2004 Polaris Pro X Factory Service Manual, Page 26Get this manual
GENERAL INFORMATION Piston Wash and Spark Plug color
Changing temperature, barometer, altitude, and fuel supply are just few of the factors that can affect the day to day performance of your engineThat is why using Exhaust Gas Temperatures (EGTs) are important for maintaining optimum performanceThere are two methods for helping you determine what the EGTs are for your machinePiston wash and the coloring of your spark plug.The piston wash is by far the most valuable tool in concluding EGTs, with the spark plug color running distant secondUse the illustrations below to help you establish the EGTs for your machine
Piston Wash
Spark Plug Color
Wet and Black wash indicates too rich fuel mixture Wash
n If the plug is wet or very dark, the fuel is running too rich
Correct Correct If the wash is 14"38" and cocoa brown, the machine's EGTs are just rightDry