Topic: 76 550 wiring harness issues

[jude0007]

I'm replacing my 76 550 wiring harness with one I bought on ebay because the PO ripped the original one to shreds.  Things were coming along nicely until two things.  I had an extra wire from the main harness (red/black) that I couldn't figure out where it went and my headlight wasn't getting power.

In doing some research on here, it looks like I bought and installed a 550 F wiring harness.

The black/red wasn't on my wiring diagram, from other posts it appears to power the headlight control.  The other issues are:
"2 other problems you might find is that on an F, the horn switch supplies power to the horn, not switching it to ground & the same with the start switch. It supplies power to the solenoid, not a ground circuit...."

My question is can I make this harness work or should I start over and try to find a correct 550 harness?

[bryanj]

Have you got a three fuse fuse box attached? the red/black should connect to the RH switch as the headlight power goes through the starter switch, then the fuse to the hi/low switch on the LH bar.

As to the solenoid it depends what switch you have.

It can be made to work BUT we need to know EXACTLY what switches you have AND how the horn and starter solenoid are wired

[jude0007]

Thanks for the response.  I have a 3 fuse, fuse box.  Main, headlight, tailight.  I had to buy one new and got one specific to my bike so that part is correct.  What I should verify is what colors (from the wiring harness) connect to the fuse block.

I bought a 79 cb750 RH switch because it was in good shape and was cost effective.  It has kill switch and then starter that kills the lights when pressed.  I only have the taillight and the Neutral/Oil Pressure light working and when I press the starter button, the lights kill so that part appears to be working.  But perhaps it isn't working correctly.  The starter solenoid makes a clicking sound but I haven't been able to test the solenoid yet.

The only reason I think I may have a F wiring harness is because of the extra black/red wire.  In my research, when there's a black/red wire.  Also, the ignition coil that is supplied by the blue wire gets really hot when I have the key on.  I haven't been able to test the coil yet either.

My horn is hooked up like a normal 550 wiring diagram that this site has as well as the Clymers manual.  The horn works.

What is the difference between a 550 and 550f?

Thanks guys.
I can post pics of the fuse box and starter switch but I think I explained it well enough above.

[bryanj]

The starter button has 3 wires to it
(1) A black wire that is power with the key on
(2) A Yellow Red that is power to the solenoid when the button is pushed
(3) A third wire (colour can vary) that has power when button not pushed and disconnects when button pushed, this should go via the loom to the headlight fuse then back via the loom to the L/H switch power to the dip/main switch, you will have to use a multi meter to check which wires but one of them is black/red

[jude0007]

Thanks for the help, I'll dig into it a bit more tonight.  I feel like I'm almost there because when I press the start button, the lights kill and the starter solenoid clicks.  I'm replacing the solenoid.

I just have to go through the lights issue right now, ensure I have power at the switch.

I can't find a complete 550 F wiring diagram that is legible.  The Clymers manual doesn't have it either, anyone have a good copy of one?

[Bankerdanny]

The F has the key and idiot lights between the gauges. The plug for the ignition switch is different, and It  has separate indicator lights for the turn signals, while your '76 K will have only 4 idiot lights in the little panel at the top of the triples, with a singal indicator light for the turns.

[jude0007]

I've decided to purchase the correct harness vs modifying the 550 F harness.  My other issue was buying a 79 cb750 RH switch.  It had the circuit to kill the lights when starter button was pushed but it appears to be a little different.  It has one less wire than the 550 harness needs.  If anyone would like to take a look at my issue, the wiring diagram can be found: http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750K_79___.pdf  My issue is that the two Black wires combine in the switch leaving a wire short at the harness.  I think this also incorrectly grounds something out in the 550.

I am just not experienced enough to be trying to piece all these odd ball pieces together.

My issue now is finding a decent 550 switch.  I can try to post an add on here but how difficult will it be to find the correct switch? 

Does anyone have a suggestion on other switches to look for from other years that would be compatible?

Thanks!

Edit:I did find one new at DSS: http://www.davidsilverspares.com/CB550K-1976-USA/part_70878/  I might have to pull the trigger but that's spendy!! (I guess not really if I just would have bought everything correct from the start)