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Discussion Starter #1
'morning all...

quick intro: new (to me) '87. bought it a couple months ago off of craigslist and promptly tore it all down; and with the help of this forum, spent some money, managed some mods and am looking forward to some trail riding this winter (it's too hot in the summer here in tucson, az).

discovered a yellow wire without a mate. did a quick search here but no luck.

gave the '87-only schematic a once over and still no luck.

any ideas?

thanks!

yellow.jpg
 

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Discussion Starter #8
hej all,

thanks for all the input, advice, and just plain funny comments. all very much appreciated.

however, I think I figured it out. I have a post '87 CDI on the bike.

thanks to Purple for providing the '88-'00 schematic with a yellow lead from the CDI that the '87-only schematic does not show.

here's a better picture showing it attached to the CDI loom:

thanks again!

wiring tub.jpg
 

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and for those of us which are visually impaired (i.e. we need magnification to see small pitchers!:p)

 

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Is it possible that your wiring harness has been changed when the newer CDI was installed? I would expect that some member here with a rather unmolested 1987 should be able to take a quick look and see what that bullet connector goes to. If the harness was changed then all bets are off. I just checked my 2006 and there is no yellow wire there at all. I do know that 1987 is different from 1988-2001 where the harness is concerned and then the 2001s get yet a different harness and there could be other updates as well. I replaced the entire harness on an 88 a while back and looked at the old harness, there is a solid yellow wire there and it appears to link to the light box by the speedometer which does have a solid yellow in it.

GaryL
 

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FWIW, I have a bone stock '87 and the factory CDI box does not have that yellow wire. What is similar are all the remaining wires, found in the same color combination coming from the CDI box as shown by the OP, in the same plug configuration.

The only variation is there is no yellow wire in the loom of the OEM '87 CDI box.

I suspect that the original 1987 wire harness is in use on the OP's scooter, based on the AWOL yellow female connection, and that someone has replaced a faulty 1987 CDI box with that of a '88 + 2nd gen CDI model.
 

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FWIW, I have a bone stock '87 and the factory CDI box does not have that yellow wire. What is similar are all the remaining wires, found in the same color combination coming from the CDI box as shown by the OP, in the same plug configuration.

The only variation is there is no yellow wire in the loom of the OEM '87 CDI box.

I suspect that the original 1987 wire harness is in use on the OP's scooter, based on the AWOL yellow female connection, and that someone has replaced a faulty 1987 CDI box with that of a '88 + 2nd gen CDI model.
I want to believe you are correct but that Yellow wire appears to be an integral part of the wiring harness in the OPs bike. I lean more toward the thought that the newer CDI unit required the updated wiring harness just so it could be incorporated into the system. If I had to guess and that is exactly what I have to do from here, I would say the OPs 1987 bike has a newer CDI unit and a wiring harness from a 1988 or above bike and I know for sure that the wiring harness for a 1988 is absolutely different than the 1987 first model year. If the part number label is still attached on which ever harness is on the bike then if it is a 1987 harness it will be 2JX-82590-00. If it has the number 2YG-82590-00 then it is 1988- around 2000 when it changed again to 2YG-82590-10-00 and again in 2001 it went to 5FY-82590-10-00. I went through this issue myself a few years back and that is why I know and hate electrics on our TWs, I had to learn more than I ever wanted to know but I saved the numbers and research.

GaryL
 

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I had my cover off and tool kit out for a oil change yesterday and specifically looked all over for that mysterious yellow wire. NOPE, not in there.
 

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I want to believe you are correct but that Yellow wire appears to be an integral part of the wiring harness in the OPs bike.
Hmmm, I don't think it is. If there is a yellow wire in the OP's pic coming from the OP's bike wiring harness, I missed it. The only lonely yellow wire I see is coming from the CDI box.

Further, my bone stock 1987 OEM does not have a CDI specific yellow wire in its harness. If you are correct and the OP's wiring harness was updated, it would have that yellow wire with a female push pin barrel connector, purpose built to mate up to the one shown in the OP's pic coming from that updated post 1987 year CDI box.

The '87 model wiring harness does not have that CDI specific yellow wire... as clarified by the lil Tommy.

The '87 model wiring that comes directly out of the CDI box, likewise, does not have any yellow wires, at all.

Your part numbers are correct, and that yellow wire is found on CDI boxes on the 2nd run / 1988 & up series.

Additionally, last summer a close friend of mine, Bob, found and purchased a 1987 leaner, (leaning against a shed), in a rural farm town. It was a well weathered blue and white scoot with under 800 miles on the odo. It needed lots of love and a few parts to make it go vroom, since whoever parked it had misplaced the coil. We did a ton of cleaning and installed new components. After a week of blaming the carb for its errant idle - lack of power - stalling and backfire issues, we discovered it was suffering from the dreaded "CDI fooled me - blame it on the carb - won't run right syndrome."

Looking back now, whoever leaned it against that shed was trouble shooting an electrical problem. I should have suspected as much, since the original coil on his bike was gone. The side benefit is that he now has the CLEANEST carb in the county. We jetting it properly while there, just made sense to do it while the carb was being cleaned for the 8th time. A side note, our bikes are in the same zip code but his preferred the stock 114 main jet with two shims under the needle as opposed to the 116 and the stock 40 pilot. A new air filter yielded smooth throttle transition over all circuits at just 1 and 3/4 out on the fuel screw, which is a full turn less than mine. Both run very well. Go figure.

Anyway, just as you found, we learned from the online microfiche that the CDI part number variations over model years was rather expansive. So, him being a cheap-O and refusing to drop $250 for the correct CDI, he found an old post from some Youtube author, (not sure of his accent maybe a New Yorker? j/k Gary!), and he followed up with a china knock off CDI that actually worked. I'll try to find that youtube video guide that Bob used and list it here. Hell, the video author might even be a member here, mentioning resources he used to put his plan in motion. I certainly don't any credit for what he did, and short of hacking the wires, (I would have pinned them), it certainly goes to show there is always a work around. *** Just like the video author says, I know Bob's '87 no longer has a kickstand or clutch safety active, but hey, pre-ride check yourself already. C'mon, do people really text and drive? Yeah, wear a helmet.

Is this your vid Gary? ;)

 

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We are mincing words here! By "Integral" I mean the yellow wire belongs there and was not just added by anyone! What we really need here is some member adapt at reading and tracing electrical schematics and telling us what the yellow bullet connector is supposed to go to. That's not me and I sure do hate messing with any electricity unless it has two or three wires, +, Neg & Ground. Actually I am surprised that a CDI from a later year would even plug up at all to the 1987 harness. My problem bike was a 1988 and at first I bought a good used harness thinking they were all the same. Not so! The harness I received was from a 1987 and completely different. Fortunately for me TW Brian was parting out a 1994 and sent me the unmolested harness from it and it was a perfect match. The idiot PO I got the 1988 from removed all the lights, blinkers and safety switches but instead of unplugging the bullet connectors he cut all the wires right out of the harness. He said the engine and bike ran fine until he took all the electrical stuff that he didn't need off of it and then he could never get it to run again. What a jerk!

GaryL
 

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He couldn't get it to run again after lopping off the wires you say? Hahaha, sounds like the previous owner of that scoot shouldn't be allowed to own wire cutters.

On topic, I see now what you're saying... there is a integral yellow wire visible in the OP's harness. The pic shows a short section of it along the frame near the seat rail, but nothing coming down with a bullet.

I did find it interesting that the Youtube video author who used the China box made mention that he thought the '87 CDI box was a DC unit as opposed to the one he installed on his 88 / 89, which he says was an AC unit.

The plugs are spot on exact between the two boxes, less that yellow wire that is not on the '87 box. Outside of that, the wiring colors, location within the plugs and the plug configuration is a mirror image. Even the CDI box dimensions hold true.

If I were to bet, I'd say that the Youtube video author is mistaken and both CDI boxes for the '87 and '88 up models are AC. Either that, or he's right, and the missing yellow wire from the '87 CDI unit wasn't necessary for the DC application?

The world may never know.
 

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all stock tw's have ac powered cdi's.

later units, when they also went to 3-phase 12v power, use a yellow wire as part of that ac power, and cdi's from those bikes would need that feed, though it's *possible* one could hack it onto the older harness by simply grounding the yellow wire from the cdi.

if you look at the old/new schematics you can see that that the little winding (ground and red) has been isolated out and is now (yellow and red). the big winding is still (ground and brown). don't know if the output voltages etc have changed, but maybe not. no garuntees.

iirc the only schematic difference between the 87 and 88+ (till the extra yellow wire era) is how the interlock is set up.

i couldn't really tell from the op photo (not fully loading for me), but are we sure that the "yellow wire" isn't in fact a faded _orange wire, which is the feed from the cdi to the coil?

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Discussion Starter #19
hej all!

another good morning and thanks for all the information and input. I've been traveling for business and just now getting caught up.

first, I agree wholeheartedly that this is an OEM '87 harness (per GaryL) with an '88 + 2nd gen CDI (per eventiller). I too am surprised that CDIs from a later year would even plug into my '87 harness, but here's proof (acknowledging the lonely yellow wire left over).

awesome wiring harness serial number information from GaryL!

thanks eventiller and littletommy for taking the time to open up your bikes and take a look and help me out!

the picture is a touch overexposed, slowmod said it best...the (generally) vertical wire is faded orange connecting the CDI to the coil.

thanks again all!
 
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