Good morning! I tried my best to troubleshoot this one without posting since I've asked so much lately but I have hit another point of confusion.

I put a brand new headlight bulb (Philips 9003 - http://ow.ly/bOmM30gbYge) into my bike about one month ago. After ~2 hours of riding time, the low beam was burned out. I switched to high beam and it burned out after ~30 minutes of riding time. I've checked and the bulb itself has charring around the prongs, but all of the wires and the socket is clean as a whistle.

So, WTF!

I did troubleshooting.

Voltmeter connected directly to battery

12.7V with no key in
12.7V - 13.1V started up idle
8.6V - 14.4V revving around 2.5k to 3.0k RPM (my guess on RPM)

I think this seems OK and does not indicate a rectifier (or regulator?) problem

Voltmeter connected directly to the bulb socket, where I would plug the bulb in

I am keeping one prong in the "GROUND" socket of the bulb socket, and then moving the other prong between the yellow/white wire sockets, which correlate with high beam and low beam

On the low beam, it is steadily between 12.7V - 14.5V .. revving, idle, etc.

On the high beam, it is 0V until I switch the high beam switch on (DUH). Once I switch the high beam on, it runs between 12.7V and 14.5V, even when I am revving. Sometimes the high beam socket spikes to 16.0V - 19.1V when I am rolling OFF the throttle after a high rev

That underlined part above is the only worry-some part, but I have just tried to replicate it with a warm bike and it's not budging from 13.7V.

Really bad online reviews

This is my third solution, if the above high beam spike does not indicate some kind of problem... the bulbs I bought have terrible reviews, some people claiming a 2-week or 2-day bulb life. I have another bulb (pack of 2) that I'll put in right now and see how long it lasts.

I think my question is: Does the spike to 19V on the high beam socket when rolling off the throttle indicate a voltage rectifier (or regulator?) issue?

Thank you!
AJ

Are you using a digital or analog meter ?

Versy , Would this harm anything if you started the bike and then unplug stator at rectifier/regulator at then check stator output voltage on each leg ,grounding meter to engine and then check each leg , I think they are the yellow wires ?

Just to add a bit ,the slight resistance is only 1-2 ohms . 100 volts @5000 rpm is ideal ,but can be as low as 80 volts ac(low limit).If your regulater was bad all bulbs that were lit on the bike at the time should have also blown, perhaps you just have a bad headlight socket or those bulbs aren't very good.

Good morning,

Thanks for all suggestions I will be checking the rectifier for 80V-100V AC. Ruttly, I use a digital multimeter. My dad told me that analog would be better to catch quick spikes in voltage here, are you getting at the same point? Looks like Batman said at 5000 rpm, that's pretty close to fully open throttle at neutral?

Had rain all day yesterday so I left the cover on and didn't get to it.

Thanks again!
AJ

J_O_G:

that would be true if it was a rectifier issue, right? So the fact that all of my bulbs are not burning out... just the headlight.. proves the rectifier is OK?

Maybe I should order the $10 headlamp socket just to see. The socket looks so clean, though, connections are clean. Could just be crappy Philips bulbs too (I thought it was a good American company).

Thanks!
AJ

Why would a faulty rectifier burn out the headlight and not the tail/running light(s) ??

I'd try another new headlight bulb (and be sure you don't "touch" the glass with bare fingers).
I always wash a new bulb with alcohol before installing to remove any contaminants

Another bulb, in the back of a connector.
Paperclip, whatever..
Somewhere on the wiring harness, there is a place.