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Help: diagnosing overcharging.

Discussion in 'The Garage' started by DESTROYASAUR, Aug 6, 2017.

  1. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Ditto, that's how my unmolested '74 with points was done before I took a sawzall to it. Also, one of the unmolested top motor mounts was broken.

  2. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    XS motors don't shake so maybe Yamaha was just being cautious about sending electricity though multiple fretting steel joints.
    Paul Sutton and mrtwowheel like this.
  3. xjwmx

    xjwmx It's just the unknown. Top Contributor

    Where there is friction there is electrical contact, and there is still plenty of friction to spare. Slather it with any kind of grease and you will not be able to measure any difference with any equipment you have. But the two parts still have to be touching, as always. Grease is good. It isn't like paint. Some people believe "dielectric" grease must mean conductive grease. The word actually means non-conductive.

  4. jussumguy

    jussumguy XS650 Addict

    Very interesting thread.
    I've got a project bike that overcharges. I'm tearing my hair out rewiring, re grounding putting it away for 6 months at a time. I was ready to part it out. I was convinced the regulator or my wiring was the problem. This is encouraging! I'll try another rotor. Thanks
  5. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    What do you mean by over charging? What is the battery voltage at idle and at 3500 to 4000 rpm?
    What year is the bike and what regulator do you have?
    Have you done resistance checks from slip ring to slip ring of the rotor? What is the resistance from either slip ring to the steel frame of the rotor?
  6. jussumguy

    jussumguy XS650 Addict

    The needle on my gauge bounces a bit past 15. Idle is 13-14 volts. I'm running a yuasa ytx5L. It's shares the same battery as my Ktm 450. Engine is 1980. Radio shack rectifiers, Chrysler reg. I havnt tested slip ring to ground. I did the Pamco auto advance but got the Chinese coil. I took a test ride. Got about 2 miles from home and it died. Pushed it home and havnt looked at it since.
  7. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    Don't buy another rotor until you do the resistance checks on your existing rotor. Since your voltage goes high to 15 volts, that means the rotor resistance from slip ring to slip ring is around 5 to 6 ohms. You now need to measure resistance from either slip ring to the rotor steel frame. It should be very high, so check to be sure.
    jussumguy likes this.
  8. jussumguy

    jussumguy XS650 Addict

    Ok will do. I wired this bike from scratch in a big hurry to make it to an event. We made the trip but it overcharged all day and burned all the lights out of it. Even the stator was affected. The bike made my shop smell like it was on fire. I've redone a lot of mistakes I made, it's getting closer to being right. There's a few things I want to take back apart and look over. I've got too many bikes. I need to hire a full time mechanic to keep them all on the road. Thanks for the help.
    gggGary likes this.
  9. Paul Sutton

    Paul Sutton Sprained Ankle Top Contributor

    gggGary likes this.

    DESTROYASAUR XS650 Enthusiast

    Alright folks.

    I got the used, but new to me, rotor In The mail yesterday! I slapped it on the bike and everything checked out right on. Charging was as it should be. I then tried to ride to another city about 200 miles away on a 100+ degree day. After about 100 miles, going between 65 and 80 on the highway, I lost charging. I checked and there is now no resistance between the sliprings. Is it possible I burned the rotor out by overheating? Or was it just maybe it's time? My bike was running pretty hot but It seems like heat shouldn't be that big an issue for the rotor. The interesting thing is when my very first rotor went bad it was under the exact same circumstances. Hot day, sustained high speed highway, failed after nearly 100 miles. (Same trip other direction, I almost got stranded in the exact same spot Luckily I was able to limp it to a rest stop 5 miles down the road) I got my battery checked just a few days ago and it checked out good. Also, yesterday I tried the new rotor with my stock reg/rec and also with the aftermarket reg/rec I have. The after market reg/recs highest charging point was about 13.9 volts DC. The stock reg/recs highest charging point was 14.3 volts DC. I went with the stock reg/rec because 14.3 seemed more correct.

    Obviously I could just get another new rotor but I'm worried that I'm jut going to burn it out again. Is it feasible that I'm overheating the rotor and that's the problem? Or is it probably just bad luck and weird coincidence that both rotors failed under the same exact conditions.

    Thanks guys, let me know what you think.
  11. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    If it wasn't for bad luck, you'd have no luck at all!
    A better choice would be to have your rotor rewound at Custom Rewind in Alabama.

    I never have any problem with my rotor, and I believe its the original OEM rotor that came on my 1978 SE. I like to provide some fresh air to my rotor, so I have the small cover on stand offs.

    Alt mod2.JPG
    Paul Sutton likes this.

    DESTROYASAUR XS650 Enthusiast

    Haha I mean you're definitely not wrong.

    So you're saying that it's unlikely to be a heat issue and I probably was just unlucky on the rotor front? Considering just how hot the engine was running and the fact that both rotors gave out in exactly the same way after the same amount of stress makes me strongly suspect that I'm frying the rotors. Is that definitely something that doesn't happen? I just need some affirmation here

    Yes, when I say get a new rotor I mean getting one from Gary at custom rewind. Should have stated that from the start

    I didn't realize the heat may be a contributing factor or else I would have do the cover spacer mod before. I figured less dust is worth more heat but now I'm thinking that may have been the wrong call.
  13. DanielBlack

    DanielBlack XS650 Junkie

    What was the resistance of the new, used rotor's before putting it into service?

    Yes, heat will kill a rotor. But was the rotor killed by excess engine and environmental temperatures, or by excess electrical demand?

    When the first rotor died, were you running the stock or aftermarket reg/rect?

    Less expensive than multiple new rotors are a permanently mounted voltmeter and an oil dipstick thermometer from member Dogbunny. I've found those two tools to be very helpful in monitoring my bike's health. I'd be wary of running a third rotor without them.

    DESTROYASAUR XS650 Enthusiast

    5.5 0hms across the sliprings, just as it oughta be.

    I'm reasonably certain I don't have excess electrical demand. The bike is running all stock lights and electrics, except the person before me got rid of the turn signals, and the kickstand switch.

    I was running the stock reg/rec when both the rotors kicked the bucket. Would it be more or less stress on the system to have the aftermarket reg/rec that only charges the battery to 13.9 volts DC? Stock ones charges to 14.2 volts DC.

    I've been researching handlebar voltmeters the last two days. Getting one is certainly in the works. Any recommendations on brands? Oil temp dipstick is a very good idea too. Thanks for the tip on dogbunny. I'll shoot them a PM. What is an unacceptably high oil temp? As in, what's the cutoff point where you simply pull over let it cool down for a while?

    With the voltmeter installed can one see the rotor slowly getting worse? Or is it simply a sudden jump from charging to not charging. Both my rotors don't just test weak, they test 0 ohms across the sliprings.
  15. DanielBlack

    DanielBlack XS650 Junkie

    Last edited: Aug 20, 2017
  16. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    I think having the alternator cover open is beneficial to reducing the heat in the alternator. I can't say how much it helps, but over the 10 years that I have owned my bike, I have never had any alternator or charging problems. Don't be concerned about dust or dirt. Did you ever notice that the alternator in your car/truck is open from the bottom of the engine compartment?

    A permanent voltmeter is a must do on these older bikes.

    You should have a careful look at your 2 failed rotors. You should be able to see where the end of the copper winding attaches to the back of each slip ring. I received a "failed" rotor from a member on this website, many years ago. I was interested in why it failed. With a VOM it did indeed show open circuit. I did some inspection, and found one end of the copper winding had broken off from the lug on the back of one slip ring. I scraped the insulation off the wire end and soldered it to the slip ring lug. I then put some JB Weld over the soldered connection. Once I did that it measured 5.3 ohms. I now keep it as a spare rotor.

    A couple of years ago, I thought I better install that spare rotor on the engine to see that it really works. Swapped out the rotors and went for a 60 kms ride and my spare rotor charged at 14.2 volts for the entire short trip.
  17. 5twins

    5twins XS650 Guru Top Contributor

    It's very possible the treatment you gave the bike, 100 miles at a sustained 65 to 80 MPH on a 100+ degree day, is the problem. I'm not sure even a new one 40 years ago would survive that. That type of running, sustained high speeds for hours on end, wasn't this bike's intended purpose. You're probably lucky you didn't blow the whole motor up, lol. If you want something for that type of riding I suggest you get a newer, bigger bike.
  18. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    These are not high speed bikes. 80 mph and 100F temperature is torture for the engine IMHO.
    My engine runs so nice at 100 kms/hr (62 mph) at about 3700/3800 rpm. Granted it seldom gets above 90F in my riding area of AB and BC.
    I have driven as much as 620 kms in one day, and my engine just loves it. If you want to run at 70 to 80 mph, you should buy a BMW that was designed to run at those speeds on the Autobahn in Germany.

    I was at a bike night a few weeks ago, and got chatting with a lad that has a Honda from the early 1980s. He imported it from Japan because that model was never sold in Canada. On the face of the speedometer, it had a small green light that would light up at exactly 90 kms/hr. He said that was the speed limit in Japan in those days.

    DESTROYASAUR XS650 Enthusiast

    I do realize that the sustained high speed is not the ideal for this bike, that's why I mentioned it as a possibility for the problem. Hitting the 5 in California though is a pretty fast highway. That being said I'll take it a bit easier next time It's a ride I rarely take but it's also the only real way to get from fresno to the Bay Area.

    Ha, my speedometer only goes to 80 too. Everything above 50mph is white as well. Love those Reagan federal speed limits

    RG: I'm getting 0 ohms across the sliprings not infinity, so I don't think a broken solder is the problem. That being said I'll have a look anyway. That was the second of three strikes with the mikesxs rotor I had. The first being the magnet was too weak and the third being that it shorted to ground.

    As for the voltmeter, I think I'm going to go with this unit:

    it's small, I can Velcro it wherever I like, and it'll plug right into the quick connect for my battery tender. The only down side is there's no fuse and no on off switch. I figure I can always just un plug it if the bike's going to sit for a while, especially because if the bike's going to sit it's going to be on the tender anyway.
  20. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    I took the reported "no resistance" to mean open circuit.
    Lessons learned......................don't buy electrical parts from Mikesxs, or rubber parts, or mechanical parts.....................basically don't buy any of the crap
    Taiwan/Chinese parts they sell.

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