Sym RS-50 Service Manual page 49

5. CYLINDER HEAD/CYLINDER/PISTON
Maintenance Information
Precautions in Operation
The inspection and maintenance of the cylinder head, cylinder and piston can be carried as engine
mounted on the body.
It should clean the engine to prevent dirt from entering into cylinder and crankcase before removal.
Remove all washes from the interfaces of cylinder head, cylinder and crankcase.
Be careful do not damage cylinder head, cylinder and piston when removing.
Inspect the removed & cleaned parts thoroughly, and apply with oil onto the rotation surfaces before
installation.
Specification
Cylinder head Deformation
Piston OD
Clearance between cylinder and piston
Piston pin hole
Piston Piston pin OD
Clearance between piston and piston pin
Piston ring end gap
ID of connecting rod small end
ID
Cylinder
Deformation
ID: inner diameter
OD: outer diameter
Tighten torque value
Cylinder head
Spark plug
Troubleshooting
Compression Pressure Too Low/Difficult
To Start/Rough Idling
1. Cylinder head gasket leaking
2. Spark plug not tighten enough
3. Worn, seized or crack piston ring
4. Damaged, worn cylinder or piston
5. Poor reed
Compression Pressure Too
High/Overheat/Knock
1. Too much carbon deposit built up in
combustion chamber
5-2
This chapter Contents
Item
1.0kgf-m
1.4kgf-m
Standard value
-
39.030~39.045
0.040~0.050
12.002~12.008
11.994~12.000
0.002~0.014
0.100~0.250
17.05~17.015
39.000~39.015
-
Exhaust pipe connection nut
Exhaust muffler mounting bolt
Piston Noise
1. cylinder and piston worn out
2. piston pin or piston pin hole worn out
3. connecting rod small end bearing worn out
Piston Ring Noise
1. Worn, seized or crack piston ring
2. Cylinder worn out or damaged
RS-21 50 series
Limit
0.100
38.935
0.100
12.030
11.970
0.030
0.400
17.025
39.050
0.100
1.2kgf-m
3.3kgf-m
mm