Sym SYM series, Manual, Page: 135 / 178

6. CYLINDER HEAD/VALVE SYM
6-2
PRECAUTIONS IN OPERATION
General Information
Ÿ
This chapter is contained maintenance and service for cylinder head, valve, and camshaft
as well as valve rocker arm.
Ÿ
Cylinder head service cannot be carried out when engine is in frame.
Specification unit: mm
Item Standard Limit
Compression pressure 12 ± 1 kg/cm² -
Intake 20.231 20.570
Camshaft
Height of cam lobe
Exhaust 19.907 19.410
ID of valve rocker arm 10.00~10.015 10.10
Rocker
arm
OD of valve rocker arm shaft 9.972~9.987 9.910
Intake 4.970~4.980 4.900
OD of valve stem
Exhaust 4.955~4.970 4.900
ID of Guide 5.00~5.012 5.030
Intake 0.020~0.042 0.080
Clearance between
valve stem and guide
Exhaust 0.030~0.057 0.100
Outer 35.250 -
Free length of valve
spring
Inner 32.410 -
Valve
Valve seat width 1.000 1.600
Torque Value
Cylinder head cover bolt 0.8~1.2kgf-m
Cylinder head bolt (LH) 0.7~1.1kgf-m
Sealing bolt of timing chain auto-adjuster 0.8~1.2kgf-m
Bolt of timing chain auto-adjuster 1.0~1.4kgf-m
Timing gear cover bolts 0.7~1.1kgf-m
(apply with oil on bolt thread & seat)
Spark plug 1.0~1.4kgf-m
TOOLS
Special service tools
Valve reamer: 5.0mm
Valve guide driver: 5.0mm
Valve spring compressor