I very much doubt some voltage regulators are set too low, they aren't made by Guzzi of course.
BUT on my Norge (identical wiring to the Breva) I had a low charge voltage at the battery (around 13.25v). The fault was partly a high resistance joint somewhere in the wire from the alternator main output, via the 30A inline fuse and another ln line connector to the battery. I ran a new heavier wire from the alternator direct to the battery positive, and immediately got 14.25 volts at tickover.
No amount of replacement alternators or regulators would have cured my low charge voltage, as the fault was in the wiring. And since your Breva is older than my Norge, I suggest you look there too.
Oh, and it's well known that the dash voltage readout can be lower than that measured across the battery, but after my wiring repair, it was much closer on my bike.
Howdy,
To each his own, mine was indeed set too low, as was mentioned by a dealer service dept, also have about a .7 volt drop between alternator output and battery.
When I changed the regulator to a properly set one, raised my battery voltage about .7 volts.
Haven't gotten around to adding a more robust wire from alternator to battery, on mine, which I'm hoping will bring it up another .5 to .7 volt.
DZ