So, any precident for a grounded rotor with 0 ohms across the sliprings causing overcharging? Has anyone seen anything like that?
Those conditions cannot cause over charging.

Edit: Update on Aug 14 after re -reading the whole thread.
You do not have 0 ohms across the slip rings, you have 5 ohms. You have a ground on the end of the rotor winding that connects to the outer slip ring . The reg/reg feeds full battery voltage in on the inner brush, so with the ground you end up getting maximum charging or over charging.
 
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RG,
That's exactly what I thought. So why does my other bad rotor, the one with 0 ohms across the sliprings but has no continuity to ground seem to eliminate the over charging? Obviously it gets no charging at all but that's to be expected. I'll show you guys a picture of the readings I'm getting on the new rotor soon and you can see what I mean.
 
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Alright folks, as you can see above I did the rotor checks with two separate voltmeters to show that the readings are not tue to a bad meter. You can see continuity to ground on the sliprings and no resistance between the slip rings. Yet we are still getting overcharging. It doesn't overcharge at idle but the second you bring it up to about 2,500 rpm the volts just steadily rise. I shut it off there so I don't fry the rest of my system.

Incidentally, a few days ago it wasent over charging until quite high rpms, but that was with the old reg/rec unit. I'll throw that back in after this and see if it changes the overcharging threshold.

My old rotor doesn't overcharge. So when I take out this rotor the overcharging issue seems to go away. Is it safe to assume that a new rotor would be my saving grace? Or could it still me something else causing my issues?
 
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Just for the sake of thoroughness here are the readings off my old rotor. The lower number on the volt meter is the bike at idle, and the larger number is the bike revved up to 6k rpm.

I'll go switch my reg/rec unit now and see if that changes anything. I'd love to just get the new rotor but I'm worried that the overcharging issue may not be with the rotor. I can't really afford to fry another rotor if that's what's happening.
 
Switching the reg/rec unit had no effect. So the fact that the threshold for the overcharging has gone from high rpms to relatively low rpms in the last few days is also interesting.

Let me know what you think! Thanks in advance guys. You're a wealth of knowledge and it's an honor to have you backing me up. Cheers.
 
Excellent pics! Really helps here.

Your rotor tests are being done on the wrong scale, 20k ohms.

Set your meters to 200 ohms, and repeat all them tests you posted...
 
Ahhaha oh man. Nothing like a momentary lapse in attention to detail to get you chasing your own tail for most of a weekend

So, now that I'm done being an idiot. My new rotor tests out fine, 5 ohms across the slip rights and no continuity to ground. Just like when I fixed it.

Shouldn't I be getting zero continuity from the sliprings to ground though when the brushes are installed? I'm getting 15.7 ohms on the out ring and 11 on the inner (my volt meter is .5 off) image.jpeg
 
Ill go through and check all the continuity tests on the wires again to make sure I had the meter in the right setting at that point. Thanks again and sorry for being bit of an idiot That's entirely my bad.
 
All righty, here are my findings. I've got battery voltage and continuity all along the brown sensing wire, from the regulator to the brushes and to the keyswitch. At idle I'm getting half a volt low on the brown wire from battery voltage.


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I am getting about 30 ohms going across the key switch. That seems like a lot. The volatage drop is very small however

I'm also finding that my ohms going across the brushes very widely when I turn my crankshaft
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About half of the inner slip ring on my rotor is pretty rough, the shielding plate from where the brushes mount came off at some point and badly dinged up half the slipring. So now only about half the brush makes good smooth contact. The other half rides on the hills. Seems unlikely but could that be the cause of the variation in the ohms going across the brushes?
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Any of this info useful for diagnostics?
 
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Allright, Let's back up again. My rotor is definitely grounding out. Don't know why it didn't read that way half an hour ago before I ideled the bike a bit but there it is.

Could a rotor that's has 5 ohms across the slip rings but is grounding out cause overcharging?
 
I'm sorry, that yes is a touch ambiguous. What you're saying is that my battery is the problem or that my rotor is the problem? Or are you saying that rotor is the problem and I've most likely cooked my battery because of that?

Just to re state: my rotor being grounded would cause overcharging like this. Is that the case? Is there a way for me to double check? Aren't the brushes allready grounded? Why would the rotor being grounded make a difference if the brushes are also connectoed to ground?
 
I only buy these rotors, never had one go bad.

https://ricksmotorsportelectrics.com/New-Yamaha-Rotor-41_400

I would not trust a rewound rotor. Anyone who works on electric motors could rewind a rotor, but the epoxy that keeps everything in place and must stand up to the heat is what makes a good rotor.

The rewinder that many use on this forum seems to have a good reputation, he must also use an epoxy that works well.

Scott
 
:umm: Alternators................I just replace the parts when I am convinced they are bad. I have complete faith in this type of system when the parts are all checked, replaced with parts of good reputation, good reputation, good reputation.

Yes, your battery was, or was close to being, compromised.

Scott
 
Haha okay, so what you're saying is you're sure that because my rotor is showing the signs of a bad rotor, i.e. Continuity to ground, that it must be the problem? Or are you saying that rotors, if they have continuity to ground, cause overcharging?

I'm going to bring my battery to oriely shortly and have them check it for me. Just so we can have that issue out of the question.

Sorry to be pedantic, I just really want to be sure about this problem before I throw another 150 towards it.
 
Yes, I have had a rotor with an intermittent short to ground over charge, cook and dry out a battery, it was wrecked.

$150, In my case it's commitment, either I'm committed to that bike or not. Sure, I could sell them all and buy something newer, I just don't want to think about that.

Scott
 
Haha no one is saying want to sell it. I just want be real sure what I'm buying is actually what I need and won't be wrecked by somethings else that's not working. I only moved back from Ireland about 2 months ago so I'm still getting my feet under me financially. I'll take your world on it with the rotor. Let's hope I can be moving again my next weekend. There's a ride I want to go on in Oakland with the EBRMC coming up.

Thanks again Scott and everyone. I appreciate all the help. I'll let ye know how it goes when I get the new rotor. Cheers.
 
I still think you have a reg/rec with a not so good reputation. I think your best insurance for your battery and rotor is to do the Chrysler or Fiat regulator with a different rectifier as explained on this forum. pamcopete has stated that he believes that rectifiers can be blamed for most of the other components failures.

Scott
 
Yeah, we'll have to see. For now I'm going to just run it because that's what I have.

So, I'm getting a good used rotor from Gggary. While we were talking he gave me some more places to look for issues, just In case the rotor wasent the only thing making problems. He mentioned that with the key switch turned on I should have continuity to ground on the green brush wire.

I'm getting 25-75 ohms reading from that wire to ground with the brush taken out of the rotor. That doesn't seem right. Even weirder is that the connection to ground shows less ohms when checking frame ground than when going directly to the battery lug Which is certainly weird as hell.

Correct me if I'm wrong here but I should have 0 ohms going from the green wire to ground right?
 
Alright, here are some images. I'm getting very inconsistent ohm readings from the green wire to ground when the key switch is turned on.

When the stator is installed, with the brush removed, I'm getting 190 ohms.
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However, the green wire to battery lug is giving me 153 ohms. How can my engine ground have less resistance to ground than my actual negative battery lug?
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Next weird thing is when I pull the stator off the bike and let it hang I'm 65.7 ohms.
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And then hanging stator to negative battery lug is giving me 108.7 ohms!
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This last picture is showing hanging stator to the black ground wire at the regulator plug .7 ohms. This reading is consistent with the reading from the green wire on the stator to the reg plug when the stator is installed over the rotor. This reading seems right and means that the bad continuity to ground is somewhere down the line from the reg plug.
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Anyone have any idea why these reading are all over the board? And how in the world there could be less resistance to frame ground that to the actual battery lug?

Could someone tell me where the frame ground is so I can check for good connection?

And lastly if I have bad continuity to ground on my green wire could that contribute to overcharging my battery?

Thanks in advance guys. I'm looking forward to hearing what you think,
 
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