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QUESTION: What is the best approach to wiring a TW from scratch with the bare minimum electrical components? Are there certain components from other bikes that I should substitute or is in better to stick with straight stock TW stuff for all of it?





I just bought my neighbor's '87 TW and it is in need of some serious TLC. It "ran fine until one day it died and didn't have spark" according to the previous (original) owner and that was a few years ago. He apparently tried to diagnose the problem because the wiring harness has been butchered and there are pieces everywhere. That's fine though, because I've really wanted to do a "hollow-mod" TW for a while now. My plan is to remove the factory airbox, plastics, light, instruments, etc. and install a mid-60's CB160 tank with a custom seat and exhaust. I don't need signals, horn, or anything else extra. Its kinda like a clean slate, so I'd like to know if there are any upgrades/mods to the electrical that would be advised. I'm probably gonna have to buy new electrical components anyway so if I can upgrade, now is the time. Should I look for a good stock TW wiring harness or just wire it myself? Thanks.
 

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If you wire it yourself, you should invest in a lot of different colors of wire.

Creating a harness from scratch can be a hair pulling, aggravating, pain in the @$$.

But if you approach it with a Zen attitude it can be a relaxing mental exercise that pays off very well in looks, usefulness, and satisfaction.



I'd start with a roll each of basic black, white, red, and green. Then buy a good 12 or 24 foot of multi-wire cable that you can pull wires from. The kind with 12 or more different colors. That will let you use color coding for left, right, stop, turn, etc., etc..



With good notes the colors will also help when you eventually need to troubleshoot the wiring a few years later.



Run the wires with an eye for rubbing & pinching that may cause a short after a while. As you run each wire use twist ties so you can hold them in bundles that you will later wrap to create an actual harness that can be more easily removed and reinstalled.



Take your time and don't get frustrated. Remember that the engineers probably spent a few months working on the first factory harness.

Be patient, and maybe, you might just find that you are good at it.

 

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I'd opt to gut it. All you need in Iowa is a running bike. You can use arm signals to turn and stop




But, ideally you'll have a headlight, tail light, and brake light at a minimum. I wired my CB350 cafe bike from scratch and enjoyed it. I invested in nice connectors, terminal blocks, fuse block, nice shrink tubing, and as mentioned... lots of colors of 14 gauge wire.



I did my grounds with 12 gauge wire and the starter wire was 8 gauge. I used a mini propane torch to heat the big wire up enough to solder my connectors to it. I soldered every terminal rather than crimped them on. I wanted to do it once and once only.





Anyway, work from the yamaha factory wiring diagram to do the CDI and utilize the factory regulator/rectifier from the stator. After you have the battery wired, the world is your oyster. Send wires from the battery to a multi terminal fuse block and wire up your lights, stereo, cb radio, and neon FX lighting
 

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all good advice. If I may add, run some extra's from battery to both the rear and front of the bike. This will give you the ability to 'add on' to what you think is enuff now. Or to replace what will go bad later. Just saying, TIM
 

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Also, in your wiring escapade, if you can figure out the answer to the 'turning the lights off' question. Topic on that question on here somewhere. How to kill the lights without overcooking the battery or damaging the electronics. Bunch of us dying to know. TIM
 

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A simple ground lift can be made to kill all the lights easily on a bike that you've wired yourself if you plan for it.



IIRC it will play hell with a bike that still has all its safeties and relays. I'd have to have another look at the spaghetti map.



One of these days I'm gunna research a regulator setup that won't self-desruct from the heat and toss about a mile of wire into the round file.
 

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I just bought my neighbor's '87 TW and it is in need of some serious TLC. It "ran fine until one day it died and didn't have spark" according to the previous (original) owner and that was a few years ago. He apparently tried to diagnose the problem because the wiring harness has been butchered and there are pieces everywhere. That's fine though, because I've really wanted to do a "hollow-mod" TW for a while now.


Just a reminder that the 1987 model year is widely reported to have CDI issues that could explain your neighbor's original problem. I believe that year also has a unique stator along with other wiring differences from the 1988 model year on.



If you decide to keep your 1987 stator and build your wiring harness around that platform, it would wise to locate a known to be good 1987 CDI and also to use the 1987 wiring diagram. Changing to a newer vintage stator would allow you to utilize a newer version CDI that is more readily available and reportedly less problematic.



I'll defer to Sir Lizrdbrth to confirm the accuracy of the above statements, and to provide any additional technical details because that's about all that I know.
 

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Looks like good advice to me.



Only thing I'd add to that is that the regulator for '87-'00 bikes is single phase. Any of them should work on an '87.



'01-up regulators are intended for the later 3-phase setup.



I'd really urge you to get that bike diagnosed and running as-is with the stock harness before monkeying with it. As Brian has pointed out the CDI's are a known failure point and you could end up pretty deep into it if that turns out to be the ca$e.



One thing which will help you keep from chasing your own tail is to keep in mind that the '87 is its own critter. On an '87 the charging system, headlight and CDI are three seperate animals, which in a way helps simplify diagnosis. None of the 3 give a rip what happens to the others. They all will work independently.



Focus only on the ignition/CDI setup.
 

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Discussion Starter #9
Thanks guys for the great input. I've seen stuff about the '87 being a one-off deal and about the problems it had with the CDI, so I was hoping someone would chime in with suggestions for those things. I would love to get the bike running with what I have in the box of stuff it came with, but if you saw the wiring harness you would understand why I'm contemplating just starting over. It has several frayed ends, cut wires, and electrical tape wads. I actually see one on ebay for $24.99 (free shipping) that claims to be for an '87. That might be worth it right there.......I'd have more than that in all those colors of wire.



Anywho, I'm really concerned about the components to use. I'd love to get away from the '87 specific CDI but does that mean I have to change other things on the bike? I've seen that guys suggest running stuff off completely different bikes all together, but what will actually work on the TW engine and is it worth messing around with? Like I said at the start, I've got a small box of electrical components (coil, cdi, etc.) that look like they've seen some weather so I might just be better off starting from scratch. I ONLY WANT TO MAKE THE BIKE RUN AND HAVE A HEADLIGHT, TAILLIGHT, AND BRAKE LIGHT so what will that require? I guess the electric start would be handy if I can get one of the tiny batteries I've read about guys using that will work the starter, but it isn't really important.





Once again, thank you all for the great input. I'm not an electrical wiring type of guy so any suggestions/advice, no matter how obvious, is greatly appreciated.
 

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Discussion Starter #10
So can I purchase a later model CDI and install it on my 87? Will it work, or is there specific stuff in the stock 1987 CDI that has to work with the 1987 engine?
 

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Any luck making a new simplified/stripped-down/bare-bones wiring diagram? I'm building a custom tw and am doing the same.
 
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