KZ440 Plug Fouled

My left cylinder spark plug keeps fouling. I swapped the plugs, then the wires, and it still always happens on the left. I assume it is from a mixture problem or a weak spark, and not oil fouling. The bike runs ok, but not great. Occasionally when the engine gets over 5,000-6,000 RPM, it feels like the left cylinder sort of kicks in and the bike takes off. But that doesn't always happen. I have adjusted the idle mixture and synced the carbs. No changes. The right cylinder runs perfect, the plugs are nice and tan, and it never misses. Overall, the bike is under powered and I can hear the left cylinder missing and sputtering while I ride. My neighbor said it smells like it's running rich. (I have no sense of smell, but he says he can smell the gas when I ride up the street.) I thought about rewire the coil as wiredgeorge suggests, but I don't think that's the cause since it's only one side.

Have you checked you valve clearance??? If the valves are not shutting all the way the compression will be low that will cause it not to fire all the fuel mixture.Do a compression check on the engine.if it is low check the valve clearances

Compression on left is 135 psi. Right is 133 psi.

might wanna check your coils. sounds like a low spark thing.:ohmy:

Voltage at coils looks good. It's around 12.5

I think I fixed the problem. The plug that goes over the idle jet was missing. I replaced it and now it works much better. I am still having a problem with the idle. I set the idle at 1,500 RPM and it's fine until I am riding and bring the RPM up over 4,000. After that, it won't settle back down. If I leave it in gear and use the brakes to slow the engine speed below 2,000 RPM, the idle will settle back around 1,500 RPM.