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Magneto windings

1950's Lucas magneto

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colin hawes29/07/2018 16:56:34
558 forum posts
18 photos

Has anybody tried to rewind a lucas motorcycle magneto and what is the wire spec, gauge, number of turns and length of wire used for primary and secondary windings? I am thinking about attempting this and any information would be of interest. Colin

clogs29/07/2018 17:32:17
626 forum posts
12 photos


I like ur style but I wouln't bother.......

too specialised job, apart from the wire size u need to know the amount of turns and we're poss talking a thousand's.....

also remember the wire is quite specialy prepared at least the insulating coating......

there are several specialist that will do the job and even insulate the windings under a Vacuum..........

mostley u get a 2 year warrenty........

u'll find em in Old Bike Mart, Classic Bike magazine etc......

good luck

martin perman29/07/2018 18:01:42
2046 forum posts
86 photos


I would agree with Colin, I get all my magneto's, used on my Stationary Engines, repaired by a friend who does it for a business, he has a lot of equipment, coil winders, vacuum chamber and pump for resin impregnation of insulation and a workshop for making commutators etc. It costs me £150 for a full rebuild including ,rewinding coils, remagnetising the magnet, new bearings and any other work required and it comes with an 18 month guarantee, its not worth the hassle.

Martin P

colin hawes29/07/2018 18:34:01
558 forum posts
18 photos

Thank you for your advice ,Clogs and Martin, I guessed it might be a bit of a problem so I am more likely to avoid this one; reluctantly as I have always been one to have a go at anything. Colin

Rod Clemett29/07/2018 20:35:18
21 forum posts
12 photos


Before you give up any idea about having a crack yourself, check out 'Mr Factotum' on YouTube. Google 'Brufnut' too.

The 'Brightspark Magnetos' website has some drawings for bearing pullers etc. Any post by Magnetoman on the various forums is worth reading, although a counsel of perfection. Remagnetising is a bigger problem, but not insurmountable.

Yes, you'd probably be best advised to use the cheque book instead, and you'd get a faster and guaranteed result, but perhaps sometimes it's better to travel hopefully, than it is to arrive!

When I thought I'd got problems with a K1F, I too reached the conclusion that prefer to try myself rather than farm out the job - because like many on here I guess, I'm cursed with a head that leaps to the conclusion that 'I could fix that' faster than it thinks 'I could buy a new one'. The K1F turned out to be fine, but I've got a couple of spare K2Fs, and I'm determined to give it a go when time permits,


martin perman29/07/2018 20:52:12
2046 forum posts
86 photos


My magneto repairman friend uses "Magnetoman" as his handle but having just read a series of posts on the Brit bike forum its not my friend. A common name smiley

Martin P

Rod Clemett29/07/2018 22:41:32
21 forum posts
12 photos

Hi Martin,

Fair comment. The 'Magnetoman' on the Britbike forum / Vincent Owners forum ( I wish!) is indeed the specific one I meant. On there, it's the handle of one Dr Charles Falco, an American physicist.


Nimble30/07/2018 08:37:43
59 forum posts
4 photos

Hi Colin,

Here are a couple of sites you might like to visit.

Like you I would like to attempt my own magneto overhaul but realistically I had my magneto overhauled professionally

With my car I had the magneto with no regrets, For my money I would have the mag professionally overhauled just imagine being out in the Boondocks, pouring rain.etc

Regards Nimble Neil

colin hawes30/07/2018 21:23:04
558 forum posts
18 photos

Neil, thank you for your references, they are what I was really looking for and it has shown me that it would take too much of my model making time to attempt a rewind with uncertain results so I shall now consider whether to get a rewind done or convert to electronic ignition in the interests of reliability. Colin

Tim Stevens30/07/2018 21:44:45
1598 forum posts

Answering the original question is not really possible, without a lot of extra info. Magnetos were not in any sense all the same, even though several versions have armatures which look (and are) similar. Info on which model had how many turns of what gauge of wire was closely guarded by makers (especially Lucas) and any that escaped is just as closely guarded by magneto specialists.

Yes, you can unwind your mag, counting the turns, and measure the thickness of the wire, but this is scarcely a practical idea with the extra thin wire used for the secondary turns, stuck up as it will be with shellac and other adhesives (including araldite). Doing the primary counting is not so difficult, with thicker and fewer turns. Then you need a source of new capacitors to fit into the armature, as well as remagnetising and sorting brush gear etc.

One option used by vintage drivers is to convert the mag to be part of a coil ignition system, relying on the battery. If you need further advice about this, send me a pm and I'll help where I can.

Another alternative is to buy a reconditioned mag - there are one or two suppliers - prices seem to start at £500 or so, rising rapidly for anything fancy or fitting a racing vehicle etc.

Regards, Tim

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