Topic: CB550K v CB550F Electrical Panel Problem

[Bristledisk]

Hi All,

I purchased a 1976 CB550K.

The electrical harness was falling apart so I bought a replacement CB550K wiring harness and sub harness. When trying to fit the replacement harness, I notice that a PO has fitted what seems to be a CB550F electrical panel. The only difference between the K and F panels are the K should have 2 boxes attached to the panel, the fuse box and another box labelled "Safety Unit Starting Motor" with a red 6 pin locking connector coming from it. See attached picture? The F panel only has the Fusebox but does have red/yellow and red/green wires coming from the starter magnetic switch.

What are my options here?

Should I try and get hold of a K panel or can the replacement K wiring loom be adapted for the F panel?

[scottly]

Your old harness should have a diode installed somewhere; it's a small black block, about 1" x 3/4" x 1/2", with two terminals and a symbol that looks something like
-l<-. This diode will replace the starter motor safety unit, and can be added to your new, older style harness. I'll have to dig through my notes to tell you exactly how it needs to be connected to the SMSU plug. BTW, your '77 400 uses the same type diode in place of an SMSU.

[Bristledisk]

Thanks Scottly. Useful information. I'll check my old harness for the diode.

[firebane]

The diode is pretty small but the receiver it plugs into isn't.

[scottly]

What colors are the wires in your harness plug? On a 750, there is a red/white, a green, a black, a green/red, and a light green red. The diode is installed between the green/red and the light green/red terminals, with the "arrow" pointed towards the light green/red.

[Bristledisk]

Hi Scotty,

The 5 wires on the red harness plug are red/yellow, green/brown, black, green, green/red. (see image in original post)

The 2 wires coming from the top of the Starter Magnetic Switch attached to the panel on the bike are red/yellow and green/brown. (see attached photo on this post).

Thanks for the help.

[firebane]

Hi Scotty,

The 5 wires on the red harness plug are red/yellow, green/brown, black, green, green/red. (see image in original post)

The 2 wires coming from the top of the Starter Magnetic Switch attached to the panel on the bike are red/yellow and green/brown. (see attached photo on this post).

Thanks for the help.

It SHOULD be top right just above the fuse box.

You can see it here .. At the top where the arrow on the right starts.

[scottly]

Hi Scotty,

The 5 wires on the red harness plug are red/yellow, green/brown, black, green, green/red. (see image in original post)

The 2 wires coming from the top of the Starter Magnetic Switch attached to the panel on the bike are red/yellow and green/brown. (see attached photo on this post).

Thanks for the help.

Yes, I was in error about the red/white wire on the SMSU plug; I realized this morning when looking at the schematic in daylight that it should have been red/yellow, or perhaps more correctly yellow/red, since it is yellow with a red stripe.
There should be a yellow/red wire on the new harness with a bullet connector, as well as a solid black wire with a bullet in the same area; plug these into the solenoid wires. It doesn't really matter if the yellow/red solenoid wire connects to the yellow/red harness wire, or the black harness wire, or vice-versa for the green/red solenoid wire, in case there is a problem with the polarity of the bullets.
 

[scottly]

Wait a minute!!! There may also be incompatibilities with your handle bar switches and the older harness style.

[firebane]

Red/yellow winds it's way up to the right bar controls and green is just a typical ground.

[scottly]

The late style systems with the diode also have the "always on headlight", which is turned off when the starter button is pressed, and passes the 12V to the solenoid on the yellow/red wire, while the earlier system grounds the solenoid through the yellow/red wire from the starter button. The earlier harness with the later switch can be made to work, but it's not "plug and play".