My daily commuter is a 2002 CBR600F4i with 85k miles (I know, time to get a fresh steed). Over the past few months have been going through batterys and headlight bulbs so decided to check voltage during commute and was charging at 17.8v. Replaced Regulator assembly (aftermarket) and still getting 15-18v, even at idle. When looking across the three "phases" from the stator (yellow wires) I get 12vac (1-2, 2-3, 1-3) and from each phase to ground about 9vac. If I disconnect the regulator from the stator I get 18vac across phases and still 9vac to ground. Resistance is 0.3ohm across phases. Readings at the green and red wires from the regulator are 15-18vdc while connected, and 26vdc if that connector is removed. Anything else to check? Bad ground somewhere? Could not find info on what stator output should be. My buddy suggestion was to wire in four more high beams and a heated vest..

 

voltages coming from the stator sound correct. might try an oem R/R. voltage should be around 13.5 at idle and no more than 15 while revving.
All else fails, install some resistors coming off the R/R