Checking The Camshaft Sprocket And Timing Chain Guide; Checking The Timing Chain Tensioner - Yamaha WR125R 2009 Service Manual

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.
Warpage limit
0.03 mm (0.0012 in)
M MMM M MMM M M MMM M
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 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, rotate the cylinder
head several times.
L LLL L LLL L L LLL L
M MMM M M MMM M M MMM M
L LLL L L LLL L L LLL L
EAS22B1004
CHECKING THE CAMSHAFT SPROCKET
AND TIMING CHAIN GUIDE
1. Check:
• Camshaft sprocket
More than 1/4 tooth wear "a" → Replace the
camshaft sprocket, timing chain and crank-
shaft as a set.
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
2. Check:
MMM
• Timing chain guide (exhaust side)
Damage/wear → Replace.
EAS24200

CHECKING THE TIMING CHAIN TENSIONER

1. Check:
• Timing chain tensioner
Cracks/damage/rough movement → Re-
place.
M MMM M MMM M
a. Remove the timing chain tensioner cap.
b. While lightly pressing the timing chain ten-
sioner rod by hand, turn it clockwise with a
thin screwdriver "1" until it stops.
LLL
c. Remove the screwdriver and slowly release
the timing chain tensioner rod.
5-10
CYLINDER HEAD
M MMM M M MMM M M MMM M M MMM M MMM
1