Pardon my ignorance, but . . .

Why are magnetos so popular with so called 'hot' engines? What are their advantages and disadvantages?

They sure look the business though.

Just read Dave Beckers post in Readers Rides, and it sparked my question.

A magneto is used because it generates High tension (ie 40,000V +) without the need of a battery. It is essentially a generator hooked directly to the engine. Hence, no revs from engine, no spark. also no battery necessary, hence often push start (race cars) or separate battery needed for starting purposes only (aircraft). Usually quite reliable, dunno why they faded from automotive scene. Blame Mr Kettering (he invented modern coil ignition)

Thanks Tony, a well written reply.

Just to get it straight in my thick skull ....

If I wanted consistant high-power, low weight, not to mention good looks - a magneto is the way to go.

However, I would need to have a seperate battery to start the engine originally, as well as powering any peripherals like radios etc. Yes?

Probably not the choice to have if you aren't intending to run down the strip I suppose.

Which brings me to your offer David. Thanks for the offer, but no thanks at this stage.

i thought magnetos were heavy... and you're better off going for a CDI IMHO. very good for giving you nasty shocks tho woohoo!!!!

Everythings relative. Yes a magnito is heavy compared to a distributor, but in a vehicle that doesn't need starting (as in push or crank etc start) and doesn't need lights etc you can throw away: Starter, solenoid, battery, generator, coil, distributor, condenstor + cables.
All things considered it is much lighter.

Obviously for a street vehicle this is not possible, so a normal coil ignition system is cheaper to produce and maintain.

Oh, turning them off is fun also

David, what brand is yours, and how much?
:thumb

hey andy isn't your bug gunna run hot with no gennie turning the fan ?
:P

:jesus
VW industrial motors used the case, shaft and bearings of the stock generator to mount the fan on (ditched the internals). Surely you knew that you silly bugger :P :P