79' CB750 DOHC regulator testing.

Drey6

Over 1,000 Posts
Per the manual. The green wire to each of the (3) yellow wires should read the same resistance. Now with the black multimeter lead to the green wire and the red to each of yellow wires I am getting 4.86, 6.32 and 6.44. Now switch the red and black leads and I'm getting nothing? Manual says it should read consistently but in the 1000's.

Now the red/white wire (with the red multimeter lead) to each of the yellow wires (with the black multimeter lead) I am getting 4.46, 6.18 and 5.53. Now switch the multimeter leads and I'm getting nothing. Even though the manual says switching them should read the opposite in the 1000's like mentioned above.

The part is now inside the house and resistance is dropping each time I go back to check, because of it being cold and now coming to room temperature? Regardless each is STILL reading different numbers BOTH when cold from being in the garage and now a bit warmer. Should this be enough to say it has failed?

Also, the rotor had good resistance (3.6-3.7), the stator isn't grounded and has continuity, the brushes tested fine and all of these parts mentioned have been replaced with new Ricks electric parts about 8 months ago. The regulator testing above represents the not even 8 month old reg/rec. I first bought a Racetech rotor when I purchased the rest of these parts and it failed in 4 monthes. Then researched and realized the rotor most commonly fails on these early DOHC Honda's so I found Ricks to be the most praised option for this as well(kicked myself for not buying it in the first place!) I'm thinking the regulator got beat on when the Racetech rotor failed and just now has failed in itself.

Let me know what you boys think, I'm convinced it's bad due to it's inconstant resistance.
 
I apologize in advance for having too much to drink when answering this, but what problem are you having? Not charging?

What's the voltage measured between the positive and negative terminals of the battery at idle and at 4,000 RPM? What type of battery and how old is it?

Rotors (or the brushes, at least) are not an uncommon failure point, but the battery still tops the list.
 
I ended up working this issue out. I swapped the regulator out and am getting 13.70ish volts at 4,000 rpm, now. For the record the battery is a Bikemaster and is only 6 months old.
 
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