Lucas K2F Magneto..

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Lucas K2F Magneto..

Postby matg80s » Mon Mar 11, 2019 10:53 am

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Last edited by matg80s on Sun Apr 07, 2019 9:29 am, edited 1 time in total.

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Re: Lucas K2F Magneto..

Postby Mick D » Mon Mar 11, 2019 11:19 am

Hi

It's a bit of a faff but you can determine the differences by reference to the Lucas list here:

http://archives.jampot.dk/technical/Ele ... 6-1957.pdf

Magnetos start on PDF page 90

Find the order number across the top of the table and compare it's component parts listed below with those of your desired mag.

Regards Mick

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Re: Lucas K2F Magneto..

Postby matg80s » Mon Mar 11, 2019 11:50 am

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Re: Lucas K2F Magneto..

Postby Groily » Mon Mar 11, 2019 5:13 pm

In reality, pretty well any K2F with ACW drive will go on no problem, and many can be made to look dead right too.

42230B was the unit for the G9s and Mod 20s from 51 to 57 as far as I can see, and would have had the cb end with the alloy dome with push button stop, and slightly nadgery fasteners with 2BA threaded ends plus a plain hex bit in the middle where the dome sits at mid-point as it were. Maybe a third c/sunk or cheesehead 2BA screw as well on a third corner. The special studs hold the camring housing and also the alloy dome. The latter comes off without slackening the housing itself, hence the design.
Manual, cable entry on left from points end for slack advance with ACW drive.

The hassle with all this is that the details of where there are threaded holes in the body / camring housing varies between K2F models, and so do the points covers and 'kill' arrangements. but the majority of K2Fs can be made to take the right points cover etc, if necessary with a bit of drilling and tapping (if the exact right bits don't come up easily).

As far as the guts are concerned, they are nearly all the same for the non-Competition models, until you get to the '60s almost, when some other changes came along.
Importantly, 42230 has the larger 18mm drive end bearing, which is good. Some versions used 15mm until about '52 and they can be fragile. Bodies are machined for the different sizes, so parts don't interchange without machining mods being carried out, and quite fiddly they are to do.

Whatever you end up with, a shiny new id plate will make it whatever you want it to be - if you can be bothered!

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Re: Lucas K2F Magneto..

Postby matg80s » Tue Mar 12, 2019 2:06 am

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Re: Lucas K2F Magneto..

Postby Groily » Tue Mar 12, 2019 7:11 am

Later type - but interchangeabe - new anti-clock contact breaker assemblies with steel backplates can usually be had from one or another of the usual suspects, but not always.
Brass types (no new ones) are harder these days but they come up on e-bay - in sometimes not very nice order though, it has to be said.
At a pinch, a BTH unit or even a Bosch can be persuaded to do the job, but the keyway on the taper may need to be 'moved'. Tapers are the same, dimensions are the same, as these things got standardised pretty early on.

Virtually any standard K2F would suit you I think, if you're not being too purist about things - with the manual end housing and camring. I have five machines with K2Fs or K2FCs on, and not a one of them is exactly how it would have been when the bikes were brand new. So far, no rivet counter has offered opinions on why they're wrong (though there are so many other 'wrong' things on some of them that they probably give up in disgust before they ever get to the mag!)

The later units used a large screw-on cover for the cb and wouldn't look quite right for an early '50s bike- but would work fine. Any of the ones with plastic cb covers with take-off wire for engine stop can take the alloy dome, subject to sorting the fasteners out. The devil is in the details every time, but the basics are extremely similar.
I've never quite understood why Lucas went to the trouble of creating such a vast array of near-identical units. Maybe they liked creating reams of parts lists, like you've been going x-eyed with!

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Re: Lucas K2F Magneto..

Postby matg80s » Tue Mar 12, 2019 9:46 am

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Re: Lucas K2F Magneto..

Postby ajscomboman » Tue Mar 12, 2019 5:28 pm

matg80s wrote:yea its complicated, but at least its well documented and trackable, sounds like you have been down this rabbit hole a few times. As I said Im gonna get my man to do the K2F build. Then Ill buy the ID tag and fit it...thnx...Matt


Groily has been down loads of rabbit holes, he ought to have been, he reconditions them and very good at it he is too! :beer: :beer:

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Re: Lucas K2F Magneto..

Postby Groily » Thu Mar 14, 2019 7:48 am

That was kind of you Rob. (Fingers crossed every time of course, 'cos shit will happen now and then.)
Yes, I do seem to live down that rabbit hole - but as an unreconstructed carnivore, more likely to eat what I 'meat' therein!
Cheers, Bill

PS - any further thoughts on yer trip over? Continent now cut-off by the looks of . . . and by more than just fog this time . . . (But where there's a will - - there's a corpse.)

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Re: Lucas K2F Magneto..

Postby ajscomboman » Thu Mar 14, 2019 5:48 pm

Groily wrote:That was kind of you Rob. (Fingers crossed every time of course, 'cos shit will happen now and then.)
Yes, I do seem to live down that rabbit hole - but as an unreconstructed carnivore, more likely to eat what I 'meat' therein!
Cheers, Bill

PS - any further thoughts on yer trip over? Continent now cut-off by the looks of . . . and by more than just fog this time . . . (But where there's a will - - there's a corpse.)


Oh yes, I'll still be invading France, Holland and Belgium after the International. I'll send over my mobile number nearer the time and you do the same then we'll attempt a tie up.

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