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Bike doesn't start in cold weather

Discussion in 'XJ Technical Chat' started by Joshua Olkowski, Oct 10, 2018.

  1. Joshua Olkowski

    Joshua Olkowski Member

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    As I come closer to restoring my 81 XJ550 Seca I still haven't figured out the weak charging problem. It idles at around 12volts and maybe peaks into the 13's when I rev it up to 3000rpms. I've brought it to two different shops and one says it's the RR and another says it's the stator. When I did tests on both of these items they both seem to check out fine. Nevertheless, I tried replacing both of these items with USED parts off of other bikes and I got the same exact results. Is it possible that a used or original 37 year old stator and/or RR can be weak so that when it's operating, it can't put out the voltage it used to? Or is it more black and white where they either work or they don't? Should I just go for broke and try replacing these items with brand new parts?
     
  2. Franz

    Franz Active Member

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    The voltage regulator could be the problem. Do you have bulbs failing? If you changed the stator and rotor and then replaced them and got the same results you could have a voltage regulator problem.
     
  3. Joshua Olkowski

    Joshua Olkowski Member

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    I'm assuming when you say the voltage regulator you are referring to the Regulator Rectifier (RR). Bulbs have been fine. I have changed the stator, rotor, and regulator rectifier with used parts and nothing changed.
     
  4. Franz

    Franz Active Member

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    Yes RR is right. I am sure input voltage is critical to the rotor. You could have resistance in the cables to the carbon brushes. There are lines on them showing the wear limits and the brushes themselves can deteriorate with age. Also the slip rings on the rotor may need cleaning. Check all electrical connections to and from the alternator and check the brushes before buying other parts that is how l would check it. It could be a voltage drop problem. It cannot be a short to ground or an open circuit if voltage is rising when you blip the throttle.
     
  5. Polock

    Polock Well-Known Member

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    what does it do/not do that your trying to fix?
     
  6. JeffK

    JeffK Well-Known Member

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    My Turbo's headlight is fairly dim until it revs to 2K or more.....always figured it was just the way the bike was. These early Japanese charging systems were at best, bad. In reality, Lucas was probably worse than Nippon at this point, but not by much!

    At least with the older ones, we could adjust the voltage. You can replace the rectifier with a modern one, just match the pins and look around 1999-2004 Yam, kaw, or reach out to these guys : https://www.regulatorrectifier.com/catalog/ I'd call and chat with them.

    FWIW: has your connector for the alt fried yet? On our turbo's, it's a common malady best fixed by a permanent solder bond.

    Good luck,

    jeff
     
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  7. JetmechMarty

    JetmechMarty Active Member

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  8. Joshua Olkowski

    Joshua Olkowski Member

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    I did everything you said and more. I've changed brushes, checked connections, cleaned the slip rings on the rotor. The only time things look like they kind of improve is if I charge the battery. The idle voltage stays the same but when I rev it to 3000rpms it might actually charge up to 14.5volts. Still no improvement hence the reason why I wonder if I replace with BRAND NNEW parts, it might fix the problem.
     
  9. Polock

    Polock Well-Known Member

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    three more things to measure, voltage at the battery after setting overnight, key off.
    then turn the key on and check again
    then check while it's cranking
    i'd start shopping for a battery
     
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  10. Polock

    Polock Well-Known Member

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    then you might want to check it running, at the battery with the meter on AC volts (it won't hurt the meter)
     
  11. Joshua Olkowski

    Joshua Olkowski Member

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    I've done that. I've done EVERYTHING, believe me.
     
  12. Joshua Olkowski

    Joshua Olkowski Member

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    Again, I'm just curious about the parts themselves. Does an old stator or RR lose it's effectiveness over time and so I should replace them? Or are they simply designed to work or not?
     
  13. Joshua Olkowski

    Joshua Olkowski Member

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    Battery is brand spankin' new. That was one of the first things I replaced.
     
  14. Joshua Olkowski

    Joshua Olkowski Member

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    It is not charging at idle. It reads 12volts if I'm luck at idle and maybe into the 13's at 3000rpms. Charging is basically weak.
     
  15. Joshua Olkowski

    Joshua Olkowski Member

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    You have my attention JetmechMarty. What does the KILL SWITCH have to do with the charging system. The pins coming directly out of the stator all measure fine both when I check resistance and also when I turn on the bike and measure the AC output. I don't have the numbers to tell you exactly at the moment but I know that when I measured in the past that they all reach spec with no problem. So, tell me about the kill switch. Also, I cleaned up as much corrosion as I could find and I also used electrical spray designed to clean the connections. Nothing has worked yet.
     
  16. Polock

    Polock Well-Known Member

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    no xj does
    look here at the orange/green chart. now decide if you really have a problem
    https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
    no
     
  17. Fuller56

    Fuller56 Active Member

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    Have you changed out the fuse panel for the blade type fuses? While it won't increase the charge rate it will make it more efficient. I thought I had a new bike when I did mine. The XJ's do take a few RPM's to get changing.
     
  18. Joshua Olkowski

    Joshua Olkowski Member

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    Check
     
  19. a100man

    a100man Well-Known Member

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    3000 rpm isn't much. What's it like at 5000?
     
  20. Joshua Olkowski

    Joshua Olkowski Member

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    It actually gets to charging voltage when I go to 5000rpm. It levels off around 14.5-14.6 volts but it takes about 5 to 10 seconds of staying at 5000rpms before it finally reaches that number. So, it does seem to be doing it's job when I'm actually riding the bike and I can see the volt meter on the bike reaching to 14volts (I know those aren't reliable but that's the highest it's gone in a while) If only it would go to 13.5 at idle and I'd be a happy man.
     

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