Yamaha CS50 - Engine Inspection and Repair

ENG
INSPECTION AND REPAIR
4-11
INSPECTION AND REPAIR
EAS00229
CHECKING THE CYLINDER HEAD
1. Eliminate:
• combustion chamber carbon deposits (with
a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid dama-
ging or scratching:
• spark plug bore threads
2. Check:
• cylinder head
Damage/scratches

Replace.
• cylinder head water jacket (CS50Z only)
Mineral deposits/ruts

Eliminate.
3. Measure:
• cylinder head warpage
Out of specification Resurface the cylinder
head.
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a. Place a straightedge  and a tickness
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.
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Maximum cylinder head warpage
0.02 mm