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Discussion Starter #1
I've replaced the stator and the R/R in my '95 Vulcan 750, and I'm still only reading battery voltage regardless of the engine speed. I've got a few ideas to try and was hoping to get your guys' feedback.

1. It's possible that the new stator is no good. I plan on checking the voltage between the stator leads as the bike's running. To my understanding, the voltage between any two leads should be about 40-80V. Is that correct? The resistance between any two leads is about 0.5 Ohms and there's no continuity between any of the leads and ground. My hunch is that the stator's good. This is the 2nd stator I've tried, and I don't want to replace it again. On a side note, if anyone has any questions about replacing the stator, I should have an answer.

2. Perhaps there's a short or open in the wires between the rectifier and the battery. I checked the continuity between the positive lead off the rectifier and the positive battery read and I'm getting zero Ohms as expected. Also no continuity between the positive rectifier lead and ground. Same successful, but reversed, readings for the negative lead. Does anyone have any idea what the resistance values should be between the brown wire and the positive battery terminal and between the brown wire and ground? When I look at the circuit diagram, I think there should be no continuity between the brown wire and the positive battery lead and maybe a few kOhms between the brown wire and the negative terminal, since current must travel through the loads. I would think this value would be the resistance of the running lights and license plate light, but I'm not entirely sure. Any ideas?

3. I've read some things on the forum that the headlight relay can go bad. How do I test this? Do I just pull the headlight fuse and see if the bike charges then? If it is do I relocate the blue wire from the 8 pin connector of the junction box? Also what's the purpose of the yellow stator lead going to the 10 pin connector of the junction box. Is this for the starter relay? Can I remove it to eliminate one more possible source of error?

4. If everything above checks out, I would think the new R/R is no good and needs to be replaced. Any thoughts here?

Thanks for your input. I've been trying to fix this charging issue for two months now, and it's starting to drive me a little insane.
 

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First step is test the stator and r/r. Nothing else matters until those results are known. Both tests are in the repair manual download.

The blue wire bypass can be done to see if the headlight relay in the JB is at fault. The yellow stator wire is what triggers the headlight relay once the bike starts. Simply pulling the headlight fuse may not eliminate the problem in the JB, if it exists.

If the stator and r/r check out good, the Two Wire mod has helped on bikes with new charging systems and continuing charge problems. This mod bypasses the start relay in the JB, which is known to be a problem, along with another circuit in the JB.

Note: the blue wire bypass and Two Wire mod are two different mods.

Need those tests on the stator and r/r.
 

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FREEBIRDS MC CENTRAL NY
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Don't wanna say it but how old is the battery?
 

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Discussion Starter #4
You're very right. If the stator and R/R don't check out nothing else matters. I ran the bike at ~3k rpms and was getting ~55V between any of the two stator leads. Still getting 0.5 Ohms resistance between the leads and no continuity to ground. To me that means the new stator's good for now. I'll check the voltage output of the R/R directly off of the pins tomorrow night.

The battery's brand new. It was the first thing I replaced in this process, as I bought the bike used and wasn't sure how old it was. In retrospect, I should have checked the charging voltage first instead of assuming the battery just wasn't holding a charge. It's still a good point though.
 

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I don't recall needing voltage readings off the r/r, would have to check. Thought the test was just different ohm readings on varying terminals, with the r/r unplugged from the harness.
 

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Discussion Starter #6
I checked the voltage readings off the rectifier terminals and was only getting ~1.2V at 3k rpm. I think that's my problem. I figured that would be a better test of the rectifier than the resistance test, because I'm directly measuring its output and eliminating any downstream factors at the same time. Nobody tells you to do it because it's a little dangerous dealing with live wires. I'll be sending this rectifier back and getting a replacement soon.

Also I was reading 12.4 V between the battery terminals at idle, but only 12V between the brown monitor lead and the negative battery terminal. I would think it should read closer to 12.4V, but maybe 0.4V drop through the wires isn't a big deal. If this voltage is a little low, a good rectifier should increase its output, which is probably a good thing. Any thoughts?
 

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You may be right.

However, something else could be pulling the voltage down, like some problem in the Junction Box or harness. Might not hurt to disconnect the r/r and ohm test it too.

Does look like the r/r could be shorted out.
 

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Discussion Starter #9
I received a new R/R from the ebay seller and it was dead on arrival as well. Then I decided I was done messing around with bad rectifiers, and I bought a MOSFET and installed it in the bike. Didn't know about the MOSFET before I bought the older OEM-type replacement. Now everything's good as far as the charging circuit goes. I'm getting 14.3 V across most of the rev range. Lesson learned here is to not mess around with diode rectifiers off eBay.

However, I took the bike out for a spin tonight, and now i've got an oil leak. It had leaked a couple of drops in the garage before I got it running, but nothing I wasn't super concerned. After I drove for ~15 min, I came back, and I had about 10 drops of oil on my garage floor right after shutting it off. It stopped dripping as soon as the bike cooled off. I have a feeling the gasket might have ripped on the bevel gear case since it's a little bit of a chore to get that cover back on.

Any suggestions for tracking down the leak and avoiding the same problem if I try to replace the bevel gear gasket again? If it's the stator cover gasket, I think I might just live with the oil leak rather than take than take the engine out of the bike for a 3rd time.
 

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Oil Leak

Oil leak after a stator change drove me crazy too. In my case, the oil was coming through the wire grommets and traveling to different areas of the motor on the same side. I went to auto parts store and purchased some GRAY oil resistant gasket maker from Permatex. I thoroughly cleaned the grommet area to remove oil and grease. Then I coated the area with the gasket maker....then let it dry for a couple days. Stopped the leak...and since its gray/silver color it blends right into the casing. Looks pretty good actually.
 

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the key to finding an oil leak is to note where its dripping off the bike.. then you can trace the oil path back to the leak.

just because you have oil dripping at the rear of the engine, dont mean its comming from there.


example.. my bike has an oil 'film' all over the lower left side, including the stator cover top area (even up by the oil fill cap). my leak.. waaay down low, where the shift shaft enters the side cover (the seal there is worn). now, to get the ambition (meaning $$$) to buy one (yea, I know, they are not real expensive) and change it.

example 2.. again, my bike.. had what looked like a leak from the seals at the starter, thats even where the oil dripped off. wasnt there.. was above that area, slightly behind it.. the gasket for the right side cover had failed.. up on the top!
 

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Same thing

The PO of my bike had just changed stator, didn't fix it is why he sold it to me. Anyway, he just completely left off any type of grommet where the stator wires exit the case. I take it the original grommet was made onto the original stator or it was damaged so he left it off. It was leaking from there, I did same thing, I used black silicone, make sure you get some down in-between the 3 stator wires so the oil can't come up between them. Put the silicone on liberally, do it quickly before it starts to film and you can smooth it out nice and make it almost look like it was made that way.

Also the o-ring on my oil fill cap was leaking, it looked to skinny too me, I put a fat one on the same diameter and it fixed it.
 

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Discussion Starter #13
I looked into my oil leak a little more, and it looked like oil was coming out of the pickup coil wire as suggested. I put some oil-resistant silicone on the wires, let it dry for a couple of days, and tested it this morning. Still getting a few drops of oil, but it's not as bad as before. I'll investigate a little more tonight and try to determine where the oil's coming from this time. I've got a feeling it's coming from the underside of the wire that I couldn't see very well when I was putting on the silicone. Maybe a second coat will stop the leak.

The oil fill cap o-ring could also be a culprit. It looked pretty thin, and I've had a drip of oil resting on top of the outer stator cover before too.
 

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I looked into my oil leak a little more, and it looked like oil was coming out of the pickup coil wire as suggested. I put some oil-resistant silicone on the wires, let it dry for a couple of days, and tested it this morning. Still getting a few drops of oil, but it's not as bad as before. I'll investigate a little more tonight and try to determine where the oil's coming from this time. I've got a feeling it's coming from the underside of the wire that I couldn't see very well when I was putting on the silicone. Maybe a second coat will stop the leak.

The oil fill cap o-ring could also be a culprit. It looked pretty thin, and I've had a drip of oil resting on top of the outer stator cover before too.
The bottom of the 3 screws on the stator cover leaks for me (right now). When I do my next oil change I'll clean it up and apply some silicon.

Might be worth checking them. The little o-ring can slip in quite easily.
 

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Discussion Starter #15
I spent some time looking under my bike while it was running and found that I still have 3 leaks to fix. One is definitely the generator cover gasket, another is the transmission cover gasket, and I'm not entirely sure where the source of the third leak is. I have a hunch that it's another spot on the generator cover gasket near where the wires come out of the outer stator cover. I really don't want to take the engine out of the bike again to replace gaskets.

Anyone know if you can remove the transmission cover with the engine still in the frame? Also, has anyone tried cleaning a leaky spot really well and applying silicone? I know it's just a band-aid fix, but it might be worth it.
 
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