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Bike not charging after rewiring

Discussion in 'The Garage' started by Erik K, Apr 28, 2022.

  1. Erik K

    Erik K XS400 Member

    Hey everyone, I recently finished chopping my xs 400 into a chopper style bike and after an engine rebuild and everything else being modified including the wiring harness I have it running great however after about 15-20 min of running the battery will be dead. With it running a multimeter shows it running at about 12.5 volts and when I start to rev the engine it will drop down a little to about 12.2 volts. So definitely not charging. Before I messed with it I believe the charging system worked fine but I decided to simplify the harness by deleting everything that was not needed besides a headlight and tail light. Looking at the wires to the stator that do look very worn and beat but after testing these wires with a multimeter there appear to be no breaks throughout. One thing I may Beleive that I have done wrong is not creating grounds to the frame. I am not sure if this is wrong and I am sinning in the electrical world but where everything on the diagram says to be grounded I just ran to a singular negative wire that goes to the negative terminal on the battery. So every ground or negative wire all leads to one wire connected to the battery. Is this wrong? And is it required to be grounded to the frame if they are all in the end connected to the negative terminal?
     

    Attached Files:

  2. CaptChrome

    CaptChrome XS400 Addict

    Theoretically the ground to the battery might be okay, but providing a ground to the frame is a good practice, regardless, and easy to do.

    What sort of voltage regulator are you using?
     
  3. Erik K

    Erik K XS400 Member

    Makes sense I will consider next time I build one. I am still using the stock original lovage regulator. However I did replace the rectifier with some random Yamaha atv one. Are they very specific on which ones they can use?
     
  4. CaptChrome

    CaptChrome XS400 Addict

    The rectifier is just some diodes wired in a 3-phase bridge, so that should not matter and can be tested pretty easily. But first I would run a temporary jumper from the engine block to the battery negative and one from the frame to the battery negative and retry your test before drawing any conclusions.

    The spark plugs ground to the engine block and the possible floating ground between the frame and engine might cause issues that will be hard to troubleshoot. Since the main thing you modified was the wiring harness grounding everything with jumpers will help rule that out.
     
  5. Erik K

    Erik K XS400 Member

    Alright I will try doing that. Is that what might result in my having no charge is just lack of grounds?
     
  6. CaptChrome

    CaptChrome XS400 Addict

    The regulator needs a solid voltage measurement with respect to ground and this is a simple first step to troubleshooting. It may not be the cause. Next step is to buy a new regulator.
     
  7. Erik K

    Erik K XS400 Member

    Alright so I took the stator out removed all of the worn wires and reworked some brand new wires. I re assembled it and still nothing. So I went and got me the 80s dodge voltage regulator that people seem to have Luck with. Still nothing. I do notice when I sit and rev the engine it maybe goes up .5 volts so there’s gotta be something right? Even though it’s nothing really. What do I do now?
     

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