No spark to left side coil

[9812vCTD]

Hey all, I recently picked up a 1982 GS450L and I'm having an issue where I'm only getting spark from the right side coil. Both coils are good, because I have switched them right to left only to have the same symptom. The strange part is that both coils are getting power to them when the key is turned on. Any ideas?

[Steve]

Popwer to the coil is only half the battle.

As power leaves the coil, it goes throught the ignitor to get switched on and off to actually make the spark.

Since you "know it's not the coil", that only leaves the pickup coil or the ignitor or the wiring between them.

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[9812vCTD]

So the ground is switched by the igniter? That is odd, because when I was taking my voltage readings (on both sides) I used the negative wire that plugs into the coil for my ground and I was getting a constant signal.

[Steve]

The switching transistors in the ignitor are normally in the ON position so that current will flow. The spark is created when current is turned OFF (similar to points opening), and that event is triggered by the pickup coils on the right end of the crank. It is a very short-duration event, so you will normally see a ground from the coil terminal.

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[9812vCTD]

Okay, that makes sense. I will take another look with my new information. Thanks!