quannon 125 Workshop-manual : Page 63

          6. CYLINDER HEAD/VALVES                                            QUANNON 125
                                                  Straight Edge
 INSPECTION
 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: 0.05mm repair or replace if
                 over




                                                        Feeler Gauge
 VALVE SPRING FREE LENGTH
 Measure the free length of the inner and outer
 valve springs.
 Service Limits:
  (IN, EX) : 29.1mm replace if below




 VALVE /VALVE GUIDE
 Inspect each valve for bending, burning,
 scratches or abnormal stem wear.
 Check valve movement in the guide.
 Measure each valve stem O.D.
 Service Limits:
 IN    4.925mm replace if below
 EX 4.925mm replace if below

 Measure each valve guide I.D.
 Service Limits:
 IN   5.03mm replace if over
 EX 5.03mm replace if over

 Subtract each valve stem O.D. from the
 corresponding guide I.D. to obtain the stem-
 to-guide clearance.
 Service Limits:
 IN    0.08mm replace if over
 EX 0.10mm replace if over
 If the stem-to-guide clearance exceeds
    the service limits, replace the guides as
    necessary. Reface the valve seats
    whenever the valve guides are replaced.


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