2008 Polaris ATV Predator 50, Sportsman Outlaw 90 Service Manual, Page 87Get this manual
ENGINETRANSMISSION Engine Idles But RPM Will Not Increase Spark plug fouledweak spark Broken throttle cable Obstruction in air intake Air box removed (reinstall all intake components) Incorrect or restricted carburetor jetting ETC switch limiting speed Reverse speed limiter limiting speed Carburetor vacuum slide stickingdiaphragm damaged Incorrect ignition timingsheared flywheel key Restricted exhaust system ETC or speed limiter system malfunction Cam lobe worn Engine Has Low Power Spark plug fouled IntakeExhaust system air leaks Cylinder, piston, ring, or valve wear or damage (check compressioncylinder leakage) CVT not operating properly Restricted exhaust muffler Dirtyrestricted carburetor Cam lobe worn Piston FailureScoring Lack of lubrication Dirt entering engine through cracks in air filter or ducts Engine oil dirty or contaminated Excessive Smoke and Carbon Buildup Excessive piston-to-cylinder clearance Worn rings, piston, or cylinder Worn valves, guides or seals Restricted crankcase vent Air filter dirty or contaminated Engine oil level too high Spark plug cap crackedbroken Ignition coil faulty Ignition or kill switch circuit faulty Ignition timing incorrect Sheared flywheel key Poor connections in ignition system wiring Ignition system wiring wet Cam lobe worn or valve sticking Lean condition Fouled spark plug or incorrect plug or plug gap Carburetion faultylean condition Rocker arm sticking Backfiring Low Compression Cylinder head gasket leak No valve clearance or incorrectly adjusted Cylinder or piston worn Piston rings worn, leaking, broken, or sticking Bent valve or stuck valve Valve spring broken or weak Valve not seating properly (bent or carbon accumulated on valve area)