Service manual

ENGINE
TROUBLESHOOTING
Engine Turns Over But Fails to Start
◎ No fuel
◎ Dirt in fuel line or filter
◎ Fuel will not pass through fuel valve
◎ Fuel pump inoperative/restricted
◎ Tank vent plugged
◎ Carb starter circuit
◎ Engine flooded
◎ Low compression (high cylinder leakage)
◎ No spark (Spark plug fouled)
Engine Does Not Turn Over
◎ Dead battery
◎ Starter motor does not turn
◎ Engine seized, rusted, or mechanical failure
◎ Kickstart components damaged
Engine Runs But Will Not Idle
◎ Restricted carburetor pilot system
◎ Carburetor misadjusted
◎ Choke not adjusted properly
◎ Low compression
◎ Crankcase breather restricted
◎ Air filter restriction
Engine Idles But Will Not Rev Up
◎ Spark plug fouled/weak spark
◎ Broken throttle cable
◎ Obstruction in air intake
◎ Air box removed (reinstall all intake components)
◎ Incorrect or restricted carburetor jetting
◎ Reverse speed limiter limiting speed
◎ Carburetor vacuum slide sticking/diaphragm damaged
◎ Incorrect ignition timing
◎ Restricted exhaust system
◎ Cam Lobe worn
Engine Has Low Power
◎ Spark plug fouled
◎ Cylinder, piston, ring, or valve wear or damage (check
compression)
◎ CVT not operating properly
◎ Restricted exhaust muffler
◎ Dirty carburetor
◎ Cam lobe worn
Piston Failure - Scoring
◎ Lack of lubrication
◎ Dirt entering engine through cracks in air filter or ducts
◎ Engine oil dirty or contaminated
Excessive Smoke and Carbon Buildup
◎ Worn rings, piston, or cylinder
◎ Excessive piston-to-cylinder clearance
◎ Worn valves, guides or seals
◎ Restricted crankcase vent
◎ Air filter dirty or contaminated
Low Compression
◎ Decompressor stuck
◎ 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)
◎ Rocker arm sticking
Backfiring
◎ ETC or speed limiter system malfunction
◎ Fouled spark plug or incorrect plug or plug gap
◎ Carburetion faulty - lean condition
◎ Intake / Exhaust system air leaks
◎ Ignition system faulty:
◎ Spark plug cap cracked/broken
◎ Ignition coil faulty
◎ Ignition or kill switch circuit faulty
◎ Ignition timing incorrect
◎ Sheared flywheel key
◎ Poor connections in ignition system
◎ System wiring wet
◎ Cam lobe worn or Valve sticking
◎ Lean condition
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