Checking The Cylinder Head - Yamaha 5YF2-AE1 Service Manual

CYLINDER HEAD
EBS00230

CHECKING THE CYLINDER HEAD

1. Eliminate:
• combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
_
Do not use a sharp instrument to avoid damag-
ing or scratching:
• spark plug bore threads
• valve seats
2. Check:
• cylinder head
Damage/scratches → Replace.
• cylinder head water jacket
Mineral deposits/rust → Eliminate.
3. Measure:
• cylinder head warpage
Out of specification → Resurface the cylin-
der head.
Maximum cylinder head warpage
0.05 mm (0.002 in)
M MMM M MMM M M MMM
a. Place a straightedge and a thickness gauge
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 cylinder
head using a figure-eight sanding pattern.
NOTE:
_
To ensure an even surface, rotate the cylinder
head several times.
L LLL L LLL L L LLL
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ENG
M M MMM M M MMM M
L L LLL L L LLL L
M MMM M MMM
L LLL L LLL