Sym Jet Euro X servicemanual - Scootergrisen
Sym Jet Euro X servicemanual - Scootergrisen
Sym Jet Euro X servicemanual - Scootergrisen
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5. CYLINDER HEAD/CYLINDER/PISTON<br />
Maintenance Information<br />
Precautions In Operation<br />
The inspection and maintenance of the cylinder head, cylinder and piston can be carried as<br />
engine mounted on the body.<br />
It should clean the engine to prevent dirt from entering into cylinder and crankcase before<br />
removal.<br />
Remove all washes from the interfaces of cylinder head, cylinder and crankcase.<br />
Be careful do not damage cylinder head, cylinder and piston when removing.<br />
Inspect the removed & cleaned parts thoroughly, and apply with oil onto the rotation surfaces<br />
before installation.<br />
Specification<br />
Cylinder<br />
head<br />
5-2<br />
Item Standard value<br />
(mm)<br />
JET 50 series JET 100 series<br />
Limit (mm)<br />
Standard value<br />
(mm)<br />
Limit (mm)<br />
Deformation - 0.100 - 0.100<br />
Piston OD 39.030~39.045 38.935 51.030~39.045 50.935<br />
Clearance between<br />
cylinder and piston<br />
0.040~0.050 0.100 0.040~0.050 0.100<br />
Piston pin hole 12.002~12.008 12.030 14.002~14.008 14.030<br />
Piston pin OD<br />
Piston<br />
Clearance between<br />
piston and piston pin<br />
11.994~12.000<br />
0.002~0.014<br />
11.970<br />
0.030<br />
13.994~14.000<br />
0.002~0.014<br />
13.970<br />
0.030<br />
Piston ring end gap 0.100~0.250 0.400 0.100~0.250 0.400<br />
ID of connecting rod<br />
small end<br />
17.05~17.015 17.025 17.05~17.015 17.025<br />
ID<br />
Cylinder<br />
Deformation<br />
39.000~39.015<br />
-<br />
39.050<br />
0.100<br />
51.000~51.015<br />
-<br />
51.050<br />
0.100<br />
ID: inner diameter<br />
OD: outer diameter<br />
Tighten torque value<br />
Cylinder head 1.0 kgf-m Exhaust pipe connection nut 1.2 kgf-m<br />
Spark plug 1.4 kgf-m Exhaust muffler mounting bolt 3.3 kgf-m<br />
Troubleshooting<br />
Compression Pressure Too Low/Difficult<br />
To Start/Rough Idling<br />
1. Cylinder head gasket leaking<br />
2. Spark plug not tighten enough<br />
3. Worn, seized or crack piston ring<br />
4. Damaged, worn cylinder or piston<br />
5. Poor reed<br />
Compression Pressure Too<br />
High/Overheat/Knock<br />
1. Too much carbon deposit built up in<br />
combustion chamber<br />
This chapter Contents<br />
Piston Noise<br />
1. cylinder and piston worn out<br />
2. piston pin or piston pin hole worn out<br />
3. connecting rod small end bearing worn out<br />
Piston Ring Noise<br />
1. Worn, seized or crack piston ring<br />
2. Cylinder worn out or damaged
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