headlights dims at idle

[bigbore2]

Been riding at night here as the daytime temps have been a little hot- noticed that the headlight is dimmer at idle [just under 1000 rpm]  than at 1300-1400 rpm and above-did the regulator upgrade from Randy and cleaned /reattached the ground wire from the starter/alternator, I forget which one, that runs to the back of the engine under the carbs.  If this is like a car, looks like the alternator?  Battery is probably needing a charge and will do that, but a good alternator should be able to handle both headlight and battery at idle?
What do you think, Oh ye merry gentlemen. 

[MyFirstNameIsPaul]

It's possible you have a weak battery if the headlight is dimming more than it should, but on most bikes the headlight dims while at idle. That's the first thing you check if your battery is dieing frequently, because if the headlight doesn't get brighter when revving from idle, then your battery probably isn't getting recharged.

Have you checked your idle with a remote tach? I don't trust the tachs on bikes. IIRC, spec is 950-1050 RPM on an FJ.

[RACER111V]

Check the fluid level in the battery if it is conventional. These bikes tend to overcharge the battery and boil the fluid out of them.
The next step is a relay or larger wiring. I did the relay mod and gel battery and the headlight is bright even at low idle.

[carey]

Might not be a problem.  Unlike a car, the output of a bike charging system increases with RPMs.  That was a standard check for Suzuki's of the same vintage.  The headlight should brighten with RPM.  At idle the charging system output is low.  For a simple check, measure voltage of the battery with the bike not running. Measure again with the bike running.  You should see an increase with the bike running.

[pdxfj]

Have you done the headlight relay mod?  If you haven't it will help everything overall since you will take a fair load off the stock wiring.

[yamaha fj rider]

All the bikes I have owned the headlight gets brighter when you rev the engine. If the battery is fully charged and in good condition you should be fine. Hope this helps?

Kurt 

[FJmonkey]

If you want super bright at any rpm then consider an upgrade to HID. If you ride at night or commute then I highly recommend it. A 55 watt 5000K HID will look like you have a mini Sun shooting light forward. I did the upgrade about two years ago, got stuck in the mountains with only my dark smoke visor, no problem, plenty of light to get home. I put them on my truck as well with the same bright results. Plus, no wires to cut, if I want to switch back, then I change back to the old bulb, and move the plug from the HID and plug it in, back to OEM in minutes. I keep the old bulb in my tail bag just in case.

[bigbore2]

Wow, thanx for all the info so QUICKLY.  This site is really great. I am just trying to get this bike up to dependable riding status. Will recharge battery first. Have not done the headlight mod yet or the coil mod. Would like to do both.
To use a HID bulb, headlight mod needs to be done first?  Takes a different plug-in?  I went thru the mod quickly one day, will go over it carefully.  I rely on being seen in town using my stock headlight on bright, would be nice to have more sun up front.

[racerrad8]

You might also want bump the idle up to the recommended 1100rpms.

Randy - RPM

[FJmonkey]

To use a HID bulb, headlight mod needs to be done first? 

Not sure about all kits but the DDM connects direct to the battery and does not require any prior mod.

[bigbore2]

thanx Randy, will try 1100, after I synch carbs and confirm float levels.   FJ- DDM is a company brand?

[FJmonkey]

thanx Randy, will try 1100, after I synch carbs and confirm float levels.   FJ- DDM is a company brand?

Yes, look up DDM HID, they ship from over seas.