Magneto contact points.

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Magneto contact points.

Postby Pharisee » Thu Feb 20, 2020 9:46 pm

mag-1.jpg


I'm looking (so far without success) for a set of contact breaker points for the Lucas NC1 competition magneto fitted to my '56 G80CS.
The nearest I've been able to come up with is a set from Feked for an early model K1F & K2F. Could anyone tell me if these are the same as the ones fitted to the NC1, please?

https://www.feked.com/contact-set-lucas-k1f-and-k2f-magneto-early-model.html

Thanks
John
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Re: Magneto contact points.

Postby Groily » Fri Feb 21, 2020 7:11 am

Should be just the same John, as all Lucas contact breakers of that type are same dimensions etc (but handed according to rotation). Same unit on singles, twins, 4 cylinder jobs - the lot.
In fact, the dimensions of contact breakers across most marques are the same - BTH, Bosch etc - but they are keyed in different places for their fit to the armature.
Some Racing mags had platinum points . . . but you need to be feeling very rich if thinking of going that way!

Quality of replica parts isn't always that great though, in the sense that the geometry isn't always spot-on.
If the ones there will clean up, and the heel and pivot hole aren't too worn, it mayn't be a bad idea to persevere with them (even graft a new contact onto the opening one). If the pîvot post is badly worn, then new points won't get you to 'perfect' on their own.
It's a funny thing, but despite parts supply for most things being better than ever, contact breaker parts are very tricky.

Worst case, steel backplate later 'low-inertia' assemblies can be had brand new. They lack the facility for the auxiliary earth brush on the rear face, but they do work pretty well.

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Re: Magneto contact points.

Postby ajscomboman » Fri Feb 21, 2020 9:06 am

Bill that rear brush, I've been led to believe that it's a pointless (no pun) item to fit, what's your view point?

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Re: Magneto contact points.

Postby Groily » Fri Feb 21, 2020 11:47 am

Tisn't going to do anything useful Rob if there is a primary brush on the body - as with N1, Ks etc. But in some cases on older mags, it is needed for the lack of any other return path for the HT current.

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Re: Magneto contact points.

Postby ajscomboman » Fri Feb 21, 2020 4:27 pm

Groily wrote:Tisn't going to do anything useful Rob if there is a primary brush on the body - as with N1, Ks etc. But in some cases on older mags, it is needed for the lack of any other return path for the HT current.


Thanks for that, confirms what I'd been told. Not had one in the comps for years and had no issues so far.

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