mxer mxu 150 Workshop-manual : Page 106

          7. CYLINDER HEAD/VALVES                                                             ATV 150/125


 TORQUE VALUES
 Cylinder head nut               2 kgf-m (20 N-m, 14 ldf-ft)     Apply engine oil to threads
 Valve clearance adjusting nut   0.9 kgf-m (9 N-m, 6.5 lbf-ft)   Apply engine oil to threads
 Stud bolt                       0.9 kgf-m (9 N-m, 6.5 lbf-ft)


 SPECIAL TOOLS
 Valve spring compressor           E040
 Tappet adjuster                   E012




 TROUBLESHOOTING
 · The poor cylinder head operation can be diagnosed by a compression test or by tracing engine
   top-end noises.

 Poor performance at idle speed                      White smoke from exhaust muffler
 · Compression too low                               · Worn valve stem or valve guide
                                                     · Damaged valve stem seal
 Compression too low
 · Incorrect valve clearance adjustment              Abnormal noise
 · Burned or bend valves                             · Incorrect valve clearance adjustment
 · Incorrect valve timing                            · Sticking valve or broken valve spring
 · Broken valve spring                               · Damaged or worn camshaft
 · Poor valve and seat contact                       · Worn cam chain guide
 · Leaking cylinder head gasket                      · Worn camshaft and rocker arm
 · Warped or cracked cylinder head
 · Poorly installed spark plug

 Compression too high
 · Excessive carbon build-up in combustion
   chamber




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