'73 TX650 Coil Wiring Question

[Chrondor]

Hey guy,
I was hoping one of you could help me out with a question.
I'm wiring a new dual output coil and the "red/white" wire is in a harness with a "brown" wire.
They obviously share a current. The "brown" wire appears to go towards the rear of the bike.
Is it safe to say this is not a "hot" wire and is reliant on the "red/white" wire for electric current from the kill switch. Any input is appreciated as the wiring on these seems to vary from year to year.
Thanks in advance.

 

[XSLeo]

Yes. The made small changes every year or so. Every once in a while they made major changes.
Things like the starter, a bunch of safety stuff.
The 72 and 73 were pretty much the same bike just a different color.
Power comes to the switch on the red wire, From the switch to the engine stop switch on a red/white wire, from the engine stop switch to the coils and safety relay, that's part of the e-start.
I think sometimes they were a bit short on red/white wire and ran brown as far as the engine stop switch.
Mainly the brown wire carries power to something, like the brake switches, Regulator, etc.
The brown wire toward the rear of bike probably runs to the rear brake switch. It get's power whether the engine stop switch is off or on. The R/W wire only gets power when the engine stop switch is in the run position.
The main thing is to not get to hung up on the exact colors you have but were the power flows. In the ignition, power should flow from the main switch to engine stop switch, coils. Electronic ignitions also need power from the engine stop switch.
If your bike is all stock and you are adding an electronic ignition, I might add a 7.5 amp fuse between that R/W wire and the ignition/ coil.
Leo

 

[Chrondor]

Thank for the tip on the 7.5 amp fuse. I'll add it to the link.
I'll just put the battery back in and check the wires for a charge for peace of mind.
Thanks for the response.

 

[5twins]

Yes, find the power wire that the kill switch turns on and off, and use that for the coil power. Brown is the common color for all switched power wires in the harness. They will all be switched on and off by the key but not by the kill switch.

 

[Chrondor]

So I wired the coil up and it was running great, then as I was giving it some gas in 5th on the second test ride *poof* died and no spark.
When I test the coil I get ohm reading out of the wires to the pamco but not to the plugs. So it looks like the coil died. Is this a "thing" with the ultimate coil? Died mid ride. Started up and ran perfect yesterday.

 

[Chrondor]

Well now it would seem "Mike'sUltimate Pamco kit" carries the #17-6822 coil and not the Ultimate coil. Guess I should have read the fine print on that one...

 

[5twins]

Well, I don't know if it's common but many times if a new electrical component is going to crap out, it does so rather quickly. If it definitely is the coil, you might want to get a better brand name aftermarket one like an Accel or Andrews. We're lucky in that we can use Harley coils and they're a dime a dozen on eBay. Another option would be a good used O.E.M. Jap coil off some other bike. Many have had good luck with a Honda MP08 coil.

 

[retiredgentleman]

What is the resistance of the primary and secondary windings of the coil?

 

[Chrondor]

Primary was 4.5 secondary I couldn't get a reading. Just nothing

 

[retiredgentleman]

Well, the coil has an open secondary winding so its finished.

 

[5twins]

How did you test the secondary? For testing the secondary on a dual output coil, you don't measure from a plug wire to one of the little terminals like you do on a single output coil, you measure plug wire to plug wire.

 

[Chrondor]

5twins, I did NOT know that! Thank you. Getting a normal reading through the wires so I guess it didn't crap out. Caps are at 4.5K too. So I guess there must be a short somewhere.

 

[retiredgentleman]

Oops..................I assumed Chondor knew how to measure the secondary side.

 

[Chrondor]

Well it looks like everything is okay with the coil.
Thanks for your help on this I've learned a lot.
It turns out it was the Pamco E-Advance unit.
There is a break in one of the circuit lines. This must have cut power to the points sensor unit (I hope.) I'll get to the bottom of this yet.
Thanks again you guys really did help speed this up a lot for me.