Topic: 76 750 K wiring issues

[KCs76Cafe]

Does anybody have a 76 750 K owners manual that they could scan the wiring diagram for me?

Im trying to figure out the mess that the PO has done to the wiring and I dont have many hairs left    I havent been able to find a 76 manual yet....and the few diagrams on the net are not for the 76 model. Im trying to make sure that all the wires are connected color to color....but Ive found some extra wires that dont have any matching wires to hook to them.....a single Black/Red and a single Brown.

I took the turn signal buzzer off to make some extra room........will the signals still work with it being in the system?

Also.....since putting the Clubmans on, theres is alot of extra length coming from the left hand contols.....horn,low/high beam,etc. Is there enough room in the headlite bucket for the extra or would it be best to cut off the extra and put new connectors on the ends?

One more.......I still cant get the starter button to work. The starter does work though, I can start the bike by jumping the contacts on the solenoid and the starter will spin the motor. I checked and cleaned the contacts for the starter button, traced the wires, and even installed a new starter solenoid and the button still wont actuate the starter

And a pic to show my recent progress....

[TwoTired]

Looking at the K6 diagram here from chapter 23 of the Honda manual.
Bk/R wire receives power from the Bk wire at the starter switch.  This is routed to the headlight fuse where it is labeled Br/R.  It looks like there is a connector and then a splice connection in between.

There is an unconnectd Br wire in the diagram.

Cheers,

[jsaab2748]

One more.......I still cant get the starter button to work. The starter does work though, I can start the bike by jumping the contacts on the solenoid and the starter will spin the motor. I checked and cleaned the contacts for the starter button, traced the wires, and even installed a new starter solenoid and the button still wont actuate the starter

Just to add, is your bike still equipped with the clutch safety switch (keeps starter from operating when bike is in gear and the clutch not pulled in) and starter safety unit? You'll see these included in a k6
wiring diagram, and a malfuction can occur if this part of the start sustem is eliminated or not properly wired.
Not for sure, but if the clutch switch has been left out/disconnected, it may also explain why you have leftovers in the headlaight housing. I THINK a k5 is wired the same way if you can't find a k6 diagram.
Hope this helps

[KCs76Cafe]

Thanks for that info TT

jsaab......I also checked the clutch switch and it was wired up right........going by my buddys 74 K diagram.  I've made sure its in neutral and have even pulled the clutch in but still no luck.  Thats why I'd like to see a 76 K diagram to check it against the wiring on my bike....to see what the PO has hacked up.The closest diagram I have found is this one.....    http://sohc4.us/files/CB750WiringDiag.pdf  but it doesnt show the starter safety unit.....so I dont know what model it covers. I know(dont think so anyway) it doesnt show the black/red wire.

 

[750duo]

This is from Honda shop manual supplement to CB750-K6

The K6 starter button is wired to turn off the headlight while you engage the starter

I have had problems with this on my K6 - due to crude fixes by the PO

Keep in mind that the bike must be in neutral or the clutch pulled in to allow the starter magnetic switch to engage the starter.

Good Luck

Tom

[jsaab2748]

KC, Sorry, I may have given you mis-info. Didn't know a k6 had the headlite off while cranking...different than k4-5..

[750duo]

This simplified diagram of the starter circuit might help understand how the circuit is supposed to work. I had to trace it out to fix my starter button problems.

good luck

Tom

[KCs76Cafe]

Thanks Tom..........that explains alot......although I cant zoom in on the diagram to see the colors on the wires. The starter circuit will get me going for now.

No worries jsaab....I didnt know that either. 

[750duo]

Thanks Tom..........that explains alot......although I cant zoom in on the diagram to see the colors on the wires. The starter circuit will get me going for now.

KC  I tried printing both diagrams from the forum - big diagram is a little fuzzy but can be read with a magnifying glass. I'm not sure how I can improve the quality unless I fax it to you.

Wiring Colors:

Black - power from ignition switch to the starter switch
Black/Red - From starter switch to headlight fuse
Yellow/Red - from starter switch to starter solenoid
Green/Red - from starter switch to clutch switch and diode
Light Green/Red - from diode to neutral switch
Green - both switches to earth (ground - bike frame)

Hope this helps
Tom

[my78k]

Can't guarantee the accuracy of these but there's a sight that lists a bunch of diagrams:
http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class

they are hand drawn so lord only knows if they are accurate...

[KCs76Cafe]

Tom......sent you a PM.

my78k.......I've tried that site before but couldnt make heads or tails out of those diagrams. Thanks anyway. 

[750duo]

Can't guarantee the accuracy of these but there's a sight that lists a bunch of diagrams:
http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class

they are hand drawn so lord only knows if they are accurate...

Have not examined the entire diagram for the CB750 k6 (covered in a diagram labeled K3 - k7), but it is not accurate regarding the starter switch circuit. Starting with the CB750f and the CB750k6, the bikes did not have separate headlight switches. The headlight was turned on(&off) with the ignition switch and momentarily off during cranking with the starter button.

[KCs76Cafe]

Thanks for emailing me the diagram Tom.....but it was still too fuzzy to make out. Hopefully the owners manual I just won on ebay will have the diagram still in it, although the seller said it wasnt, but he also said that he didnt think Honda made a "K" model in '76.   

[amattel]

I think I finally got a good enough pic for you to read the wiring color codes...

Adam

http://members.toast.net/rdaniels/cb750k6wire.jpg

[KCs76Cafe]

Oh Yeah!  Thank you very much..........youre a lifesaver.     

[KCs76Cafe]

Ok........I've figured out what the problem is. The wires coming from the control are not circa "76. Going by the diagram Adam posted, the colors dont match. I was wondering about the "K3" that was stamped in the handlebars underneath the right hand control 

I guess at some point a previous owner swapped bars,contols, and everything related over to this '76 frame. Where the 76 diagram shows a yellow/red and a black/red coming from the starter button.....I have a yellow/red and green/red.

Now that I've got something to go by, I'll have it wired up and ready to ride. Got the tank, seat, and side covers back from being painted today. Hurried home so I could get them on and get a pic before daylight ran out. Will post them later.....it looks sweet. 

[andy750]

If you get really desperate I have an intact all-original K6 wiring hanress that you could buy off me. Used but very good condition.
Good luck,
Andy