A little back story...

I installed a new undertail and in doing so I disconnected the low beam headlight connector at the housing so it wouldn't drain the battery every time I switch the ignition on to check my wiring work. *deep breath*

Of course I ended up killing the battery anyway - but I knew it was on the way out after the previous owner let it sit for a while. It was on borrowed time.

So this weekend I bought a new Yuasa battery, topped it off on the charger, and put it in the bike. Bike has never started so quickly and affirmatively. But I noticed the headlight went out after the bike's first start. So I killed it and checked the connector - tight, no movement. Started it again and it stayed on. That was the last time I touched the bike.

Fast-forward to today...

Forecast called for a calm day so I decided to ride to work. First time I started the bike, the light went out again. It's on when I turn the ignition switch to "ON", then dims when I hit the starter button like normal, and cuts out when the engine fires. Same thing it did this weekend. Killed it and started again - worked. Rode to work without any problems.

I worked late and left work around 7:15pm (dark). Didn't have any problems until after I turned left at an intersection 3 miles from where I started. I was behind an SUV and next to another car, and I didn't realize my headlight was out until I changed lanes to pass the SUV - total darkness in my lane! Since there was no one behind me for miles, I pulled off, killed it, and started again quickly - worked. Didn't have a problem the next 5 miles to home.

WTF?

BTW, flicking the high beam switch when the light goes out does nothing.

 

I think, it could be a loose connector at the headlight harness (the one that plugs into the main harness, and connects to high/low turns and the tip sensor). Check that.

Sounds like you aren't running hids, because i had the same thing with a set of hids but it turned out to be the ballast.

What type of bulbs are they and how much power are they drawing from the bike?

Do you also have a volt meter?

 

All lighting up front is stock, haven't touched a single wire except for unplugging the low beam connector once for a week then plugging it back in.

I do have a meter.

 

The way the headlight works on the 250, is that the pulse generated by the starter, toggles a relay and the lights come on. If the wires rattled the lights would go out. They could not be turned on again, until another pulse from the starter triggered them.

Not sure if it is the same on your bike, but I would not be surprised if it was - as many bikes intentionally turn the lights off during starting.

 

woot, thanks for that tip. maybe I can troubleshoot the relay.

 

Alright, I haven't ridden in the dark since the last post and noticed it again today. This time I saw exactly how it happens.

Stand is up
Bike in Neutral
Key is OFF
Kill switch is OFF
Clutch is OUT
----------------
Turn key ON
Flip kill sw. ON
Pull in clutch
Hit starter button
*BIKE FIRES*
*LIGHT IS ON*
Release clutch
*LIGHT GOES OUT*

Seems to happen with that clutch release.

Now I'm worried it is going on/off during the day, making me less visible (and illegal, I believe).

WTF?

 

I had a similar issue, but it was a faulty ground wire... the green one...

 

Thanks, but...where?

 

Alright I took the left fairing and ram air tube cover off and jiggled all the wires, no change. Sometimes it cuts off, sometimes not. I put a multimeter on the bulb connector and got 13-14v.

 

I had the same problem with my '05 cbr f4i. There is a wire inside the plastic where your starter button is. If you open that up the middle wire (i think it is blue) not sure as I only fixed it once and havent opened it up since might have come un-soldered. It kills your lights and will do it intermittently because it still sits on its connection and will connect and disconnect as you ride around. Just a quick soldering job on that 1 wire inside the plastic housig on your right handle bar where your push button start is could fix your problem. Yeah my light would just go out without rhyme or reason so I would for sure check that wire...there are two screws on that plastic casing and then it just pulls apart but be careful with it because there are lots of delicate parts inside that housing...Good luck.