How about the question of should there be power to the main fuse with the ignition off?
The 76 CB550K wire diagram in the Honda Shop Manual clearly shows a red wire going directly to the fuse terminal. Red wires route directly back to the battery POS terminal. This would make it normal for one fuse terminal to be "hot" with the fuse removed, and both terminals would be "hot" with a good fuse installed.
If anyone is blindly tweaking the regulator, just to see the effect, almost certainly this will screw up the adjustment so it can't do it's job correctly. At best, with an ill adjusted SOHC4 regulator, the system will keep the battery undercharged. At worst, the battery will be damaged by overcharge during cruise conditions.
Despite its label, the device "regulates" only indirectly, and it's primary purpose is to keep the battery from being overcharged when the alternator is at peak output. It does not serve to maintain a constant system voltage, as that voltage is whatever the battery's charge state happens to be at the moment, which can vary between 10 and 14.5V on a running bike with an SOHC4 regulator working at optimum function.
For damn sure, it is not to be adjusted while the alternator is idling. Because at that speed the alternator cannot produce more power or voltage than the bike consumes. The "voltage regulator" for the SOHC4 is more aptly labeled a voltage limiter, as the only thing it can do is command the alternator to "back off" when the battery reaches peak charge. The battery will certainly lose any peak charge whenever the alternator turns at idle RPM, because it's peak output is reduced by 2/3rds, which is far less than what a standard bike consumes.
