Johnny Mac wrote:
. Thanks Slick. I did disconnect the alternator from the system and only checked the output from the 3 (2) wires. After 3K RPM, the AC voltage went down as the revs went up. The magnets on the rotor are also not nearly as strong as the other slightly larger BSA Lucas rotor. Also, this rotor looks beat to hell. There is a hole on the rear side of it.... not sure that's supposed to be there. I'm not used to seeing the backside of a rotor so it's anyone's guess.
That IS a beat to hell rotor! The magnets are strong enough if the DC voltage at the battery attains 14 V at 3K rpm or less. Checking the DC volts will verify that the rotor and stator are up to par. The hole may be a crude attempt at balancing the rotor.
A perfect regulator would simply rectify the AC from the stator and otherwise do nothing whenever the rms (root mean square) voltage is less than 14 DC (note: 14 is typical, actual may be +\- 0.2 V). Then, as rpm rises, the regulator should begin to momentarily short the AC input to prevent the DC from going above 14. As the rpm further rises, the regulator should progressively increase the shorting (to compensate for the stator tending to increase voltage as rpm increases) to maintain 14 V.
In other words, as rpm increases, the DC voltage at the battery should steadily increase until 14 V, then remain steady at 14 as rpm continues to increase. I suspect your regulator is not transitioning from the "do nothing" phase, to the "shorting" phase, and you will not see this pattern. The DC volts vs rpm will/should confirm this hypothesis.
Slick
