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1978 Xs650SE Barn Find

Discussion in 'The Garage' started by ElCamMan515, Jun 25, 2020.

  1. gggGary

    gggGary When a whole one is just too much. XS650.com Supporter Top Contributor

    ElCamMan515 likes this.
  2. 5twins

    5twins XS650 Guru Top Contributor

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    The wobble extension will also help with #9 and 10, the two bolts under the spark plugs. Taking the covers off the points and advance housings will help too.
     
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  3. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    Hey everyone,

    So while bike is running battery voltage across terminals is less than 12v, around 11.6. Where should I look regarding the battery not charging??

    Tim
     
  4. 5twins

    5twins XS650 Guru Top Contributor

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    That's pretty much normal at idle with the headlight on. It won't go up into the mid 14's until you rev it to like 3K. If it doesn't go up when you rev it then, yes, you do have charging issues.
     
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  5. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    @5twins I just checked voltage while reviewing engine and it stayed at 11.80v. Where should I look now?

    Thanks for all your input.

    Tim
     
  6. 5twins

    5twins XS650 Guru Top Contributor

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    Well, you'll have to start checking and testing things related to the charging system. Start with the alternator brushes. They're considered a wear item on these bikes and once they wear too short, charging will drop off or even quit. New, they're about 14mm long. The wear limit is 7mm and if they're originals, there should be a wear line etched in the side of the brush .....

    [​IMG]

    You can remove them to measure their length but it may be easier just to pull the alternator off. The spring on the brush will force it out of the holder enough so you can see the wear line .....

    [​IMG]

    As they wear, the carbon that rubs off them turns the slip rings they bear against black. If they get too dirty, you can start losing contact. Maybe that's the issue. You can clean them with chrome cleaner. Here's one cleaned, the other not .....

    [​IMG]

    ..... and then both cleaned .....

    [​IMG]

    If the brushes are OK then you'll want to test the rotor. To do that, you measure the resistance between the two copper slip rings. It should be 4 to 5 ohms. You can't have the brushes in contact with the rings when measuring so while the alternator housing is pulled off is the perfect time to do this test (and clean the rings of course).

    So, do these checks then get back to us. If they check out then it's time to move on to the regulator and rectifier. If one of them proves to be the issue, we can provide info on good, cheap replacements.
     
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  7. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    5twins - Where could I get replacement brushes? I will check them tonight after I get out of work. Also do I test the resistance while bike is running or just key on??

    Thanks,

    Tim
     
  8. 5twins

    5twins XS650 Guru Top Contributor

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    Neither, key off and brushes not touching slip rings. Personally, I prefer original brushes, I think they're made better and last longer than the aftermarket ones. Go on eBay, there's lots on there. Your inner and outer brushes differ from one another (different brackets) .....

    [​IMG]

    Here's an inner w/ part number .....

    [​IMG]

    ..... and here's the outer .....

    [​IMG]

    You can usually find N.O.S. originals for about the same price as the aftermarket knock-offs, sometimes even cheaper.
     
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  9. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    Thank you. Ill look for some while at work and do some testing when I get home. I'll report back late tonight.

    Tim
     
  10. 5twins

    5twins XS650 Guru Top Contributor

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    Even if your brushes are still good, if you keep the bike a while, eventually you're going to need to replace them. And you just know they'll fail on a Sunday, lol. So, it's a good idea to keep some on hand as spares. Here's some inners at a good price. I'd buy a pair .....

    https://www.ebay.com/itm/262786007393

    ..... and here's a pair of outers. The outers wear faster than the inners because they cover more distance with each revolution .....

    https://www.ebay.com/itm/274679110796?hash=item3ff4269c8c:g:o1IAAOSwUmRgJDqK
     
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  11. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    Tonight's findings:

    The brushes are at the end of the usable limit. The wear is just above the line. I'll be purchasing new brushes. Tomorrow's plan is to clean up the rotor and test the resistance. I'm hoping it tests good.

    Thanks again everyone for the input.

    Tim
     
    Mailman, jetmechmarty and Raymond like this.
  12. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    Good morning everyone,

    Went out to the garage early before my kids got up and did some diagnostics.

    The brushes will need to be replaced (ordered) and did the ohm test on the rotor. I am not getting any type of reading. I believe my rotor will need to be replaced based on my research. Anyone have a good lead on a good rotor or know where to purchase one?

    Also how do you clean the stator? As you can see in the pictures below it is dirty.

    Thanks,

    Tim
     

    Attached Files:

    Mailman, Jim and Greyandridin like this.
  13. Raymond

    Raymond XS650 rider & fettler XS650.com Supporter Top Contributor

  14. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Have a read here.
     
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  15. Jan_P

    Jan_P XS650 Junkie

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    Have not read it all but as a thought
    Since the rotor appears to be open circuit
    One coping strategy could be to at the same time consider upgrade the regulator
    and rectifier
    ..I have heard of Suzukis from that time period shorting out Both alternator and
    Regulator.
    So that replacing the alternator and not the regulator ended in a freshly burnt second alternator
    Depending on the bikes setup :but it can be that the bike has the stock " Relay " type
    Regulator that has been sitting
    Regulator which does not have the best reputation.
    And as it seems there are Electronic Equivalents out there for not so much money.
    again I have not read it all and these decisions depends on When and Finances.
    But I put it here for Consideration.
    Others might come in.
     
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  16. jetmechmarty

    jetmechmarty What should I put here? XS650.com Supporter Top Contributor

    I just made a repair this week. In the connector from the stator is a red wire that I believe feeds current to the charging rotor. That connection overheated and damaged the connector. I replaced the connector and all of the pins. 25 mile road test is all it got. Something like that will turn the charging system off.
    6BC0B31F-2166-49B1-9500-552E29406523.jpeg
     
  17. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    I looked over all the wiring and everything looks good. I will test the regulator tomorrow morning. I was able to source a good rotor from a old HS friend that has a bike shop that tested out. I have ordered a rotor puller and now just playing the waiting game once again.

    Thank you all again for all your help.

    Tim
     
  18. 5twins

    5twins XS650 Guru Top Contributor

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    Don't throw that old rotor away, consider sending it off to Jim for a rewind when time and finances permit. I've been running my '78 since 2005 and the original rotor finally gave out late last season. I think eventually all these old originals will. You can lessen the load and strain on it by upgrading your reg and rec.
     
  19. ElCamMan515

    ElCamMan515 XS650 Enthusiast

    @5twins I am going to hang on to my old rotor. Never know when I may need to send it in for a rewind or as a core. I think I am very close to being able to ride this bike. Also are you able to clean the stator or should I leave it as is?
     
    Last edited: May 4, 2021 at 2:48 PM

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