Daelim S4 50cc Service Manual - Mojo

10. CYLINDER / PISTONSERVICE INFORMATION···················10-1TROUBLESHOOTING ····················10-1CYLINDER··························10-2PISTON· ··························10-3PISTON / CYLINDER INSTALLATION··············10-5SERVICE INFORMATIONGENERAL SAFETY● Be careful not to damage the mating surfaces by using a screwdriver when disassembling the cylinder. Do not strikethe cylinder too hard during disassembly, even with a rubber or plastic mallet, to prevent the possibility of damage tothe cylinder pins.● Take care not to damage the cylinder wall and piston● Check parts after disassembling, and clean and dry with an air hose prior to taking measurements.SPECIFICATIONSCYLINDERPISTON,PISTONP I N ,PISTONRINGITEM STANDARD VALUE SERVICE LIMIT39.000-39.010mm39.04mm-0.05mm-0.05mm-0.05mm38.970-38.980mm38.92mm13.008-13.012mm13.04mm12.994-13.000mm12.98mm0.008-0.018mm0.04mmTOP0.05-0.15mm0.04mmSECOND0.05-0.17mm0.04mmINNER DIAMETERTAPEROUT-OF-ROUNDHEAD CONTACT WARPAGEPISTON SKIRT OUTER DIAMETERPISTON PIN HOLE INNER DIAMETERPISTON PINOUTER DIAMETERPISTON TO PISTON PIN CLEARANCEPISTON RING TOGROOVE CLEARANCEPISTON RINGJOINT GAPCYLINDER TO PISTON CLEARANCECONNECTING ROD SMALL END INNER DIAMETERGAP BETWEEN CONNECTING ROD SMALL END AND PISTON PINTROUBLESHOOTINGOIL RING 0.020-0.040mm13.013-13.028mm0.013-0.034mm0.08mm13.05mm0.06mmUnit : mmCompression pressure too low● Piston worn● Piston ring worn or damaged● Cylinder wornEmission of white gas from muffler● Cylinder, piston, piston rings worn● Bad adjustment of piston rings● Piston, cylinder wornOver heated● Excessive carbon built up on top of pistonAbnormal engine noise● Cylinder, piston worn● Worn connecting rod small end bearing or piston pins● Damaged piston rings● Excessive carbon built up on top of piston