A discussion of Thorspark power draw.
I have read various comments on forums saying that the fitting of an electronic ignition to a 6 volt bike will leave you stranded. We make the Thorspark electronic ignition, and beg (obviously) to differ. The comments normally go on to recommend various 12 volt conversions and magneto re-conditioners.
The 12 volt Thorspark kit draws a maximum of 1/4amp, the 6 volt version a bit less. This equates to a power draw of less than 3 watts for the 12 volt version, and just over 1 watt for the 6 volt. This is not a large extra heavy load on the bike's electrics.
I have seen advise on various forums that if you do not upgrade your bike's charging to 12 volts, it will not be up to providing 1 watt of power for the electronic ignition. This is self evidently rubbish. It doesn't matter whether you have 6 or 12 volts, as long as you have a battery that isn't shagged out, and that actually charges as you drive along, then you will be fine.
If you use the Thorspark, and you develop a charging fault, with either 6 or 12 volt, you will still have several hours of running with your lights off, but yes, you will eventually get stranded when the battery goes flat, whichever voltage you have. Obviously a working magneto has the advantage of being self powering, and also if you are running a bike like many of us used to, basically with no electrics, then that is the only way to do it. These days, however, many of us have bikes that are more or less up to scratch, and lights that actually work.
I run a 1956 Matchless G11 on 6 volts. This is unrestored, still has the original six volt dynamo, which as far as I am aware hasn't been re-conditioned, and the Thorspark electronic ignition. When I bought the bike it had a recently reconditioned magneto, which didn't work despite costing several hundred pounds, and the original Lucas voltage regulator, which seemed to work sometimes but not at others. I fitted a solid state voltage regulator made by AO services and supplied by Draganfly motorcycles, which has transformed the electrics. The lights, although not as bright as modern bikes, now work similarly, they dim very slightly on tickover, and go to full brightness the moment you rev above a tickover. With the lights on, the ammeter is charging at 15 miles per hour in 4th gear.
Magnetos are an excellent piece of kit. However we offer a reasonably priced modern alternative, that has some practical advantages.
It doesn't matter if you have 6 or 12 volts, as long as you don't have a charging fault, then you will have not have a problem.