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Drained battery anyone know why?

Discussion in 'The Garage' started by londoncabby, May 18, 2020.

  1. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    The trick is to make it read about 14.2V at the battery terminals when it's revved to about 3K in neutral. Look for the thread Charlie's Expanded Charging Guide (or somesuch) by gggGary. I worked on mine forever, and the problem finally ended up being heavily tarnished wires just barely twisted together, down inside the harness. First thing, you'll have to put your battery on a charger and try to get it up close to 13V. Also the connectors can go bad -- components can test good but the connectors they plug into will be bad, making it look like a bad component. Had some of that too
     
    Paul Sutton and londoncabby like this.
  2. Jim

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

    As longs as your battery is topped up... I doubt they're related.
    Pull the plug and see if it's fouled?
     
  3. londoncabby

    londoncabby XS650 Enthusiast

    I seem to be in a catch 22 situation hear as I can't address my charging issues until I can get it running on both cylinders it just seems strange that since getting it home after breaking down it won't run on the left cylinder it was starting and running spot on before and up to it broke down I've swapped the plugs over and tried a spare set with no change as I said in an earlier post if I pull the left plug lead off while it's running I can hear it arcing across to the plug so it seems to be getting power to the plug I don't know where to go from here any ideas?
     
  4. Jim

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

    What's the plug look like? Dry.... fuel soaked? Pull the float drain and see if there's fuel in the bowl?
     
  5. londoncabby

    londoncabby XS650 Enthusiast

    Thanks for your suggestions Jim plug doesn’t look fouled I just pulled the float drain and fuel was there after it drained I turned the fuel tap sorry pet cock over to prime and fuel started running out so its getting fuel I will get two new plugs tomorrow to eliminate duff plugs and if it’s getting spark and fuel it should bloody well run on both cylinders!!
     
    Jim likes this.
  6. londoncabby

    londoncabby XS650 Enthusiast

    Just an update fitted two new plugs today and with a fully charged battery it fired right up on both cylinders it’s still not charging though so I am going to go down the pma route,my bike is fitted with a Boyer Bransden Ignition would this be compatible with the pma setup?
     
  7. Have you tested your Reg/Rec? PMA is good...Hugh's is best, but he's laid up right now, but if your Reg/Rec is bad, you will never charge. Good luck.
     
  8. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi 'cabby,
    unless it's been fitted with an aftermarket magneto (Yes they are available, cost ~ a grand) all XS650 ignition systems run off a battery.
    Keeping the battery charged is a different problem.
    I reckon that fixing the bike's stock charging system is a better thing than swapping to a PMA.
     
  9. londoncabby

    londoncabby XS650 Enthusiast

    image.jpg Even though I’ve got a pma kit on order I would still like to fix my stock charging system when I took the capacitor off that sits under the battery on the battery tray it looked a bit suspect! does anyone know a good replacement for this part?
     
  10. 5twins

    5twins XS650 Guru Top Contributor

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    That is your rectifier. Although many do look pretty crusty, they still work fine. There are detailed testing procedures for it in your shop manual. The rectifier's job is to convert the AC current produced by the alternator into the DC current the bike uses. The AC current is fed into the unit from the alternator on the three white wires, DC current comes out on the red wire and is sent to the battery. The black wire is a ground.

    The 650 uses an automotive style 3 phase alternator. This requires a 3 phase rectifier. These are readily available from the electronics world for around $10 or less. Many of us use this unit .....

    https://www.windynation.com/Rectifier/35-Amp-3-Phase-Bridge-Rectifier/-/218?p=YzE9MjA=

    Your '78 model is unique. It was the last year that had a headlight on-off switch on the handlebar and the first year that had the headlight safety relay. That relay bypasses the on-off switch, rendering it useless, once the motor starts. Fortunately, it's very simple to eliminate the safety relay and restore normal operation to the on-off switch so it functions at all times .....

    [​IMG]
     
    Paul Sutton likes this.
  11. londoncabby

    londoncabby XS650 Enthusiast

    Thanks for the reply 5twins that’s really helpful it’s all gradually started to make sense now I’m sure I can find a similar rectifier to the one in the link over here in the uk
     
  12. londoncabby

    londoncabby XS650 Enthusiast

    So I’ve fitted the pma to my bike and it’s now starting running and charging fine I also fitted new air filters and plugs (ngk bp7es) as I said it seems to be running fine but I am getting popping and banging on the overrun which I didn’t have before I fitted the pma could it be related?
     
  13. 5twins

    5twins XS650 Guru Top Contributor

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    I suppose that's possible but it's more likely that changing the air filters may require some carb tuning and minor re-jetting. The popping on decel is usually an indication you're running lean, usually in the pilot circuit. Adjusting the mix screws (opening them up more) may help but if that won't totally cure it, a larger pilot jet may be needed.
     
    Team Junk likes this.
  14. londoncabby

    londoncabby XS650 Enthusiast

    Well the colour of my plugs suggests it could be running lean so your probably on the right track 5twins I noticed my mixture screws have got what looks like plastic covers on them do I pull these of? And just to confirm I screw them out to make it richer? Thanks again for replying
     
    Team Junk likes this.
  15. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, those are tamper-proof caps so you don't mess with the factory settings. They will just pry off. Under them you'll find a normal slotted screw you can adjust. Factory spec was 2.25 turns out but keep in mind, that's only a suggested starting point. When my '78 was mostly stock, it liked more near 2 5/8 turns out. Yes, screwing them out makes it richer. If you can't cure the decel popping by the time you get to about 3 or 3.5 turns out then a larger pilot is probably needed.
     
  16. 5twins

    5twins XS650 Guru Top Contributor

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    Here's what the mix screw will look like with the plastic cap removed .....

    [​IMG]

    Your mix screws also have an o-ring on them to seal them into the carb body. You might want to inspect the condition of that. If it's bad, that might be adding to the popping problem .....

    [​IMG]

    Through some trial and error, we've managed to find a nice fitting replacement .....

    [​IMG]
     
    Team Junk likes this.
  17. londoncabby

    londoncabby XS650 Enthusiast

    Brilliant! Thanks so much what a great forum this is..
     
    Team Junk likes this.

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