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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 15 Nov 2021 09:57 #857962

  • KraZyJoe67!
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I have a 1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. I have put #2 wire on plug 3 then it fire then plug #2 doesn't. I have checked directly on the coil with a spark tester. The sparkplug wires are totally removed from the coil. I have checked all the wiring to the coil . Could it be only half the coil is not working. everything else has been replaced with new parts. 
 

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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 15 Nov 2021 11:07 #857963

  • F64
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Swap the spark plugs as well.

You could have a bad plug
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 15 Nov 2021 18:33 #857970

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It could be the plug but since it fires with you use plug wire #2 does make me think it is not the plug.  Rather it points to the plug wire for #3. Have you checked it? If there is enough length can you cut a short part off and put the plug cap back on to the cable to see if it sparks.  Are the plug caps the resistance type, as sometimes the resistor part in the plug cap goes bad and does not make a contact to the plug as it should and so does not spark. 

I am by no means the expert here on this subject, but a coil on a wasted spark system should provide to both of the plugs associated with that coil.  I can not see how it would only provide it to one plug, but again what do I know. 
1977 KZ650 B1
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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 15 Nov 2021 18:37 #857971

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The plug wires and caps are easy to replace.  7mm copper core wire and NGK plug caps will fix you right up.  I did just that on my 750, recycling the outer wire sheath wire covering.  It's a simple bit of maintenance that's also low cost.  Check Z1 for parts.
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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 15 Nov 2021 23:06 #857975

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Last edit: by KraZyJoe67!.

1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 15 Nov 2021 23:15 #857976

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Im asking if only half the coil can be bad. The sparkplug wires plugs are all new.. I said it before. I'm testing the coil directly nothing connected to the coil but the power and ground wires  I have no spark pug wires connected to the coil Im testing directly off the coil itself with a multimeter. #2 has Power #3 does not.

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Last edit: by KraZyJoe67!.

1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 16 Nov 2021 00:17 #857977

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..... but a coil on a wasted spark system should provide to both of the plugs associated with that coil.  I can not see how it would only provide it to one plug, .
 

You are correct.  On 'dual fire' coils, both plugs on a single coil are required to complete the 'spark' circuit.  If one plug is firing but it's partner on the same coil is not, it means the 'missing spark' is happening somewhere else between the coil and the plug - probably sparking between the wire and the frame or motor - this would be visible in the dark - you've probably got a bad wire(s) or cap(s).
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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 16 Nov 2021 09:17 #857986

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I just figured out the problem The IC igniter is bad A friend gave me one off his old wrecked bike Now it runs great. thank you all for your help
 

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1980 KZ750 LTD 4 H #2 COIL, only #2 is sparking #3 is not sparking. 18 Nov 2021 12:09 #858036

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Besides ebaying a used part, there are few other options...

If you can source the correct aftermarket GM, HEI modules you can make an igniter from them:
General Motors HEI Ignition Module For GPZ550 (gpzweb.s3-website-us-east-1.amazonaws.com)

Or you can make one from scratch.  The parts (or substitutes) should all be available at Digikey.
Ignition Module (gpzweb.s3-website-us-east-1.amazonaws.com)

I soon hope to have a simpler one with all active Digikey part numbers.  It should cost around $25 or less in parts.

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