Gurus - I have a 69 AT1 that has turned into more of project than I anticipated.   In short, when I got it, it reportedly had a CT1 crank with little compression in the AT-1 cylinder so I put a Ct-1 top end on it.  Bike has lights, etc but coil was wired like a dirt bike to bypass key and stop with kill switch.  Additionally, original wiring harness was cut-up and pretty much useless.  Fast forward, I'm installing an E-bay sources 69 CT-1 wiring harness to mate up with the lighting coils, etc.  I'm mostly put together (swapping back to 6v from 12)  but have some questions.  NOTE, SYSTEM WON"T ALLOW ME TO UPLOAD PHOTOS

1)  The spark coil has an orange wire and a brown wire.  when I connect the orange to black magneto wire and brown to ground it runs like a dirt bike, but switch doesn't kill bike.
Where do I connect the brown wire (male plug) from spark coil?   I have a brown female wire available out of the harness that has DC voltage but thinking that and the pink wire drive the horn? , but looking at a wiring diagram seems like maybe coil should plug into it (but my senses say no as it's carrying battery voltage when key on)?   I want to make sure I can turn off the bike with the key switch.  Bottom line, how should I wire the spark coil?

2)  My ignition switch (from DT1/RT1 - original switch had 3 pins and wouldn't mate to "new" harness) has a 6 pin plug, plus single female red, black, white, blue, wires:  The switch plug wires are : 1. Green/red stripe, 2.  Green,  3.  Yellow,  4. Black with white stripe,  5. Brown  6. Blue with white stripe.

the harness has a 6 pin plug which are:  1.  Empty, 2.  Green (to lighting coil), 3. Yellow (lighting coil), 4. Black, 5. Brown, 6.  Blue.

Question:  I'm unsure about pin 4.  I connected the single black wire back into the harness near the coil (note it has continuity back to the magneto park coil).  Is it OK for pin 4 black/wh to connect to harness black only?

Also, pin 6 mates keyed blue white stipe to harness blue wire.   I also have a single blue wire coming out of the switch that is carrying DV voltage on 2nd click of key - the blue with white stripe has no voltage.  - I'm assuming I need to mate Blue to Blue and bypass the one with white strip?  (I tried it with jumper wire and headlight and tail light come on/ off via battery power.)

Thanks for any advice before I fry something!!!

Best,
Marshall


 

There's a Notice on photo posting at the top of most pages.  Site is too big and photo hosting is down.  You need to upload to 3rd party like Imgur and link here.

1)  You still have the AT1 "Battery ignition" ignition coil.  Probably best to get a CT coil which will have one black/white (sometimes just solid black) wire that goes to the magneto points.  If you want to use that coil, ground one wire and leave it that way.  You had spark with brown grounded...  so that works.  Polarity might be wrong and probably not optimum.  Your choice.

Do NOT connect the old ignition coil brown to the brown that has power.  See  below for engine kill.

2) To kill engine, you need to connect the black/white from the key to the black from the stator to the coil...  You said the harness at ignition switch has a black that has continuity to magneto black?  Connect that to the black/white out of key.  (So yes to your question) Since you don't have a separate ground wire out of key (black), make sure key switch is bolted to a good ground.  With key off, black/white connects to ground at key switch which grounds black magneto wire killing spark. 

Hope this all makes sense.

2a) You have an early bike harness and a later switch.  No, you don't want to connect the blue from switch to the blue in harness.  Leave it as it is.  So no to that question.  Solid blue out of switch is not used in your application.  With engine running, and key in "lights on" position, lighting coil (yellow) will power blue/white out of key which powers headlight and taillight off engine. 

 

Wow you're sure getting right into it--impressed doesn't come close. Brown would have been dc power into the coil but hey if it works & it's ac now anyway you're using in the black. Often wondered how a dc coil would work, so now we know. Thanks for sharing. ps i use google photos & just put a link up here.

Mark - Make sense.  Throw a ground back to the source coil from switch, just like kill switch.  Can't tell you how much I appreciate it.  Need a little more feedback if you don't mind.  My source coil for spark is black, double female outlet.  I have one male going to spark coil (which is firing when grounded, the other male black wire inserted from wiring harness which was next to the battery box.  The black wire on harness has continuity back to six pin plug, as well as another plug below main body ground screw under spark coil.  Before this wiring job the handlebar mounted kill switch was wired  back to the source coil and works fine.

From the switch there is the single black wire which I've plugged in (below coil), and the black/white stripe in connector which also plugs into the harness solid black wire.  There is continuity between the black and black/white wires when ignition is off, continuity goes away in 1st and 2nd key positions. My challenge is when key is off it's not grounding out spark, and there is no continuity to ground in black wire running back to source coil.  There is continuity between ignition switch and frame so it seems to be grounded well.  Am thinking there are some gremlins in switch?  

Your thoughts?

Thanks so much!

Sorry.  Your descriptions are making me dizzy.  And there was no handlebar kill switch on an AT or CT so not sure what you have.

I'm going to repeat myself.  There is a black (or black/white) wire from magneto to ignition coil.  That wire needs to also connect to black/white at key switch which you said it is.  With key off, that black/white at key should now be grounded which grounds out the magneto.  With key on, that black/white is no longer grounded.  That's it.  It's not complicated. 

You need to be careful with random black wires on the bike.  Many are grounds! If you connect them to your ignition black you will kill spark.  Why Yamaha didn't use black/white consistently for the ignition and solid black for ground I'll never understand.

As I said, I find it odd that your key switch doesn't have a black wire coming out of it that goes to ground.  With key off, the black/white needs to be grounded somehow.  You might have a missing wire?  Or maybe key switch bracket provides the ground.

Pictures would help.  You can see what you're working on, we can't. 

If you still have the AT1 starter button by the throttle, you could connect that single wire to magneto black that goes to ignition coil.  That switch grounds to handlebar when button is pressed and would kill spark.

Mark - thank you. Will try to put up photos so it's not so confusing.  I believe I have the coil wired correctly now, it's just not grounding out when key is in off position (still strong spark in each key position).  I purchased a used key switch and it may have some issues I'll need to dig into.

Thank you again!!

You're welcome.  If black/white coming out of key is not connecting to ground with key off, that's where I'd start.  Look at back of switch (under boot if it still exists) and there should be a "solder point" that connects to the black/white "solder point" with key off.  That "solder point" might connect to metal switch body with a jumper but normally I thought there was an actual black wire at solder point?

Good luck!

Thanks so much.  Great suggestion about using the starter button for kill switch.  Just down to the short rows of trying to make switch work to make it a little less difficult to ride away w/o key:-(

I didn't have an app to upload photos so I shot this short (2 min) Youtube that walks through the situation.  



Thanks again!

Found problem! Break in black ground wire in harness near connector at grounding screw. Jumped the wire and switch works fine! Thanks for the tips in keeping from going down the wrong path for days and days and .........