Topic: Wiring How-To for CB750?

[sirdaft1]

Does anyone have a quick write-up on the wiring needed to run the minimum needed on the 750? (ie: headlight, tail light, battery recharge?) I know some other bikes need you to keep the horn or turn signals wired to complete the circuit- wasn't sure what was necessary on the 750.

[Don R]

You can just unplug the signals. Leave the unattached wires for when you or the next owner change your mind. Same with the horn. What is your goal? It's difficult to help without knowing if you are building a cafe, drag bike, road racer, chopper or what ever else is out there.

[joe750]

If Don R's advice doesn't help,
I wired my hardtail from scratch with only headlight brake light and charging system with one of those 3 way ignition switches from cycle-x.
I'd be glad to help if you still need it.

I'm building a cafe racer now and I plan on ripping all that wiring mess out and doing the same thing to this one.

Also, I used the regulator/rectifier combo to make it even more simple.

[thrutheframe]

  Here is a super simple diagram for a chopper or bobber.  It's been posted a bunch of times here and on the webs but its simple and effective.

[sirdaft1]

DonR- It's getting the cafe treatment so as minimal wiring as possible.

Joe750- would love to chat. The PO did some jenky wiring on this thing (including using a part of a cut up extension cord??), so a start from scratch wire up might be in the cards. Just like your setup, I plan on running just a headlight, tail light and charging system.

[Brantley]

Fully untape your existing harness. You might be able to eliminate the PO's BS. At least you can use it as a template if you do start from scratch.

[farmertom]

..headlight needs a ground on the green wire in the simple diagram.

[sirdaft1]

Made some good progress today (thanks Joe750 for the coaching!) I unwrapped all of the wires and sorted through the wires to determine what needed to stay and what needed to go. I decided that I'm going to keep the speedo on the bike and either source or make a custom bracket for it.

Here are the wires getting sorted out...


Here is the pile of unnecessary wires...


I followed Thrutheframes diagram, starting at the battery and going down the line.


It was going pretty smoothly until I tried sorting out the key switch. The wire colors threw me for a loop. My key switch has wires that are brown, brown, brown/white, black and red. Whereas the diagram it showing black, green, blue, red, yellow and green. I didn't know where to start, so I figured that would be a good place to call it a day.

Here's how I left her...

[Don R]

Try to keep your kill button. They sometimes come in handy.

[cougar]

sirdaft ; Here is an interactive diagram that you can remove/add circuts that you want. http://oldmanhonda.com/MC/wiring750K1.html . Hope this helps.   ...cougar...

[Don R]

Black is 12 Volt hot. Black /white is switched 12V hot. Green is always ground. Brown/wh usually is switched for lights.  I think stripes are usually switched, solids go to a switch, Some circuits are double fused, through the main, switched then back, to a fuse, then to a light. Don't forget grounds. I like to tie them to the frame and loop them together also.

[sirdaft1]

Cougar- Ya kidding me! That's amazing. I think that may have made this job 10x easier being able to see each circuit individually. Thanks for the share.

And unless I'm missing it in the interactive diagram- it looks like they only included one fuse going from the battery to the ignition switch. Does that sound right?

And Don R., I'm thinking about keeping the kill switch. Thanks for the input.

[cougar]

sirdaft ; I just went and checked it out again and your correct I only see 1 fuse. I just looked through my manual and it seems to be showing 1 fuse. Not sure what's factory, never seen 1,LOL.    ...cougar...

[sirdaft1]

I'm a bit perplexed. The diagram shows a black wire connecting to the starter solenoid in this diagram, and I have an open black connector, but no idea where it connects to the solenoid. Any advice?

By the way, Cougars diagram has been incredible in helping me wire this up for the first time. http://oldmanhonda.com/MC/wiring750K1.html

Here's the solenoid and black wire (hanging down to the right)... **scratches head**

[Brantley]

Yellow/red to switch. Treat the green/red as black.

[sirdaft1]

^^^ perfect. Makes much more sense now.

[sirdaft1]

She's alive!

After a few nights of un-wiring and re-wiring, she's up and running. Took her for a spin and aside from there being a short somewhere on the circuit for the headlight... she's running great. Thanks for all of the help guys.

[Don R]

Hope I helped, and am positive others did.
 The reason I am committed to the kill switch is I had an improperly routed K0 throttle cable catch on a reflector once and  when I turned the bike hard it pegged the throttle in a tight parking lot. I pulled in the clutch and killed the motor. Would have been hard to do without that kill button handy.