6. 4-STROKE: CYLINDER HEAD/VALVES VITALITY 50 TORQUE VALUES Cylinder head cover bolt 0.81.2kgf-m Cam shaft hold nut 1.21.6kgf-m Apply engine oil to threads Tappet adjusting nut 0.71.1kgf-m SPECIAL TOOLS Valve spring compressor E040 Tappet adjuster E036 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 6-3