Topic: Tail light question

[brett_bike]

So I just purchased a new Lucas style tail light for my '73 CB500.  It is a two wire system, but my current (stock) tail light is has three wire's.  How do I correctly hook up my new tail light So I don't bugger everything up?

[Gordon]

The new tail light probably grounds through its mount while the stock light grounds through the wiring harness.  As long as your fender has a good metal-to-metal connection with the frame it should work.

[Zaipai]

I believe your ground wire for the tail light is green, if your fender is painted, powdercoated or figerglass you may need to connect that green wire to the tail light housing. Once you hook it up if it does not work odds are you will need to ground it.

[brett_bike]

I will still be running the stock fender, but it will be chopped and tucked under the seat.  So that means I should be able to ground the light to the fender, right?  Then the other wire will take care of the tail/brake changes?

[Gordon]

I will still be running the stock fender, but it will be chopped and tucked under the seat.  So that means I should be able to ground the light to the fender, right?  Then the other wire will take care of the tail/brake changes?

You should have a good ground connection through the stock fender, so just hook up the two available wires to the wires from your harness that run the two separate filaments in the bulb.  They'll be the two that aren't dark green.  IIRC one is orange and one is green with red stripe. 

I just noticed you're in Denver, too.  Maybe I'll see you around!

[brett_bike]

Gordon

Thanks for the direction.  I think I'm finally getting the demons out of my bike, see you 'round Denver.

[Gordon]

I had a feeling I was wrong on the wire colors.  One is brown and the other is green with yellow stripe. 

[Really?]

Just plug one of the bikes wires into either the black or red wire.  Activate the brake to get some light action.  If it is not the right one, plug it into the other.  You will figure it out real quick.  And there is one for the ground which grounded on the fender through the mounting screw and worked well.

The red and black wire did come short, just added some length.

[JS550]

I put a lucas style on my 750, it has two wires, grounded fine to the mount.