Spark Plug Selection; Normal; Wet Fouled - Polaris INDY TRAIL RMK Service Manual

MAINTENANCE / TUNE UP

Spark Plug Selection

Original equipment parts or their equivalent should always be used. However, the heat range of spark plugs is
of utmost importance. A spark plug with a heat range which is too high will cause engine damage. A spark plug
with a heat range which is too low will cause excessive fouling.
In selecting a spark plug heat range for production, a manufacturer is forced to assume that the engine is going
to be operated under extreme heavy duty conditions. This protects the engine from internal damage in the event
that the purchaser actually does operate the engine in this manner. This selection however, could cause the cus-
tomer who normally operates the engine under medium or light duty to experience spark plug failure.
CAUTION:
A plug with a heat range which is too high may cause engine damage if the engine is operated in conditions more
severe than that for which the spark plug was intended.
A new engine can cause temporary spark plug fouling even though the heat range is correct, due to the preserva-
tive which has been added during assembly of the engine to combat rust and corrosion. Avoid prolonged idle
speeds, as plug fouling and carbonization will result. Always use resistor type spark plugs.
NOTE: Incorrect fuel mixture can often cause a spark plug to appear to be too dark or too light in color. Before
changing spark plug heat ranges, be sure the correct jetting is installed in the carburetors and proper carburetor
function is verified.
The spark plug and its condition is indicative of engine operation. The spark plug firing end condition should be
read after the engine is warmed up and the vehicle is driven at higher speeds. Immediately check the spark plug
for correct color.

Normal

The insulator tip is gray, tan, or light brown. There will be a few combustion deposits. The electrodes are not
burned or eroded. This indicates the proper type and heat range for the engine and the service.
NOTE: The tip should not be white. A white insulator tip indicates overheating, caused by 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. 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 injec-
tion oil, excessive idling, idle too low or too rich, or weak ignition output.
1. Inspect electrodes for wear and carbon buildup. Look for a sharp outer edge with no rounding or erosion of the
electrodes.
2. Clean with electrical contact cleaner or a glass bead spark plug cleaner only.
CAUTION:
A wire brush or coated abrasive should not be used.
3. Measure gap with a wire gauge and adjust to specifications by bending ground electrode carefully.
4. Coat spark plug threads with a small amount of anti-seize compound.
5. Install spark plug and torque to specification.
Spark Plug Torque:
12-14 Ft. Lbs (16.6-19.3 Nm)
2.14