Checking The Cylinder Head - Yamaha XF50W Service Manual

CYLINDER HEAD
EAS00227

CHECKING THE CYLINDER HEAD

1. Eliminate:
8combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid damag-
ing or scratching:
• spark plug bore thread
• valve seats
2. Check:
• cylinder head
Damage/scratches
3. Measure:
• cylinder head warpage
Out of specification
inder head.
Maximum cylinder head warpage
0.05 mm (0.0020 in)
• • • • • • • • • • • • • • • • • • • • • • •
a. Place a straightedge 1 and a thickness
gauge 2 across the cylinder head.
b. Measure the warpage.
c. If the limit is exceeded, resurface the cylin-
der head as follows.
d. Place a 400 ~ 600 grit wet sandpaper on
the surface plate and resurface the cylin-
der head using a figure-eight sanding pat-
tern.
NOTE:
To ensure an even surface, rotate the cylinder
head several times.
• • • • • • • • • • • • • • • • • • • • • • •
5-9
%m
ENG
-» Replace.
-» Resurface the cyl-