Polaris Sportsman 450 Owner's Manual page 117

TROUBLESHOOTING
Engine Backfires
Possible Cause
Weak spark from spark plugs
Incorrect spark plug gap or heat range
Old or non-recommended fuel
Incorrectly installed spark plug wires
Incorrect ignition timing
Mechanical failure
Engine Runs Irregularly, Stalls or Misfires
Possible Weak Spark Cause
Fouled or defective spark plugs
Worn or defective spark plug wires
Incorrect spark plug gap or heat range
Loose ignition connections
Water present in fuel
Low battery voltage
Kinked or plugged fuel vent line
Incorrect fuel
Clogged air filter
Reverse speed limiter malfunction
Electronic throttle control malfunction
Other mechanical failure
Possible Lean Fuel Mixture Cause
Low or contaminated fuel
Low octane fuel
Clogged fuel filter
Incorrect jetting
Possible Rich Fuel Mixture Cause
Overuse of choke
Fuel is very high octane
Incorrect jetting
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Solution
Inspect, clean and/or replace spark plugs
Set gap to specs or replace plugs
Replace with new fuel
See your Polaris dealer
See your Polaris dealer
See your Polaris dealer
Solution
Inspect, clean and/or replace spark plugs
See your Polaris dealer
Set gap to specs or replace plugs
Check all connections and tighten
Replace with new fuel
Recharge battery to 12.5 VDC
Inspect and replace
Replace with recommended fuel
Inspect and clean or replace
See your Polaris dealer
See your Polaris dealer
See your Polaris dealer
Solution
Add or change fuel, clean the fuel system
Replace with recommended fuel
Replace filter
See your Polaris dealer
Solution
Inspect, clean and/or replace spark plugs
Replace with lower octane fuel
See your Polaris dealer