Checking The Cylinder Heads - Yamaha VMX12 2001 Service Manual

CYLINDER HEADS
EAS00223
REMOVING THE CYLINDER HEADS
1. Remove:
• cylinder head nuts
NOTE:
@
• Loosen the nuts in the proper sequence as
shown.
• Loosen each nut 1/2 of a turn at a time. After
all of the nuts are fully loosened, remove
them.
@
EAS00230

CHECKING THE CYLINDER HEADS

The following procedure applies to all of the
cylinder heads.
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 1
Mineral deposits/rust → Eliminate.
3. Measure:
• cylinder head warpage
Out of specification → Resurface the cylin-
der head.
Maximum cylinder head warpage
0.03 mm
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.
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ENG