WR 400 - Homemade dual sport kit problem

1 reply to this topic
  • beavis2732

Posted April 30, 2007 - 06:32 PM


hi all,

was wondering if anyone could help me out with this little problem. I have recently dualsported my '98 WR 400 and for some reason I can only get 6V to the battery. Even when I rev the motor. I spliced my main power connection to the main lighting curcuit after my voltage regulator.

It is my understanding that the VR runs in parallel with the lighting curcuit (according to the wiring diagram in the manual) and just "pulls off" the excess current kind of as it passes by.

The head/tail light work but are still not very bright. I'm pretty sure they are dimmer than before. That would explain the amount of voltage in the curcuit.

I have it hooked up to a main switch so as I can go "stealth" if need be and with that on I also have a headlight off/low/hi switch so I can only run with the tail/brake light. Which I might add is a nice thing to have even off road.

Not that the switches and such will have any bearing on my situation. That is just in here for information in case anyone had ANY ideas.

The only thing I can think of is to wire the Rectifier in before the VR. My thought on this are that since you have your full 12V coming out of the VR (-6V to +6V on your sine wave) does the rectifier only go with the +6V and omit the -6V. This could explain a lot if I am right on this.

I was just wondering what people smarter than I think on this before I start tearing into again. The last thing I want to do it take it all apart and hook it all back up to find the same problem exists.

Of course any and all responses are welcome and just for good measure I will post in the dual sport forum as well.

Thanks all


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  • Rich_in_Orlando

Posted May 01, 2007 - 05:41 AM


The first thing I would do is check the voltage before the regulator. It should peak at 15-18 volts. If it is less than 12 volts, it would indicate a bad connection or possible a short in some of the windings. The service manual gives instructions on how to test the stator.

If the unregulated volatge is sufficient, then it would indicate a bad VR. Also, is the rectifier rated for the current you are putting through it? It should be rated for at least 10 amps. The one I use on my bike is rated for 35 amps. If it is too small, it may have burned out part of the circuit. The ones they sell at Radio Shack should be big enough and they are cheap.

Did you do the Baja Designs stator modification? If so that may be the problem if it has loosened up or wasn't done correctly to begin with.

The order of the VR and rectifier doesn't really matter, but just for comparison, the VR is before the rectifier on my bike.


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