Stator Questions

If you connect a digital voltmeter across the AC output from the alternator with nothing else connected, the reading will leap around all over the place. You need to measure the DC voltage after the recifier with a battery connected. The battery will stabilise the voltage somewhat. An old-style analogue meter will give a better indication since the inherent damping smooths the voltage fluctuations. Alternatively a DMM that has an averaging capability.

If just checking the alternator I think you need an AC meter.

The peak open circuit (no current) alternating output will give much higher peak voltages in both directions than the battery voltage.  Al will probably turn up soon and explain all!

Modern multi meters are prone to interference from ignition systems, you need an old technology type analogue meter. A cheap one will do. 

Is the rotor to stator clearance OK. I had a  problem with the same set up, the stator clearance varied set true and tickertybo.

Mike Brazier

Yes cheap digital meters pick up ignition interference and hence not reliable.

But I do not advocate trying to 'measure' the AC from the stator, the waveform is disgusting and its frequency is out-side the range of your AC Voltmeter (no matter what type). A more meaningful check is to use an old headlamp bulb. If it glows brightly at modest throttle then you have 45 W or so! To complete the check on the Stator take one lamp lead to Earth (other lamps lead still on stator) and make sure the lamp does NOT light up.