Rotor/Stator

[BullMagnum]

Can anyone tell me how a rotor goes bad?
Isn't it just a magnet?

[Re-run]

Depends on your bike. Most are NOT a permanent magnet. They are electro-magnets and require power to generate the magnetic field. What usually happens is the wiring goes bad.

[BullMagnum]

Do you mean the wiring in the rotor?
It kinda looks like there may be some there.
Or do you mean the wiring in the stator?
Stator, regulator/rectifier, and battery are new, still losing volts in battery when running.
Any thoughts??
Thanks for the help.

[Re-run]

What is the battery voltage when running above 2000rpm? You should generally be above 13 volts. If not, first is to check battery. Charge it and check voltage. Then let it sit overnight and check again. If the voltage holds, then the system is at fault. It is entirely possible to have a bad reg/rect even if it is new.
If you have a manual, check the stator for continuity. As a simple thing, check the connections. Those connectors could just be dirty enough to not allow things to charge right.

[BullMagnum]

Battery is charged to almost 13 volts on 2 amp charger.
Install in bike and start, battery goes down to 12.7, 12.5, 12.3, etc...
Disconnected all lights, horns and such not needed for charging to narrow down fault.
Checked reg/rec, stator and rotor according to manual and they check out exactly as it says it should.
Brushes are fine as well.
Grounds were checked and seems fine.
When I disconnect battery while bike is running it shuts off.
hard wired all the wires coming from the stator going to the reg/rec also.
Loved riding this bike when it ran but am getting discouraged.
Any ideas???
I appreciate all your thoughts, thanks!

[Re-run]

Without knowing what bike you have, I cant say much more. I know the 79-92 years of the 750 seemed to have issues with the stators.

[magnum56]

This might be a little obscure, but I had a similar issue years ago with my 74 CB750.  Tested everything "by the book" and I could not find the problem.

Eventually, while tinkering, I noticed the rotor itself was turning (slipping) on the end of the crankshaft.

The rotor on mine was held in place on the tappered end of the crankshaft by a bolt into the end of the crank.  There was no key or keyway utilized to keep the rotor from slipping if the bolt loosens some.

Remember that the rotor makes and breaks the magnetic field created by the interaction between the stator and field coil.  If you can turn the rotor by hand (without the engin "turning over as well) the rotor is loose and when the magnetic field is created, the rotor will slip on the end of the crank.

Re-torquing the bolt on the end of the crankshaft was all mine needed to correct the issue.  

Good luck ...