Questionmy 1976 (blue) Honda xl250 is blowing headlight. a/c volts going too high. 15 volts at idle. do you know where resistor is located in harness on bike to keep voltage at proper level. id tag on bike is 5/75 but most stuff on bike matches up to a 1976 model. has blue paint job with honda wings on tank. bikebandit classes it with 1976. 1975 bikebandit pics have only large stipes on gas tank.
AnswerHi Alan,
It sounds like a 1976 Candy Sapphire Blue Honda.
The serial number began XL250-4000001 on those.
The only resistor I know of is usually inside the headlight shell.
It is shown on this wiring diagram: (copy/paste in browser)
http://www.hugedrive.com/published/WG/show.php?q=RFJVSURFQ0s=-f33044af
I think it is made to cut the voltage down for low beam however.
The usual cause for high voltage is poor connections.
This could be poor grounds or bad connections
going through the headlight switch.
Also clean the headlight bulb socket.
Some bikes use the battery to soak up
excessive voltage as well.
Another cause could be the AC coils in the
alternator stator are shorted.
Clean all the wires and contacts with electronic cleaner and
if all else fails you can add a voltage regulator yourself.
You can get a basic 6 volt yamaha ac regulator and
just run the wire to your headlight power wire coming from the stator
to your headlight switch and ground the regulator body.
It is yellow I believe.
Yamaha had a good 6 volt AC regulator on their enduros:
http://cgi.ebay.com/YAMAHA-XT500-DT250-DT400-6VOLT-AC-REGULATOR-NOW-HERE-/360165...
If you tried to use a standard regulator you would
have to first run it through a AC to DC voltage rectifier.
or buy a regulator with built in rectifier.
Some chinese bikes use these.
Adding a small regulator might be the cheapest fix
as stators are fairly expensive to experiment with.
There is no way to test them other than checking the AC output.
Wayne S
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