N1 Magneto, safety gap screw

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Groily
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Re: N1 Magneto, safety gap screw

Post by Groily »

Hmm . . don't like that slipring at all at all at all. It'll be a pita to get the thing off if the solder has taken on the HT wire from the coil - you will probably have to melt it to get the slipring off, which will further wreck the plastic / bakelite it if it's not already fubarred. Could be that the heat applied has caused deterioration in the bit of the slipring under the HT wire where it sits on the armature's spindle, thereby allowing an HT short to earth under load . . .

Whatever happens, don't rip the HT spike clean out of the coil by just pulling the slipring till it comes off, or you're into 'no option except a rewind' in a heartbeat. That was a foolish thing for someone to have done.

Could be something on your ring-cam contact breaker, of course, but not all that likely I would think if the points are OK and the gap's good. Worth checking the opening point isn't very wobbly on its pivot, but even some wear there won't usually cause trouble when running, other things being equal.
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

Thanks again...

No wobble at all on the opening point, visually the whole CB assembly is in good condition.

I have a spare slip ring and although I cannot vouch for its serviceability it looks in good nick and doesn't have a hole with a blob of solder in it. I will 'carefully' attempt to swap them over. It won't prove anything one way or another unless it solves the problem, but nothing to lose other than a few hours in the shed.

A few years back I made the puller to get the bearing off... I wonder where it is now?
Groily
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Re: N1 Magneto, safety gap screw

Post by Groily »

If you find that puller, you'll be a happy shed-dweller! If in doubt about the spare slipring, you could probably run over to Shaftesbury and get a new one from Paul Lydford at APL, he's bound to have a stack I'd have thought.
I just wonder WHY your one has been soldered - could it be because the spike on the HT lead off the coil was cut too short to go deep into the brass section? Or did someone think there was a poor connection that needed 'help' for other reasons? It can be hard to get a good connection there, as the spike is only a push fit with no mechanical help involved.
And if you do find your puller, you'd be able to get the coil off too, and investigate the goo . . . without breaking the submerged low tension wires, if attacked very gently . . . Good Luck!
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

I had it in my head that Paul Lydford had retired, is that not so?
I had a mag armature rewound by Moathouse Magnetos near Swanage and I thought the fella there had retired as well, perhaps I'm mixing the two up.
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Pharisee
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Re: N1 Magneto, safety gap screw

Post by Pharisee »

I had a magneto rebuilt by Paul Wolf, who lives near Bristol. Excellent service.
I'm from the Fens.... Gimme six.
Groily
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Re: N1 Magneto, safety gap screw

Post by Groily »

Not sure about Paul L, although I know he was poorly for a bit - hope he's OK.
Paul W would also definitely have the bits but is more geared to full overhauls with rewound coil etc etc, to ensure a warrantable result and his - and our - peace of mind.
Don't know about Moathouse though. But do know that the skills are getting all too rare and are concentrated in people who are over normal retirement age (like we who are members of the Club). Given the way it's all going, people like Thorspark, and the new BT-H company, are going to play a rôle that is more and more important in keeping old machinery on the road.
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

The BTH website gives no details of the drive end on their mags. Do their platform mags accept an AMC sprocket?

I do like the concept of the new BTH magnetos. The KD1"TT" would make a nice substitute for a NR1/NC1, but it would probably cause some domestic trouble if one showed up on the joint account statement
Groily
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Re: N1 Magneto, safety gap screw

Post by Groily »

Drive end taper etc was standardised on all mags many moons ago J-B, so the sprocket or ATD or any pinion would not be a problem. The new gizmo has the same.
Have heard conflicting reports on the BT-H instruments, most of it pretty good, but one or two less so. About the same cost, tad less maybe, as buying a Joe Hunt twin cylinder magneto from the US, to give a direct 'new - to - new' cost comparison. (Also a good thing, their twin cyl design, which uses a wasted spark on non-V engines and has a very powerful kick - but not so easy to fit on 'just any twin' owing to dimensions and need for adaptor plates in some cases. Full off-the-shelf spares availability is nice though, for them as have these things installed!).
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

I hadn't seen the Joe Hunt mags before so took a look, they seem a bit bulky and nothing for a single.

What is needed is for someone to design and manufacture a miniature alternator with an easily adjustable electronic timing unit that just pops into an existing N1 housing together with a miniaturised coil hiding in a plug cap, all coming in at just under the price of a mag rebuild... A nice little project for ya. :)
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Re: N1 Magneto, safety gap screw

Post by Groily »

I think that is, to some extent, what Thorspark reckon to have done J-B. Electronic trigger goes where the points are, with remote HT coil (doesn't fit in a plug cap though!), and not pricey either. Ones I have seen have been pretty good. However, not totally 'independent' like the BT-H, as it needs a very small externally-supplied current to power it.
Me, I'm happier with the old-fashioned mag personally, for as long as things can be kept going and parts can be had. But I'm not one-eyed about it, and there are a lot of smart people doing smart things out there, from the old-established and well-proven like Boyer, through good people like Pazon, Thorspark, Minimag etc etc. All share the same ambition - to keep things running while incorporating improvements made possible by modern technology. It is good that they are there.
You could always use the magneto as a mini-alternator, though, and power an external HT coil . . . people have done it as a work round fora duff HT coil, but it's not a bullet-proof approach owing to the potential difficulties associated with picking up the primary current from a traditional type of magneto with a rotating coil. Not forgetting also that an external power source provides conveniently constant voltage, regardless of revs, whereas a rotating primary winding doesn't.
There are many ways to skin a cat I guess . . . in which context, yes, Joe Hunt only skins twin cylinder felines, with an emphasis on V twins given where they are based. But those mags do what it says on the tin and are very much like a modern version of the Lucas SR2 in fact physically - but firing both plugs at once on parallel twin engines. I've played with them on classic Triumph twins built for Moto Cross etc etc, and have been impressed.
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