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No Alternator // 1979 XS650

Discussion in 'The Garage' started by AndresM, Aug 27, 2018.

  1. AndresM

    AndresM XS650 New Member

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    After many years searching for an XS650 in Mexico in decent condition(they weren't originally sold here). I've finally found one thats close to where I live and in good condition. However it doesn't have an Alternator, I'm sure this question has been asked a thousand times but English being my second language and my "extensive" (read: zero) electrical knowledge, i couldn't find anything usefull.

    What route should I take to replace it? look for an original one or change it to a more modern system? If so, which one?

    I'm new to forums in general and if I'm breaking any rules by posting this please let me know.

    Thanks!
     
    Jim likes this.
  2. Jim

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

    Welcome to the forum Andres!!
    You might want start here and figure out what's wrong first... then decide what to do.
     
  3. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

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    Welcome, Andres. Sitting on the bike your left side is the "left" of the bike. On the front of the left engine side cover there is a 5 inchish plate. Could we get a picture of what is underneath the cover?
     
    robinc and Jim like this.
  4. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi Andres and welcome,
    did you look under the ~5" (that's ~130mm) access plate yet?
    The alternator should be under that plate.
    If the alternator is there but it's not charging the battery remember that the alternator is only one part of the charging system.
    The rectifier (turns the alternator's AC (alternating current) into DC (direct current) to charge the battery.
    The regulator ( limits the rectifier's output to the ~ 13 Volts the battery needs to be safely charged)
    The battery.
    And all the wiring needed to connect them all.
    Perhaps the fix will be no more than a broken wire. The hard part will be finding the break.
    If the alternator is missing it needs to be replaced. Look in this list's classified section to find a used one.
    There are aftermarket charging systems available but they are costly and not as well suited to the bike as the original.
     
    Jim likes this.
  5. AndresM

    AndresM XS650 New Member

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    I'm going to go pick up the bike this weekend. I just wanted to get a headstart on ordering parts for it since shipping stuff from the US is kinda slow.
    Unfortunatly there is nothing under the plate. I'll upload the photos when I have the bike.

    I have to admit I haven't done much work on the electric system of a bike as I would want to and don't know much about it (its the part of the project that worries me the most), therefore I was willing to buy an aftermarket charging system if it was worth the money and it gave me a bit more peace of mind...

    Anyway, I think I'll keep researching the topic and bother you guys with stupid questions once I have the bike with me

    Thanks everyone!
     
    Jim likes this.
  6. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    5,668
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    Yes hold up on purchasing till you know more.
     
  7. 650Skull

    650Skull Dinosaur Lives Top Contributor

    +1 with Wer...............Spend the time doing the research and asking questions before making decisions is a good way to work on a bike like this. Once you get the bike post up pics, often parts have been altered and we can identify and advise on what you have and ways to test for work-ability, and what is the best, cheapest and easiest way to move forward.

    Need to identify what model bike you have. There was a major change in the charging system, ignition systems and carbs in 80.
     
    robinc likes this.
  8. AndresM

    AndresM XS650 New Member

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    Hey I finally got my bike a 1979 XS650F. Before diving into the electrical issues of the bike I ran a few tests, (motor seems in great shape! w/ 14 psi compresion) and ran into something I wasn't familiar with whilst cleaning the carburetors and gas tank, there is a connection behind the fuel tank petcock, one on the boot that goes between the motor and the carb, an a few between the heads that are cancelled or not connected to anything.

    I got the bike running but it bogs down if I give it a lot of gas. How should these connections go?

    To be honest the carbs I'm familiar with have the slide conected directly to the cable.
     
  9. 650Skull

    650Skull Dinosaur Lives Top Contributor

    Need to post some pics.........learn the proper terminology...........your explanations are not clear at all.........If you can't explain things very well how are we expected to know..........

    14 PSI is so bad the motor needs to be taken apart to see what damage is in there. To try to run the motor with such a low Compression with out a diagnostic could lead to more major problems to internal components

    There should be a hose from the petcock to the nipple on the inlet manifold. This is called a vacuum hose and without it the bike will run rough at best and not run at all at worst.

    79 Models can be problematic if not identified properly..........What is your vin no, if you don't want to post the whole no the first 6 digits will be enough to confirm the model/year.........The vin no should between 2F0-020101 and 2F0-1000000
     
    Last edited: Sep 7, 2018
  10. Brassneck

    Brassneck XS650 Guru

    Welcome Andres!

    Did you mean 140psi? As 650Skull's mentioned 14psi is extremely low... and I can't even imagine it would run that low...

    The one on the carb boot is a vacuum port, designed to go to the petcocks, and draw fuel when the bike is running. If they aren't connected, then you MUST either connect them to the petcocks OR cap them off...or your bike won't run well. You should have one on each side.

    The one between the head is likely a breather port for the engine. This doesn't need to connect to anything, but it's a good idea to attach a hose and route it to the airbox (as it was intended) or down to the bottom of the frame so you don't get oil splattering on you.

    You can connect them to your petcocks with small diameter fuel hose or tubing. I am assuming you have the correct gas tank/petcocks...but if this was changed and you don't have vacuum petcocks, then you can simply cap them off.

    1979's came with Mukini BS38 (CV- Constant Velocity) carbs. You are probably use to the VM style, where the slide is directly connected to the cable/throttle. The BS38's have a different operation and utilize a butterfly valve to allow airflow into the carbs, and then the slides are pushed up via vacuum and magic... needles to say, they work but are a bit more complicated in some ways. However, they do have a lot of tuning ability...which can be good or bad. There is only one throttle cable, and it connects to the left carb...and the right carb is "linked" to the left one. There's a lot of discussion on the carbs within the tech section... but if you got the bike to run, that's a good sign. :)

    I think it would be good to post some pictures of your bike and the parts you're referring to whenever you have a question...so we can see what you're looking at and it may help with the translation/terminology.
     
  11. AndresM

    AndresM XS650 New Member

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    I’m sorry about my poor description of the issue. My biggest problem is that, like 650Skull said, I don’t know the proper terminology and it’s pretty difficult to know what to search for in the forums without these terms.

    Anyway thank you very much Brassneck! Thanks to your explanation (and a whole lot of cleaning) I got the thing running much better. Unfortunately the petcocks developed a pretty severe leak which I’ll have to deal with this weekend.

    I'm sorry about the typo, I meant 140 psi.

    If I need to bother you guys with more questions I’ll be sure to post my VIN and pictures.


    I must admit I’m amazed with awesome community these motorcycles have around them, I cant thank you guys enough!
     

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