kxr 50 90 2 Manuel atelier : Page 103

          7. CYLINDER HEAD/VALVES
  (Mongoose/KXR 90)                                                    Mongoose/KXR 90/50


 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
                 Item                        Standard (mm)             Service Limit (mm)
                               IN                  0.1                         
 Valve clearance (cold)
                               EX                  0.1                         
 Cylinder head compression pressure           162kg/cm
 Cylinder head warpage                                                        0.05
                               IN               26.4881                       26.33
 Camshaft cam height
                               EX               25.8073                       25.65
 Valve rocker arm to shaft clearance          0.0340.09                        0.1
 Valve stem-to-guide           IN            0.0100.037                       0.06
 clearance                     EX            0.0250.052                       0.08
                               IN                 32.3                        30.8
 Valve spring free length
                               EX                  35                          33.5
 Valve spring                  IN        3.473.87kg(at 26.0mm)                  
 compressed force              EX        8.2910.19kg(at 29.0mm)                 




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