Author Topic: CB750 K4 wiring question, desperate for help  (Read 5450 times)

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Offline nightpoison

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CB750 K4 wiring question, desperate for help
« on: July 13, 2014, 10:41:29 AM »
ok, so I've done a bunch of research and have come across several articles. Hondaman is the man it seems when it comes to wiring our bikes. I wired up the bike and had four extra wires. well it seems I need to bridge the brown and black wire that was left over and the brown/white with the brown/red that were left over. when I did that I got tack and speedo lights lighting up, and then the brake light started to work as well. the Headlight would turn on only when I had the High Beam on.

the issues: no running lights at all, turn signals won't work at all, no low beam(running lights again, I think), starter/kill switch, and horn. So I've created a list of questions that I'm hoping I can get some help with.

1) Motion Pro start stop switch. (see attached photo of wiring diagram for right hand control)
        A) ON/OFF SWITCH: does it matter which wires I connect this too? the motion pro has a black and blue/black. right now I'm running the black with the black/white on the harness & the blue/black to the black wire on the harness.
       B)   there are two sets of wires that work the starter switch. for my bike I believe I only use one set of these. do I use the white & yellow or the gray & red/black combination? and which of those would I connect to the yellow/red & green/red wires to operate the starter?

2)Left hand controls.
      A) Head light: so the headlight plug has three lines. Black(ground) Red(drive) green(pass). I came across another post where they said that the Black is ground, red is low beam, and green high beam. So I connected the red wire directly to the LHCs to the yellow low beam wire, and the green wire to the green Highbeam wire along with the Positive wire for the High beam indicator light. HL main wire from the LHC is Red and Im connecting it to the Brown/red wire on the harness. the HB LED ground I'm running to a green ground.

      B) turn signals: so I have dual filament signals for both front and back. the back I'm only using the ground wire and the flasher(positive) wire. as there are only single filament connections for the rear I just left it that way.

for the front. the red is the flasher(positive) wire which I connect to Orange(left) & light blue(right) on the harness.I also connect the LTS wire(brown) from the LHC to the orange harness wire & I connect the RTS wire(dark green) from the LHC to the light blue harness wire.

the Black/white wire is the ground which I run to the green harness wire for both the LT and RT front signals.

The last wire is black which is labeled as running light, which I run to the orange/white(left) & the light blue/white(right). I don't connect anything else to the orange/white or light blue/white

Main turn signal wire on the LHC I run to the brown/white wire on the harness

is this correct?

     C) Horn LHC pink wire connects to light green signal harness white, and the horn ground from LHC(black) I connect to the black harness wire

correct?

sorry this is such a long desperate post. I was hoping to have the bike on the road last week.

« Last Edit: July 16, 2014, 03:08:03 AM by nightpoison »

Offline nightpoison

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Re: CB750 K4 wiring question, desperate for help
« Reply #1 on: July 16, 2014, 03:10:48 AM »
Can anyone suggest a shop i can take the bike too on the north shore of Boston to have the electrical looked at? at this point I might just need to have someone else do the work. As I'm having very little luck with it.

Offline Vinhead1957

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Re: CB750 K4 wiring question, desperate for help
« Reply #2 on: July 16, 2014, 05:09:53 AM »



This is for a 73 but should be the same!

Offline Vinhead1957

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Re: CB750 K4 wiring question, desperate for help
« Reply #3 on: July 16, 2014, 05:14:30 AM »
I would say that any color/white combo signifies switched power from the key switch.

Offline Vinhead1957

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Re: CB750 K4 wiring question, desperate for help
« Reply #4 on: July 16, 2014, 05:17:47 AM »
Black is 12 v   Green is ground

DH

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Re: CB750 K4 wiring question, desperate for help
« Reply #5 on: July 16, 2014, 10:28:13 AM »
And if this will help ya..

Offline nightpoison

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Re: CB750 K4 wiring question, desperate for help
« Reply #6 on: July 16, 2014, 12:14:26 PM »
Vinhead, thanks ive actually been going off of the clymer wiring diagram. The one you posted looks good, might work better. Im going to try to print it off

DH, the color chart is cool. Actually might help me a bit morw to understand whats going on, thanks

Offline bjbuchanan

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Re: CB750 K4 wiring question, desperate for help
« Reply #7 on: July 16, 2014, 04:48:10 PM »
I like to use oldmanhonda.com because you can switch circuits on and off using the interactive wiring diagram.

Easiest way to wire these is to understand completely how the stock systems work. This is stock Honda

Turn signal circuit   Receives black switched power from harness to TS Relay. Grey wire out that follows harness up to Handlebar switch. Out of Handlebar switch is orange and blue. You gotta sub out your TS input off of stock grey harness wire and use your TS outputs

Killswitch  Black switched power from harness to Handlebar switch. Black/white out to your coils. I would keep the solid in, stripe out convention on your bike to simplify it

Start Switch.  Yellow red from solenoid thru harness to handlebar switch. Green/red out thru to main harness to solenoid.

***Green/red is part of a combined clutch/neutral safety switch on our bikes. If your clutch isn't pulled in or the bike isn't in neutral then a stock setup doesn't complete the GROUND circuit that allows the start solenoid to work. The dark green/red and light green/red splice together buried in the main harness.

If you deleted the stock clutch perch then you gotta do something with the circuit. I personally separate them, deleting the splice out and running the stock circuits. This removes clutch safety switch but I think it is redundant, it is manufacturers/DOT dumbing the bikes down in my opinion

Headlight is confusing and depends on the switches you have stock and your new switches. The main thing is whether or not you have a headlight always on bike or not. Since you are running kinda custom I think the easiest thing is to keep it simple.

Stock Headlight--simplified by me--Brown/red from fusebox in to your new Headlight switch power wire. Run your low beam out to the white HL wire and high beam output to Blue HL wire. I believe your passing function may be your high beam unless indicated otherwise on the switch or something.

This simplified circuit can function just fine for all of the bikes and use the stock HL fuse too.

If you wish to run your running lights at all times the bike is powered just connect them to black switched power.

Horn  Black switched in to switch power and light green solid out of stock switch.
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers