Ignition System; Compression System - Yamaha YW50AP Service Manual

IGNITION SYSTEM

Spark plug
Ignition coil
CD I unit system
Switches and wiring

COMPRESSION SYSTEM

Cylinder and cylinder head
Piston and piston rings
Crankcase and crankshaft
Reed valve
STARTING FAILURE/HARD STARTING
PROBABLE CAUSE
8 Improper plug gap
8 Worn electrodes
8 Wire between terminals broken
8 Improper heat range
8 Faulty spark plug cap
8 Broken or shorted primary/secondary coil
8 Faulty spark plug lead
8 Broken body
8 Faulty CD I unit
8 Faulty source coil
8 Faulty pick-up coil
8 Faulty main switch
8 Broken or shorted wiring
PROBABLE CAUSE
8 Loose spark plug
8 Loose cylinder head or cylinder
8 Broken cylinder head gasket
8 Broken cylinder gasket
8 Worn, damaged or seized cylinder
8 Improperly installed piston ring
8 Worn, fatigued or broken piston ring
8 Seized piston ring
8 Seized or damaged piston
8 Improperly seated crankcase
8 Improperly sealed crankcase (Damaged oil
seal)
8 Seized crankshaft
8 Deformed reed valve stopper
8 Improperly seated read valve
8 Loose intake manifold
8 Broken gasket
8 Broken reed valve
8-2
TRBL
SHTG