7. CYLINDER/PISTON K-PIPE 125 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 Item Standard Limit (mm) Service Limit (mm) I.D. 52.4 Warpage 0.05 Cylinder Cylindricity 0.05 True roundness 0.05 Ring-to-groove Top 0.12 clearance Second 0.12 Ring end gap Top 0.10.25 0.5 Second 0.10.25 0.5 Piston, Oil side rail 0.10.25 0.5 Piston ring Piston O.D. 51.76551.58 51.6 5mm from bottom of 5mm from bottom of Piston O.D. measuring position skirt skirt Piston-to-piston pin clearance 0.0050.014 0.1 Piston pin hole I.D. 13.00213.008 13.0 Piston pin O.D 12.99412.000 12.944 Connecting rod small end I.D. bore 13.01613.027 13.08 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 · Excessive carbon build-up in combustion chamber or on piston head Abnormal noisy piston · Worn cylinder, piston and piston rings · Worn piston pin hole and piston pin · Incorrectly installed piston 7-3