Removing The Cylinder Head; Checking The Timing Chain Guide (Exhaust Side); Checking The Cylinder Head - Yamaha WR450FB 2012 Owner's Service Manual

EAS1DX3171

REMOVING THE CYLINDER HEAD

1. Remove:
• Cylinder head bolts
TIP
• Loosen the bolts in the proper sequence as
shown.
• Loosen each bolt 1/2 of a turn at a time. After
all of the bolts are fully loosened, remove
them.
• M6 35mm: "1" – "2"
• M10 165 mm: "3" – "6"
×2 ×4
6
2
1
3
EAS1DX3172
CHECKING THE TIMING CHAIN GUIDE (EX-
HAUST SIDE)
1. Check:
• Timing chain guide (exhaust side)
Damage/wear Replace.
EAS24160

CHECKING THE CYLINDER HEAD

1. Eliminate:
• Combustion chamber carbon deposits
(with a rounded scraper)
TIP
Do not use a sharp instrument to avoid damag-
ing or scratching:
• Spark plug bore threads
• Valve seats
FWD
4
5
6-15
CYLINDER HEAD
2. Check:
• Cylinder head
Damage/scratches
TIP
Replace the titanium valves with the cylinder
head.
Refer to "CHECKING THE VALVE SEATS"
on page 6-21
• Cylinder head water jacket
Mineral deposits/rust
3. Measure:
• Cylinder head warpage
Out of specification
der head.
Warpage limit
0.10 mm (0.0039 in)
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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.
TIP
To ensure an even surface, turn the cylinder
head several times.
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Replace.
Eliminate.
Resurface the cylin-