81 GSX400L no spark

[MrJones]

Good evening. New member. Please forgive me if this has been asked, I am still reading past posts but figured I would get this out here if anyone is able to help in the mean time. I recently picked up an '81(well, manufactured 09/'81, so probably actually an '82) GSX400L for basically nothing from previous owner as he was having hard time powering the starter?... I cleaned contacts and installed a new battery. And then came to find the 4 wires for ignition were not wired to the aftermarket ignition correctly and the main 15a fuse was blown(as a result, I guess). I followed a wiring diagram I found online and got the bike to turn over nicely.
I believe I have confirmed the kill switch is working properly as I can't get the bike to turn over while in off position with clutch lever pulled. Only turns over while in run position with clutch lever pulled. I have looked for a kickstand switch but don't see any wiring on the bottom end of motor aside from the main engine ground, which I have cleaned and tested for continuity to neg battery terminal, which was good.
The reason I have posted here.. I have 12.2-12.3v at both terminals on both coils... I have 12.2v at the spark plug tip constantly. When I turn the bike over, I have no spark, but see the voltage drop to 10.5ish on either spark plug. I have 12.2v at the 4 wire connector(green/white)to the signal generator, but only when that 4 wire plug is disconnected. When I plug it in to the connector to the signal generator(is this part also referred to as the exciter/ pickup coil?), I lose the voltage at that green/wire(igniter side) of that connection and don't see any voltage on the SG side of connector. Would this indicate an internal short of sorts or am I chasing my tail thinking this is the issue? Do coils generally have full voltage on both terminals as well as at the tip of spark plug and inside the wire cap?
Thank you anyone who sees this and takes time out of your day to help me.

[sgtcall]

Welcome!
Here are a couple of things to check out.

You can pull your service manual from here.
INTRUDER MANUALS AND INFORMATION
viewtopic.php?f=19&t=14168

POSTING PICTURES ON INTRUDERS ALERT
viewtopic.php?f=19&t=13992

[sgtcall]

I am sure someone smarter than me will be along shortly to give some good advice.

[hillsy v2]

Disconnect the coils and test them for resistance. You shouldn't be seeing constant DC voltage at the spark plug lead.

[FallenAngel]

YOU SHOULD SEE steady 12 VOLTS AT THE POSITIVE SIDE OF THE COIL WITH IGNITION ON
Sorry about the caps
I stubbed my toe
And you might see voltage at the spark plug wire when cranking if the coils are getting a charge But I wouldnt use my multi meter to test it

You found that a couple wires on the ignition module wire installed incorrectly causing a 15 amp fuse to blow
chances are that the ignition module needs to be replaced
I could be wrong
15amps is a big fuse
How to test Ignition coils
https://bigbikereviews.com/test-motorcy ... tion-coil/

To test your ignition signal (Be very careful not to short out your multi meter/ make sure you have no voltage in this circuit )
Disconnect the negative side of all your coils
Select voltage on your multi-meter and connect the pos wire to the coil wire and ground to a good ground
Crank the bike or rotate the engine with the ignition on
you should not see any voltage
If you do you have a short in the signal from the pick up
If you dont see voltage continue
Select OHMS on your multi-meter
with the wires still connected you should see an infinite resistance
then crank or rotate the engine you should see the needle jump or the values change
I use a graphing Multi meter
It has a bar graph that is more sensitive to changes and is very cool
If you get fluctuation than your coils are getting a signal from your points or ignition pickup

[FallenAngel]

I am sure someone smarter than me will be along shortly to give some good advice.

Its OK Sarge you have other strengths

[hillsy v2]

You found that a couple wires on the ignition module wire installed incorrectly causing a 15 amp fuse to blow
chances are that the ignition module needs to be replaced
I could be wrong
15amps is a big fuse

That's quite possible also.

Seeing constant voltage at the spark plug lead would indicate the coil is bad - hopefully that's all it is and the Ignitor is still OK.

[sgtcall]

I am sure someone smarter than me will be along shortly to give some good advice.

Its OK Sarge you have other strengths

[Herb]

take both of the wires off of the coil. Turn on the ignition and check for power on both wires. Only one wire will have power and the other should have nothing. The ignition box provdes a ground to cause the spark. If there is power on the negative wire, you have a wiring issue.

To test the coils. hook up the hot wire to the positive side of the coil. hook up a wire to the negative terminal (should be a black wire), put a spark plug in the spark plug wire and hold the outside of the spark plug to a good ground. short the negative terminal to ground. every time you touch the wire to ground you should get a spark.

I believe that a meter will show bat voltage at the negative post because it is waiting for the ground to cause the coil to make the spark.

I have never checked the sparkplug wire for votage so I am not sure if there is normally bat voltage on it.

My concern is if the trigger wire is shorted to a hot wire or installed incorrectly in the ignition box it may be getting voltage to the negative post and not getting the ground signal that causes the spark.

[FallenAngel]

I believe I have confirmed the kill switch is working properly as I can't get the bike to turn over while in off position with clutch lever pulled. Only turns over while in run position with clutch lever pulled. I have looked for a kickstand switch but don't see any wiring on the bottom end of motor aside from the main engine ground, which I have cleaned and tested for continuity to neg battery terminal, which was good.

Are you referring to the Ignition switch or the kill switch
If it only turns over with the kill switch in the run position then you have a wiring problem where the Starter circuit is wired through your ignition circuit and May just by hogging the voltage needed to charge your coils

The reason I have posted here.. I have 12.2-12.3v at both terminals on both coils... I have 12.2v at the spark plug tip constantly.

You should not have any voltage at the plug wire unless the coils are discharging

What Herb suggested is a good for checking your coils on the vehicle
The best and proper way to test coils is to remove them and do an Ohms test