Headlight getting dim, then bright...what's wrong?

[Renegade]

The past few days, as I'm riding when it's dark, my headlight will slowly dim, then all of a sudden get really bright. It keeps doing this the whole time that I'm riding. Has this happened to anyone? Is there something wrong with my charging system? This is on a 2008 btw.

 

[Sirius815]

Does it happen in response to RPM? If so, it's because of the charging system cannot keep with the demand at idle rpms. You get almost full current after 1400-1600 RPM.

 

[Shawns]

What kind of bike is it? 1125? If so I would check your charging system for sure. Bad grounds can cause lights to dim as well. If you can add HID lights some of the new ones compensate for voltage loss and won't dim.

 

[djs2k2]

No he has a xb12r, but I would still check charging system. Do the stator/ voltage regulator test.

 

[Renegade]

Does it happen in response to RPM? If so, it's because of the charging system cannot keep with the demand at idle rpms. You get almost full current after 1400-1600 RPM.

It happens at idle, and as well as at speed. It's not discriminatory as far as different RPM's or Speed that I'm going.

DJ - What's the Stator test you speak of?

 

[Zeroflat24]

I think the first thing i would do is just swap out the bulb. That would be the easiest thing to try first. If that doesnt work go in with a volt meter and see what your voltages are when its dim/bright. Is it JUST the headlight dimming or is it all the dash lights?

 

[djs2k2]

Start here, 3-wires come from the stator to the regulator, must test between all the terminals in all the combinations. While running, with the meter on A/C volts. Voltage at 2000rpms 20-30 volts, 3-4k rpms 60-70volts 5000+ i've seen 80-90volts. Higher RPMs if significantly lower than that you have stator issues.

If that checks out, go to your battery on D/C volts, with a good charge on the battery 13.5+ volts is what you should read. If the voltage is in the 12s suspect VR is bad, if you what the voltage it should slowly drop as well.

Yes there is also a stator test but don't know it off hand let me get my manual when I get home. Its probably covered above.

 

[07Bolt]

Be sure and check ur battery cables are tight and ur bulb wire-connections are tight to. Check the ground connection below the trees for dirt/looseness

 

[Sirius815]

Agree with all the above since your problem is not rpm related.

 

[Renegade]

Ok...bike died today. Dont think it's the battery as I just replaced it a couple months ago. DJ - I will be calling you when I get off work.

 

[djs2k2]

No problem.

 

[djs2k2]

Hey Cole you need to charge your bike up before you can test since it died.