81 Kz750 ltd needs an expert in electrical

I am having an issue with this bike. I had it running and idling perfectly after 2 years of restoring. Took it for a ride and it ran well. Brought It home to my garage and turned it off. I figured now would be a good time to install a new headlight ring. After installing it I decided to turn on the bike before going inside. Nothing. Pulled a spark plug out and no spark on all of them. Thought it could be a pinched or bad wire from inside the headlight. Checked with a meter and all is fine. The bike kicks over but no spark on any spark plug. This story gets better. I replaced the ignition coils, wires, and ic igniter. I also switched out the electronic points, regulator/rectifier, starter relay and wiring harness with spares that I have from the same year motorcycle. No spark. I have checked everything in the ignition system as for as wiring and components and still cannot get a spark. My stator tests fine, ignition coils are getting power and the bike kicks over but no spark. Then I noticed that when I turn off the ignition switch that's when the plug sparks. I can turn the key back on and when I turn it off the plug sparks. Where should I look? Could this be a short somewhere?

This would indicate that the igniter is shorted to constantly-on... meaning the igniter never tries to fire a spark, or it is getting erroneous signal from the pickups.

What ignition system? Factory?

If that is the case what is the voltage on the green wire on the 2-3 coil, and the black wire on the 1-4 coil?

thank you loudvhx for the response. it is the factory setup. i am getting a reading of 1.335 on the black wire and a little less on the green wire. the battery is charging now and it is reading 11.55 volts. fully charged it will read 12.55. i tested both wires with positive lead on red and negative on battery ground and also negative lead on frame. the readings were identical. i also swapped out igniter with a spare and same issue. then i thought maybe both igniters were bad so i built an igniter using the hei modules from a car and the info posted on building an igniter. same issue. btw i tested the battery and the wires on the same setting with my fluke meter. should these wires be reading this? i did these tests with the homemade igniter currently installed . thanks again loudvhx

Sounds like you have been doing a lot. Do you have the diagram? If not this might be good.
www.kzrider.com/filebase/doc_download/295-z750h2

So you have power at the battery, what is the voltage with key on at the Red Wires on the coils?
You have a Meter, also a test light?
Since it was running, and all you did was shut if off. Check Voltage to coils, with switches on, should be near battery voltage. Hopefully within .5v, it could be a switch, key switch, start run switch, fuse, and I'm not sure but some have a Side Stand Switch, a quick look above it will determine if yours does.

Look inside the right handlebar switch pod, some of the older bikes have been suffering from crumbled solder joints on the start and run/stop switch. This is where the Red wire goes to the ignition coils.


Hand Soldering

Rosin flux(the paste type)works the best for me when soldering. Also get an acid brush and some 91% rubbing alcohol to clean the soldered joint(s). Use it to flush away any rosin residue as it's a non conductor.

A couple(2)of toothpicks to apply the rosin flux, a damp sponge to wipe the soldering irons tip occasionally, and rosin core solder is about all you'll need for this repair.

If the soldering iron is new, it probably needs "Tinning", to do so. follow these steps:

1.Have on hand either a damp, clean sponge or rag.

2.Plug in the soldering iron and let it get hot(maybe 2-3 minutes).

3.Unroll a few inches of the solder and then using a paper towel damp with rubbing alcohol, wipe away the fingerprint oils you left when handling the solder.

4.Apply a small amount of solder to the tip of the now hot soldering iron.

5.Using the damp sponge or rag, wipe away the excess solder, leaving a thin amount.

6.The iron is now "Tinned" and ready for use.

7.Periodically wipe the soldering iron tip & apply solder to keep the working surface in good shape, keeping in mind to not have too much solder on the tip.

Just to confirm... when you have the low reading on the green wire and black wire at the coils, you have approx. 12v on the red/yellow wires on the coils?

Disconnect both G terminals on the HEI modules. Do you still have the low (approx 1v) reading on the green wire and black wire at the coils?

If so, disconnect the C terminal on the HEI modules. Do you still have the low (approx 1v) reading on the green wire and black wire at the coils? Then the green wire and black wire are somehow shorted to ground. Is there a tachometer wired to the ignition? Maybe that has shorted.


(All readings should be done using battery negative post as ground for the meter's black lead).

Thank you all for your responses. I am getting battery voltage on red wires at the coils. Checked the right hand switch and connections are good. The run stop switch is held in place by screws so no solder joints. Wires are making the connection when in the run position. I thought the igniter was bad and I switched it out with a spare and the same issue. Built an igniter and the same issue. I am certain the igniter is not the problem. To have the same issue on 3 igniters is unlikely. The coils are new dynatek 3 ohm green coils with new wires. Coils are not the problem. Switched the pick up coils with a spare and same problem. I am leaning towards a short somewhere. Although when I switched the wiring harness I had the same problem no spark. This bike does not have a side stand switch. It does have a connection with the clutch lever thus the lever has to be pulled in to get the bike to start. I do have a clymer and shop manual. I do have a multimeter but not a test light. Will be working on the bike today and I will keep you all posted. Going to run the test with the green and black wires at the igniter as loudvhx recommended. Something shorted to ground makes sense. Going to investigate that theory further. Open to anymore suggestions. They are all very helpful.

Btw I do have the original tach and speedo gauges on the bike. They are connected with the stock setup. No modification.

So to confirm, does the bike have an electronic, or cable driven Tach? If electronic, un plug it, and see if that's the Problem.
If you have a Manual, use your meter to test the wiring from pick up coils to the Ignitior box. I see where you replaced the Harness, perhaps it is faulty. You could have a bad wire in that harness, I would check the connections in and out of the Ignitior, and the Grounds.

A very common issue with Dyna coils is a short at the primary wire screws. They often back out and contact the mounting hardware. Check to make sure the screw heads have at least 1/16th inch of clearance from the spacer used to mount the coils. According to your symptoms, it would be the green or black wires shorting at the coil mounts.

If that is not the case, disconnect the pickup wires at the HEI modules (G connection) and see if you get the same symptom of the spark happening when you turn the ignition switch on and off. Then try it with the green and black coil wires disconnected at the HEI modules. That would confirm that the short is on the green and/or black wires. A shorted electronic tach couls short the black wire.

The tachometer is not electronic but the original one to the bike. The tach cable is hooked up to the upper front of the engine. I will do the green black wire test and will keep you posted. The coils are brand new and installed recently. Everything with coils looks great. I checked the right switch inside out connections with the wiring reads good. Also the clutch switch wiring reads good. Talk soon

Disconnected both g terminals on Hei modules and I got battery voltage. Then disconnected the c terminal and got battery voltage. I did check my red wires to the coil. After reconnecting everything i turned the bike on and checked red wires but am not getting full battery voltage on both wires. Fully charged battery and i am getting a couple volts lower than 12 at the ignition coils. Could this be the problem? Not enough juice at the coils. I tested the black and green wires leaving the coils to the Igniter and they test fine. I put my meter to sound an alarm when wiring connections meet. I can say there are no shorts in these 2 wires.