Suzuki test is 5000rpm with lights on high beam the DC volts across the battery should no lower than 13.5v and no higher than 15.5v, if outside this you shoul test the no load voltage of the genny at 5000rpm. Set meter to ac volts and test between each yellow wire at the at the connector that comes from the genny, 50v sounds abit low but at least 50v. You can also check there is no circuit between the three coils when the engine is not running by setting the meter to ohms and checking each wire to another and there should be no circuit between either yellow wire, ie, they are independant of each other. The reason there are lots of wires going to the black/white wire is that this is the common/return for the bike and so is effectivly made into one circuit by connecting all the black/w wires together and as your loom is in a bit of a state looks like its been repaired.