Kymco Agility 50 - Service manual > Cylinder Head/Valves

SERVICE INFORMATION

GENERAL INSTRUCTIONS

• The cylinder head can be serviced with the engine installed in the frame.
• When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable parts, valve arm and camshaft sliding surfaces for initial lubrication.
• The camshaft is lubricated by engine oil through the cylinder head engine oil passages. Clean and unclog the oil passages before assembling the cylinder head.
• After disassembly, clean the removed parts and dry them with compressed air before inspection.
• After removal, mark and arrange the removed parts in order. When assembling, install them in the reverse order of removal.

SPECIFICATIONS

TORQUE VALUES

Cylinder head nut   1.8~2.2kgf-m   Apply engine oil to threads

Valve clearance adjusting nut   0.7~1.1kgf-m   Apply engine oil to threads

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

• Compression too low

Compression too low

• Incorrect valve clearance adjustment
• Burned or bend valves
• Incorrect valve timing
• Broken valve spring
• Poor valve and seat contact
• Leaking cylinder head gasket
• Warped or cracked cylinder head
• Poorly installed spark plug

Compression too high

• Excessive carbon build-up in combustion chamber

White smoke from exhaust muffler

• Worn valve stem or valve guide
• Damaged valve stem seal

Abnormal noise

• Incorrect valve clearance adjustment
• Sticking valve or broken valve spring
• Damaged or worn camshaft
• Worn cam chain guide
• Worn camshaft and rocker arm

• Camshaft removal
• Cylinder head removal
• Cylinder head installation

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