KYMCO Vitality 50, Руководство пользователя, Страница: 109 / 275

7. CYLINDER HEAD (2-STROKE)/
CYLINDER/PISTO
N
7-3
VITALITY 50
SERVICE INFORMATION (2-STROKE)
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
2-Stroke
Cylinder head warpage 
0.10
Piston O.D.(5mm from bottom of piston skirt)
38.970 38.955 38.90
Cylinder-to- piston clearance  0.10
Piston pin hole I.D.
12.002 12.008 12.03
Piston pin O.D. 11.994 12.0 11.98
Piston-to-piston pin clearance 
0.03
Piston ring end gap (top/second)
0.10 0.25 0.40
Connecting rod small end I.D. 17.005 17.017 17.03
Cylinder bore
39.0 39.025 39.05
TORQUE VALUES
Cylinder head bolt 1.0 1.2kg-m
Exhaust muffler joint lock nut 1.0 1.4kg-m
Exhaust muffler lock bolt
3.0 3.6kg-m
Spark plug 1.1 1.7kg-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