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Discussion Starter · #1 ·
Hi all,

Apologies in advance if you're all bored of seeing "Ultima Harness" by now, I did a search of the forum and couldn't really find the answers I was looking for :(

I am nearing the end of my CX500 build, and it will soon be time to wire her up again.

However, my original loom is completely shot, the bike did start and run fine, but upon stripping her down there were cables shorting out, bad terminations, and what looks like 647674 failed attempts at splicing into the stock loom, it's a complete birds nest of cables.

So I am planning on purchasing an Ultima wiring harness, and running fresh cabling to all of the new equipment on board. All of the parts going back on are brand new and I'm also running LED's now, and apparently the Ultima unit works really well with them.

My question is, would I need to keep the CDI unit, the Regulator/Rectifier and the fuse unit on the handlebar area?

Or would the ultima harness just get run to the relevant locations and then the bike should fire up?


If I do need to keep all of the stock units, has anyone done it? can they send/explain how the wiring should work?

Sorry, complete n00b with motorcycle wiring.


Thanks in advance! :)
 

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Discussion Starter · #3 ·
I thought that might be the case, the ultima wiring diagram on their website doesn't account for them, so how would they fit into the ultima wiring?

I will be relocating everything under the seat in a custom tray :)
 

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Discussion Starter · #6 ·
I've seen one guy has used it, but he said he used it for starting and accessories and then the engine management was all done via the stock cdi and regulator etc...

But that gave me the impression you could use it to handle everything, and that he'd only used it to do half. Hence why I'm confused haha!

I'm hoping someone has integrated this with the stock cdi and regulator that can just send me a wiring diagram or explain how you wire them into the ultima harness :)
 

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No idea what the "ultima harness" is? made for CX's or for an "ultima as in the car" ?? Basically, unless you get a wiring harness thats a "CX" wiring harness its not going to be a drop in. If the plan is to use a wiring harness from something else to fit the bike, your best option is to make a "wiring harness loom" (board with paths and nails to get every wire to and from the right place at the the right length). If you go this route, use the old existing harness to make the loom, then use new wire to make a new harness. Its a LOT of work, Other option is see if you can get a harness on Ebay or from a junkyard.
 

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Discussion Starter · #11 ·
The ultima harness is almost a universal harness that can be used on custom builds, I believe they are mainly used on custom harley's, but there shouldn't be any reason that I can't combine it with the stock units on the CX500 to make it run? It comes packaged with the correct lengths and gauges of wire to be used for each component, it's all colour coded too for easy installation, so it's essentially a "pre made" loom, you just wire it to each component.

However I'm not sure if I need to keep the CDI, regulator etc. And if I do, I don't know how to combine them with the ultima, like where they would sit in the wiring diagram :(

Motosythensis appears to have used one effectively!
 

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It would be far far easier to grab a 2nd hand harness from eBay.

The CDI unit and R/R would still need to be used. By the sounds of it, the harness is literally just the wires.

You would need to be putting connectors onto all the wires - going through this: http://cx500forum.com/forum/attachm...c-cdi-p2-install-schaltplan_1978_cx500_am.jpg

2nd hand harness ftw - even if you end up having to fix/tidy it up a bit - its going to be worlds apart from using a universal solution.
 

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I have seen lots of people trying to minimise the wiring on a CX but unless you start by not fitting lights or gauges the cx has basically the minimum amount of wiring to function correctly, there is little to lose from the standard harness.
 

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The ultima harness is almost a universal harness that can be used on custom builds, I believe they are mainly used on custom harley's, but there shouldn't be any reason that I can't combine it with the stock units on the CX500 to make it run? It comes packaged with the correct lengths and gauges of wire to be used for each component, it's all colour coded too for easy installation, so it's essentially a "pre made" loom, you just wire it to each component.

However I'm not sure if I need to keep the CDI, regulator etc. And if I do, I don't know how to combine them with the ultima, like where they would sit in the wiring diagram :(

Motosythensis appears to have used one effectively!
OK, now it makes sense. The main problems I see is that the harness is made for custom builds (I guess like OCC does, Harley clones etc) which means the wire count and lengths will be completely different from a CX harness. Also, I wont have a lot of what you need which makes things harder (yes, CDI, RR etc ARE required as is other bits air cooled engines dont have). You MAY be able to use the harness as a "starting point, but its only feasable IF the harness is cheaper than buying loose wiring. Here are the options as I see it;

1- Easiest option is get another CX harness, because if you get the right one for the year and model, its basically then just a plug and play.
2- Make a harness using the old one as a guide. This can be a bit time consuming in making a loom board, but will result in the wiring being ALL NEW, the right count and length. The color code will probably be far different as finding "Honda colored wire" would be very hard.
3- Try to adapt the "ultima" harness, which WILL involve adding MORE wiring to the harness, and also in trying to modify the existing harness wires to the right length.

If it were me I would make the choices based on their listed order. Regardless of any claims, Wiring IS a PAIN IN THE ASS, especially if you have never done it before (made looms for years and HATED IT)
 

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@delabourke I am probably going to be using the Ultima wiring harness in my build, as I have read good things about it as well. I am a good year from that point on my build, so I won't be of help much now, but I will be in a year. :) I usually build my wiring harnesses for all of my bikes, but a friend who builds has also used their harnesses in his builds, so I figured I'd give it a go this round. If I get more time to look ahead to that phase of the bike, I'll let ya know.
 

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Discussion Starter · #17 ·
I have come to loathe the word "universal"
Haha yeah it does make it sound like plug and play, I meant it in a sense of, the unit and wiring is all done and you adapt it as necessary to suit the application. But yes I see your point haha!
 

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Discussion Starter · #18 ·
OK, now it makes sense. The main problems I see is that the harness is made for custom builds (I guess like OCC does, Harley clones etc) which means the wire count and lengths will be completely different from a CX harness. Also, I wont have a lot of what you need which makes things harder (yes, CDI, RR etc ARE required as is other bits air cooled engines dont have). You MAY be able to use the harness as a "starting point, but its only feasable IF the harness is cheaper than buying loose wiring. Here are the options as I see it;

1- Easiest option is get another CX harness, because if you get the right one for the year and model, its basically then just a plug and play.
2- Make a harness using the old one as a guide. This can be a bit time consuming in making a loom board, but will result in the wiring being ALL NEW, the right count and length. The color code will probably be far different as finding "Honda colored wire" would be very hard.
3- Try to adapt the "ultima" harness, which WILL involve adding MORE wiring to the harness, and also in trying to modify the existing harness wires to the right length.

If it were me I would make the choices based on their listed order. Regardless of any claims, Wiring IS a PAIN IN THE ASS, especially if you have never done it before (made looms for years and HATED IT)

I agree, I think thats the route I am going to head down for ease, I'm not great with motorcycle wiring, Audio Visual gear yes! but not automobile wiring haha!

I was planning on the ultima because the bike has been changed so much, everything on it is brand new and the though of all fresh wiring being run made the OCD part of my brain very happy! I saw motosynthesis did it with his build and the photos made it look a doddle, but then incorporating the CDI, R/R etc started giving me headaches. So I think I'll pick up a new (used) "stock" harness and tidy it up, re-terminating everything with fresh/good connections and then follow the original wiring diagram to hook it all back up. I may have to extend some cables as all my electronics are located under the seat in a custom tray so the original cables may not reach!

That should be easier in theory then, being able to troubleshoot against the original wiring diagram in my Haynes manual would be helpful!

Do I need a harness to match the year and model? or would one from say a "1979 Eurosport/Custom" work?


Thanks for your time and help :)
 

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Discussion Starter · #19 ·
@delabourke I am probably going to be using the Ultima wiring harness in my build, as I have read good things about it as well. I am a good year from that point on my build, so I won't be of help much now, but I will be in a year. :) I usually build my wiring harnesses for all of my bikes, but a friend who builds has also used their harnesses in his builds, so I figured I'd give it a go this round. If I get more time to look ahead to that phase of the bike, I'll let ya know.
Awesome! well I wish you all the best haha! I hope you're good with wiring ;)

I'm looking to finish the build end of this year/early next year so I will be done by then hopefully!
 

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I know there are slight changes between year and model numbers, but for the most part any harness for a CDI CX should get you 90% there. Just stay clear of GL harnesses or ones for 82 Custom, as they use TI ignition and the wiring is a lot more "different". If you get a new harness, save any good wire from the old one so that if you need to extend some wires you may be able to keep the color code the same, makes things a lot easier
 
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