I think I remember seeing a kit somewhere a while back that used a 6v battery for the lights, and the white wire would trickle charge the batt when the lights weren't in use.
I have been too lazy to hook up my own scope, but I read a post by a guy who did and he described the output (going by memory) as "3-50 volts peak to peak and not very clean" or something like that.Have you put an oscilloscope on the magneto output? I've done electronics for a while so I'm wondering what type of waveform it has.
Norm, no offense or anything, but I personally would be more interested in an actual electrical system than just a bulb that works. It would allow you to run brighter lights, taillights/blinkers and not have to worry about drawing too much power from the mag...You could just buy one of my bulbs or lights and be done with it so you can work on something more fun like squeaking a little more power out of the engine.
divide the dropped voltage by the LED current to get the value of the dropping resistor. If you divide volts by amps, you get the resistor value in ohms. If you divide volts by milliamps, you get the resistor value in kilo-ohms or k.I've been pondering this idea myself and I think you will probably need a voltage regulator on the white wire to prevent overcharging and possibly a diode to keep the battery from feeding back into the magneto. Hopefully Norman will see this. He has done some work using the white wire to power a light. It might be easier to use a motorcycle battery to run a regular bicycle light system directly then just charge the battery at home periodically.