Cleaning the Spark Plug Caps
Short explanation: The inside of the hard plastic caps accumulate crud the can short out the spark. This can cause rough running or failure to start. Every time you do any work on the bike: remove them disassemble and clean them and renew the wires or at least the connections.
The long Explanation, Warning engineering information can cause Drowsiness.
The ancient cylinder design of the EX engine dictates that the spark emanate form the center of the combustion chamber. In order to get it there, the plugs had to be located down deep in a well between the cams. This well is a perfect place for dirt and moisture to accumulate. Then because there is no cooling water at this point the metal around the plug runs very hot. Surround this with the large amount of cool metal and you have a recipe for condensation. Further exaggerating the situation we have two leaky coolant connections that drip coolant into the wells. Now K did drill a drain hole between the fins to help (a little) but it often gets plugged up.
The moisture boils off the base of the plug and the vapor condenses on the cool plastic cap and the plug insulator. This moisture forms a easier path for the electrons to ground than jumping the gap at the plug to make a spark. Misfire.
This issue is right up there with Pilot jets as a cause of trouble.
Kawasaki did make a feeble attempt to help this problem. at one of the engine design reviews they closed the end of the gallery between the cams. presumably to keep out the water. Of course this served to help keep the water in better. (the engineers at Kawasaki must be Democrats)
Fixes: Trash the whole plug lead from the coils and replace with a set of molded caps with copper wire. Clean them often certainly after any rain or washing. be sure the drain holes are open. blow the wells clean with compressed air at every opportunity.
You can add this feature to the long list of deficiencies that are designed into this engine. Like the Starter clutch, the water pump, The oval cylinders , etc, etc... And you can see why I have a dim view of this power plant.
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