> A magneto works much the same way as a coil - except it is self excited.
> There is a low tension side which is "normally" short circuited by some
> sort of switch, and a high tension overwind similar to the secondary
> winding of the coil or transformer. The magnet moving past the windings
> induces a current in the primary which, at the appropriate moment, is
> interrupted by the switch opening. The current in the primary suddenly has
> "nowhere to go" and the voltage across the primary rises dramatically.
> Since the secondary winding is on the same magnetic circuit, it's voltage
> rises even more dramatically as it has more turns and is sufficient to
> break down the spark gap & fire the mixture.
> To my knowledge there are no systems that generate the secondary voltage
> directly from the magnet/coil arrangement - and spark timing would be a
> major problem with this system anyway.
>
> As I noted earlier,  2 stroke engines can have points (generally well
> buried under the flywheel) or more commonly these days, a transistorised
> module that detects the current in the primary winding and opens the
> transistor switch as soon as this current starts to decay (i.e. as the
> magnet moves away from the gap in the coil) - or something like that (I
> haven't looked in detail but have had to replace a module or 2).

        Thank you very much for the description, I've never taken one apart so I
simply assumed it was a coil and a magnet, obviously I was wrong! :(

> Hope this helps. I realise you may not want to get too involved with
> rewiring the magneto so suggested the spark plug shorting method. Another
> advantage that comes to mind is that  it may be possible to
> arrange it as a
> kill switch if the car flips etc. although vibration could be a problem.

        Hmm, the car flipping, there's something I don't even WANT to think about!
:) TTYL

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