G80CS Magneto Kill Switch

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Peter Baker
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G80CS Magneto Kill Switch

Post by Peter Baker »

I am a new member having just acquired a 1961 G80CS. I wonder if any of the more experienced members can help me with a query. The bike has a Lucas NC1 Magneto (which is producing a healthy spark and runs well). However this mag is not fitted with terminal/carbon brush on the end cap to earth the LT side of the contact breaker by way of a kill button. The valve-lifter system of stopping the engine works OK, but I should like to fit a cut-out switch for safety- it would also give me the ability to immobilise the bike with a key switch. I seem to remember seeing reference to a Lucas conversion kit for the end-cap of this magneto in a spares list somewhere, but I'm blowed if I can find it now- its not in the standard Lucas parts list. Has anyone else found an easy solution for this problem?

Cheers

Peter
norman_john
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Re: G80CS Magneto Kill Switch

Post by norman_john »

Peter Baker
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Re: G80CS Magneto Kill Switch

Post by Peter Baker »

Thanks for your help John- I am looking at these, but not sure yet if the solution works for a rotating magnet "wader" magneto (Lucas NC1)

Cheers
Peter
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GOLDSTAR
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Re: G80CS Magneto Kill Switch

Post by GOLDSTAR »

dunno much about the dark art but I have a NC1 fitted, these were competition mags I didn't think they were rotating magnet, probably never fitted with a cut out, comp bikes would just lift the decompressor surely? or am I talking out of the tail end? kind regards
sorry it is a NR1 the NC1 is still in its box but is there a lot of difference?
Groily
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Re: G80CS Magneto Kill Switch

Post by Groily »

Just to clarify - all N1 variants are rotating coil magnetos (as Richard Goldstar says), but the basic NI has a 'face-cam' contact breaker operated by a short pushrod and doesn't lend itself to a stop or kill button very easily. (Same cb as a magdynamo MO1).
Competition and Racing versions have a rotating contact breaker set with a camring (same as a K series and some others), and some were equipped with a cover with a kill facility of one or other sort.

But . . . it depends on the mag's end-housing as to what cover (of the many variants) will fit. The possible permutations are quite confusing, but the basic parts can be seen in the Lucas service sheets for the various mags which are accessible in many places. See, for example, pages G10 and G17 in the file here for the basic options with pix, and to identify what you have got: http://www.brightsparkmagnetos.com/libr ... 20ATDs.pdf

You'll see that some parts were shared across the N and K series mags, just as some others were shared across the N and MO series of magdynos.
It's a minefield, no two ways about it. And quite often, to make matters worse these days, mags are bitsas comprising parts from similar units which happen to fit, but which aren't strictly correct.

Careful (and somewhat painful) study of the parts lists does help though, and also can resolve questions to do with rotation, side of entry of adv/ret cable, what sort of pick-up, etc.
This Lucas link is also useful to match specific parts to specific machines (for the years it covers) - but involves even more cross-referencing between different bits of the Lucas lists: http://www.brightsparkmagnetos.com/libr ... achine.pdf
Peter Baker
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Re: G80CS Magneto Kill Switch

Post by Peter Baker »

Thanks Groily- that's a really good starting point. My NC1 Magneto has an end cap that looks like the 459315/459199 in the parts list. It looks as though 459205 might be a replacement with a facility for earthing for a cut-out, but I can't be sure unless I see one. The quest continues...

What a knowledgeable bunch you are!

Cheers

Peter
Groily
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Re: G80CS Magneto Kill Switch

Post by Groily »

Yes - 459205 has the breather (used on the C and R) versions AND a terminal for stopping the thing; 459315 & 459199 don't have the terminal attachment. But the middle bits can actually be swapped around to get the required solution if a remote kill is necessary.
All these covers require the cb bearing end-housing with the large threaded bit for screwing said bits onto - not the basic N1 version which uses a clip and a plain cover.
The covers can be had from Dave Lindsley, among others - not bad replicas. However, if you could find an original it would be slightly neater, as the replicas I've seen have a thicker 'knurl' on them and often require the brass triangle that locks them on to be bent to an unnatural angle - and the breather part of the casting often isn't as nice as the original. (Sometimes the breather doesn't actually breathe, owing to poor casting quality blocking the 'ole.)
It depends how picky you want to be!
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GOLDSTAR
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Re: G80CS Magneto Kill Switch

Post by GOLDSTAR »

while we are on this Bill, do you know of any differences between the NC1 and the NR1? kind regards
Groily
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Re: G80CS Magneto Kill Switch

Post by Groily »

To be dead honest Richard, I don't know. Good question.
There are some small part number differences in the lists for NC1 and NR1 per the Lucas data referenced above as you probably saw (eg waterproof sleeving for plug lead or AR cable iirc), but they don't amount to a hill of beans really as far as I can see. The guts seem the same. I wondered if the NR1 used platinum points or something, but the part numbers are the same for both - whether they did or not. It has been said that there's more wire on the coils of the C and R than on standard versions of Lucas, also that there were stricter requirements at the factory for winding them, but, again, I don't know, and I doubt there were any differences between the Cs and the Rs. Probably academic these days anyway, as there won't be too many factory-original coils still going strong I wouldn't think.
Colour comes into it of course - with the plain alloy, gold finish, and green, but that's as much as I can say. A lick of paint often 'converts' the mundane into the sought-after. There are a few gold or green bog-standard N1s out there!
An important difference I have seen, though, for a very few K series 'R' and 'RR' mags from the late '40s, are ?titanium? drive ends made from solid (rather than having a steel shaft on a brass cheek) - but I have never seen that with Ns.
Sorry not to be more use - maybe someone else knows a bit more?
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GOLDSTAR
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Re: G80CS Magneto Kill Switch

Post by GOLDSTAR »

thanks Bill, Tony Holder who rebuilt my NC a good few years ago, mentioned that it was stainless steel not sure which part though, Kind regards
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