KYMCO MX 125 - Troubleshooting

7. CYLINDER HEAD/VALVES
7-3
MX’er SYSTEM
TORQUE VALUES
Cylinder head nut 1.82.2kgf-m Apply engine oil to threads
Valve clearance adjusting nut 1.41.8kgf-m Apply engine oil to threads
Stud bolt 0.71.1kgf-m
SPECIAL TOOLS
Valve spring compressor E040
Tappet adjuster E012
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