Spark plug only making one spark per start?

[martune]

I've got kind of an odd problem I'm wondering if you guys could help me out with. I'm fixing up an 87 fz600, it's never ran, I got it as a project bike. The coil connected to cylinders 2&3 only fires once each time I try and start the bike. One nice spark and then it's done until I release the starting button and try again. The coil connected to 1 & 4 never sparks.

There was no ignition switch when I got it so I bought a new one. Mice did a number on the wires so I swapped out the entire loom with one from a parts bike. CDI box swapped (behaves the same). Checked resistance on the HT coils and they both come out fine. Replaced all the spark plugs. New battery. When I swap the connections to the coils the one spark symptom moves to the other set and the other one is then completely dead. Running out of ideas, can anyone point me in the right direction?

So just to outline what's been tested & replaced already...

-New Ignition Switch
-New Wire Loom
-HT Coils test out fine
-New Spark Plugs
-CDI Box Swapped
-New Battery

[DonTZ125]

Sounds like 2 TCIs with damaged coil drivers. Check your safety switches, diode block, and relay for security and function, just to be sure.

You DO have a wiring diagram and schematic for this in-depth electrical snipe hunt, correct?

[martune]

It looks like it must have been one of the safety features causing me headaches. I cut the black and white wire going into the box and now I've got solid spark. I still hope to figure out exactly which one, but for now I should be able to get the bike running.