Mikesmith,
Thanks for the update. Unfortunately, all of the KX500 coils are made by Electrex, so they are all bad. You are 100% on the money on the battery, but that is the last resort. However, once I get the lighting coil worked out, I might add a small rechargable battery to provide better lighting at idle.
Also, on the 125, since a power jet carb was not used on the 2002 KX125, the kit that runs off the power jet carb for the KX250 will not work. I tested the CDI on the KX125 last week, and found DC voltage, but only 5 volts. Unfortunatly, I don't believe DC voltage can not be stepped up with a transformer like AC voltage can, so out of luck on using the stock ingition system.
My current thought is to just wind my own lighting coil. I have an old KX500 stator coil and have removed the wire. Tonight, I will rewind the coil with 14 guage solid copper wire, all in the same direction. This should give me DC voltage, but not sure if I will have enough voltage or wattage. As long as the voltage is great than 12 volts, the regulator will control the additional volts, so I just need to get to 12 volts or above. I will probably have to rewind the coil plate a couple of times to get the correct wire length/gauge, and might have to use a diode if I can't get DC voltage.
On the 125, the stator has lots of extra lugs, so once I figure out the wire length and gauge for the 500 I can then just insulate a couple of lugs on the 125 stator and wrap on the wire (again making sure I wrap all the same direction). I'll let everyone know how this experiment turns out, and will keep good notes on wire length and gauge in case someone wants to duplicate the process. If there are any electornics folks out there than can provide some guidance, it would be great. I'm just an old gear head that knows a little about a lot of different things, so not affraid to experiment.
This is the kind of stuff I love.
Rick