Yamaha WR426F 2001 Manuel D'atelier page 434

CYLINDER AND PISTON
3. Measure:
Ring end gap
G
Out of specification → Replace.
NOTE:
You cannot measure the end gap on the
expander spacer of the oil control ring. If the oil
control ring rails show excessive gap, replace
all three rings.
Top
ring
2nd
ring
Oil
ring
Piston pin
1. Inspect:
Piston pin
G
Blue discoloration/grooves →
Replace, then inspect the lubrication
system.
4 - 46
ENG
End gap
Standard
WR426F:
0.20 ~ 0.30 mm
(0.008 ~ 0.012 in)
WR400F:
0.20 ~ 0.35 mm
(0.008 ~ 0.014 in)
WR426F:
0.35 ~ 0.50 mm
(0.014 ~ 0.020 in)
WR400F:
0.40 ~ 0.55 mm
(0.016 ~ 0.022 in)
0.20 ~ 0.50 mm
(0.01 ~ 0.02 in)
Limit
WR426F:
0.55 mm
(0.022 in)
WR400F:
0.60 mm
(0.024 in)
WR426F:
0.85 mm
(0.033 in)
WR400F:
0.90 mm
(0.035 in)
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