'78 750K charging issue - just looking for confirmation

[cebcb]

Hello everyone. I'm new to the site but have gotten a lot of helpful tips and hints from readings posts. I just wanted to get a couple nods about what i suspect my problem to be.

My bike fires up but slowly drops voltage from the battery. It is a year and a half old, Trugel, but it was running great before I had a very slow dump that prompted me to tear it down to frame and rebuild it, which i wanted to do anyhow.

Charging checks.

1. Stator leads all read .7-.8 ohms
2. Field coil - 7.8 ohms
3. Question. Is the rotor much of an issue on this year of bikes?
4. I think it is the RR, which I have one coming tomorrow or thursday which I hope will resolve the issue.
5. Continuity for the electrical checks too.

Basically, although the '79 and up years seem to have a problem with the rotor, or so I gather from reading, does the 78 rotor tend to be a culprit? It only has one ring to check, not the two like I have read everywhere, so that is what led me to believe the RR is the bad guy.

I apologize that this type of thread has been posted, but just wanted some opinions on the rotor because i haven't found any particularly solid info about it.

cebcb

[LukeM]

While you're looking stuff over, check the 3 yellow wires coming from the alternator, going to the regulator/rectifier.  Sometimes corrosion will build up there, turning the connector black, and not delivering the full voltage to the R/R.  Easy enough to check:  Pull the connector apart, and look for charred bits.  You can either replace the connector ends with something more robust, or just strip and solder the wires.  Soldering makes it a bit of a pain to change out the R/R and/or alternator, but you get a better connection.

Other than that, I would compare your findings with what's in the FSM for your model motorcycle.

Good luck, and keep us in the loop.
Luke M