Yamaha YW125Y_ Utility Trailer User Manual


 
ENG
5-9
1
2
CYLINDER HEAD
EAS00227
CHECKING THE CYLINDER HEAD
1. Eliminate:
8combustion chamber carbon deposits
(with a rounded scraper)
TIP
Do not use a sharp instrument to avoid damag-
ing or scratching:
8 spark plug bore thread
8 valve seats
2. Check:
8cylinder head
Damage/scratches J Replace.
3. Measure:
8cylinder head warpage
Out of specification J Resurface the cyl-
inder head.
Maximum cylinder head warpage
Less than 0.05mm (0.002in)
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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.
TIP
To ensure an even surface, rotate the cylinder
head several times.
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