1999 Polaris SLH, SLTH, SLX, SLTX, PRO785 Factory Service Manual, Page 64Get this manual
MAINTENANCErrUNE UP Troubleshooting Rich Fuel Mixture
Symptoms: Fouled spark plugs; black sooty exhaust; rough idle, idle unstable; poor fuel economy; rough running ("four cycling"); misses; poor performance; bogs; loads up; backfires (plug fouling) Thermostatpopoff leak, dirty or damaged Carburetor mixture needles damaged or adjusted incorrectly Needle and seat damaged Misuse of choke Fouled spark plugs Fuel pump diaphragm damaged (ruptured) Carburetor synchronization incorrect Needle and seat control arm too high or sticking Collapsed exhaust hose or pipe (restricted) Air intake restricted Broken, cracked or poorly sealing reed valve Low compression Ignition problem Anti-siphon valve worn or broken
Symptoms: Engine backfires Weak spark from fouled, defective, worn or wrong spark plugs Broken reed petals Symptoms: Engine "pinging" or "knocking" Lean fuel mixture Poor quality, low octane gasoline Incorrect ignition timing Spark plug heat range too high Weak spark Incorrect fuel or fuel mixture Water in fuel system or oil tank Fuel filter restricted Jet intake clogged Cooling system clogged