1992-1998 Kawasaki PWC Jet Ski Service Repair Manual., Page 114Get this manual
SPARK PLUG EVALUATION mixture, the in the combustion is high enough to burn off the deposits the insulator
Too Cool dark insulator, with deposits, indicates the plug is running coolThis condition caused by low compression by using spark plug of an incorrect rangeIf this condition shows on only plug is usually caused by low compression in cylinderIf both plugs have this appearance, the it is probably due the plugs having too-low rangeFouled fouled spark plug may caused by the oily deposits on the insulator shorting the high-tension ground inside the shellThe condition may also caused by ignition problems which hightension pulse from being delivered the spark plugCarbon Deposits Heavy carbon-like deposits indication of excessive oil in the fuelThis condition the result of worn piston rings excessive ring end gap
This spark plug foul from operating with an overrich airlfitel mixture, possibly caused by an improper
carburetor adjustment