6. CYLINDER HEAD/CYLINDER/PISTON SUPER 9 50 SERVICE INFORMATION GENERAL INSTRUCTIONS · The cylinder head, cylinder and piston can be serviced with the engine installed in the frame. · Before disassembly, clean the engine to prevent dust from entering the engine. · Remove all gasket material from the mating surfaces. · Do not use a driver to pry between the cylinder and cylinder head, cylinder and crankcase. · Do not damage the cylinder inside and the piston surface. · After disassembly, clean the removed parts before inspection. When assembling, apply the specified engine oil to movable parts. SPECIFICATIONS Standard (mm) Service Limit (mm) Item SH10DA SF10DA SH10DA SF10DA Cylinder head warpage 0.10 Piston O.D.(5mm from bottom of piston 38.97038.955 38.90 Cylinder-to- piston clearance 0.030.07 0.10 Piston pin hole I.D. 12.00212.008 12.03 Piston pin O.D. 11.99412.0 11.98 Piston-to-piston pin clearance 0.0020.014 0.03 Piston ring end gap (top/second) 0.100.25 0.40 Connecting rod small end I.D. 17.00517.017 17.03 Cylinder bore 39.039.025 39.05 TORQUE VALUES Cylinder head bolt 14.716.66N-m Exhaust muffler joint lock nut 9.813.72N-m Exhaust muffler lock bolt 29.435.28N-m Spark plug 10.7816.66N-m TROUBLESHOOTING Compression too low, hard starting or poor performance at low speed Abnormal noisy piston · Leaking cylinder head gasket · Worn cylinder and piston · Loose spark plug · Worn piston pin or piston pin hole · Worn, stuck or broken piston and piston rings · Worn connecting rod small end bearing · Worn or damaged cylinder and piston Compression too high, overheating or knocking Abnormal noisy piston rings · Excessive carbon build-up in cylinder head · Worn, stuck or broken piston rings or on piston head · Worn or damaged cylinder 6-1