Service Information; Troubleshooting - KYMCO ZX/SCOUT 50 Service Manual

6
. CYLINDER HEAD/CYLINDER/PISTON

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.
specified engine oil to movable parts.
SPECIFICATIONS
Item
Cylinder head warpage
Piston O.D.(5mm from bottom of piston
Cylinder-to- piston clearance
Piston pin hole I.D.
Piston pin O.D.
Piston-to-piston pin clearance
Piston ring end gap (top/second)
Connecting rod small end I.D.
Cylinder bore
TORQUE VALUES
Cylinder head bolt
Exhaust muffler joint lock nut 1.0 1.4kg-m
Exhaust muffler lock bolt
Spark plug
●TROUBLESHOOTING
Compression too low, hard starting
or poor performance at low speed
• Leaking cylinder head gasket
• Loose spark plug
• Worn, stuck or broken piston and piston rings
• Worn or damaged cylinder and piston
Compression too high, overheating
or knocking
• Excessive carbon build-up in cylinder head
or on piston head
Standard (mm)
SC10AS
38.955 38.970
12.002 12.008
11.994 12.0
0.10 0.25
17.005 17.017
39.0 39.025
1.5 1.7kg-m
3.0 3.6kg-m
1.1 1.7kg-m
Abnormal noisy piston
• Worn cylinder and piston
• Worn piston pin or piston pin hole
• Worn connecting rod small end bearing
Abnormal noisy piston rings
• Worn, stuck or broken piston rings
• Worn or damaged cylinder
When assembling, apply the
Service Limit (mm)
⎯
←
ZX / SCOUT
SC10AS
0.10
38.90
0.10
12.03
11.98
←
0.40
17.03
39.05
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