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Author Topic: Custom wiring? half of this looks correct(original), the other half looks insane  (Read 1953 times)

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Offline [Blank]

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Custom wiring? half of this looks correct(original), the other half looks insane
« on: November 20, 2014, 10:58:23 PM »
Hi all,

Once again, I got a partially modded cb 750 k2. The brake light turns on but doesn't respond upon use of brake pedals etc. The headlamp was small halogen bulb that I have removed and find it only has a spiral black and green threaded wire housing with two wires in side. I have a headlight signal switch for handlebars and some turn signals with unfinished ends that ideally I will eventually connect. But for now I only need the headlamp and hopefully turn signals working. For now I would settle for a headlamp because I can still ride Legally. I have read and looked into past wiring scenarios and nightmares but honestly I don't know the terminology but am incredibly motivated to learn. Can someone confirm what is "custom wiring" and what is bull5hit and hopefully give me a simple answer as to how I can attach my headlamp at bare minimum? Here are some photos. New Headlamp wiring included.

I'll start from the new headlamp and work backwards to battery to best display this chain of wiring evidence. Fyi the two red wires going to positive terminal has a 25 fuse that I'm holding. The other fuse in the photos is another 25 as well. Anyone know what that red and black threaded housing is for? Prolly goes to brake light. Ugh. I'll save that for another day that I can try to figure out solo.

Thanks for any suggestions.
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Offline MoMo

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #1 on: November 21, 2014, 01:25:30 AM »
nothing original there,   looks like Harry the Butchers work.  All HOnda wiring is color coded the same, download the manual from this site and go through your harness( new harness is 72$ btw)...Larry
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Offline seanbarney41

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #2 on: November 21, 2014, 03:18:30 AM »
Yep, that is neither custom or correct.  That is a mess.  My advice to you is, especially if you don't completely understand 1970's motorcycle electrics, buy a new or used good condition harness and start again.  You are gonna need the correct wiring diagram and the ability to use it...oem manuals are available here for download.  Someone will hopefully post up a color schematic here for ya.  They are a lot easier to read.
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Offline dave500

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #3 on: November 21, 2014, 03:26:38 AM »
that's why I ever so rarely post in electrical threads,i gots to see it in my own hands!
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Offline ekpent

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #4 on: November 21, 2014, 05:27:12 AM »
The color codes on the head light are correct but the bullet connectors are gone. Looks like the stock ground strap has been replaced coming off your battery and as others have mentioned ,without looking don't know where all the other wad is going.
« Last Edit: November 21, 2014, 06:07:37 AM by ekpent »
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Offline PeWe

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #5 on: November 21, 2014, 05:36:20 AM »
Maybe the brake light is ON constantly due to the brake pedal switch is not correctly adjusted?
Brake light get power from the general 12V power 15A fuse (black wire in original harness) NOT same as rear light that is powered by brown cable, 5A fuse.

Short circuit in brake light or the wires to it will stop the bike and make it completely black and dead! I learned that 1 month ago due to new brake pedal switch bullet plug insulation that was crap. It should never happened if I had used the old dirty switch from 1976.
« Last Edit: November 21, 2014, 12:26:21 PM by PeWe »
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline madmtnmotors

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #6 on: November 21, 2014, 05:41:28 AM »
Quote from: [Blank] on November 20, 2014, 10:58:23 PM
Once again, I got a partially EXTENSIVELY modded cb 750 k2.

FTFY  ;)

That wiring harness has been hacked pretty badly. You need to download the wiring diagram and either sort that harness out or replace it. The use of the cheapo crimp connectors is worthy of a slap to the head...
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Offline [Blank]

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #7 on: November 21, 2014, 11:53:06 AM »
LOL. Thanks everyone. I did some rewiring on my newer triumph T100 so when I opened this up, I just knew something had to be disastrously incorrect. I have the diagrams, I'll search for a new harness. Are these easy to come by? Will a replacment harness be enough? Retracing and reattching the new harness is something I can do. It's just the "electrical" knowledge that I'm not always positive on. So if I understand, there is absolutely NOTHING original here, so my only other question is, will I have room to attach or "hide" the old wiring harness once attained?
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Offline calj737

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #8 on: November 21, 2014, 12:20:32 PM »
New harness connections are pretty straightforward. Refer to the parts fiche for routing. Some of the new harnesses have a few idiosyncrasies in them, but there's ample resources here for overcoming that.
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Offline PeWe

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #9 on: November 21, 2014, 12:35:17 PM »
Triumph harness should be possible to find new nowadays when a lot of people restore the old forgotten bikes.
Googled Triumph T100 harness and found direct.. like this one
http://www.classicmotorcyclespares.com/index.php/default/triumph-t100-t120-bonneville-tr6-wiring-harness-54957095.html#Default_Category

CB750 harnesses are sold everywhere, soon in the local drugstore! ;D Just be sure to order for correct model

I was thinking about replacing my harness on my CB750 K6 1976 during the last restore last year, but I remembered that I replaced it to season 1984, t should be good then :) I still have the receipts left from that restore 1983.
And it was OK. The first engine take outs were not that nice to the original harness. Still Honda spare harness in.
The cables from handle bar switches however very not good, new complete switches and pilot lamp harness did it.
« Last Edit: November 21, 2014, 12:37:51 PM by PeWe »
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline MoMo

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #10 on: November 21, 2014, 02:32:52 PM »
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Offline [Blank]

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #11 on: November 21, 2014, 09:09:45 PM »
Dude! Mono! Thanks! I hope I get this in before thanksgiving. It'll give me a reason to avoid the mother in law :)

:puts mono on Xmas list:
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Offline MoMo

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #12 on: November 22, 2014, 11:14:45 AM »
Quote from: [Blank] on November 21, 2014, 09:09:45 PM
Dude! Mono! Thanks! I hope I get this in before thanksgiving. It'll give me a reason to avoid the mother in law :)

:puts mono on Xmas list:



no problem,  I helped a fellow forum member install the same harness, which is very well made.  BTW,  lots of cash is on my wish list
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Offline [Blank]

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #13 on: November 22, 2014, 03:08:37 PM »
LOL. And women?
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Offline MoMo

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #14 on: November 22, 2014, 03:26:54 PM »
Quote from: [Blank] on November 22, 2014, 03:08:37 PM
LOL. And women?

probably too old to do anything about the latter :( ::)
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Offline [Blank]

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Re: Custom wiring? half of this looks correct(original), the other half looks insane
« Reply #15 on: November 22, 2014, 03:33:36 PM »
Bahahaha. Ok. Bags of money it is.
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