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Yamaha YZ450F(Y Owner's Manual: Checking Piston Pin; Installing Piston Ring And Piston; Installing Cylinder

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3. Measure:
• Ring end gap
Out of specification → Replace.
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.
End gap:
Standard
0.20–0.30
Top
mm (0.008–
ring
0.012 in)
0.35–0.50
2nd
mm (0.014–
ring
0.020 in)
0.20–0.50
Oil
mm (0.01–
ring
0.02 in)
CHECKING THE PISTON PIN
1. Inspect:
• Piston pin
Blue discoloration/grooves → Re-
place, then inspect the lubrication
system.
2. Measure:
• Piston pin-to-piston clearance
Measurement steps:
a. Measure the outside diameter
(piston pin) "a".
If out of specification, replace the
piston pin.
Outside diameter (piston
pin):
17.991–18.000 mm
(0.7083–0.7087 in)
b. Measure the inside diameter (pis-
ton) "b".
Inside diameter (piston):
18.004–18.015 mm
(0.7088–0.7093 in)
c. Calculate the piston pin-to-piston
clearance with the following for-
mula.
Piston pin-to-piston clearance =
Inside diameter (piston) "b" -
Outside diameter (piston pin)
"a"
d. If out of specification, replace the
piston.
<Limit>
0.55 mm
(0.022 in)
0.85 mm
(0.033 in)
INSTALLING THE PISTON RING
AND PISTON
1. Install:
• Piston ring
Onto the piston.
• Be sure to install the piston rings so
that the manufacturer's marks or
numbers are located on the upper
side of the rings.
• Lubricate the piston and piston
rings liberally with engine oil.
2. Position:
• Top ring
• 2nd ring
• Oil ring
Offset the piston ring end gaps as
shown.
a.
Top ring end
b.
2nd ring end
c.
Oil ring end (upper)
d.
Oil ring
e.
Oil ring end (lower)
3. Install:
• Piston "1"
• Piston pin "2"
• Piston pin clip "3"
CYLINDER AND PISTON
Piston pin-to-piston
clearance:
0.004–0.024 mm
(0.00016–0.00094 in)
<Limit>:0.07 mm (0.003
in)
4-28
• Apply engine oil onto the piston pin
and piston.
• Be sure that the arrow mark "a" on
the piston points to the exhaust side
of the engine.
• Before installing the piston pin clip,
cover the crankcase with a clean
rag to prevent the piston pin clip
from falling into the crankcase.
• Install the piston pin clips with their
ends facing downward.
INSTALLING THE CYLINDER
1. Install:
• Dowel pins
• Cylinder gasket "1"
• Cylinder "2"
Install the cylinder with one hand
while compressing the piston rings
with the other hand.
• Pass the timing chain "3"
through the timing chain cavity.
• Be careful not to damage the tim-
ing chain guide "4" during instal-
lation.
2. Install:
• Bolt (cylinder)
Bolt (cylinder):
10 Nm (1.0 m•kg, 7.2
ft•lb)
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  • nick Jan 26, 2016 10:47:
    The download is jacked up, so it's only really viewable on the site, but can't really complain since it's free.