N1 Magneto, safety gap screw

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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

I have a spare non-functioning N1 mag and have previously thought of getting the Thorspark kit to go with it to have an alternative ignition system in the bank so to speak.
I didn't think of it as a solution to my suspect mag as that is off a16cs with no generator. But you saying it needs a very small current to power it prompted me to look, they say it draws no more than 0.25 amp.
Do batteries actually do what they say on the tin? Would a 6 Ah battery fire a Thorspark unit for hours and hours?
Groily
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Re: N1 Magneto, safety gap screw

Post by Groily »

Joker_Bones wrote: Thu Jun 30, 2022 11:44 pm Do batteries actually do what they say on the tin? Would a 6 Ah battery fire a Thorspark unit for hours and hours?
Batteries should; and 6Ah should be perfectly OK for hours, yes. Would even support some LEDs for a good while too. If worried, one could fit a voltmeter to keep an eye on things as well . . .
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

I already have a battery, I fitted one to overcome my fear of riding the Queen's highway without a brake light. I even wired in a little charging point on the bottom of the toolbox.

If I fitted a Thorspark unit and ran it total loss... Presto, a bang up to date Plug-In Hybrid!

Mind you, if the battery life claims of my motorcycle battery manufacturer are anything like those of my cordless vacuum cleaner manufacturer I'm not sure I'd get to the end of the road and back.
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ajscomboman
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Re: N1 Magneto, safety gap screw

Post by ajscomboman »

I run total loss lights on my CS using full LED's and can say for certain the battery easily lasts hrs.
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

Yes... When I fitted the stop light I fitted a rear light and front daytime driving light as well, all LEDs and the battery holds up no problem.

I used a combined rear/stop LED bulb which caused me no end of head scratching. When the brake was applied the front light came on as well as the stop light, but I couldn't figure what was wrong with my wiring. In the end I swapped the LED bulb for a filament bulb and all was good. Never really understood what was happening but stopped it by putting a diode in the circuit to stop the front light getting back fed.
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

IMG_20220706_161158.jpg
I unsoldered the blob of solder on the slip ring.
I assume that is the HT spike now visible.
There is now no continuity between the spike and the brass ring but there is 4k ohms between the spike and armature earth.
I cannot see, even with a loupe, if the spike enters the brass but I assume it is too short and doesn't... Explaining why the blob of solder was there.
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

IMG_20220706_171259.jpg
The spike did go into the brass ring... But appears continuity was provided by the blob of solder.
The slip ring was reluctant to come off at first but did so when warmed with an old hairdryer. Found a couple of winds of tape around the shaft.
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Groily
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Re: N1 Magneto, safety gap screw

Post by Groily »

That's what was worrying me J-B - looked suspiciously like a bodge to try to re-establish continuity after 'an accident' with the coil. Ouch.

Just seen your 2nd pic, so am canxing what I had written and will come back in a few!
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Re: N1 Magneto, safety gap screw

Post by Groily »

Easy things first J-B.
The i.d. of the slipring should be 11/16ths, which is (should be!) the dia of the armature brass shaft it sits on. The armature looks OK, but maybe the slipring hole has been enlarged. If so, bad plan. All Lucas sliprings have the same dimensions, so if yours is 'off' it's been messed with or was made wrongly.
The spike on a coil can be a PITA to get to sit well in the slipring. It's only a push fit and if the hole is enlarged it can be hard to get a good connection. If the connection is bad from the start there'll be arcing and the hole will get, er, bigger, and the problem will get worse. It is VERY important when assembling an armature to check that the simple HT resistance from brass track to earth after it's fitted is exactly what it was from 'coil HT spike to earth' before it was put on.
I suspect there were 'issues' when this was put together, and the bodge didn't sort it further than the end of the road.

That slipring is damaged anyway due to attacks by soldering iron, regardless of whether the hole is oversize, so needs replacing.

With a new one, now we know the HT spike is OK, it SHOULD be possible to fit it and maintain the resistance. Sometimes it helps to tin the bare wire where it enters the slipring if it's a bit sloppy; sometimes a squeeze with pliers to deform the extreme end a bit can help to get a good snug fit.

The chances are - not guaranteed, but probable - that the coil is perfectly OK. Your symptoms of misfire under load is a classic of slipring to coil trouble and / or short through slipring to armature spindle owing to damage or weakness in the dielectric strength of the plastic material owing to - in this case - either the enlarged hole up the middle, or the poor connection to the coil, or both.

That said, it would ideally be a plan to test the coil properly. But the least you can do is heat it up with the hairdrier to about 50°C and make sure it stays solid to the touch. The resistance will rise with heat, about 10% in doing that. If it becomes squidgy, or the resistance goes 'silly', then there is a problem. If you wanted, you could construct the sort of test rig Lucas refer in their service books for these things, using a decent spark test gap, but that's a bit of an ask unless you have time on your hands!

My gut feeling is that with a new slipring and careful reassembly and generous use of some heat-shrink on the insulation of the exposed spike from the coil, you'll get to happy. Often it is good to enlarge the first part of the hole into the slipring (in the 'nose' bit) to let extra insulation pass into this outer part - and that applies strongly where, as in your case, the HT spike has got a bit out of shape on its way from A to B. You have to avoid any risk of any unsheathed part of the bare spike being exposed, even in the slipring nose before it enters the flange and the brass bit, because sparks can jump a long way. Aways good to straighten out kinks carefully, using suitable pliers, so that the spike goes home in a straight line if possible! The length on your exposed spike, pardon the expression, looks about right!

Good luck!
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Joker_Bones
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Re: N1 Magneto, safety gap screw

Post by Joker_Bones »

Thanks for your thoughts and help Groily. Always interesting and much appreciated!
I will try a replacement slip ring taking your points into account.
IMG_20220706_183455.jpg
The spike certainly has a kink in it, looks like it was pushed when it didn't want to be. I will straighten it as best I can.
When you speak of tinning the spike... I think of tinning a wire as running on some everyday electrical solder with a soldering iron. Is that what you meant or more to it than that?
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