So, why did Harley in 2006 finally upgrade to the 3-phase system years and years after the other major MC manufacturers if it isn't a better system?

 

Not saying that the three wires is not a better system, since it has more amperage output lower in the RPM.s, hence gets the system up to 14.1+ at lower rpms over the two wire system instead.

So two wire loop.


Three wire loop,


So with the extra pole at the voltage regulator, the voltage regulators is able to put out more lower RPM amps at lower rpms isntead.
Hence both put out about the same amperage at full tilt higher rpms, but with the three pole system able to put out 14.1+ lower in the RPM, gets the charging system up to 14.1 volts where AGM batteries start to recharge correctly.
Note, on the vets, instead of oem three pole alternator that only puts out about 14 amps at idle (radiator fan alone has a 15 amp draw itself when you are sitting at a stop light), the Aftermarket 6 pole altenators put out 45 amps+ at idle isntead. Hence the faster you can get the battery charged back up, and hold it voltage of fully charged while the alternator just deals with the cars light demands, the longer that both the battery and coils (stator on a Harley) last isntead.

But, where most miss the problem on the both systems, not between the stator and regulator, but regulator to the battery instead. Hence voltage regulator is trying to hold the voltage to 14.1 (battery voltage feed back), and when you have problems with the voltage regulator not seeing the real voltage of the battery that is fully charged, the voltage regulator is still pulling full draw from the stator trying to get the battery charged/charging system up to 14.1 volts, and why the stator burns up (dying battery even with a good charging system will burn up a stator quickly as well.

So again, stator gets A/C charged by the magnets moving around the coils when the motor is running, but until the voltage regulator pulls that charge to convert it to DC for the demands of the bike/battery, the coils do not become hot. Normal cycle for the stator is the voltage regulator pulls amperage hard for a min or two to charge the battery back up from say stating the bike, then from there once the battery is charged, light pull as it just maintaining the needed voltage of the bike itself. Dying battery, or voltage regulator not able to see the battery charged back up, voltage regulator pulls full amperage off the stator full time, and this burns the coils wiring up from the inside out isntead. Also, don't forget that the coils are in the primary, so are also being cooled with primary fluid as well.
Note, Stator coil wires are clear sheild coated, so you don't have wire to wire contact on the wiring. That is until the wires become over heated by too long of amperage draw from them, and in most cases just melt's the outer clear sheilding off them, to cause stator wires to stator wires shorts instead.

Fall out from a 7 year old battery on a three wire system, since the battery would not take a full charge, and voltage regulator keep pulling full amps from the stator trying to get the battery back up to full charge (feed back on the charging system from the battery voltage).

 

Go with cycle electric if you have to replace again!