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My rotor keeps dying!


CB750 New member
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Been having charging issues lately, and it seems to be the rotor, and I'm wondering what has killed two of them so far... Here's a rundown of the issues:
-new battery late last year, rode it about 200km total before parking it over the winter (with trickle charger on occasionally)
-wasnt charging at the beginning of this season, voltage across the battery at idle was ~11.6 And dropping
-replaced regulator/rectifier early May of this year, issue persisted
-checked brushes, still lots of life on them and no continuity issues
-metered 0.4 ohms across the slip rings of the existing Rotor, which research led me to believe was way too low.
-new rotor arrives, meter 4.5 ohms across the rings. Much better!
-after much struggling, get the old one off, new one on, meter 12.6V across battery @ idle, rising to 14.5v @5000 rpm and holding steady. Great!
-rode it about 4-5 times over the last two weeks (~200km total), and it dies on my commute home.
-check the rotor again, and the new one is now down to 0.4 ohms as well.
Is there anything can can cause a brand new rotor to fail that quickly? Could it be heat buildup? Did i just end up with a faulty new part? Keeping in mind the Reg/Rectifier was changed at the same time. I know I need to replace the rotor again, but I don't want to just replace a $200 part without sorting out the root cause.
Any ideas?
I just found this quick schematic of a motorcycle charging circuit. Its generic. The thing to note is that the rotor resistance is dependent on the battery, regulator, rectifier, main fuse, ignition switch and the whole bikes electrical system......

Seems like even a loose ground wire or even a loose mains distribution connection at the battery, starter solenoid etc could alter that resistance. I would check all grounds, connectors and cables. Spend a day removing the panels and check your mains distribution (regulator, starter solenoid, battery) integrity. That's a major component that shouldn't blow after a few rides. Check the integrity of each wire in each connector, if it's loose, broken or corroded, I would look into replacing it. Check grounds tight and on clean metal. Check +12 V connections are super tightly made with no corrosion. Go from there.