I guess I would go here http://engines.honda.com/parts/ownersmanuals/gx620
to start and see what manuals I could find on the Honda. It appears to come with a 20A charging system which is equivalent to the Onan. I think your test so far is a good one... I don't know anything about the Honda but electromagnetics hasn't changed in a couple hundred years at least... my experience is the AC voltage from stator with engine running should be in the 20 --> 40 VAC range and vary with engine rpm. Since the Honda is not original, you'll have to see how the wiring was adapted to 318.
to start and see what manuals I could find on the Honda. It appears to come with a 20A charging system which is equivalent to the Onan. I think your test so far is a good one... I don't know anything about the Honda but electromagnetics hasn't changed in a couple hundred years at least... my experience is the AC voltage from stator with engine running should be in the 20 --> 40 VAC range and vary with engine rpm. Since the Honda is not original, you'll have to see how the wiring was adapted to 318.