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Old 09-17-2012, 06:06 PM
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TopCatGr58 TopCatGr58 is offline
Join Date: Jul 2002
Location: Portsmouth, Va.
Posts: 12,620
Hey there "Dude",

Okay, the headlight turns ON when the relay gets a power signal from the ALT that it's charging, and if it's NOT charging, or charging weakly, then it may not have enough power to latch the RELAY and turn on the light.

You replaced the Reg/RECT, but sounds like you may not have done some of the necessary diagnostics first?

We don't know what you've done to this bike? Does it have the OEM glass fuse block or the replacement solid ATCO style fuses? Secondly, pull the fuse block PLATE, look behind it, you'll find a few large white plugs that come from the ALT, they often CORRODE and can then even MELT due to resistance! Inspect, clean, and even replace the plug if you have to, you don't HAVE to use OEM plugs, you can get and use almost any automotive style plug/socket combo as long as it's rated for 20 amps or more.

There are 2 main ground connections, the one on the battery to the frame, take it off the frame, clean, derust, reapply and then cover with dielectric grease. Second is below/behind carbs..the starter motor case to frame strap, same for that one.

Get a multi-meter if you don't have one, Harbor Freight sells one for a few bucks!! Then check your charging voltage at the battery at idle, will probably be close to 12 volts or even a little less, but then should go up to ~14.5 volts at 2500+ rpms. IF it stays at 12, then further diagnostics are needed.

Hopefully you also have a proper car trickle charger....set on 2 amps and charge your battery every night until you find out why your bike isn't charging.

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