Motorcycle Repair: Loss of Power due to Coil?, old motorcycle, header pipe

Question
I have a 78 kz1000a2a, it has 19,000 miles, the coils are Accel (possibly used) and were installed when I bought the bike. Recently while at a stop light the idle changed pitch and there was a lack of power, I limped to a gas station for a tow. I thought it was a fouled plug, changed the plugs and bought a new battery, same problem. Switched coils it ran but same problem. While tinkering I've noticed that the #4 cyl. or the outer, riders right header pipe was not hot to the touch and the plug was wet when pulled. Does this sound like a coil problem, and can a coil just quit on one cylinder?  

Answer
Hi Jeremiah.
 This does sound like either a coil problem, a carb problem or a short in the ignition system.

Based on your description, I would say to start by checking the wiring to the affected coil for that cylinder from power to coil.  Use a multimeter as well as visual inspection.

You have a 26 year old motorcycle, which probably has the original wiring harness.  That means that you could have a short in the ignition system or it could be grounding out somewhere.

Let me know what you find.
Good luck.
FALCON