Being in the process of collecting parts to build a featherbed based Model 50 racer, I'm wondering which magneto I could be using. It needs to be a mount based magneto, as my timing cover doesn't allow for a flanged one.
Having said that, I've got a Lucas SR magneto lying around that's suitable for a twin. Can this one be converted for use on a single? Mind you, this one has a flange, which would mean I need to source a suitable timing cover too. And while writing this, I realise it may be rotating the wrong way too. Has yet to be determined...
It's all about costs and having options. But for now, I'm clueless which path to choose and any input would be appreciated.
There are a couple of…
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Thank you David, I was…
Thank you David,
I was actually trying to avoid asking these guys, as they must get dozens of e-mails every day. And I can imagine that can be quite tiring and boring.
But, admittingly, they do have a lot of interesting information on their websites.
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SR1
Tim there was a bloke at the Australian All British Rally a few years ago who had one on an ES2. I would expect that would have been a single cylinder type.
I did buy one I was going to put on a Velocette, but it was too much trouble.
However I did find out from Brightsparks website that changing direction was very easy. Just turning the cam around or changing position of the points. Can't exactly remember which. It was on their FAQ . You would probably need a single cylinder cam as well.
Mine had a flange mount that was just bolted on. Very easy to remove.
I'd keep trying you might need to fabricate a base mount or drill some bolt holes in the timing cover. And check Brightsparks FAQ.
One other issue is you wouldn't have any Advance Retard. You would need to give it a decent OLD kick to avoid a back fire. Not a big problem if it is a racer and it was push start.
Good luck!
Don Anson
Melbourne Australia
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You can change the timing…
You can change the timing case to a flanged one, ive done it on two M50 bottom ends, (MP 520 top ends) and an es2 and you can buy new BTH mags to fit, they are super reliable, auto advance and a bit pricey!
Dan
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Thanks for the replies both!…
Thanks for the replies both!
I've read about the BTH ones and that would be the easiest route, but also the most expensive one. Although you do get what you pay for, from what I've heard.
However, I'm always interested in learning new things, so converting seems interesting. Or swapping the SR2 for an SR1 of course. Good thinking about the advance/retard. I sometimes don't bother with my standard M50, so it won't be a problem. But indeed, you have to do it with a bit of authority and a good follow through.
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The SR magnetos are designed…
The SR magnetos are designed to allow base mounting or flange mounting. There are screw threads cut for the flange mount adaptor, and the base is machined for 35mm spindle height above platform, as on Matchless/AJS single. For a Norton you want a 10mm spacer. A while ago I lent an SR1 to a friend, as his Matchless's mag was playing up. It had the 10mm spacer fitted, he removed it to fit the thing.
You could probably use the SR2 as long as you ground the second plug lead. Or swap it for an SR1.
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Cheers Paul, Making a spacer…
Cheers Paul,
Making a spacer won't be a problem. I thought about grounding the second lead, but don't know if that could result in damage inside the magneto.
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Thinking about the second…
Thinking about the second lead. Is there a way of joining plug leads in a "Y"? You could then send both sparks to the one plug. As far as the plug is concerned, it would be just the same as the commonplace lost spark used on electronic ignition systems on twin cylinder bikes.
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Don't think so!
I don't think such a trick would work, I would say 'the jury is out' and wait for a decent magneto man to appear! But surely a single mag should give a better spark as it only has to spark the once with the turn, a twin spark would have to generate the two sparks in the same 'turn' time?
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Don't both types of mag…
Don't both types of mag create two pulses? The Single type only has one cam lobe, so only sparks on one of the pulses per rev. Twin types have two cam lobes. You could grind off one lobe!!
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Well, there's an interesting…
Well, there's an interesting thought! Grinding off one cam lobe would definitely do the trick and it wouldn't cost a penny.
Though, it would terminate a good twin magneto that somebody else might have been looking for. I hate my conscience sometimes...
Then again, there are still many new parts available. Would these lobed shafts still be available? If so, I wouldn't feel guilty of grinding one lobe off.
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To conclude this post: I…
To conclude this post: I found out there's a man in the Netherlands, Jan de Laat of wikkeltechniek.nl who knows an afwul lot about dynamo's and has a website with loads of information.
I know I said I wouldn't bother professionals with questions they must get a dozen a day, but ended up speaking to him anyway. He told me grounding the second lead is the way to go, as otherwise it would ruin the second coil. So Paul, you were right. But because you said 'probably', I had to make sure of course.
He also said SR2's were harder to find than SR1's. Which gave me a bit of a guilty concience, as I'm occupying a magneto that someone else might need more. However, for now I know I don't have to invest in a magneto. It will work and when I can swap with someone, I'll do that.
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There are a couple of websites with illustrations of different magnetos. "Brightspark" and "Magnetoguys".