Introduction and charging issues


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Hi. New to the forum yesterday, and am glad I found it. I hope I can help someone out soon, but I need some help now.

I have an 81 XS400 that I have hardtailed and stretched. I put it together last year and rode it for a few months to make sure it was ok.

This winter I took it apart and cleaned it up, painted, modified a few things, etc. I am close to being "done" with it now, but after wiring it I am now having some problems. I do not have anything but the charging and ignition wired so far.

It starts and runs no problem but I cannot get it to charge. I have followed the pdf diagram attached to wire it, except that I don't have an ignition switch yet, all the power wires are going to the battery positive terminal.

I found a second diagram here that is virtually identical to the one I used except that the brown wire from the alternator is not teed off to go the the regulator, alternator and power but goes directly to the power, not back to the alternator at all.

I have checked and re-checked the wiring, but it all seems to match the diagram. The plug for the three white wires coming from the alternator has been removed, so I am not sure if the order of those wires is correct (if it matters). I di repair those wires just where they come out of the alternator cover, they had worn through, but it still does not charge.

I'd like to test the alternator to see if it doing anything at all, so how to I bypass the regulator?

Does anyone have specs on testing the regulator and the rectifier? I followed the tests in the Haynes but they are not even close, so either I have the wrong specs or I am royally screwed.

I probably should mention that the bike has not been running for more than a few minutes at a time.

Also, I removed the alternator cover and side cover, and everything appears to be in good condition there.


  • XS-400.pdf
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  • XS400_simplified_wiring_diagram.JPG
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For everyones information I figured it out. I read somewhere that if you grounded the green regulator wire it would bypass the regulator and produce un-regulated power. I di that and immediatly got over 14v. I revved the engine and it jumped to 16.

I then installed a Dodge regulator like the one below and it is now charging at 14.7v all the time.
I is a Standard Motor Products VR-125 There is also a pigtail for it, but I am not sure what the pt# is.