Checking The Cylinder Head - Yamaha 2004 YXR660 Service Manual

CAMSHAFT AND CYLINDER HEAD
4 - 21
b. Removing the screwdriver and slowly
release the timing chain tensioner rod.
c. Make sure that the timing chain tensioner
rod comes out of the timing chain tensioner
housing smoothly. If there is rough move-
ment, replace the timing chain tensioner.
L LLL L LLL L L LLL L L LLL L

CHECKING THE CYLINDER HEAD

1. Eliminate:
• carbon deposits (from the combustion
chamber)
Use a rounded scraper.
NOTE:
Do not use a sharp instrument to avoid damag-
ing or scratching:
• spark plug threads
• valve seats
2. Check:
• cylinder head
Scratches/damage → Replace the cylinder
head cover and cylinder head as a set.
• cylinder head water jacket
Mineral deposits/rust → Eliminate.
3. Measure:
• cylinder head warpage
Out of specification → Resurface.
Cylinder head warpage
Less than 0.03 mm (0.0012 in)
M MMM M MMM M M MMM M M MMM M
a. Place a straightedge and a thickness gauge
across the cylinder head.
b. Use a thickness gauge to measure the
warpage.
c. If the warpage is out of specification, resur-
face the cylinder head.
ENG
L LLL L L LLL L LLL
M MMM M M MMM M MMM