WR250 (2001-02) Electrical Lighting Question(s) - Possible Issue

Hello,
Looking for some input on a maybe/maybe not electrical issue on a second hand 2001 WR250 (Canadian model) I recently purchased.
I apologize in advance this is a little preliminary and I have not had the chance to test resistance and things like that (I'm new to electrical troubleshooting).
I've searched this and other forums and read a number of posts, and in some cases aftermarket lighting was installed and caused issues, or other time bad regulator/rectifier was the culprit. My symptoms are slightly different but I think might be in the realm of a bad regulator/rectifier but just looking for some advice.





Just bought the bike recently and only rode twice, first around to test ride it when buying and then again a little in a parking lot just getting used to the bike.


When I first rode it and I was test-riding the bike (in the evening with fairly low light) the front headlight was very dim. You can see it was on and yellow, but too dim to actually shine any light. The tail light was even dimmer and ever so slightly a faint resemblance of red in it. When I rode it on the throttle it slightly got brighter but very minimal change.


Last night went out to ride it a second time to a parking lot to get used to the bike (again in the evening with fairly low light). This time the headlight was non existent, would not run on. The tail light was bright and working very well.


I find it strange that the headlight failed and now the taillight works, and I'm hoping it's simply a headlamp bulb that let go and just needs replacing.
But would the headlamp crapping-out cause the taillight extra power to light up nicely? Sounds to me either both front and rear bulbs might need replacing, or possibly and regulator/rectifier issue as well?


Any input / advice would be really helpful, and thank you in advance.

First make sure the bike is charging well, if you have good voltage - test the bulb circuit to ensure it has a good ground and a good 12v comming into the plug.

If both are good - then you might have a wiring issue / intermittent issue, just trace the wiring back to see what you can find.

Sounds like you have a ground issue.

Be forewarned: Dirt bike charging systems are different from most bikes and cars. Usually the three phase alternator current gets rectified to charge the battery with DC and everything runs off the battery. Dirt bikes typically use one phase to charge the battery, one phase for the ignition and one phase for everything else... so it is possible that that you have 14volts at the battery, and the other two phases are dead.

For a "new to you" bike get the electrical schematic for your model. Buy and learn how to use a multimeter, to test electrical connectivity. You cannot visually see if a wire, connector, switch, fuse is conducting electricity. You must use a multimeter. Check each and every wire, connection, switch, fuse, bulb, socket, anything electrical, with your multimeter, to ensure it conducts properly. Clean all connections, add some dielectric grease, and then check it off your electrical schematic. Once thoroughly checked you'll have years of trouble-free usage. Otherwise you're just guessing at the location of the short. Be systematic and check the whole bike. Bikes are not large and are easily checked. By being thorough you'll be rewarded with reliability. You will also see if the previous owner did anything bad to the bike.

Thanks for the replies. Changed the bulb and it's all good now after a couple of rides.
If it blows again prematurely then will definitely start checking grounds and also possibly new voltage regulator.