Yamaha PW50W 2007, Service Manual

Page: 104 / 168

ENG
5-11
CYLINDER HEAD, CYLINDER AND PISTON
2. Remove:
9
Top ring
9
Second ring
(with expander ring)
NOTE:
When removing a piston ring, open the end
gap with your fingers and lift the other side of
the ring over the piston crown.
CHECKING THE CYLINDER HEAD
1. Eliminate:
9
Combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid dam-
aging or scratching.
9
Spark plug bore threads
2. Eliminate:
9
Exhaust port carbon deposits
(with a rounded scraper)
4. Measure:
9
Cylinder head warpage
Out of specification
→
Resurface the
cylinder head.
Warpage limit
0.03 mm (0.0012 in)
3. Check:
9
Cylinder head
Damage/scratches
→
Replace the cylin-
der head.
5PG-7-10 102 06.5.16, 17:43:49