2005 YAMAHA VX110 Service Manual

5-86
EPOWRCONNECTING RODS AND PISTONS
Piston pin inspection
The following procedure applies to all of the
piston pins.
1. Check:
Piston pin
Bluediscoloration/grooves →
Replace
the piston pin and then check the lubri-
cation system.
2. Measure:
Piston pin outside diameter a

Out of specification →
Replace the pis-
ton pin.
Piston pin outside diameter:
16.991–17.000 mm
(0.6689–0.6693 in)
: 16.98 mm (0.67 in)
3. Measure:
Piston pin bore diameter (in the piston)
b

Out of specification →
Replace the pis-
ton.
4. Calculate:
Piston-pin-to-piston clearance
Out of specification →
Replace the pis-
ton pin.
Piston pin bore diameter
(in the piston):
17.002–17.013 mm
(0.6694–0.6698 in)
Piston-pin-to-piston clearance =
Piston pin bore diameter (in the piston)
b – Piston pin outside diameter
a
Piston-pin-to-piston clearance:
0.002–0.022 mm
(0.0001–0.0009 in)
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5-87
EPOWRCONNECTING RODS AND PISTONS
Connecting rod inspection
1. Measure:
Big end oil clearance
Out of specification →
Replace the big
end bearings.
Big end oil clearance:
0.016–0.040 mm
(0.0006–0.0016 in)
Measurement steps:
The following procedure applies to all of the
connecting rods.
CAUTION:
Do not interchange the big end bearings
and connecting rods. To obtain the cor-
rect big end oil clearance and prevent
engine damage, the big end bearings
must be installed in their original posi-
tions.
Clean the big end bearings, crankshaft
pins, and the inside of the connecting rod
halves.
Install the big end upper bearing into the
connecting rod and the big end lower
bearing into the connecting rod cap.
NOTE:
Align the projections a
on the big end bear-
ings with the notches b
in the connecting
rod and connecting rod cap.
Put a piece of Plastigauge 1
on the
crankshaft pin.
Assemble the connecting rod halves.
1
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5-88
EPOWRCONNECTING RODS AND PISTONS
NOTE:
• Do not move the connecting rod or crank-
shaft until the clearance measurement
has been completed.
 Lubricate the bolts threads and nut seats
with molybdenum disulfide grease.
 Make sure the “Y” mark c on the con-
necting rod faces towards the front side of
the crankshaft.
 Make sure the characters d on both the
connecting rod and connecting rod cap
are aligned.
 Tighten the connecting rod nuts.
Refer to “Connecting rod and piston
installation”.
 Remove the connecting rod and big end
bearings.
Refer to “Connecting rod and piston
removal”.
 Measure the compressed Plastigauge
width e on the crankshaft pin.
If the big end oil clearance is out of speci-
fication, select replacement big end bear-
ings.
cd
e
2. Select:
 Big end bearings (P
1–P4)
NOTE:
The numbers stamped into the crankshaft web
and the numbers on the connecting rods are
used to determine the replacement big end
bearing sizes.
P4
P3P2
P1
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5-89
EPOWRCONNECTING RODS AND PISTONS
For example, if the connecting rod “P1” and the
crankshaft web “P
1” numbers are “5” and “1”
respectively, then the bearing size for “P
1” is:
Bearing size of P
1:
“P
1” (connecting rod) –
“P
1” (crankshaft web)
5 – 1 = 4 (green)
BEARING COLOR CODE
1brown
2 black
3blue
4 green5 G
P4P3P2P1
Connecting rod and piston installation
The following procedure applies to all of the
pistons and connecting rods.
1. Install:
Oil ring
2nd ring
Top ring
NOTE:
Be sure to install the piston rings so that the
manufacturer’s marks or numbers face up.
2. Install:
Piston 1

Connecting rod 2

Piston pin 3

Piston pin clips 4

NOTE:
Apply engine oil onto the piston pin.
When installing the connecting rod to the pis-
ton, make sure that the “Y” mark a
on the
connecting rod faces towards the left when
the exhaust valve recesses b
on the piston
face upward. Refer to the illustration.
Reinstall each piston into its original cylinder
(numbering order starting from the front: #1
to #4).
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5-90
EPOWRCONNECTING RODS AND PISTONS
3. Offset:
Piston ring end gaps
aTop ring, oil ring expander spacer
b2nd ring, lower oil ring rail
cUpper oil ring rail
ÈExhaust sidebc
a È
90˚
45˚
90˚
4. Lubricate:
Piston
Piston rings
Cylinder
(with the recommended lubricant)
Recommended lubricant:
Engine oil
5. Lubricate:
Bolt threads
Nut seats
(with the recommended lubricant)
Recommended lubricant:
Molybdenum disulfide grease
6. Lubricate:
Crankshaft pins
Big end bearings
(with the recommended lubricant)
Recommended lubricant:
Engine oil
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5-91
EPOWRCONNECTING RODS AND PISTONS
7. Install:
Big end bearings
Connecting rod assembly 1

(into the cylinder and onto the
crankshaft pin)
Connecting rod cap
(onto the crankshaft pin)
NOTE:
Align the projections on the big end bearings
with the notches in the connecting rods and
connecting rod caps.
Be sure to reinstall each big end bearing in
its original place.
While compressing the piston rings with pis-
ton ring compressor 2
, install the connecting
rod assembly into the cylinder with the other
hand.
Make sure the “Y” marks a
on the connect-
ing rods face towards the front side of the
crankshaft.
Make sure the characters b
on both the con-
necting rod and connecting rod cap are
aligned.
8. Align:
Bolt heads
(with the connecting rod)
Piston ring compressor:
YM-08037/90890-05158
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5-92
EPOWRCONNECTING RODS AND PISTONS
9. Tighten:
Connecting rod nuts
WARNING
Replace the connecting rod bolts and
nuts with new ones.
Clean the connecting rod bolts and nuts.
NOTE:
The tightening procedure of the connecting rod
nuts is angle controlled, therefore tighten the
nuts using the following procedure.
Tightening steps:
Tighten the connecting rod nuts to the
specified torque.
T R..
Connecting rod nut:
1st:
20 N  m (2.0 kgf  m, 14 ft  lb)
Tighten the connecting rod nuts further to
reach the specified angle 120°.
T R..
Connecting rod nut:
Final:
Specified angle 120
± 5°
WARNING
When the nuts are tightened more than
the specified angle, do not loosen the
nut and then retighten it.
Replace the bolt and nut with a new one
and perform the procedure again.
CAUTION:
Do not use a torque wrench to tighten
the nut to the specified angle.
Tighten the nut until it is at the speci-
fied angle.
NOTE:
When using a hexagonal nut, note that the
angle from one corner to another is 60°.
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5-93
EPOWRCRANKSHAFT
CRANKSHAFT
EXPLODED DIAGRAM
REMOVAL AND INSTALLATION CHART
Step Procedure/Part name Q’ty Service points
CRANKSHAFT REMOVAL
Follow the left “Step” for removal.
Crankcase Separate
Refer to “CRANKCASE”.
Connecting rod caps Refer to “CONNECTING RODS AND
PISTONS”.
1 Crankshaft 1
2 Crankshaft journal lower bearing 5
3 Crankshaft journal upper bearing 5
Reverse the removal steps for installation.
2
21 33E
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