Service Information - KYMCO NEXXON 50 Service Manual

6
. CYLINDER HEAD/VALVES

SERVICE INFORMATION

GENERAL INSTRUCTIONS
• The cylinder head can be serviced with the engine installed in the frame. Coolant in the radiator
and water jacket must be drained first.
• When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable
parts and valve arm sliding surfaces for initial lubrication.
• The valve rocker arms are lubricated by engine oil through the cylinder head engine oil passages.
Clean and unclog the oil passages before assembling the cylinder head.
• After disassembly, clean the removed parts and dry them with compressed air before inspection.
• After removal, mark and arrange the removed parts in order. When assembling, install them in
the reverse order of removal.
Item
Valve clearance (cold)
Cylinder head compression pressure
Cylinder head warpage
Camshaft cam height
Valve rocker arm I.D.
Valve rocker arm shaft
O.D.
Valve stem O.D.
Valve guide I.D.
Valve stem-to-guide
clearance
TORQUE VALUES
Cylinder head cap nut
Valve clearance adjusting nut
Cylinder head cover nut
SPECIAL TOOLS
Valve spring compressor
Standard (mm)
IN 0.02
EX 0.02
13kg/cm²
⎯
⎯
IN
⎯
EX
⎯
IN
⎯
EX
⎯
IN
⎯
EX
IN 4.92～4.970
EX 4.90～4.950
⎯
IN
⎯
EX
⎯
IN
⎯
EX
1.0～2.0kg-m
0.9kg-m
1.2～1.6kg-m
NEXXON 50
Service Limit (mm)
0.04
0.04
0.05
25.8
25.6
10.
10.
9.78
9.78
4.9
4.9
5.
5.
0.1
0.1
6-2