8. CYLINDER HEAD/VALVES                           MXU 550EXi /MXU500i



 INSPECTION

 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
                    EX: 0.1 mm
 If   the stem-to-guide clearance exceeds
   the service limits, replace the cylinder
   head is necessary.




 Cylinder head

 Check the spark plug hole and valve areas for
 cracks.

 Check the cylinder head for warpage with a
 straight edge and feeler gauge.

 Service Limit: 0.05 mm (0.002 in)




 Valve spring

 Measure the free length of the inner and outer
 valve springs.

 Service Limit:
                  Inner: 33.4 mm
                  Outer: 38 mm



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