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1972 Eldorado Generator light question

Discussion in 'Loop & Tonti' started by iosteyee, Sep 3, 2020.

  1. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Wow that's a clean machine. For a 47 year old, very neat and orderly.

    You can do it.

    Attached is a copy of the wiring diagram for an 850 Eldo from Chilton's shop manual.

    Good luck,

    Alex

    View attachment 20458
     
  2. Moto-Uno

    Moto-Uno Tuned and Synch'ed

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    This is a suggestion for a bench test of your generator .
    Tools : a vise (wood or metal) , jumper cables and a good 12v battery.
    Remove generator and mount snugly in vice.
    Attach a jumper from battery -ve and attach to generator body.
    Attach another jumper from the generator field lead to the body of the generator.
    Attach another jumper from the generator armature lead and touch to the battery +ve.
    The armature should spin .
    If it doesn't spin , the generator needs work . This is no guarantee of full output , but don't
    waste time with other tests until it at least passes this simple test . Good Luck, Peter
     
  3. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    The correct schematic for your Eldorado is in the Downloads section.
     
  4. iosteyee

    iosteyee Just got it firing!

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    Gents,
    Thanks for the help. I'll get started and check back in as I make headway, or get stumped. I really appreciate you guys showing me the basics of this, what a great way to get accustomed to this bike.
     
  5. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Hey John, that wiring diagram for the V850 in downloads sure is cleaner and easier to follow than the one in the Chilton's manual.
    Thanks for the tip,

    Alex
     
  6. iosteyee

    iosteyee Just got it firing!

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    OK gents, here's where I am, please remember I am an electrical newby.
    I attempted to test the generator. I detached both the D+ and DF wires from the generator, then I connected those terminals with a jumper, then started the bike, put the positive lead from my multi-meter to the D+ terminal and the ground to the frame with the voltmeter on 20v. The display was erratic showing number from 13XXX to 19XXX. Can anyone shed light on what, if anything, that means?
     
    Last edited: Sep 7, 2020
  7. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    It means absolutely nothing. The field coils need voltage to be an electromagnet so the armature will generate current. Take the generator off and bring it to an automotive electrical shop. Let them test it and rebuild if needed. I'm hoping you haven't fried anything.
     
  8. iosteyee

    iosteyee Just got it firing!

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    Well, I hope I haven't fried anything either. Since the last post and before reading John's post I decided to try another test. I ran a wire from D+ on the Generator to D+ on the regulator directly. I started the bike and tested put the meter on the battery. The battery was at 12.8v sitting attached to the bike, then once started it would rise to 13.3v at roughly 3000rpm.
     
  9. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    That is encouraging. Still that voltage is a bit low. Now is the time to go by the schematic and check continuity of your wires.
     
  10. iosteyee

    iosteyee Just got it firing!

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    I made separate jumpers for both D+ and DF and ran them directly to the Regulator. There is no change in voltage, so I assume the original wire in the harness is good. The generator light goes off low in the rpm band, but on my meter the high point of output appears to be around 2700rpm's and only 13.26V. I have ordered a solid state regulator to test vs my recently installed Bosch mechanical model. If that test yields no improvement, then my guess is that my generator is tired.....or my meter faulty.
     
  11. Amboman

    Amboman Cruisin' Guzzisti

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    Any good auto electric repair facility should be able to set it right for not a lot of $$. The generator may not be "fried", maybe it just needs to be serviced.
    http://thisoldtractor.com/moto_guzzi_loopframe_generator_repair_-_bosch.html
     
    V700Steve likes this.
  12. iosteyee

    iosteyee Just got it firing!

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    Thanks Fellas, I've removed the generator and will drop it off at a shop today. I figured that even if that wasn't the fault, I might has well have it tested/re-built while the I've got it partially disassembled.
     
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  13. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Good move.
     
  14. iosteyee

    iosteyee Just got it firing!

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    The generator is re-built. I had to remove a broken stud from the cradle that holds the generator. Drilled, easy out, and tap to clean up threads. Once I hooked it all up I was still only getting 13.15v at 3000 rpm's. I'll put the solid state regulator in when it gets here and check again. In the mean time, what, if anything, has everyone done to improve cornering clearance? Add rear shock height? Remove center stand? all the above? Or, just never take a corner over 20mph? I live in the mountains, so it can matter, especially with a passenger.
     
  15. Moto-Uno

    Moto-Uno Tuned and Synch'ed

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    After all of this , are you sure your belt tension is good and firm ? And I'm sure you polarized your rebuilt generator ?
    The devil is in the details now , Peter
     
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  16. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Loop frames have their limits on cornering clearance. Correct rear shocks and properly set sag helps. Also your front springs may be tired. Also the Eldorados tend to do better with 30 weight fork oil. A special tool is needed if you want to separate the chrome piece from the lower fork leg. I know a couple guys that can really ride the loops well, but they have done suspension work.
     
  17. iosteyee

    iosteyee Just got it firing!

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    Yes, I'll have to spend some time dialing that suspension. I, did, polarize the generator, and dialed the belt tension as a est guess. I don't have a tool to measure 10kg at 1 cm, but kind of went by feel. It could be tighter I suppose, but I'm sure there are negative effects to having it too tight.
     
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  18. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Yes, too tight is not good. It can damage generator bearings and damage the belt. As long as it turns the generator without slipping you are good. Also a little belt dressing doesn't hurt.
     
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  19. Amboman

    Amboman Cruisin' Guzzisti

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    Too tight also stresses the two generator bracket mounting bolts, leading to them snapping off and/or the bracket fracturing.
     
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  20. iosteyee

    iosteyee Just got it firing!

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    Hello Gents,
    Firstly, I'd like to thank you fellas for all the support and ideas you offered in fixing the charging system on the Eldorado. It's very good of you all to help out some guy way up here in the Adirondack's, that isn't very good with some of the aspects of motorcycle repair.
    As I chased the problem I was able to learn some new things about the bike, but also repair some problems I didn't know existed. I re-wired the connections between batter and regulator as those wires had some bare spots, and bad splices. I had the generator cleaned up by a guy in an alternator/starter shop, and I replaced the regulator. In the process I had to drill and remove broken bolts from the generator bracket, the rear had broken, and the front was a bit stripped. I also learned how to adjust the generator belt, and that's nice to know.
    In the end, it was probably, just, the regulator. This morning I had it all back together and tested it volts at the battery with no, big improvement. I, then, removed the new Bosch, mechanical regulator and installed a new Bosch solid state regulator. Started the bike and had over 14v at the battery. So, the new Bosch, mechanical regulator was bad the whole time. There is no way to know if any of the rest of the fixes helped at all, but they couldn't hurt, and certainly the generator bracket was a good fix to have done.
    Thanks again, Ian
     
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