mxu 500 irs efi Manuale-dofficina : Pagina 175

          9. CYLINDER/PISTON                                                                     MXU 500 IRS


 SERVICE INFORMATION
 GENERAL INSTRUCTIONS
 · The cylinder and piston can be serviced with the engine installed in the frame.
 · When installing the cylinder, use a new cylinder gasket and make sure that the dowel pins are
   correctly installed.
 · After disassembly, clean the removed parts and dry them with compressed air before inspection.

 SPECIFICATIONS                                                                           Unit: mm (in)
                 Item                                            Standard               Service Limit
           I.D.                                      92.005 (3.6802)92.015 (3.6806)   92.1 (3.684)
           Warpage                                   0.01 (0.0004)                    0.05 (0.002)
  Cylinder
           Cylindricity                              0.01 (0.0004)                    0.1 (0.004)
           True roundness                            0.01 (0.0004)                    0.1 (0.004)
           Ring-to-groove            top             0.03 (0.0012)0.065 (0.0026)      0.08 (0.003)
           clearance                 Second          0.015 (0.0006)0.05 (0.002)       0.065 (0.0026)
                                     top             0.15 (0.006)0.3 (0.012)          0.5 (0.02)
     Piston,       Ring end gap      Second          0.03 (0.012)0.45 (0.018)         0.65 (0.026)
     piston ring                     Oil side rail   0.2 (0.008)0.7 (0.028)           1 (0.04)
                   Piston O.D.                       91.96 (3.6784)91.98 (3.6793)     91.9 (3.676)
                   Piston O.D. measuring position    10 mm from bottom of skirt                
 .                 Piston-to-cylinder clearance      0.01 (0.0004)0.045 (0.0018)      0.1 (0.004)
                   Piston pin hole I.D.              22.002 (0.8801)22.008 (0.8803)   22.04 (0.8816)
 Piston pin O.D                                      21.994 (0.8798)22 (0.88)         21.96 (0.8784)
 Piston-to-piston pin clearance                      0.002 (0.0001)0.014 (0.0006)     0.02 (0.001)
 Connecting rod small end I.D. bore                  22.016 (0.8806)22.034 (0.8814)   22.06 (0.8824)

 TORQUE VALUES
 Cylinder bolt 1 kgf-m (10 N-m, 7.2 lbf-ft)


 TROUBLESHOOTING
 · When hard starting or poor performance at low speed occurs, check the crankcase breather for
   white smoke. If white smoke is found, it means that the piston rings are worn, stuck or broken.

 Compression too low or uneven
 compression                                              Excessive smoke from exhaust muffler
 · Worn or damaged cylinder and piston rings              · Worn or damaged piston rings
 · Worn, stuck or broken piston rings                     · Worn or damaged cylinder and piston

 Compression too high                                     Abnormal noisy piston
 · Excessive carbon build-up in combustion                · Worn cylinder, piston and piston rings
   chamber or on piston head                              · Worn piston pin hole and piston pin
                                                          · Incorrectly installed piston


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