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Annoying Electrical Issues

Discussion in 'The Garage' started by doritos slayer, Aug 2, 2015.

  1. Hey guys, newbie here trying his best

    I've been working on the charging system for my '77 xs360 here for a while and still haven't been able to figure out why when the bike is running I can't get the 14.5v across the battery. Mad props to the guys on here that show so much detail on checking your stator and replacing the wiring for the charging system.

    So my issue started when my old battery died while I was idling in traffic, figured it was my charging system so I started with the rectifier and regulator. I couldn't get the correct continuity as the manual explained through the rectifier so I since have replaced with a combo rectifier / regulator....twice. I have also gotten a new maintenance free battery.

    I have gone through checking the stator and coils, I have measured 0.8, 0.8, and 0.9 across the white wires (this is with a little corrosion on the plugs and a 0.1 tolerance on my multimeter). The coil and wires are surprisingly in good condition (there is only ~6500 miles on the bike if that means anything to you)

    The first combo (cant remember the model, got it off amazon) appeared to work, although the regulator part I was skeptical about. After riding for while with no issues thought I was good, but then it blew up on me; over heated and broke the main fuse.

    The second combo (RR38) has me a little confused; with the bike running I only measure what the battery is currently charged to, 12.8v, and still do not get the 14.5v. Everywhere I measure on the bike to check voltage (horn, flasher relay, rectifier, etc.) I get 12.8v. I haven't taken the bike out since cause I don't want it breaking down on me again in traffic.

    Do yall have any suggestions on where I need to look next? I feel like I've done everything, but rewire the entire bike. Is it possible that even though the coils looked clean they are bad, or that I could be dumping the extra voltage off on the ground of the bike?
  2. bcware

    bcware Well-read Top Contributor

    I won't be terribly helpful, but I don't think you can "dump off" exactly the amount of extra voltage the charging system should be supplying; I would imagine if you have some kind of short you'd simply get rapid and violent discharge of the battery.

    The coils "look" clean? Are you basing their performance on physical appearance or have you tested them? They can definitely be bad and appear, physically, to be good. Sometimes the glue/goo will ooze out of them if you REALLY cook them, however. Bad coils should not prevent your bike from charging; they would just make it run like crap and die on you.
  3. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    How do you have the field coil wired?

    You know that the issue is between the stator/field coil and the regulator/rectifier.
  4. Thanks for the responses.

    The coil physically looked good; no discoloration of any kind, the coating on the coils is uniform (no oozing), and the wires leading out of the case were not broken and did not show any signs of wear. And yeah, the bike runs like a champ and has no issues staying on.

    The bike wiring is still stock, so I'm assuming the field coil goes straight to the regulator/rectifier. I'll go through the wiring on the bike next time I have a chance and make sure the leads are connected correctly.

    Edit (this just came to mind):

    The first regulator/rectifier was putting out 14.5V (would actually go above this at higher RPMS which is why it blew up) wouldn't that mean the wiring going to the regulator/rectifier should be okay? Or maybe there's something else that I'm missing after the first regulator/rectifier failed.
    Last edited: Aug 3, 2015
  5. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    14.5 won't fry a rectifier. Our systems can actually put out more at times. Also, if you have the field coil ground going straight to the ground wire on the rr38, you need to splice it and run a ground to an actual 'ground', either the frame or another grounded wire
  6. I noticed that it would put out more voltage at higher rpm and thought that was from a faulty regulator.

    The RR38 does have only one ground wire, on the rectifier plug, and no ground wire on the regulator plug. I will splice the single ground from the RR38 to the ground it to the wire on the regulator plug as well as the rectifier ground. Perhaps my woes came from a bad regulator/rectifier and I over complicated things.

    I will update once I am able to do this.
  7. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    The regulator will adjust the voltage as needed. You could see between 11 and 15 ;)
  8. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    How exactly do you have the RR 38 wired up? I find in most of these threads people miss a wire here or a wire there and that's all it takes. These after market parts aren't one size fits all and wiring differs from bike to bike and year to year. If you can explain where you ran each wire to, I can tell you if it's wrong or not.
  9. skhagen

    skhagen XS400 Member

    check the wiring behind the front sproket for rubbing.
  10. Th RR38 came with two plugs, one for the rectifier and the other for the regulator. The rectifier plug has 3 white, 1 red, and 1 black wire; I have matched color for color with the bike's matching end. The rectifier plug has 1 brown and 1 green wire; I have matched color for color with the bike's plug, this does leave the black ground open on the bike's regulator plug.
  11. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    Yep then you should just be able to run a ground and be all good!
  12. Well I ran the ground this afternoon and I'm still measuring the same voltage. For the time being I'm just going to leave it as it is and see how it holds up; this month is gonna be super busy for me and I won't have much time to check in and try any other tests, also it's good enough to ride at the moment. If I need to put it on a trickle charge every now and then I'll be okay with that since I only ride it for pleasure on the weekends.

    Thanks for y'all's help :thumbsup:
  13. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    It's probably all good. Just ride it and enjoy it!

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