Yamaha WR250FM 2021, Owner'S Service Manual

Page: 218 / 404

CAMSHAFT
5-18
EAM30082
CHECKING THE TIMING CHAIN AND
CAMSHAFT SPROCKET
1. Check:
• Timing chain “1”
Damage/stiffness

Replace the timing
chain and camshaft as a set.
2. Check:
• Camshaft sprocket
More than 1/4 tooth wear “a”

Replace the
timing chain and camshaft as a set.
EAM30083
CHECKING THE TIMING CHAIN
TENSIONERS
1. Check:
• Timing chain tensioner
Crack/damage

Replace.
a. While pressing the tensioner rod lightly
with your fingers, use a thin screwdriver
“1” to wind the tensioner rod up fully clock-
wise.
b. When releasing the screwdriver by press-
ing lightly with your fingers, make sure that
the tensioner rod will come out smoothly.
c. If not, replace the tensioner assembly.
EAM30084
CHECKING THE DECOMPRESSION SYSTEM
1. Check:
• Decompression system
a. Check that the decompressor cam “1”
moves smoothly.
b. Check that the decompressor lever pin “2”
projects from the camshaft.
EAM30085
INSTALLING THE CAMSHAFTS
1. Install:
•
Exhaust camshaft “1”
• Intake camshaft “2”
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
a
b
1
2
2 2 2
1 1