Compression Too Low, Hard Starting Or Poor Performance At Low Speed; Compression Too High, Overheating Or Knocking; Abnormal Noisy Piston; Abnormal Noisy Piston Rings - KYMCO SUPER 9 50 Service Manual

6
. CYLINDER HEAD/CYLINDER/PISTON

SERVICE INFORMATION

GENERAL INSTRUCTIONS
• The cylinder head, cylinder and piston can be serviced with the engine installed in the frame.
• Before disassembly, clean the engine to prevent dust from entering the engine.
• Remove all gasket material from the mating surfaces.
• Do not use a driver to pry between the cylinder and cylinder head, cylinder and crankcase.
• Do not damage the cylinder inside and the piston surface.
• After disassembly, clean the removed parts before inspection. When assembling, apply the
specified engine oil to movable parts.
SPECIFICATIONS
Item
Cylinder head warpage
Piston O.D.(5mm from bottom of piston
Cylinder-to- piston clearance
Piston pin hole I.D.
Piston pin O.D.
Piston-to-piston pin clearance
Piston ring end gap (top/second)
Connecting rod small end I.D.
Cylinder bore
TORQUE VALUES
Cylinder head bolt
Exhaust muffler joint lock nut 9.8～13.72N-m
Exhaust muffler lock bolt
Spark plug

TROUBLESHOOTING

Compression too low, hard starting
or poor performance at low speed
• Leaking cylinder head gasket
• Loose spark plug
• Worn, stuck or broken piston and piston rings
• Worn or damaged cylinder and piston
Compression too high, overheating
or knocking
• Excessive carbon build-up in cylinder head
or on piston head
6-1
Standard (mm)
SH10DA
38.970
0.03～0.07
12.002
11.994
0.002～0.014
0.10
17.005
39.0
14.7～16.66N-m
29.4～35.28N-m
10.78～16.66N-m

Abnormal noisy piston

• Worn cylinder and piston
• Worn piston pin or piston pin hole
• Worn connecting rod small end bearing

Abnormal noisy piston rings

• Worn, stuck or broken piston rings
• Worn or damaged cylinder
SF10DA
SH10DA
⎯
～
38.955
～
12.008
～
12.0
～
0.25
～ 17.017
～
39.025
SUPER 9 50
Service Limit (mm)
SF10DA
0.10
38.90
0.10
12.03
11.98
0.03
0.40
17.03
39.05