Dirt bike engine troubleshooting guide

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  2 STROKE CARURATED ENGINE

ENGINE WILL NOT TURN

  • Piston seizure
  • Damaged pistion rings
  • Damaged piston
  • Crankshaft bearing seizure
  • Connecting rod bearing seizure
  • Damaged connecting rod
  • Gear seizure
  • Bearing seizure
  • Failed gear shaft
  • Broken gear(s)
  • Failed shifting mechanisms
  • Failed kick shaft return spring
  • Ratchet gear not engaging

ENGINE WILL NOT START

  • Kill switch stuck
  • Kill switch circuit shorted
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • Bad ignition module
  • Bad connections (connectors)
  • Kill switch stuck
  • Kill switch circuit shorted
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • Bad ignition module
  • Bad connections (connectors)
  • Fuel tank empty
  • Fuel tank vent blocked
  • Fuel line clogged
  • Fuel tank valve closed
  • Float valve stuck closed
  • Improper float adjustment
  • Clogged jets
  • Wrong fuel type
  • Contaminated fuel
  • Oil premix incorrect
  • Reeds not working correctly
  • Pilot screw adjustment incorrect
  • Pilot jet clogged/dirty
  • Pilot jet size incorrect
  • Choke circuit problem
  • Improper float adjustment
  • Flooding
  • Restricted intake
  • Bad alternator
  • Bad ignition module
  • Piston ring wear
  • Excessive piston/cylinder clearance
  • Loose spark plug
  • Cracked cylinder head
  • Leaking head gasket
  • Loose cylinder head
  • Failed crankshaft seal
  • Clogged intake
  • Dirty air filter
  • Air filter over oiled
  • Slide valve not opening
  • Reed valve stuck closed
  • Clogged muffler
  • Damaged exhaust

POOR ENGINE PERFORMANCE

  • Kill switch intermittent
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • Bad connections (connectors)
  • Wrong fuel type
  • Contaminated fuel
  • Fuel octane rating incorrect
  • Fuel/air ratio incorrect, low RPM
    • Pilot screw adjustment incorrect
    • Pilot jet clogged/dirty
    • Pilot jet size incorrect
    • Choke circuit problem
    • Improper float adjustment
    • Reeds not working correctly
    • Oil premix incorrect
  • Fuel/air ratio incorrect, mid RPM
    • Needle position incorrect
    • Needle type incorrect
    • Needle scratched/worn
    • Needle bent
    • Slow jet size incorrect
    • Slow jet clogged/dirty
    • Slide valve worn
    • Choke circuit problem
    • Improper float adjustment
    • Reeds not working correctly
    • Oil premix incorrect
  • Fuel/air ratio incorrect, high RPM
    • Main jet size incorrect
    • Main jet clogged/dirty
    • Choke circuit problem
    • Improper float adjustment
    • Reeds not working correctly
    • Oil premix incorrect
  • Bad alternator
  • Bad ignition module
  • Piston ring wear
  • Excessive piston/cylinder clearance
  • Loose spark plug
  • Cracked cylinder head
  • Leaking head gasket
  • Loose cylinder head
  • Failed crankshaft seal
  • Clogged intake
  • Dirty air filter
  • Air filter over oiled
  • Reed valve not fully opening
  • Clogged muffler
  • Damaged exhaust
  • Power valve incorrectly adjusted
  • Power valve sticking closed
  • Carbon build up in exhaust port
  • Carbon build up on power valve
  • Inadequate lubrication
  • Fuel mixture too lean
  • Oil premix incorrect
  • Low coolant level
  • Improper coolant mix
  • Failed coolant pump
  • Clogged radiator fins
  • Contaminated coolant
  • Blockage in coolant system
  • Engine mechanical problems
  • Incorrect spark plug
  • Worn clutch plates
  • Weak/failed clutch springs
  • Damaged pressure plate
  • Damaged clutch basket
  • Wrong transmission oil
  • Improperly adjusted clutch
  • Clutch cable or line problem
  • Improper lever adjustment
  • Damaged brake line
  • Damaged master cylinder
  • Damaged slave cylinder
  • Damaged slider pin(s)
  • Bent brake disk
  • Bad disk alignment
  • Improper caliper mounting
  • Damaged caliper

ENGINE KNOCKS

  • Wrong fuel type
  • Contaminated fuel
  • Fuel/air ratio incorrect
  • Fuel octane rating incorrect
  • Oil premix incorrect
  • Bad alternator
  • Bad ignition module
  • Inadequate lubrication
  • Fuel mixture too lean
  • Oil premix incorrect
  • Low coolant level
  • Improper coolant mix
  • Failed coolant pump
  • Clogged radiator fins
  • Contaminated coolant
  • Blockage in coolant system
  • Engine mechanical problems
  • Incorrect spark plug
  • Carbon in combustion chamber
  • Power valve stuck closed
  • Wrong piston
  • Missing head gasket
  • Combustion chamber volume too small
  • Worn piston
  • Worn rings
  • Worn rod bearings
  • Power valve/piston interference
  • Worn crankshaft bearings
  • Worn piston pin
  • Warped cylinder head
  • Worn cylinder walls

  4 STROKE CARURATED ENGINE

ENGINE WILL NOT TURN

  • Piston seizure
  • Damaged pistion rings
  • Damaged piston
  • Crankshaft bearing seizure
  • Connecting rod bearing seizure
  • Damaged connecting rod
  • Broken valve
  • Valve seizure
  • Seized cam shaft bearings
  • Gear seizure
  • Bearing seizure
  • Failed gear shaft
  • Broken gear(s)
  • Failed shifting mechanisms
  • Failed kick shaft return spring
  • Ratchet gear not engaging
  • Compression release not opening
  • Cylinder full of water/coolant
  • Exhaust valves not opening
  • Exhaust system blockage

ENGINE WILL NOT START

  • Kill switch stuck
  • Kill switch circuit shorted
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • Bad ignition module
  • Bad connections (connectors)
  • Kill switch stuck
  • Kill switch circuit shorted
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • Bad ignition module
  • Bad connections (connectors)
  • Fuel tank empty
  • Fuel tank vent blocked
  • Fuel line clogged
  • Fuel tank valve closed
  • Float valve stuck closed
  • Improper float adjustment
  • Clogged jets
  • Wrong fuel type
  • Contaminated fuel
  • Failed accelerator pump
  • Accelerator pump misadjusted
  • Pilot screw adjustment incorrect
  • Pilot jet clogged/dirty
  • Pilot jet size incorrect
  • Choke circuit problem
  • Problem with hot start circuit
  • Improper float adjustment
  • Flooding
  • Cam timing incorrect
  • Timing chain failure
  • Bad alternator
  • Bad ignition module
  • Improper valve adjustment
  • Improper valve adjustment
  • Valve wear
  • Bad valve spring
  • Carbon on valve seats
  • Valves not seating
  • Piston ring wear
  • Excessive piston/cylinder clearance
  • Loose spark plug
  • Cracked cylinder head
  • Leaking head gasket
  • Loose cylinder head
  • Compression release not working
  • Compression release misadjusted
  • Clogged intake
  • Dirty air filter
  • Air filter over oiled
  • Slide valve not opening
  • Dirty back fire screen
  • Intake valves not opening
  • Clogged muffler
  • Damaged exhaust
  • Exhaust valves not opening

POOR ENGINE PERFORMANCE

  • Kill switch intermittent
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • Bad connections (connectors)
  • Wrong fuel type
  • Contaminated fuel
  • Fuel octane rating incorrect
  • Fuel/air ratio incorrect, low RPM
    • Accelerator pump failed
    • Accelerator pump misadjusted
    • Pilot screw adjustment incorrect
    • Pilot jet clogged/dirty
    • Pilot jet size incorrect
    • Choke circuit problem
    • "Hot start" circuit problem
    • Improper float adjustment
  • Fuel/air ratio incorrect, mid RPM
    • Needle position incorrect
    • Needle type incorrect
    • Needle scratched/worn
    • Needle bent
    • Slow jet size incorrect
    • Slow jet clogged/dirty
    • Slide valve worn
    • Choke circuit problem
    • Improper float adjustment
  • Fuel/air ratio incorrect, high RPM
    • Main jet size incorrect
    • Main jet clogged/dirty
    • Choke circuit problem
    • Improper float adjustment
  • Cam timing incorrect
  • Bad alternator
  • Bad ignition module
  • Improper valve adjustment
  • Improper valve adjustment
  • Valve wear
  • Bad valve spring
  • Carbon on valve seats
  • Valves not seating
  • Piston ring wear
  • Excessive piston/cylinder clearance
  • Loose spark plug
  • Cracked cylinder head
  • Leaking head gasket
  • Loose cylinder head
  • Compression release not working
  • Compression release misadjusted
  • Dirty air filter
  • Air filter over oiled
  • Dirty back fire screen
  • Intake valves not opening
  • Clogged muffler
  • Damaged exhaust
  • Exhaust valve(s) not opening fully
  • Inadequate lubrication
  • Fuel mixture too lean
  • Low coolant level
  • Improper coolant mix
  • Failed coolant pump
  • Clogged radiator fins
  • Contaminated coolant
  • Blockage in coolant system
  • Engine mechanical problems
  • Incorrect spark plug
  • Worn clutch plates
  • Weak/failed clutch springs
  • Damaged pressure plate
  • Damaged clutch basket
  • Wrong transmission oil
  • Improperly adjusted clutch
  • Clutch cable or line problem
  • Improper lever adjustment
  • Damaged brake line
  • Damaged master cylinder
  • Damaged slave cylinder
  • Damaged slider pin(s)
  • Bent brake disk
  • Bad disk alignment
  • Improper caliper mounting
  • Damaged caliper

ENGINE KNOCKS

  • Wrong fuel type
  • Contaminated fuel
  • Fuel octane rating incorrect
  • Fuel/air ratio incorrect, low RPM
  • Bad alternator
  • Bad ignition module
  • Cam timing incorrect
  • Improper valve adjustment
  • Inadequate lubrication
  • Fuel mixture too lean
  • Low coolant level
  • Improper coolant mix
  • Failed coolant pump
  • Clogged radiator fins
  • Contaminated coolant
  • Blockage in coolant system
  • Engine mechanical problems
  • Incorrect spark plug
  • Carbon in combustion chamber
  • Exhaust valves not opening correctly
  • Wrong piston
  • Missing head gasket
  • Combustion chamber volume too small
  • Worn piston
  • Worn rings
  • Worn rod bearings
  • Worn camshaft bearings
  • Worn crankshaft bearings
  • Worn piston pin
  • Warped cylinder head
  • Worn cylinder walls

  4 STROKE EFI ENGINE

ENGINE WILL NOT TURN

  • Piston seizure
  • Damaged pistion rings
  • Damaged piston
  • Crankshaft bearing seizure
  • Connecting rod bearing seizure
  • Damaged connecting rod
  • Broken valve
  • Valve seizure
  • Seized cam shaft bearings
  • Gear seizure
  • Bearing seizure
  • Failed gear shaft
  • Broken gear(s)
  • Failed shifting mechanisms
  • Failed kick shaft return spring
  • Ratchet gear not engaging
  • Compression release not opening
  • Cylinder full of water/coolant
  • Exhaust valves not opening
  • Exhaust system blockage

ENGINE WILL NOT START

  • Kill switch stuck
  • Kill switch circuit shorted
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • ECU problem
  • Bad crank shaft sensor
  • Bad connections (connectors)
  • Kill switch stuck
  • Kill switch circuit shorted
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • Wet alternator
  • ECU problem
  • Bad crank shaft sensor
  • Bad connections (connectors)
  • Fuel tank empty
  • Fuel tank vent blocked
  • Fuel pump not working
  • Fuel pump inlet clogged
  • Fuel injector not working
  • Fuel injector clogged
  • ECU problem
  • Throttle position sensor problem
  • Wrong fuel type
  • Contaminated fuel
  • Inadequate fuel pressure
  • Fuel injector malfunctioning
  • ECU problem
  • Throttle position sensor problem
  • Cam timing incorrect
  • Timing chain failure
  • Bad alternator
  • ECU problem
  • Crank shaft position sensor problem
  • Improper valve adjustment
  • Improper valve adjustment
  • Valve wear
  • Bad valve spring
  • Carbon on valve seats
  • Valves not seating
  • Piston ring wear
  • Excessive piston/cylinder clearance
  • Loose spark plug
  • Loose injector
  • Cracked cylinder head
  • Leaking head gasket
  • Loose cylinder head
  • Compression release not working
  • Compression release misadjusted
  • Clogged intake
  • Dirty air filter
  • Air filter over oiled
  • Throttle body not opening
  • Dirty back fire screen
  • Intake valves not opening
  • Clogged muffler
  • Damaged exhaust
  • Exhaust valves not opening

POOR ENGINE PERFORMANCE

  • Kill switch intermittent
  • Wet kill switch contacts
  • Bad ignition coil
  • Bad spark plug
  • Bad spark plug wire
  • Incorrect spark plug
  • Spark plug gap wrong
  • Spark plug wire connection bad
  • Bad alternator
  • Damaged alternator wires
  • ECU problem
  • Bad crankshaft sensor
  • Wet alternator
  • Bad connections (connectors)
  • Wrong fuel type
  • Contaminated fuel
  • Fuel octane rating incorrect
  • Inadequate fuel pressure
  • Fuel injector malfunctioning
  • ECU problem
  • Cam timing incorrect
  • Bad alternator
  • ECU problem
  • Bad crankshaft sensor
  • Improper valve adjustment
  • Improper valve adjustment
  • Valve wear
  • Bad valve spring
  • Carbon on valve seats
  • Valves not seating
  • Piston ring wear
  • Excessive piston/cylinder clearance
  • Loose spark plug
  • Loose injector
  • Cracked cylinder head
  • Leaking head gasket
  • Loose cylinder head
  • Compression release not working
  • Compression release misadjusted
  • Dirty air filter
  • Air filter over oiled
  • Dirty back fire screen
  • Intake valves not opening
  • Clogged muffler
  • Damaged exhaust
  • Exhaust valve(s) not opening fully
  • Inadequate lubrication
  • Fuel mixture too lean
  • Low coolant level
  • Improper coolant mix
  • Failed coolant pump
  • Clogged radiator fins
  • Contaminated coolant
  • Blockage in coolant system
  • Engine mechanical problems
  • Incorrect spark plug
  • ECU problem
  • Worn clutch plates
  • Weak/failed clutch springs
  • Damaged pressure plate
  • Damaged clutch basket
  • Wrong transmission oil
  • Improperly adjusted clutch
  • Clutch cable or line problem
  • Improper lever adjustment
  • Damaged brake line
  • Damaged master cylinder
  • Damaged slave cylinder
  • Damaged slider pin(s)
  • Bent brake disk
  • Bad disk alignment
  • Improper caliper mounting
  • Damaged caliper

ENGINE KNOCKS

  • Wrong fuel type
  • Contaminated fuel
  • Fuel octane rating incorrect
  • ECU problem
  • Bad alternator
  • ECU problem
  • Bad crank shaft sensor
  • Cam timing incorrect
  • Improper valve adjustment
  • Inadequate lubrication
  • Low coolant level
  • Improper coolant mix
  • Failed coolant pump
  • Clogged radiator fins
  • Contaminated coolant
  • Blockage in coolant system
  • Engine mechanical problems
  • Incorrect spark plug
  • Carbon in combustion chamber
  • Exhaust valves not opening correctly
  • Wrong piston
  • Missing head gasket
  • Combustion chamber volume too small
  • Worn piston
  • Worn rings
  • Worn rod bearings
  • Worn camshaft bearings
  • Worn crankshaft bearings
  • Worn piston pin
  • Warped cylinder head
  • Worn cylinder walls

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