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Discussion Starter #1
Hi All,

Earlier this summer I replaced my stator and R/R because my battery was not being charged by the bike. The old stator passed both the continuity test and the ground test, but failed the dynamic output test as one of the phases gave significantly less output than the other two phases. Now with the bike all put back together, the new stator is testing bad in the exact same way, it shows no shorts or fused coils, but one of the phases gives about 1/10th the output of the other two. Is it possible that my alternator rotor is bad? Or is there some other part of the charging system that might be the culprit? I would like to hear any possible alternatives before I go and order a new alternator rotor.

Thanks for your insights!

P.S. all electrical readings on the stator have been taken with the bike at operating temperature, and the stator leads disconnected from the rest of the wiring.
 

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1986 VN750
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3,255 Posts
That's really weird. It would be odd for it to be the rotor, I'd think the readings would be low across the board if so.

Any chance there is any odd pinching/etc of the wiring within the stator cover? Wiring rubbing the rotor?

Is the stator perfectly centered (if you're using a stator mod plate)? If it was closer to one side of the rotor, the leg furthest from the rotor would produce less voltage.
 

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Discussion Starter #3
I have not made any modifications to the generator housing (although at this point I'm kind of wishing I had done the tuxedo mod), so the stator should be centered in there. As far as the stator leads are concerned, I was very careful when I installed the new part, and I don't think I pinched any of the wiring. I'll make a close inspection of the stator leads and post my findings. Thank you for the reply!
 

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Discussion Starter #4
I couldn't find any evidence of damaged, pinched, or shorted wires coming from my stator. Now my questions is, since I had the exact same problem before and after I replaced the stator (and r/r), could something else must be the cause of my problem? Any thoughts?
 

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the rotor is essentially a bunch of permanent magnets mounted in a circular shape. each magnet will pass by all legs of the stator during a revolution. the odds of one magnet being bad are pretty low, but a sharp impact on the rotor assy can cause one or more to break. but that wouldnt cause low output on only a single leg, it would effect all legs, since all magnets pass all poles in a rotation.

would look at wiring (as mentioned) not only inside the engine, but the wiring outside as well. there are a set of 3 bullet connectors between the stator and the R/R that are common points of failure, as well as the connector at the R/R
 

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Discussion Starter #6
Thanks, when I initially tested the output from the stator I did so at those bullet connectors. Also, those connections were shiny clean even at the start of my whole charging fiasco. The things that troubles is that both the old, and new stator are reading as 'bad' in the exact same way.
 

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Discussion Starter #7
I just found this on JP cycle.

4. Stator Checks/Rotor Check: Each of the following tests isolate the stator & Rotor, If AC Output test Fails and Resistance Check, and Stator IB Test Pass then Rotor is at fault (Pull Primary covers and inspect rotor for damage).
 

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1986 VN750
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Since it's a single leg it really can't be the rotor. Still worth checking for damage, but I would be hard pressed to think that's it.
 

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FREEBIRDS MC CENTRAL NY
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Just duct tape six batteries to your fender
 

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have you tested the battery at all ? or the junction box connection ? if you replaced them with oem parts our charging system dont kick in till around 2 to 3k rpms so rev the motor and then test it.
 

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Just duct tape six batteries to your fender
Dumbest idea ever. It is much easier to duct tape a car battery to the luggage rack.

Borrow a friend's tester to double check your readings? Couldn't hurt. What is the voltage charging the battery?
 

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FREEBIRDS MC CENTRAL NY
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Dumbest idea ever. It is much easier to duct tape a car battery to the luggage rack.

Borrow a friend's tester to double check your readings? Couldn't hurt. What is the voltage charging the battery?
Kinda gets in the way of the spare tire mount,so yea dumb idea.I modded the front end to take a rear rim so I don't have to carry two wheels.I have to make a rack for the motorcycle stand too as I have no centerstand. Sarcasm. It's what's for dinner.now back to the woods for me
 
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