Motorcycle Repair: charging system diagnosis, honda cb750k, stator rotor

Question
Hi Mark,

My question involves a 79 Honda CB750K, which I know is not in your particular area of expertise, but I thought my question might fall into the "general" category, so here goes.

I am getting very low AC voltage (.12 volts) coming from the stator.  Continuity tests on slip rings and stator all check out, but there is almost no juice coming out.  I have heard that a bad regulator rectifier can cause this, as it is needed to magnetize the rotor.  

I am at my wit's end and cannot figure out where to proceed on diagnosing this charging system.  I am getting NO juice at the battery; voltage just drops as bike runs.

So my question is, before I start shotgunning parts and getting a new regulator rectifier, does the low voltage at the stator indicate that the problem is in the stator/rotor, or is it possible that a bad regulator could be responsible?

Thanks for your time.

Answer
Hi Joe,

More times than not, if your staor output is the case, thats whos' responsible for the low voltage at the battery.
Try and do an Ohms resistance test at both or all of the terminales from the stator. Usually the 2 colored ones are the in/ output for AC current and when resistance is checked with one of the colored wires to the ground wire, and you here a consistant "tone" or "OL" from your multimeter, one or more of the coils is grounded, thus marking the stator as bad.
Make sure you are doing all of your tests as well with a fully charged battery. This is very important as some systems just do not have the ability to bring an almost dead battery back to life.

Hope this helps!

~Mark Panka