Spark Plug boots

what effect can cracked spark plug boots cause? My number 4 is actually to the point of having a piece of the outside plastic broken?

Misfires come to mind:whistle:
Pat

rough running, backfires, extra vibrations, rich fuel smell sound about right?

If the spark jumps out the crack, it won't fire the spark plug. this is a misfire. you might hear it as an irregularity in the exhaust note. If your hand is near, you might feel it as the spark enters your hand and jumps out your thigh to the frame. Ow! Remember with the dual-wire coils on the 4-cylinder bikes, the charge travels down one wire, thru the plug, thru the head, thru the other plug, and back up the other wire to the coil. If you have the timing light hooked up to the other wire in the pair, when it shorts you'll notice the light skipped a beat. Aside from the 'lectricity getting out, dirt and moisture can get in.

My wires didn't even look bad, but after noticing the above things (including the OW when I touched a wire while sitting on the running bike) I replaced mine and was glad I did. I bought a nice cheap set of wires from Z1enterprises.

i guess that would also make the bike feel like it was missing at a constant throttle too?