I've got a 1965 Gilera with a 6V AC system, no regulator, no battery. When I try to measure voltage at a light, or anywhere, the reading are too erratic to see. They jump around like a crazy man.
And yes, the multimeter is set to AC voltage.
Is this usual?
Digital or analog? You have a spare condenser , put it in parallel with probes. Start with stator light coil unhooked for a bench mark . You may have a bad connection from coil or ground.
Is the bike running or are you just kicking it? Voltage is based on rpm. If you have a constant rpm you should have a sorta steady voltage, enough to get a close range.
This is with the bike idling, and I'm measuring with a digital multimeter.
Bike runs fine, but I'm doing some electrical work so I want a baseline reading.
Crappy connection? You should be able to get a good reading if everything is working properly. How many coils in the magneto? Can you check another one? I have checked my peds even when pedaling an got a good reading. Try revving it a little also when checking and see if that makes a difference in stability of meter readings.
There are two coils, a lighting coil and an ignition+tail light coil. I tried the taillight and had problems. I'll try the headlight too. Also see if reving it changes things.
It was strange. I also got readings, jumping around, just with one contact on the frame, and the other contact hanging mid-air.
I recall hearing that on systems with a lot of "noise" like my unregulated AC bike, the spurious signals can prevent good voltage readings.
But that adding a capacitor to the line dampens erratic noise and allows the meter to work. Anyone know what size or type of capacitor?
the quality of your meter affects the quality of your results, what meter are you using?
the ignition has a condensor built into it, i don't think that is the answer.
my best advice is the min / max feature, if yours lacks that, you may not get reliable results.
i have a few threads on multimeter testing.
You'd probably get a more reliable reading on an analog meter, or a digital meter with a low impedance mode.
Most digital meters have an input impedance of 10+ Million ohms, so tiny low-current spikes of higher voltage will throw the measurements off.
Most analog Volt-ohm-meters come with anything from 20 thousand ohms per volt down to 1000ohms. The latter would certainly stamp down on very low current pulses... (edited)
A condenser is a capacitor. Got a spare, you should get one, any cheap one with a wire.
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