DOHC Alternator rotor specs

[alehman]

My 79k is not charging... For those of you familiar with DOHC, if my rotor reads 3 ohms between slip rings, is that too far out of spec to charge well? Also, what factors are involved in a rotor going bad?

[icerigger]

The most common rotor failure is a short in the windings resulting in low resistance.
Unfortunately, when the resistance drops, it draws too much current through the regulator, frying it.
If you've run it below spec for any length of time, your regulator is probably pooched as well.

[alehman]

I just got a new r/r about a week ago, and when I tested the rotor then, it was good. Think I could've fried the r/r in 1 week of a dying rotor?

[icerigger]

It's a possibility. The FSM has static tests for the R/R, CH 16 I think. The alternate chapter has more depth, I think it's from the GL1000 FSM. 3 ohms doesn't sound that bad (mine was 0.5) but it's the first thing I would check. Start with the rotor, stator and then check the R/R. Check ALL the connections, cleaning the connectors as you go. Check for loose, pinched or frayed wires and secure or replace as you find them.

Let us know how it goes.

[Hoosier Daddy]

Does your rotor measure 3.0 or 3 something? Big difference because...

the rotor spec is 3.6 - 4.4 ohms

For the stator
B-W:  10-12 ohms
Y-Y : 0.4 - 0.5 ohms
Y - ground: should be infinite

For the rectifier
Resistance in one direction
Green and any yellow 5-40 ohms
Red/white and any yellow 5-40 ohms

Resistance in the other direction (leads reversed)
Green and any yellow 2000 ohms minimum
Red/white and any yellow 2000 ohms minimum


This is from the factory service manual for CB1000 charging system chapter18  It is supposedly much better in troubleshooting than what's in my 750's manual and apples to apples. I have it on .pdf if you need it but it's 11.6 MB and not much more than what I posted.  I'd have to e-mail it if you'd rather have it for yourself PM me your e-mail address.

[Hellbilly429]

Any chance you could post that up in the manual/s section? Am sure lots of people could use precise information like that!

[Hoosier Daddy]

I'll give it a go.
at 11.6 MB  I was hesitant to try...

[icerigger]

Here's a link to that

http://www.cb750c.com/publicdocs/CB900C_Manual/Chapter_18_Charging_System.pdf

[Hoosier Daddy]

... and I posted a link to the CB1000 manual in the "manuals" thread that Hellbilly mentioned.

http://honda-cb750-s NEW-Repair-manuals-April-26-2011-Updated

[icerigger]

ReRun, can we get that link bumped up to the first post??