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 9-2