Topic: Help me Confirm I have a Bad Stator Coil Please

[scottly]

(If you want to confirm if the voltage drop is indeed the root of your problem the quick-and-dirty way, temporarily disconnect the white regulator wire, jumper it to battery +, and check the battery voltage with the engine running. If it goes up, it means the bullet connectors, stator, and field are OK, and the problem is the voltage drop into the regulator on the black wire.)

I did this on a battery that read 12.26V with the bike off. After starting it the battery read at 11.44V and when I revved it to 5k rpm it got to a max of 11.52V. This doesn’t seem like the desired behavior.

I also tried another user’s advice and jumped the reg white and reg black wires to each other and revved the bike as well and while I don’t remember the exact numbers, the behavior was similar in that it only went up a max of .07V

I also tried measuring amps on the field coil and I got nothing. With my leads directly connected to the green and white wires (that were not connected to the harness) I got 0A for both a/c and d/c. Idk if this is at all right but I thought it was worth mentioning. I did replace the bullet connectors on the white wires because it broke. Do I have a bad field coil?

This bypassed the regulator as well as the wiring from the battery through the fuse box and ignition switch. What rectifier are you using?
BTW, that's not how you measure amps, you measure the resistance (ohms) that way.

[scottly]

1977 Honda CB550k3



But I was still hopeful maybe that wasn't a huge issue, so I RAN the bike and checked AC voltages. At least two videos have told me that each coil should read:
25Vac @ idle and 70Vac @ 5k rpm

My bike, however, reads:
~8Vac @ idle and 43Vac @ 5k rpm

Do the AC test again with the white field wire jumpered to battery +. ( The first time you did the AC test the alternator had some output, so the field was getting some power, but not enough. This may have been caused by the lower voltage getting into the regulator on the black wire.)

[damianiscool]

Yes, I can assure you the bike was off when I did these tests. In fact, I had already taken the battery off for charging so there was no way it was on. I will rerun the other tests when I get the chance, thank you!