Carbs pop when key is turned off

So the timing is tit's. Carbs are clean. Petcock is flowing fuel to both inlets. Valves are in clearance. The bike starts and isn't firing on all four. I turn her off and the 3 exhaust pipe is cool compared to the others. When I take the plug wire off the plug and lean it on the motor it arcs. This is with the motor off and just turning the key to on. Then every now and then when I flip the key to off it pops through the carbs. This is weird. The high tension lead may be bad or the coil? But wouldn't both 2 and 3 cylinders be cold if the coil was bad?(kz900)

This never happen to anyone? Any ideas?

What ignition are you using?
Wayne

If using a dyna s igniton it will "pop" when shutting the key off with the bike not running. I believe its just releasing the power stored in the coils. But as far as the dead cylinder it could be a bad or unplugged plug wire. I have seen them work out of a dyna coil if not pushed in properly. It could be bad plug. Or could be worse like lack of compression because of valve adjustment or other motor damage.

not sure what your carbs look like but with mine I would look for a needle/slide not shutting and spark/boom right in the fuel bowl. from what I understand the 900 would have the non throttle slides so it is over my head.

Dyna ignition. I heard the dyna will pop sometimes because it is releasing it's energy or something. Plugs are brand new but the wires and coils are what I had before. The coils aren't kawi. I believe they are gs1000. They are light tan.

Are the coils the right ohms for that ignition? I would try running the motor or cranking it over with a known good plug on number 3 lead and see if it sparks continuously. You need to confirm no spark. Hopefully just an electrical issue. Is the non firing cylinder getting wet with fuel?

Wayne

I have a good spark. I checked the float level and it was fine. I cleared all passages in carb again. The plug is brand new. That one cylinder is not responding/ Would it do this if the coils are the wrong the ohms?

I am not sure about running diffrent coils. But i know you can run other than 3ohm. but i know with a dyna s igniton and dyna coils, Your not suspose to run supression caps. Like kzz1king said, is the plug wet after removal? what all did you mess with? did it run before you messed with it? Are you sure its only dead on one cyclinder and not two? If so could be crossed plug wire.

when I bought the ignition Z1 said I could run with other coil, but to get the most bang for my buck I would need 3 ohm coils. The exhaust on 3 is cool to touch while the others are hot when fired up. I did the coil mod recently. But last night I hard wired again to see if it was the mod somehow?.. No difference. So now it's back on the coil relay. New Dyna s ignition. But this problem had occured before the ignition. See, previously I had thought it was the condensers that was causing this. But with the new ignition it hasn't fixed it. How do I tell if it's a suppression cap? That one cap is different than the rest.

The dead cylinder has a Nichiwa LB05F cap on it. The others have ngk and are running fine. Is that gonna effect it. Surely not. That's not a suppression cap is it? And neither are the plugs.

You still have a dirty carb. Find a shop with an ultrasonic cleaner and have them clean it.