I don't use my XJ 600 so often and a few months ago, it wouldn't start due to an empty battery. The battery was old. I got a new one, and a SC10 "smart" charger to take good care of it.
Two weeks ago, I recharged the battery (charger in fully charged / maintenance mode) then used the motorcycle a few times until the other day the battery ended up empty again and I couldn't start at all.
I charged the battery to full charge (it took a few hours) and now the motorcycle starts again.
I'm trying to figure out which part is broken.
During those last two weeks, I noticed the speedometer light bulb didn't light and I figured it needed a replacement. Since the battery is charged, it lights again. I guess it was due to a low voltage battery.
The full battery has a voltage of about 13 V. Once I start the motorcycle, the voltage doesn't rise, even when I open the throttle up to 5000 rpm. From what I was told, this would indicate a faulty alternator.
I did a few tests (from this french webpage).
I opened the alternator and saw no obvious defect on the stator.
I unplugged the alternator to check the voltage at its connections. There is about 30 V between phases, going up to 60 V when opening the throttle. Those are approximate values but at least the 3 coils seem to behave the same.
I also checked each connector was not grounded and I measured the resistance of each coil at about 0.6 ohm.
From what I understand, this would indicate the alternator is fine and point at the regulator.
Is there any check I can perform to ensure the regulator is the broken part before I try to replace it?
Is there a fuse I'd need to check? (No idea, just asking.)