7. CYLINDER HEAD/VALVES AGILITY 125
TORQUE VALUES
Cylinder head nut 2.0kg-m Apply engine oil to threads
Valve clearance adjusting nut 0.9kg-m Apply engine oil to threads
Stud bolt 0.9~1.1kg-m
SPECIAL TOOLS
Valve spring compressor
TROUBLESHOOTING
· The poor cylinder head operation can be diagnosed by a compression test or by tracing engine
top-end noises.
Poor performance at idle speed White smoke from exhaust muffler
· Compression too low · Worn valve stem or valve guide
· Damaged valve stem seal
Compression too low
· Incorrect valve clearance adjustment Abnormal noise
· Burned or bend valves · Incorrect valve clearance adjustment
· Incorrect valve timing · Sticking valve or broken valve spring
· Broken valve spring · Damaged or worn camshaft
· Poor valve and seat contact · Worn cam chain guide
· Leaking cylinder head gasket · Worn camshaft and rocker arm
· Warped or cracked cylinder head
· Poorly installed spark plug
Compression too high
· Excessive carbon build-up in combustion
chamber
7-2
4.7 / 5