Topic: need wiring harness help '78 K

[medic09]

My bike is a '78 K model.  Some of the wiring is fried, so a while back I picked up cheap a harness from an F model.  Turns out they're not quite identical.  I am an electical imbecile (mechanically I'm just an idiot).

So far I've noticed that one connector up at the headlamp (for the light/horn/signals assembly) differs.  I think the wiring that comes out by the coils may be different.  The F even looks like it might be a little different length.  Haven't really noticed anything else yet.

Do I try to make this work?  Doesn't seem a good choice to me.
Do I go for an Ebay/other used item?  They turn up from time to time, but quality is unknown.  The F harness I got from a forum member, and true to his word it was in pretty good shape.  It gets iffy on Ebay and other places.
Do I buy new?  WHERE?  I've called a few places, and they've all said not available.

[dusterdude]

eldar,oh great 78k guru,your help is needed.

[medic09]

eldar,oh great 78k guru,your help is needed.

Thanks, duster.

Do we have to invoke his name, chanting in unison; or does he just appear?   

[kettlesd]

How do the connectors differ? Pics?? What year is the F harness you bought?

I have a 78K and and an F too, but i did the harness on the F from scratch, so unable to just go out and have a peek and help u there.

[mazingerzeca]

Hello. I own a cb 750 K8 too. The wireharnes was in a bad shape, burned wires and so on. I looked everywhere for a new wireharness, but I didn't find one, so I bought a second hand wireharness on e-bay. It seemed to be ok, and it worked, but when I retired the plastic that involved it, I found that the wires were burned and repared in almost exactly every place that my old wireharness was. As a conclusion, any used wireharness will have the same age pains, so I decided not to buy a third one. I could not make a perfect wireharness using two, but maybe if I buy 20 I could make a semi-perfect wireharness. Anyway, if you decide to buy more of them, buy a k8 wireharness, because there are some differences from one model to another.
I decided to rebuild my wireharness, but it was impossible to buy in a spanish shop all the wires with the same colour, in order to maintain the Honda colour codes, neither the same type of connectors.
I found in this forum the following addresses. There you can buy the wires and connectors and enjoy the winter afternoons rebuinding wire by wire the complete wireharness. These are my christmas plans.
ttp://www.cyclewareables.com/pages/electrical_connectors_terminals/electrical_terminals_and_connectors.htm
http://www.casporttouring.com/store/merchant.mvc?Screen=PROD&Product_Code=17125&Category_Code=ECONN
http://www.vintageconnections.com/
www.vehicleproducts.co.uk

I can send you the wiring diagram, if you want to. It was too large to post it here. Patience and good luck!

[medic09]

How do the connectors differ? Pics?? What year is the F harness you bought?

I have a 78K and and an F too, but i did the harness on the F from scratch, so unable to just go out and have a peek and help u there.

Pics aren't loading up, for some reason.

Okay, here's the first difference I find:

The F harness has a black connector for the wiring going to the Left handlebar assembly (signals, etc.?)  The black connector has 4 slots for hooking up to.  The wires going in are Brown/Orange, Grey, Lt. Blue, and Orange.  Coming out seperately from the connector with female hookups are Orange, and Lt. Blue wires.

The K harness on the bike now has a white connector with 6 slots, 5 of which are actually used.  Wires going in are Brown/Orange, Grey, Lt. Blue, Lt. Green, and Orange.  Coming out seperately from the connector with female hookups are Orange, and Lt. Blue wires.



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[dusterdude]

eldar,oh great 78k guru,your help is needed.

Thanks, duster.

Do we have to invoke his name, chanting in unison; or does he just appear?   

you have to go into the desert and bring back cactus fur,you then start a campfire and burn the cactus fur while chanting eldar, oh eldar, great god of the k8,i implore you to come forth.

[medic09]

eldar,oh great 78k guru,your help is needed.

Thanks, duster.

Do we have to invoke his name, chanting in unison; or does he just appear?   

you have to go into the desert and bring back cactus fur,you then start a campfire and burn the cactus fur while chanting eldar, oh eldar, great god of the k8,i implore you to come forth.

I was okay until the 'great god' part.  I live in high desert in NM, so the rest sounds pretty normal.

[jdpas29]

i had the same problem on my 78K.  i suggest putting the old harness back on like it was and replacing the burned wires with new ones or patching where necessary with good, waterproof connectors. 

that's what i did and my bike runs like a scalded dog.

[medic09]

i had the same problem on my 78K.  i suggest putting the old harness back on like it was and replacing the burned wires with new ones or patching where necessary with good, waterproof connectors. 

that's what i did and my bike runs like a scalded dog.

Yeah, the wife and I were just talking about that.  Transplant surgery may be the route to go.  I'm a complete novice at all of this.  Thought I was going to spend the winter learning to do mechanical things my bike's been waiting for. I find the electrical stuff more daunting.  Wiring diagrams make *no* sense to me.  That's why I'm looking for help.  Guess I'll have to learn this now, rather than later.

Did you repair your harness while on the bike?  Seems like it would be easier to manipulte off of it...

[medic09]

Am I correct in understanding that the '77 K and the  '78 K use the same harness?

[jdpas29]

i did all the work with the harness still on the bike.  there is just enough slack in the existing wires if you loosen them from around the headlight and the coil area to do whatever patching you need to  do with ease.  it IS a daunting task, but i found that if you do 4 or 5 wires and then drink a beer it becomes kind of like a drinking game.  anywho...  yes i think the 77 wiring is very close to the 78.  maybe not exact, but probably closer than any other year's harness.  i still say your best bet is patching the one you have.

good luck and holla if you need help. 

[medic09]

good luck and holla if you need help. 

I may end up doing a lot of hollering, and yelling, and cussing...

 

[SD750F]

Medic09,

To help here are some answers, maybe...

You wrote:
The F harness has a black connector for the wiring going to the Left handlebar assembly (signals, etc.?)  The black connector has 4 slots for hooking up to.  The wires going in are Brown/Orange, Grey, Lt. Blue, and Orange.  Coming out separately from the connector with female hookups are Orange, and Lt. Blue wires.

On the F series here are the colors and function:

Brown/Red (Br/R easy mistake with aged wires) = Head Light 2 Circuit. This is the headlight power from the starter switch through the 7A Headlight fuse. Yes the starter switch. The ignition switch will turn on a Black (Bk) wire and this goes to the starter switch and when it is not depressed for engine start, it supplies the headlight. Note when your depress the starter, your headlight will be off.

Grey (Gr) = Winker Supply. This is the winker supply that provides the flashing 12V supply to your turn signals.

Orange (O) = Left Front & Rear Turn Signal supply. Note this is supplied through the winker relay and the turn signal hand switch.

Light Blue (LB) = Right Front & Rear Turn Signal supply. Note this is supplied through the winker relay and the turn signal hand switch.

And the second Orange could be Orange/White (O/W) = Left Front Position Light?

Light Blue/White (LB/W) = Left Front Position Light.

You also wrote:
The K harness on the bike now has a white connector with 6 slots, 5 of which are actually used.  Wires going in are Brown/Orange, Grey, Lt. Blue, Lt. Green, and Orange.  Coming out separately from the connector with female hookups are Orange, and Lt. Blue wires.

The wire should be the same as above... Honda tended to use the same colors for the same function basically from K2 on... The Sandcast (K0-K1) I think with my basic review of the wiring harness will be different.

Scott

[Andrew Foss]

if you take apart the old harness and look at it, you can get an idea of how simple it really is. if you are willing to eliminate certain things (such as the headlight going out with the starter) you can build a new harness fairly easily. i built a harness for my f witch eliminated lots of stuff, but works great (no cluster lights, idiot lights, blinkers, horn) i also eliminated the key (it has one toggle for ignition/brake light, and another for headlight). with this harness i lost all of the bull that i was going through with the fried peice of crap that was on there. take a look at some "chopper" harness diagrams online and you will get an alright idea of how to make one. i bought turnsignals, a horn and a left control from mikesxs.com (made for a yamaha) because my old controls are fried. if you take your time and plan it out, it is very simple to build a harness that will run consistently. i was super afraid of electrics too. still have to replace my stator but thats another topic for another day....
-andrew

[medic09]

Well, it's looking like I'm going to have to learn a little motorcycle neurosurgical transplant technique the old-fashioned way.     I hope it's less traumatic for the patient than some other things I've done in the past.   

[seaweb11]

http://www.world-playground.com/Bike/CB750wire.JPG   

[medic09]

http://www.world-playground.com/Bike/CB750wire.JPG   

Thanks, Seaweb.  Nice link.  Scott Christenson also sent me a good diagram.  I'll just have to be patient and learn to make sense of them.

So, as far as I gather, I'm better off trying to rehabilitate the harness that's in there (I *did* commute 600+ miles/week on it until the weather stopped me), than reworking the F harness that I have.

Well, this means the cardiovascular/respiratory rehab surgery I planned (cleaning and rebuilding the carbs) will be put off a while.

[medic09]

Okay, gonna head out in a bit to get the few items I  need to work on this during the week.

A few stupid questions (but still less stupid than not asking!):

Will any normal crimping tool do?

What gauge wire do I need?  What sort of bullet connectors?

Since I'm going to attempt repairing what I've got, I shouldn't need alot of anything; so I figure on looking in Home Depot or Auto Zone for what I need.  The only motorcycle shop where I might get some help/parts is closed for a few days.  I'd like to work on this a bit tonight, since I'll be working Monday/Tuesday.  Oh, and I have to go move the Triumph project in out of the snow...

Thanks all!

[SD750F]

Medic09,

I think the best way for you to tackle your wiring issue is to break it down one major function at a time. Again if you please, let me know where the problem is, or what you would like to work on first. I think that you would like the ignition/starter working first then we can branch out from there...? If this is done this way, I think it will help you out of the quadmire of the huge bundle of wires you are looking at. And if we attach and check one major circuit at a time, you will have all the remaining connectors available for the circuits not yet wired.

So let me know what you would like to do first, and I will provide hopefully a step by step re-wire and check that makes sense.

Crimping tools, well I always use the one designated for my connector/pin... And of course it needs to be able to crimp properly while considering the gauge of the wire or a over crimp and wire conductor damage. So in my shop I have around 20 different crimps! But the type you should have for your connectors is a typical "fold back" not compression crimper with two locations with different wire gauge ranges.

And as far as the correct wire gauge to use, if you provide the list above I can make sure you have the right gauge for your project and the end use.

Hey! By the way... Happy Christmas Eve!

Scott

[seaweb11]

Take the harness to the store with you.

[medic09]

Seaweb, thanks for hanging in there with me.    Gotta get those shocks of yours back on the road come spring.

Scott,  you're more than generous, and I will gratefully take you up on your help.  I'm working the next two days, so all I may do in the evenings is repair/replace some sloppy splices from the PO, and clean contacts, etc.  I started a little tonight.  Wednesday I'll be recovering from work, and putting a few hours in on the bike (provided the pager doesn't go off!).

We can do this two ways.  Off the forum, so as not to bore everyone with my newbie electrical training  ; or we can purposely keep this thread alive in case any other total novices can learn something from it.  Let me know what you think.  I'll look for you later.

If you all are riding, please be extra careful.  We see alot of DWI injuries and deaths this time of year.  Watch out for the idiots around you...

[750goes]

keep the thread alive, as any electrical problem will get responses from a few members of the forum...I'm not electrically inclined either but have managed to have a working harness after a bit of fiddling - not perfect and original but all connectiions work and with other members helping made it a lot easier - Jonesy & Two Tired but to name a few........

[medic09]

Bump,

Keeping this alive.  Maybe get to work with Scott and co. tomorrow or Thursday (still at work).  Meanwhile, had some time last night at work to read a brief intro to wiring diagrams in Mark Zimmerman's book.  It's actually just a little less mysterious now.  If I can get admin stuff out of the way, and we're not too busy with post-holiday idiots, I may look at the actual diagrams a bit today or tonight.  Usually lots of stupid folks in the mountains with their new toys getting hurt and lost, so we'll see...

Scott, I've basically disconnected everything in the headlight bucket, cleaned contacts, replaced a few bad splices, and reconnected the multi-connectors.  Next we'll get down to circuit assessment...  Oh, I reconnected the turn signals, but I crossed them, so I'll have to go back to that. 

[750goes]

there is also a neat wiring interactive at the following link..

http://oldmanhonda.com/MC/wiring750K1.html

it helps in understanding the basics -

I actually isolated each circuit- then printed it out - then when working on one circuit at a time found it easier to understand where things went and what they connected to...