Topic: 1976 CB750K_Now I Need to Sort Things Out Behind the Headlight

[CB_Jeff]

Now that I have my starter button woes resolved, some new problems have popped up in it's place.
So now I have what should be a new K6 wiring harness hooked-up to a new set of right hand controls.
The starter button works, but now the headlight, the left turn signals and marker lights and possibly the ignition switch do not work.  I followed the reasonable line of thought hooking:
 - Black with red stripe to black with red stripe,
 - Yellow with red stripe to yellow with red stripe, and
 - Green with red stripe to green with red stripe.... and then there are the two black wires.
The controls that were previously on the right were an earlier set with the headlight on / off slide switch.
I think that I need to buy Hondaman's book.
The one step forward and two steps back with this project is getting discouraging, although I expect it is helping with my technical troubleshooting skills.

[goldarrow]

tripple check the connection in headlight bucket?

[CB_Jeff]

I'll give the bucket connections a double check in the morning.  I should offer that the bike also has  new harness...everything else is working.

[78whiteorbs]

Same thing was happening to me.turned out a wire was being pinchedin the harness and grounding out. Wiggle your harness one section at a time while holding the start button. Frustrating but comes withe the territory. Gluck

[Xnavylfr]

Sometimes the contacts inside the start button gets corroded and won't make good contact when you push it. You can pull the button apart and clean everything with a brush  and some baking soda.


Xnavylfr(CHUCK)

[Bootlegger56]

Or maybe a leaky master cylinder in the past contaminated the internals of the right hand switch housing.  I had that issue with my K5 when I first got it back on the road.  When I disassembled the right hand control it was full of an oily mess that smelled of brake fluid.  I had to rebuild it.  A pain but a good education.

[CB_Jeff]

Wouldn't a good continuity test of the starter switch rule it out?  The switch continuity tests in the headlight bucket and the starter relay both showed good continuity when the starter button was pushed (i.e. my multi meter made a buzzing noise when the starter button was pressed).
Another question that I have related to the new used right controls that I have, I noted that there is an aluminum pin that keys into the stock handle bars.  I have new bars and was considering grinding that out, any reason to keep and drill the new bars?
Also, no signs of brake fluid in the controls.

[MoMo]

Does your bike have the clutch lock out switch to prevent the bike from being started unless the clutch is pulled?....Larry

[ekpent]

Does your bike have the clutch lock out switch to prevent the bike from being started unless the clutch is pulled?....Larry

Good point as my regular rider K4 has to have the clutch pulled in for the starter to work.

[CB_Jeff]

I tried pulling in the clutch lever and pushing the start button....nothing....
I will check for a switch, I vaguely recall seeing something looking like a switch on the bottom front of the clutch housing.
I did try jumping the starter relay it works....meaning the starter powers up and tries to start the bike.  I also changed the starter relay out with one that I know works...so I am pretty  sure it isn't the relay.

[phil71]

Your continuity test isn't telling you anything about wether or not that switch is working. Ground the Yellow/red. if the starter spins, your switch isn't making contact to ground.

[CB_Jeff]

I grounded the yellow / red wire and the starter did not spin.
With that and the continuity test I am satisfied that the problem is not the switch.
I am back home today and plan to look into the possibility of a clutch switch being the culprit.
More on this later.....

[MoMo]

You can check the solenoid by putting 12v to the two wires(probably y/r and b) coming out of the solenoid.  You click and start up...Larry

[CB_Jeff]

Well, I figured it out, the issue was that I was unknowingly trying to run a non-k6 set of controls on a k6 harness (the controls that I was running were the kind with the headlight  on /off switch).  Anyhow, I installed a new set of k6 controls (sans headlight on/ off switch) and now the starter button works. 
Quick question for those out there in the know, what is the correct connection on the two black wires from the right hand controls.

[MoMo]

black to black/white and black to red/black should work...Larry

[CB_Jeff]

Huh, I wouldn't have thought that.... I went with:
 - black with red stipe to black with red stripe,
 - green with red stripe to green with red stripe,
 - yellow with red stripe to yellow with yellow with red stripe, and then there are the two black wires.
Anyhow, before everything worked except the starter button, and now I have the starter button working, but have lost the headlight, lost the left turn signals and cannot be sure about the ignition (red on-off switch).
A marginally discouraging repair / upgrade.

[CB_Jeff]

Updated my post... my woes have changed a bit.  Might be time to get out there with the multi meter and sort out the jumble that is the headlight bucket.

[phil71]

leave the multimeter in the toolbox and use a good old fashioned test light. It'll save you time

[bjbuchanan]

Black/red is hot power out of the RH switch for the headlight. Yellow/red is starter in RH switch. Black should go in to the RH switch

The black in the RH switch is where the juice comes from, two of those wires. One for coil power via the killswitch and the other that powers the combo start and HL switch. When the button is idle power flows through from black in to your black/red out for HL power. When button is pressed it cuts HL power and directs that black power thru to the yellow/red giving juice to that starter relay.

Green/red is clutch safety switch, it actually round about grounds the starter solenoid using the neutral switch and clutch safety switch in combination on the k6.

For the left TS make sure your grounds haven't been disturbed, the ground via the HL bucket bolts. Make sure the bullet connectors fit snugly. Light blue and orange are your turn signal wires

oldmanhonda.com  Use the interactive diagram for a 750. It will work enough to get you moving after the color coding for the switch I gave you

[CB_Jeff]

Thanks! I will give that a try.

[cgarbe]

CBCafe_Jeff, what were your starter issues? I'm having starter issues with my 1978 Honda cb750f right now!

[Don R]

Te best thing I did was copy the old man honda color diagram and paste it to a piece of cardboard. Then hang it or prop it where you can look at it while working. It can be confusing at first but follow your colors to the components and after a while you too will be an expert. Remember the colors. black is 12V feed, green is always ground. The stripes all have a purpose too. There will ba an extra wire or two. Usually a green and a brown/white maybe a black. The European bikes have a park light in the headlight reflector, the wires for that will be there and unused.

[Don R]

And, the earlier switches can be used but it takes some wiring changes. They won't work uless you duplicate the early wiring circuits.

[CB_Jeff]

The problem that I was originally was having was that everything worked except the starter button....and when jumped the starter worked fine.  The issue turned out to be a set of pre-K6 controls on a K6 / K6 wiring harness....I know that now, but it took me getting through multiple sets of right controls to figure it out.
The task currently at hand is getting the wiring back to the stock k6 configuration which was partially modified to work with pre-K6 controls....with the notable exception of the starter button.

[Don R]

You are on the right track, good luck!

[CB_Jeff]

Quick update, the ignition switch on the right controls is now working... which is a good development, now I just need to get the headlight and right turn signals back online.... both of which should have nothing to do with the right controls.