Yamaha MBK MW125 2014, Service Manual

Page: 216 / 380

CYLINDER HEAD
5-13
2. Check:
• Cylinder head
Damage/scratches
→
Replace.
• Cylinder head water jacket
Mineral deposits/rust
→
Eliminate.
3. Measure:
• Cylinder head warpage
Out of specification
→
Resurface the cylinder
head.
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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 cylinder
head as follows.
d. Place 400–600 grit wet sandpaper on the sur-
face plate and resurface the cylinder head
using a figure-eight sanding pattern.
TIP
To ensure an even surface, rotate the cylinder
head several times.
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EAS31232
CHECKING THE CAMSHAFT SPROCKET
1. Check:
• Camshaft sprocket
More than 1/4 tooth wear “a”
→
Replace the
camshaft sprocket, timing chain and crank-
shaft as a set.
EAS30279
CHECKING THE TIMING CHAIN TENSIONER
1. Check:
• Timing chain tensioner
Cracks/damage
→
Replace.
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a. Remove the timing chain tensioner plug.
b. While lightly pressing the timing chain ten-
sioner rod by hand, turn the tensioner rod ful-
ly clockwise with a thin screwdriver “1”.
c. Remove the screwdriver and slowly release
the timing chain tensioner rod.
Warpage limit
0.05 mm (0.0020 in)
1
2
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
1