Sym GTS 250 - Precautions in Operation

6. Cylinder Head / Valve
6-2
Precautions in Operation
General Information
 This chapter is contained maintenance and service for cylinder head, valve, and camshaft as well as
rocker arm.
 Cylinder head service can be carried out when engine is in frame.
Specification
Item
Standard
Limit
Compression pressure
12±2 kg/cm2
---
Camshaft
Height of cam lobe
Intake
34.880
34.860
Exhaust
34.740
34.725
Rocker arm
ID of valve rocker arm
11.982~12.000
12.080
OD of valve rocker arm shaft
11.966~11.984
11.936
Valve
OD of valve stem
Intake
4.975~4.990
4.900
Exhaust
4.950~4.975
4.900
ID of valve guide
5.000~5.012
5.030
Clearance between
valve stem and guide
Intake
0.010~0.037
0.080
Exhaust
0.025~0.062
0.100
Free length of valve
spring
Inner
38.700
35.200
outer
40.400
36.900
Valve seat width
1.600
---
Valve clearance
Intake
0.10±0.02mm
---
Exhaust
0.15±0.02mm
---
Tilt angle of cylinder head
---
0.050
Torque Value
Cylinder head cover bolt 1.0~1.4kgf-m
Exhaust pipe stud bolt 2.4~3.0kgf-m
Cylinder head bolt 1.0~1.4kgf-m
Cylinder head Nut 3.6~4.0kgf-m
Sealing bolt of cam chain auto-tensioner 0.8~1.2kgf-m
Bolt of cam chain auto-tensioner 1.2~1.6kgf-m
Cylinder side cover bolt 1.0~1.4kgf-m
Cam sprocket bolt 1.0~1.4kgf-m
Tappet adjustment screw nut 0.7~1.1kgf-m
Spark plug 1.0~1.2kgf-m
Tools
Special service tools
Valve reamer: 5.0mm
Valve guide driver: 5.0mm
Valve spring compressor
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