Generic XOR 125, Service Manual

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CYLINDER / PISTON
SERVICE INFORMATION PISTON REMOVAL
TROUBLESHOOTING PISTON INSTALLATION
CYLINDER REMOVAL CYLINDER INSTALLATION
SERVICE INFORMATION
GENERAL
Camshaft lubrication oil is fed to the cylinder head through an oil orifice in the cylinder head and engine
case. Before installing the cylinder head make sure the orifice is not clogged and the gasket, O-ring and
dowel pins are
in place.
ITEM STANDARD SERVICE LIMIT
I.D. 57.400 - 57.410 57.50
TAPER ------------ 0.10
OUT OF ROUND ------------ 0.10
Cylinder
WARPAGE ACROSS TOP ------------ 0.10
PISTON O.D. 57.3075 - 57.3095 56.500
PISTON PIN BORE 15.002 - 15.008 15.04
PISTON PIN O.D. 14.994 – 15.000 14.960
PISTON-TO-PIN CLEARANCE 0.002 – 0.014 0.02
PISTON-TO-PIN
CLEARANCE TOP 0.015 – 0.050 0.12
SECOND 0.015 – 0.050 0.12 PISTON RING-TO-RING
GROOVE CLEARANCE
TOP/SEC 0.10 –
0.25
0.5
Piston
Piston pin
Piston
rings
PISTON RING END GAP OIL 0.2 –0.7 ------------
CYLINDER-TO-PISTON CLEARANCE 0.0005 – 0.1025 0.1
CONNECTING ROD SMALL END I.D. 15.010 – 15.028 15.06
TROUBLESHOOTING
Low or unstable compression
Worn cylinder or piston rings.
Overheating
Excessive carbon build-up on piston or combustion chamber wall.
Knocking or abnormal noise
Worn piston and cylinder.
Excessive carbon build-up.
Excessive smoke
Worn cylinder, piston, or piston rings.
Improper installation of piston rings.
Scored or scratched piston or cylinder wall.
Damaged valve stem seal.