6. CYLINDER HEAD/VALVES DINK 50/ 125 INSPECTION Combustion Chamber Remove carbon deposits from the exhaust port and combustion chamber. Be careful not to damage the cylinder head mating surface. Exhaust Port Valve /Valve guide Inspect each valve for bending, burning, scratches or abnormal stem wear. If any defects are found, replace the valve with a new one. Check valve movement in the guide. Measure each valve stem O.D. Measure each valve guide I.D. Subtract each valve stem O.D. from the corresponding guide I.D. to obtain the stem-to-guide clearance. Service limits: IN: 0.08 mm (0.0032 in) EX: 0.1 mm (0.004 in) If the stem-to-guide clearance exceeds the service limits, replace the cylinder head is necessary. Valve spring Measure the free length of the inner and outer valve springs. Service Limit: Inner: 29.3 mm (1.172 in) Outer: 32 mm (1.28 in) 6-17