headlight gets dimmer at lower rpm's

should my headlight get dimmer as rpm's decrease and brighter as rpm's go up ? if not what could be some possible causes of this ?

 

Nope it shouldn't.

Weak Battery?
Alternator brushes within spec?

 

Have you replaced your fuse box yet? Always a good upgrade and will help get a more positive connection.

 

Funny mine dims a touch when the rpms go from high to low. Everything is in spec also. Everything was gone through with a fine toothed comb during the rebuild. XJ750J did the same thing also. I would call it normal IF and only IF
Alt brushes are within spec- Min 10mm
All connectors clean and corrosion free
Battery is in good shape
alt output is within spec

 

Lights may be dimmer below 2K rpm.

 

I believe less power gets to the lights under low RPMs. However, this is near-stall low RPMs. Headlight should be full bright at idle.

 

Actually I think on all of my seca's the headlight reaches full brightness around 2,000, maybe 2500. I will have to look up in the manual when its making the most power at what RPM. It has always been one way of making sure that the charging system works. Pointing headlight to garage door, when reving up the light got brighter. If that was the case then I knew the charging system was working.

 

Most vary somewhat at idle to about 3K rpm. It is the degree of change that is important. What is in question would be the alternator or the headlight's supply system. So do what has been suggested. Check alternator brushes, contacts, fuse box, battery and output of charging system by using a multimeter. At idle you should get at least 13.5 to 14 volts. When reved up to about 2500 you should get above 14 volts.

 

thanks for the input all.i will go thru the things mentioned and make sure everything is up to snuff.as it comes down to idle it gets dimmer than i believe it should.thanks again.