Polaris Sportsman 400 Service Manual page 146

SPARK PLUG FOULING
S
Spark plug cap loose or faulty
S Choke cable adjustment or plunger/cable sticking
S Foreign material on choke plunger seat or plunger
S
Incorrect spark plug heat range or gap
S Carburetor inlet needle and seat worn
S Jet needle and/or needle jet worn or improperly adjusted
S Excessive carburetor vibration (loose or missing needle jet locating pins)
S Loose jets in carburetor or calibration incorrect for altitude/temperature
S
Incorrect float level setting
S PVT system calibrated incorrectly or components worn or mis-adjusted
S
Fuel quality poor (old) or octane too high
S Low compression
S
Restricted exhaust
S Weak ignition (loose coil ground, faulty coil, stator, or ETC switch)
S ETC switch mis-adjusted
S
Restricted air filter (main or pre-cleaner) or breather system
S Improperly assembled air intake system
S
Restricted engine breather system
S Oil contaminated with fuel
S
Restricted oil tank vent
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ENGINE
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