coil Wiring Question

[MikeCas]

Hello friends. I have what I hope is a simple question. The coil from my '83 XS650K is shot. I bought a new replacement from CB750. The wires that power my stock XS dual cable coil are orange and red with a white stripe. The replacement dual cable coil wires are blue and black with a white stripe. What wires to I splice to what wires? Thanks for your help with this. The more I learn, the more I know how much more I have to learn!

 

[gggGary]

Polarity makes no difference on dual tower coils, wire it up!
The new coil has primary resistance in the 2 to 3.5 ohm range?

 

[MikeCas]

Polarity makes no difference on dual tower coils, wire it up!
The new coil has primary resistance in the 2 to 3.5 ohm range?

Thanks, Gary!

 

[5twins]

As Gary said, it doesn't matter how you wire the coil but primary resistance should be right. I think the original coil was rated at just under 3 ohms. If you wanted to wire the "new" coil as Honda did (not that it matters), on the Honda MP08 coils I've dealt with, the black/white is power and the blue is the signal from the ignition unit. On your original, the red/white is power and the orange is the signal from the ignition unit.

 

[MikeCas]

As Gary said, it doesn't matter how you wire the coil but primary resistance should be right. I think the original coil was rated at just under 3 ohms. If you wanted to wire the "new" coil as Honda did (not that it matters), on the Honda MP08 coils I've dealt with, the black/white is power and the blue is the signal from the ignition unit. On your original, the red/white is power and the orange is the signal from the ignition unit.

Looks like I got lucky! I connected black and white to red and white.

Mike

 

[GreySquare85]

Hey im hoping someone sees this. My 81 xs650’s crapped out the other day and was wondering if i took the coil’s off of a tx750 and just tied the wires together it would work. Basically mine is dual tower and the tx has two coils. Will i smoke something doing this or am i smoking something thinking this will work??

 

[gggGary]

You sure the coil is the problem? Coil is pretty far down the list on TCI ignition failures. Goto coil replacements are GM or Honda coils.

 

[GreySquare85]

Primary windings tested ok but secondary says OL. Have i tested it wrong?

 

[GreySquare85]

So heres what i have. First pic is tx coils and the other is my dual tower and one of the tx coils. I also have a honda cb350 out back but it also has two coils.

 

[gggGary]

If you HAVE to try this: I think I would wire them in series. You don't want to overload the TCI's output.

Nothing like a kludge to ADD to your troubleshooting woes.....

 

[gggGary]

The stock TCI coil primary resistance is 2.5 ohms. Secondary through the spark plug caps is 11K ohms.
Pick up coils, open connector, either orange or gray to black 700 ohms +- 10%
The TX750 coil's primary is 3.9 ohms secondary 8K ohms +- 10%

 

[GreySquare85]

Overloading that tci is my fear bc i cant afford one of those. Last one i saw was like $400…i will buy a new coil but i have yet to find a dual tower coil like mine. Any suggestions? All i find is two coils instead of dual tower single coils. Oh and when i tested across the plug wires it was OL which told me the coil was dead.

 

[Kevin Werner]

MP08 coils are ~$15 on eBay. As stated above, check the resistance before you replace it.

 

[gggGary]

Check the plug caps, they ARE notorious for going open circuit.
test wire to wire on the secondary (unthread) the plug caps.
Prepare the coil wire ends like this

before reinstalling the caps.

 

[gggGary]

Search Gonzo on here, so cheap they are worth buying (carrying?) as a TCI back up plan.

 

[GreySquare85]

Ok so im going to attach a picture of the volt meter reading after i took the spark plug caps off.. im so confused now.

 

[GreySquare85]

is this the correct reading for the secondary side without spark plug caps?

 

[GreySquare85]

Also just checked with the spark caps off one of the leads show’s community to the ground the other shows OL. I have to assume the insures the coil is bad correct?

 

[gggGary]

the 221 is weird should be up around 10,000 and there should be no continuity to ground.

 

[gggGary]

Is your VOM battery fresh?
try setting the range to K ohms.
Just for grins measure your TX750 coils. ;^)