Yamaha WR400F Fahrer- Und Wartungshandbuch Seite 344

CYLINDER AND PISTON
Piston ring
1. Measure:
Ring side clearance
Use a feeler gauge 1.
Out of specification → Replace the pis-
ton and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
Top
ring
2nd
ring
2. Position:
Piston ring
In cylinder.
NOTE:
Insert a ring into the cylinder and push it
approximately 10 mm (0.39 in) into the cylin-
der. Push the ring with the piston crown so that
the ring will be at a right angle to the cylinder
bore.
a 10 mm (0.39 in)
3. Measure:
Ring end gap
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
4 - 41
ENG
Side clearance
Standard
0.030 ~ 0.065 mm
(0.0012 ~ 0.0026 in)
0.020 ~ 0.055 mm
(0.0008 ~ 0.0022 in)
End gap
Standard
0.20 ~ 0.35 mm
(0.008 ~ 0.014 in)
0.40 ~ 0.55 mm
(0.016 ~ 0.022 in)
0.20 ~ 0.50 mm
(0.01 ~ 0.02 in)
<Limit>
0.13 mm
(0.005 in)
0.13 mm
(0.005 in)
Limit
0.7 mm
(0.028 in)
0.8 mm
(0.031 in)
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