kymco mo bw 50 Manual Do Serviço

6

. CYLINDER HEAD/CYLINDER/PISTON

6-1

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

Standard (mm)

Service Limit (mm)

Item

B&W50

B&W50

Cylinder head warpage



0.10

Piston O.D.(5mm from bottom of piston
skirt)

38.970

_

38.955

38.90

Cylinder-to- piston clearance

0.03_ 0.07

0.10

Piston pin hole I.D.

12.002

_

12.008

12.03

Piston pin O.D.

11.994

_

12.0

11.98

Piston-to-piston pin clearance

0.002_ 0.014

0.03

Piston ring end gap (top/second)

0.10

_

0.25

0.40

Connecting rod small end I.D.

17.005

_

17.017

17.03

Cylinder bore

39.0

_

39.025

39.05

TORQUE VALUES
Cylinder head bolt

14.7_ 16.66N-m

Exhaust muffler joint lock nut 9.8_ 13.72N-m
Exhaust muffler lock bolt

29.4_ 35.28N-m

Spark plug

10.78_ 16.66N-m

TROUBLESHOOTING

Compression too low, hard starting

or poor performance at low speed

Abnormal noisy piston

• Leaking cylinder head gasket

• Worn cylinder and piston

• Loose spark plug

• Worn piston pin or piston pin hole

• Worn, stuck or broken piston and piston rings

• Worn connecting rod small end bearing

• Worn or damaged cylinder and piston
Compression too high, overheating

or knocking

Abnormal noisy piston rings

• Excessive carbon build-up in cylinder head

• Worn, stuck or broken piston rings

or on piston head

• Worn or damaged cylinder