Polaris 2003 Universal Snowmobiles - Manual (Page 125)

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MAINTENANCE
General Maintenance
A new engine can cause temporary spark plug fouling due to the
preservative added during the assembly process. Avoid prolonged idle
speeds, which cause plug fouling and carbonization.
D
Use recommended spark plugs with the proper gap. Refer to your
Owner’s Manual Supplement for specific information on your ma-
chine.
D
Spark plug torque is 18-22 ft. lbs. (2.5-3 kg/m).
D
Always carry spare spark plugs in case of an emergency.
The spark plug condition indicates how well the engine is operating.
Check the color of the spark plug immediately after the engine has
been warmed up and after the snowmobile has been driven at higher
speeds.
NOTE: Incorrect fuel mixture can often cause a spark plug to appear
too dark or too light in color. Before changing spark plug heat ranges,
be sure the correct main jet is installed in the carburetor(s). Refer to
the Owner’s Manual Supplement or see your dealer.
Normal:
The insulator tip is gray, tan, or light brown. There will be a few
combustion deposits, but the electrodes are not burned or eroded. This
indicates the spark plug is the proper type and heat range for the engine
and the service.
Overheating:
The insulator tip is white. General causes are use of an improper spark
plug or incorrect carburetion adjustments.
Wet Fouled:
The insulator tip is black. A damp, oily film covers the firing end, and
there may be a carbon layer over the entire nose. Generally, the
electrodes are not worn. General causes are excessive oil, use of
non-recommended injection oil, excessive idling, idle set too low or
too rich, or weak ignition output.