EDIT:: Forgot to mention that the bike when running off the car battery measured 14.5-14.1 (seemed to get lower as the bike warmed up) while running.
First I very rarely give advice without knowing first hand, I have a 2007, just disconnected the negative because I have several connections on the positive. Warmed the bike up, when it went to idle speed I disconnected the battery, bike continued to run but I got a F1 light on. I was fully expecting that as there is no filtering on this or any other automotive system, so there would be a excessive amount of ripple or AC, as to the bike, absolutely no change in idle speed, and headlight was on along with all the other lights, ( I have the higher wattage Osram Hyper 65w).
Check the manual for testing the regulator, you need to do that. Since you already have mastered running off the car, and you have a meter, I will give you some tests that are similar to the manual, but different.
You need to disconnect the regulator multi-pin connector at the regulator ( it pulls out towards the brake pedal side.
Run the bike off your car, you can have your car idling to maintain battery charge. The best is to measure with the bike at idle rpm, what I need you to do is measure the connector,ONE WORD OF WARNING the top connection is positive from main fuse, live ALL the time, the bottom has three black wires, call them A,B,C.( BK-1, BK-2, BK-3) You need to measure AC volts in the range of 55 to 65 volts , measure A to B , then B to C , last C to A. The voltages should be within 2 to 3 volts of each other.
See manual 16-34,
Another place you can measure it is on the connector from the alternator, although you need very small probes to get into the connector, the connector is about 1 foot above the alternator, three white wires in the bottom and three black out the top, use the same test method, except you are measuring the white wires.