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81 KZ750H LTD No spark 29 Jul 2021 10:35 #852781

  • Elfarm98648
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Old igniter has been bench tested and failed. I cut the wires, soldered in my temporary harness and I still get nothing, I’ve got the grounds running to ring terminals and bolted to
the grounds on the modules, I made sure the diodes were facing the right way, resistor direction doesn’t matter. All other terminals run to a female spade and are crimped on. Followed the schematic to a T. Plug it in, ground out a spark plug and get nothing. Any way to test the new harness? Diodes and whatnot, I will post a picture of what it looks like when I get home from work. 

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81 KZ750H LTD No spark 29 Jul 2021 14:12 #852795

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I won't be able to include an image with colored circles as I'm on my pc instead of my mac.
Lou, shouldn't he be able to probe the coil green and red wires at the coil terminals for DC V--hit the switch and see the voltage change from 0v to 12V?
This would rule out everything but the coils.
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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81 KZ750H LTD No spark 29 Jul 2021 15:21 #852798

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I believe I should be able to as long as my multimeter is responds fast enough to read it. I’ll be sure to try that when I get back to the bike. I have a real spark plug spark tester so this is how I am confirming the spark is non-existent from now on. The plugs are gapped accordingly, .035” IIRC. 

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81 KZ750H LTD No spark 29 Jul 2021 16:14 #852802

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Just to check.
With your spark plugs attached to spark plug wires. Measure the resistance of a pair of spark plugs from center electrode to center electrode. This should check the electrode through the cap, wire, secondary windings and through the path to the other center electrode.

You should be able to see the voltage change from the firing test as you manually control the switch.
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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81 KZ750H LTD No spark 29 Jul 2021 16:31 #852805

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So it will have to be cylinder 1 & 3 or 2&4 correct? I understand what you’re saying but with the voltage thing, it shouldn’t show anything because I’m no getting any spark correct? 

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81 KZ750H LTD No spark 29 Jul 2021 16:57 #852809

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It should be
1 and 4
2 and 3

The voltage test should still work.
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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81 KZ750H LTD No spark 29 Jul 2021 21:58 #852831

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here’s the temporary harness. 
Attachments:

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81 KZ750H LTD No spark 30 Jul 2021 07:26 #852840

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I won't be able to include an image with colored circles as I'm on my pc instead of my mac.
Lou, shouldn't he be able to probe the coil green and red wires at the coil terminals for DC V--hit the switch and see the voltage change from 0v to 12V?
This would rule out everything but the coils.


 

Yes.  The first setup test to do would be the bench test "without pickups" as the diagram is labeled.  When pressing the appropriate switch, (or just touching the wire to the terminal), the voltage on the coil will be 12v.  To be clear, that means the red wire on the coil will have 12v, and the green wire on the coil will be near zero.  That should be checked first.  If it's not the case, then I would suspect the HEI modules are the wrong type.  Then a 9v battery test on the module should be done to confirm the module type if it was not already done.

I'm not sure enough information was posted to conclude the igniter was definitely bad.  I did not see it mentioned whether it was confirmed the igniter output state was not changing.  

There is a small chance both coils simultaneously failed.  This can happen if a spark test were done without giving a complete path for each high tension line.  I've also had both coils failed within the same day after riding through a bad rainstorm.  Coils can develop small cracks over time but will continue to work fine as long as they don't get wet.  Then when both get wet at the same time, they can fail within hours or minutes of each other.

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81 KZ750H LTD No spark 30 Jul 2021 11:04 #852851

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Well, I did as you said and tested for ohms between center electrodes and got nothing, I also tested the incoming voltage to the coils and it would start at 0V, hit the button, it would only go to .3V and maybe max out at 1V. This is with both the duralast control module and the wells from rock auto. I have plug boots coming in on Monday so I can pull the old ones and try to test the copper inside of the spark plug wires between coils. I hope that makes sense, so the coils are definitely not getting 12V but I also don’t know the prior history of the bike so it is very possible that they both failed from a bad test. What way can I test the coils? Can I test the voltage I am receiving from the pickups? Just to eliminate that from my problem list. 

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81 KZ750H LTD No spark 30 Jul 2021 20:51 #852893

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We are trying to eliminate as many variables as possible.  Since you don't get a voltage on the coils using the push-button diagram, we know it's something with the HEI modules or their wiring.  This means we can ignore the pickups, the adapter circuit, and the coils for now.

We can assume the coils are not shorted, or at least that being shorted is not the root cause of not getting voltage on them because if the modules were turning the coils on, and they were shorted, the 10 amp fuse would have blown.

So was the prescribed test done using a battery on the modules to determine the voltage on the W terminal?  That lets us know if we have the correct type of modules.

 

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81 KZ750H LTD No spark 30 Jul 2021 23:40 #852894

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Alright, if the push button diagram is installing them on the bike and pushing the start button to test voltage then I did, sorry if I am still unfamiliar with the lingo yet. I did the 9v test and here are my results. Keep in mind I have a duralast dr-100 and a Wells that I ordered from rock auto so I have tested both. Wells: 1.25v 
10k ohms w to G
134.4 @ 200k ohms g to ground
109.8 @ 200k ohms w to ground

 Duralast: 2.73V
10k w to G
.721 @ 2m ohms g to ground
.729 @ 2m ohms w to ground

I tested both duralasts and got the same 2.73V for both tests. 
 

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81 KZ750H LTD No spark 31 Jul 2021 12:37 #852911

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The test to do is the bench test without pickups.  I posted that diagram several posts back.  It uses switches in place of the pickups. 

The biggest variable to eliminate by using the bench test, is the bike itself.  Testing on the bike will only wear out the starter, and worse...the starter clutch.  That requires major disassembly and difficulty, and is a known problem on the 750 inline family.  So we want to avoid that at all costs.  Plus, it doesn't do any better job at troubleshooting than a simple bench test can do and it's much easier to see what's connected to what on a bench test with minimal wiring.

If you do the "bench test without pickups" as it's labeled, and you don't get spark, then you will want to check the voltage on the green wire and black wire to see that their states are changing when you press the buttons. 

Regarding the HEI modules:  It appears the Rockauto modules are the desired, older style igniters.  It would be preferred to use two of those.  The other 2.73v modules may possibly work, but I haven't come across those yet to experiment with.  For the switch test, they may work, but I can't say for sure.


 

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