a complete chimp would be unable to produce fine fat sparks from it with almost no effort at all. I read her words with minor gloom, as you’d surely expect. I have never successfully rebuilt a magneto. Or anything else, it sometimes feels like. I did build a gearbox once. It would select first and third or second and fourth. Life can be a challenge.
That said, fitting one of Mr Joe Lucas’s K2F magnetos is hardly difficult. Three fastenings and the timing pinion. Did someone mention timing? Ignition timing? I’ll get back to that.
First things first. Once this remarkable device is back in its rightful place, I will never ever want to remove it again. I know this. I also know that you will not want to read about my removing it again, so it is important to we Noted Experts that we fit the thing properly the first time. Although practice almost certainly makes perfect, I have no wish to become more perfect in the black art of fitting magnetos. All I want to do with a magneto is forget it’s there, and simply revel in its most excellent sparks. Real Experts like Jacqueline PUB bask in global admiration because of their technical expertise. I am delighted about this, and not at all envious. A mechanical electrical genius I have no wish to be. Which is fortunate.
Part of the fitting the thing only once involves fitting it properly, as you may already know. Failure to fit a technical thing like a magneto – or worse, a carburettor – simply means that the wretched instrument of torture will need to be fitted more than once. Possibly very much more than once. I know this. I once fitted a carburettor more than a few times because when it was fitted the engine would not run. It would not run when the carb was not fitted either, but I took no solace in that sad fact. Mixing up the throttle and choke cables is an easy mistake to make.
Part of my relentless pursuit of perfection involved searching for all the peripheral – read ‘non technically difficult’ – bits which
transport the awesome discharge from the magneto to the spark plugs, ensuring riding delight for Proud Owner. Which would be me, in this case. It is easy to acquire the cables and stuff, of course. All a chap needs to do is storm off to the nearest event which has a decent jumble, seek out the purveyors of such tackle and buy it. Can you spot the flaw in this?
As I write this, the UK is still in the clammy grip of The Great Lockdown, which means of course that autojumbles and old bike events are somewhat thin on the ground. This has been the case since the glorious magnetoid relic of our great British electrical industrial heritage returned from PUB’s palatial estates in the remote east of this wide island. But never mind. Several fine emporia have remained open etherically to service needs such as mine. Hurrah. I zapped online to find the bits I need to convey sparks to plugs.
And I found them. I found a wide variety of them. And I found that it is still – amazingly – possible to acquire genuine Lucas bits in genuine Lucas boxes. This is astonishing stuff. I should of course not have been even faintly astonished, because I’d discovered the exact same thing when seeking bits for the great headlamp replacement exercise. That had not been an entirely delightful process, mostly because too many of the nice new nicknacks either didn’t fit or didn’t work, which is irritating. And a waste of both time and money.
I am of course the very definition of an eternal optimist, and ordered the parts I needed. Sometimes I ordered the same thing more than once. This is because with age comes forgetfulness. I think. I could be wrong. Who knows?
Let’s make up some nice new HT leads. What could simpler? Did you know that motorcycle HT leads are 10mm in diameter? I’d never given HT lead diameter a single moment’s thought in a half-century of hapless two-wheelery. HT leads are simply HT leads. All I knew – if indeed I knew anything, which seems unlikely – was that I needed to use old-fashioned copper-cored HT lead and not some mysterious modern nonsense which uses no copper at all, but some magical black stuff which claims to be carbon. I know nothing about that, of course. c What I now know, however, is that HT leads are available in more than one diameter. I now have several examples. 10mm is what we w need. Not 7 or even 8mm. Ten. The strimmer with which the Better Third T cheerily destroys entire swathes of hapless plants uses 7mm HT le ead, formed into a single unified item with both the pick-up and plug cap. c This knowledge, although impressive, is of no use whatsoever when w equipping a K2F Lucas for a Matchless motorcycle. But I try to be b helpful.
Having finally acquired the correct HT lead and a nice smart set of pick-ups, p gaskets, little brass split washers and plug caps – all branded Lucas L and supplied in smart green boxes, I set to, applying the secret
skill which is making up plug leads. Can there be a more satisfying, rewarding enterprise? No need to answer that. First…
…I refitted the magneto. This is a good idea, if only because it makes gauging the lead lengths required easy. Timing can wait.
Next, the pick-ups, both complete with nice new carbon brushes (and I have a couple of spare new sets of brushes, because … you know… because). Nice neat job. A job well done, I considered. Next, offer up the pick-ups to the magneto itself, remembering to fit the nice new (and peculiarly pink) gaskets. Nice tight fit over the process on the pick-up body. Offer up the assembly to the magneto body. It refuses to seat. This is no use at all. Rain might get in, and Jacqueline would tell me off. A puzzle: why don’t they fit?
Because the remarkable pink gaskets are not quite the right shape. File the gaskets. Now they fit. Why not, I ask again with only a tinge of exasperation, make the things the right size in the first place? It would cost no more and would encourage me to buy more stuff from the supplying company. Moving on…
Measure up the length of lead required to allow it to reach the spark plug from above, between the rockerbox covers rather than just dangling around, as we so often see. Why dangle leads all over the place? It’s messy and when it rains you can experience the rare delight of sparks jumping between the lead and your leg. This produces a mysterious misfire, as you may know already.
Right. On with the handsome shiny black plug caps, non-suppressors, because modern tellies don’t generate snow when you hooligan past on your bikes, so ruining the evening’s episode of Z-Cars, or whatever. The caps are nice and shiny. Did I say that? The first one broke as soon as I screwed it onto the lead. The little brass screw connector simply snapped. I tried the other. Same result. Plainly that Charles Atlas course with Dynamic Tension worked. I am a superhero with superstrength. This is good to know but unhelpful when reassembling an ignition system. I threw away the genuine Lucas bits. Rubbish. Genuine rubbish.
Happily, in the top drawer were a pair of less flamboyantly branded plug caps. They were modest about it, but careful examination revealed that they were made by NGK, a Japanese company of which you may have heard. Unlike the Lucas junk they fit easily and strongly, and even come with little rubber boots to keep out the rainwater, should I be so unlucky.
There’s no putting it off any longer, is there? I cast about for excuses – I even mowed the lawn, such was my desperation – but no, it really was time to set the ignition timing and to close up the timing case. Hang on! The throttle cable’s inner is miles too long. I must replace it at once with an item of the correct length. But the strangely wrong cable claims to be the right cable? O joy! More procrastination opportunities! I dug out a pile of new cables left over from decades of time wasting but valiant rebuilds. One marked as suitable for a 1971 500 Triumph fits the 1965 650 Matchless perfectly. That didn’t take long. Back to the ignition timing.
Why I make a fuss about this I have no idea. It’s actually really easy. I know this. Given that I know this and have in fact timed many many ignitions, why do I make a fuss? Life is endlessly puzzling.
Should you be on a quest for arcane information, I can reveal that this is what you need to know: 650cc AMC engines need to be timed with the right-side piston at 11/32”, which is 35°, before top dead centre. There you go. You need never to lie awake fretting about this again. Setting the piston at the correct point is easy too. Most folk I know use a spoke from a wheel to poke into the plug hole to measure the distance. I use a little tool I picked up at a jumble which is possibly even less inaccurate than an old spoke marked with magic marker.
Whip off the inlet valve cover (easy on AMC’s elegant twins), then turn the engine using the kickstart lever until the piston is exactly at the top of its stroke after the inlet valve has closed. Screw in the little tool to check that the piston is where it should be. Promise chocolate reward to someone conveniently proximal
– I prefer to ask the Better Third to do this,
because she is sympathetic about things like ignition timing – and instruct them to gaze at the little marks on the little tool, explaining that you are going to perform Complex Boy Stuff and wind the rear wheel backwards while she looks at the little tool. She will, at this point, gaze upon you as though you never had any marbles, never mind lost them. Smile encouragingly and say, brightly ‘You’ll see the little thing move down until it reaches the little line I showed you.’ Smile more, and try to look intelligent.
Heave on the wheel.
At this point your hopefully glamorous assistant will say something like: ‘OK, it moved. It’s past that mark now. Now what?’ Try not to scream, because you will certainly regret that later and at length. It was, remember, your explanation that was at fault. Be cheerily helpful about this. Because eventually you will, between you, get it right.
At this point, you remember that you should have checked that the magneto points gap was between 0.010” and 0.012”. This should be checked before the wheel-heaving thing, because chocolates are decently costly and funds may be tight. Be brave: we’re nearly there.
The piston is now at the point where the contact breaker should be about to separate. In olden times, enthusiasts stranded at the roadside in thick fog and pouring rain would check for the exact points separation moment by using a presumably soggily disintegrating fag paper, but we move in enlightened times and the bike’s on a bench and I have an electric meter, which is good at this kind of circuit spotting thing. Set the little fibre foot-thing on the cam ring thing at the separation point and stand back. Time to breathe and to contemplate the many advances made in motorcycle ignition systems since your bike was built. Then take a deep breath, because it is now time to connect the magneto’s drive to the engine.
And it is very easy to rotate the magneto’s armature while tightening the nut which holds the timing pinion onto the armatur re’s tapered shaft. This completely wastes all that time you spent setting the points at the exact break point. And did you remember to set the manual magneto at full advance before you set the points? Of course not. Do it now and repeat what you’ve already done, at least twice. Practice maketh the man. Or something. Your own Better Third need not be present for this, so it is OK to blaspheme, at least a little. Except on Friday, Saturday or Sunday, depending upon your religious inclination. Maybe all three days, just to be on the safe side. Right then. I’d set it up. I refitted the timing cover, using no gasket because I’ve never seen one fitted to an AMC twin timing case, and tightened all those little screws with great care. Only one of them appears to be stripped, which is good going for one of these engines, and I stuck that screw in place with a little dob of thick grease, like you do. Or like I do, in case you do not.
And then, beware, for the moment of truth approaches. But before that, a chap should fit the fuel tank properly, not in some half-hearted way using all manner of mysteriously random fittings. Pause. Ignore that bit. I decided at that point that I simply wanted to see whether the thing would run – Jacqueline assured me that it would and she is never wrong – so I just rested the fuel tank on the frame, added fuel, made absolutely sure that the Better Third wasn’t nearby, so had no inkling that failure and despair were about to set in, and I kicked it over a few times.
It started. Well… it fired, once. I tickled the carb and said generous things to no one in particular. Set the choke
about halfway and kicked with vigour. It started. Properly. Both cylinders. My gob was smacked. It always is at the start-up moment, somehow, even though I do in fact know that it should.
My eyes started to water. Was this a supreme emotional moment? No, my eyes were watering because The Shed was filling with acrid smoke. The smoke was blasting in huge swirling billows from the CSR’s silly fat silencer. This is because well-worn AMC twin oil pumps sump if left standing for a few years. Three things result from this well-known phenomenon: clouds of smoke, oil returns mucho rapido to the oil tank, because that oil pump is a good pump, and a huge pool of filthy oil forms on the bench because crankcase pressure blows oil from the crankcase through the drive-side main bearings, into the primary chaincase and then out of said case through the hole provided to allow breathing and onto the bench. Or floor, depending.
As I was congratulating myself in an only slightly immodest and hysterical way, I became aware of the presence of the Better Third, who was appearing and disappearing again through the vast drowning clouds of dense smoke. Smoke which, incidentally, discourages insect life from nesting in the rafters. AMC thought of everything. But what was she doing? She was waving her cell phone around. This is mysterious behaviour, even for a young woman high on the promise of imminent chocolate overload, but…
The engine stopped. It had in fact run out of fuel. The Better Third was in hysterics. ‘ That’s going to crack them up on Facebook!’ she cried, vanishing again. And she was correct. As always…
The old pick-ups. Maybe there’s a clue to the non-running here?
One expertly refurbished magneto, ready for reinstallation
The way we were: a magless Matchless, poised
Timing side inlet valve: how to get your pistons in the right place for the sparks
One of the new pick-ups. Observe how the gasket is actually too large. The new brush, however, looks encouraging
You’re correct. The little brass screw should not just shear off like this
Finding TDC is easy with one of these, and it has handy little marks for you to locate the right piston position for timing
Where the spark starts for the right-side plug
FW’s NOS (aka, old junk) box comes in handy again
a nice new gasket of course
One ofthe more useful toolsinThe Shedtoolboxes
One magneto, back in place, complete with
Guess what! Some gentle exhaust exhalations may be apparent…
Tank resting in place, fuel line connected. This machine should run