CYLINDER HEAD (YP250R)
5-70
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.
IP
To ensure an even surface, rotate the cylinder
head several times.
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EAS23870
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.
EAS24190
CHECKING THE TIMING CHAIN TENSIONER
1. Check:
• Timing chain tensioner
Cracks/damage → Replace.
2. Check:
• One-way cam operation
Rough movement → Replace the timing
chain tensioner housing.
3. Check:
• Cap bolt
• Spring
• One-way cam
• Timing chain tensioner rod
Damage/wear → Replace the defective
part(s).
Warpage limit
0.05 mm (0.0020 in)
1
2
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
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