That was 14.42 V with a failed Pb battery (internal short in one cell, apparently).
I dunno how this voltage regulator works, it being controlled (I think) by the bike's Motronic CPU (ECU). I just went out and started the bike and got a 13.81 V reading above 2500 engine rpm, with the new LiFePO4 battery installed, which, I believe, is insufficient to charge it. This was with a cold alternator (less than a minute after starting up) in a vehicle I know not to charge well until the electronics are warm.
I plan to do some more testing tomorrow morning, especially on the rest voltage (13.2 V with ignition, fuel pump and headlight working).
Meanwhile, I bought an IMax charger for it just in case....