Yamaha XV19SW(C), XV19W(C), XV19MW(C), XV19CTSW(C), XV19CTW(C), XV19CTMW(C). Service Manual - part 17

CYLINDERS AND PISTONS

5-48

3. Measure:

• Piston ring end gap

Out of specification 

→

 Replace the piston 

ring.

NOTE:

The oil ring expander spacer’s end gap cannot 
be measured. If the oil ring rail’s gap is exces-
sive, replace all three piston rings.

EAS24440

CHECKING THE PISTON PINS

The following procedure applies to all of the pis-
ton pins.
1. Check:

• Piston pin

Blue discoloration/grooves 

→

 Replace the 

piston pin and then check the lubrication sys-
tem.

2. Measure:

• Piston pin outside diameter “a”

Out of specification 

→

 Replace the piston pin.

3. Measure:

• Piston pin bore diameter “b”

Out of specification 

→

 Replace the piston.

4. Calculate:

• Piston-pin-to-piston-pin-bore clearance

Out of specification 

→

 Replace the piston pin 

and piston as a set.

EAS24460

INSTALLING THE PISTONS AND 
CYLINDERS

The following procedure applies to all of the pis-
tons and cylinders.
1. Install:

• Top ring “1”
• 2nd ring “2”
• Lower oil ring rail “3”
• Upper oil ring rail “4”

 

Piston ring

Top ring

End gap (installed)

0.20–0.35 mm (0.0079–0.0138 
in)

Limit

0.55 mm (0.0217 in)

2nd ring

End gap (installed)

0.45–0.60 mm (0.0177–0.0236 
in)

Limit

0.95 mm (0.0374 in)

Oil ring

End gap (installed)

0.20–0.70 mm (0.0079–0.0276 
in)

 

Piston pin outside diameter

22.991–23.000 mm (0.9052–
0.9055 in)

Limit

22.971 mm (0.9044 in)

 

Piston pin bore inside diameter

23.004–23.015 mm (0.9057–
0.9061 in)

Limit

23.045 mm (0.9073 in)

• Piston-pin-to-piston-pin-bore clearance =

Piston pin bore diameter “b” -
Piston pin outside diameter “a”

 

Piston-pin-to-piston-pin-bore 
clearance

0.004–0.024 mm (0.00016–
0.00094 in)

CYLINDERS AND PISTONS

5-49

• Oil ring expander “5”

NOTE:

Be sure to install the piston rings so that the 
manufacturer’s marks or numbers face up.

2. Install:

• Piston “1”
• Piston pin “2”

• Piston pin clips “3” 

NOTE:

• Apply engine oil onto the piston pin.
• Make sure the arrow mark “a” on the piston fac-

es towards the front of the vehicle.

• Before installing the piston pin clips, cover the 

crankcase opening with a clean rag to prevent 
the clip from falling into the crankcase.

• Install the piston pin clips, so that the clip ends 

are 3 mm (0.12 in) “b” or more from the cutout 
in the piston.

• Reinstall each piston into its original cylinder 

(numbering order starting from the left: #1 to 
#2).

3. Lubricate:

• Piston
• Piston rings
• Cylinder

(with the recommended lubricant)

4. Offset:

• Piston ring end gaps

5. Install:

• Cylinder “1”

NOTE:

While compressing the piston rings with one 
hand, install the cylinder with the other hand.

New

New

3

b

 

Recommended lubricant

Engine oil

a. Top ring
b. Upper oil ring rail
c. Oil ring expander
d. Lower oil ring rail
e. 2nd ring
A. forward

90 ˚

90 ˚

45 ˚

a.c 

b

d.e

A

1

CLUTCH

5-50

EAS25060

CLUTCH

Removing the clutch cover

Order

Job/Parts to remove

Q’ty

Remarks

Engine oil

Drain.
Refer to “CHANGING THE ENGINE OIL” on 
page 3-11.

Left side cover

Refer to “GENERAL CHASSIS” on page 
4-1.

Horn 1/Canister

Refer to “THROTTLE BODIES” on page 6-6.
For California only

Fuel tank/Sub-fuel tank

Refer to “FUEL TANK” on page 6-1.

Left rider footrest assembly/Shift rod/Sidestand

Refer to “ENGINE REMOVAL” on page 5-1.

Generator cover

Refer to “GENERATOR AND STARTER 
CLUTCH” on page 5-72.

Drive pulley case

Refer to “TRANSFER GEAR CASE” on 
page 5-81.

1

Crankshaft position sensor coupler

1

Disconnect.

2

Shift arm

1

3

Clutch  cover

1

4

Clutch cover gasket

1

T

 

R

12 Nm (1.2 m 

•

 

kg, 8.7 ft

 

•

 

Ib)

5

3

4

5

2

1

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

New

(11)

(5)

CLUTCH

5-51

5

Dowel pin

2

For installation, reverse the removal proce-
dure.

Removing the clutch cover

Order

Job/Parts to remove

Q’ty

Remarks

T

 

R

12 Nm (1.2 m 

•

 

kg, 8.7 ft

 

•

 

Ib)

5

3

4

5

2

1

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

New

(11)

(5)

CLUTCH

5-52

Removing the crankshaft position sensor

Order

Job/Parts to remove

Q’ty

Remarks

1

Oil seal

1

2

Bearing

1

3

Clutch cover damper plate

1

4

Clutch cover damper

1

5

Crankshaft position sensor lead holder

3

6

Crankshaft position sensor

1

For installation, reverse the removal proce-
dure.

5

6

5

5

4

3

T

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

1

2

New

LS

LT

LT

LT

LT

LT

LT

CLUTCH

5-53

Removing the clutch

Order

Job/Parts to remove

Q’ty

Remarks

1

Clutch spring plate retainer

1

2

Clutch spring plate

1

3

Clutch spring plate seat

1

4

Pressure plate

1

5

Short clutch push rod

1

6

Friction plate 1

1

Inside diameter: 124 mm (4.88 in)

7

Clutch plate

9

8

Friction plate 2

9

9

Clutch boss nut

1

10

Conical spring washer

1

11

Washer

1

12

Wire circlip

1

13

Clutch plate

1

14

Friction plate 3

1

Inside diameter: 135 mm (5.31 in)

15

Clutch damper spring

1

16

Clutch damper spring seat

1

17

Clutch boss

1

E

E

7

8

6

21

20

22

23

27

28

26 25

23

19

24

18

17

16

15 14

13 12

10

9

11

3

2

1

4

5

29

30

31

33

32

(6)

T

 

R

8 Nm (0.8 m

 

•

 kg, 5.8 ft 

•

 Ib)

New

New

New

New

LS

E

LS

E

E

T

 

R

105 Nm (10.5 m 

•

 kg, 75 ft 

•

 lb)

 

R

100 Nm (10.0 m 

•

 kg, 72 ft 

•

 lb)

CLUTCH

5-54

18

Thrust washer 1

1

19

Clutch housing

1

20

Circlip

1

21

Washer

1

22

Oil pump drive gear

1

23

Dowel pin

2

24

Bearing

1

25

Collar

1

26

Thrust washer 2

1

27

Ball

1

28

Long push rod

1

29

Spacer

1

30

Crankshaft position sensor rotor

1

31

Primary drive gear

1

32

Straight key

1

33

Washer

1

For installation, reverse the removal proce-
dure.

Removing the clutch

Order

Job/Parts to remove

Q’ty

Remarks

E

E

7

8

6

21

20

22

23

27

28

26 25

23

19

24

18

17

16

15 14

13 12

10

9

11

3

2

1

4

5

29

30

31

33

32

(6)

T

 

R

8 Nm (0.8 m

 

•

 kg, 5.8 ft 

•

 Ib)

New

New

New

New

LS

E

LS

E

E

T

 

R

105 Nm (10.5 m 

•

 kg, 75 ft 

•

 lb)

 

R

100 Nm (10.0 m 

•

 kg, 72 ft 

•

 lb)

CLUTCH

5-55

Removing the left balancer

Order

Job/Parts to remove

Q’ty

Remarks

1

Left balancer idle gear shaft holder

1

2

Dowel pin

2

3

O-ring

2

4

Left balancer idle gear

1

5

Left balancer idle gear shaft

1

6

Left balancer drive gear

1

7

Straight key

1

8

Left balancer driven gear

1

9

Left balancer weight 1

1

10

Left balancer weight 2

1

11

Left balancer driven gear housing

1

12

Gasket

1

For installation, reverse the removal proce-
dure.

8

1

2

2

5

3

3

4

6

7

11

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

T

 

R

40 Nm (4.0 m 

•

 

kg, 29 ft

 

•

 

Ib)

T

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

New

New

E

E

LT

LS

(6)

9

10

LT

LS

LS

12

New

(3)

CLUTCH

5-56

Removing the clutch master cylinder

Order

Job/Parts to remove

Q’ty

Remarks

Clutch fluid

Drain.
Refer to “BLEEDING THE HYDRAULIC 
CLUTCH SYSTEM” on page 3-15.

1

Left rearview mirror

1

2

Clutch master cylinder reservoir cap

1

3

Clutch master cylinder reservoir diaphragm 
holder

1

4

Clutch master cylinder reservoir diaphragm

1

5

Clutch lever

1

6

Clutch master cylinder push rod pin

1

7

Clutch switch coupler

1

Disconnect.

8

Clutch switch

1

9

Clutch hose union bolt

1

10

Copper washer

2

11

Clutch hose

1

12

Clutch master cylinder holder

1

13

Clutch master cylinder

1

For installation, reverse the removal proce-
dure.

1

2

3

4

5

8

12

13

7

10

9

11

T

 

R

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

T

 

R

30 Nm (3.0 m 

•

 

kg, 22 ft

 

•

 

Ib)

LT

New

6

LS

CLUTCH

5-57

Disassembling the clutch master cylinder

Order

Job/Parts to remove

Q’ty

Remarks

1

Clutch master cylinder push rod

1

2

Dust boot

1

3

Circlip

1

4

Washer

1

5

Clutch master cylinder kit

1

6

Clutch master cylinder body

1

For assembly, reverse the disassembly pro-
cedure.

3

4

5

6

2

1

New

New

LS

CLUTCH

5-58

Removing the clutch release cylinder

Order

Job/Parts to remove

Q’ty

Remarks

Clutch fluid

Drain.
Refer to “BLEEDING THE HYDRAULIC 
CLUTCH SYSTEM” on page 3-15.

Muffler/Exhaust pipes

Refer to “ENGINE REMOVAL” on page 5-1.

1

Clutch pipe union bolt cap

1

2

Clutch pipe union bolt

1

3

Copper washer

2

4

Clutch pipe

1

5

Clutch release cylinder

1

6

Dowel pin

2

For installation, reverse the removal proce-
dure.

6

3

1

4

5

2

T

 

10 Nm (1.0 m 

•

 

kg, 7.2 ft

 

•

 

Ib)

 

R

7 Nm (0.7 m

 

•

 kg, 5.1 ft 

•

 Ib)

T

 

R

26 Nm (2.6 m 

•

 

kg, 19 ft

 

•

 

Ib)

 

R

19 Nm (1.9 m 

•

 

kg, 13 ft

 

•

 

Ib)

New

CLUTCH

5-59

Disassembling the clutch release cylinder

Order

Job/Parts to remove

Q’ty

Remarks

1

Boots

1

2

Clutch release cylinder piston

1

3

Clutch release cylinder spring

1

4

Clutch release cylinder piston seal

1

5

Bleed screw

1

6

Clutch release cylinder body

1

For assembly, reverse the disassembly pro-
cedure.

LS

LS

1

2

4

6

3

5

New

6 Nm (0.6 m

 

•

 

kg, 4.3 ft

 

•

 

Ib)

CLUTCH

5-60

EAS25080

REMOVING THE CLUTCH

1. Loosen:

• Clutch boss nut “1”

NOTE:

While holding the clutch boss “2” with the univer-
sal clutch holder “3”, loosen the clutch boss nut.

2. Remove:

• Clutch boss nut “1”
• Conical spring washer “2”
• Washer “3”
• Clutch boss assembly “4”

NOTE:

There is a built-in damper between the clutch 
boss and the clutch plate. It is not necessary to 
remove the wire circlip “5” and disassemble the 
built-in damper unless there is serious clutch 
chattering.

EAS25090

REMOVING THE PRIMARY DRIVE GEAR

1. Loosen:

• Primary drive gear bolt “1”

NOTE:

While holding the generator rotor “2” with the 
sheave holder “3”, loosen the primary drive gear 
bolt.

ET1D71021

REMOVING THE LEFT BALANCER DRIVE 
GEAR

1. Loosen:

• Left balancer drive gear bolt “1”

NOTE:

While the holding the generator rotor “2” with the 
primary sheave holder “3”, loosen the left bal-
ancer drive gear bolt.

 

Universal clutch holder

90890-04086
YM-91042

2

1

3

4

1

2

5

3

 

Sheave holder

90890-01701

Primary clutch holder

YS-01880-A

 

Sheave holder

90890-01701

Primary clutch holder

YS-01880-A

1

2

3

1

CLUTCH

5-61

EAS25100

CHECKING THE FRICTION PLATES

The following procedure applies to all of the fric-
tion plates.
1. Check:

• Friction plate

Damage/wear 

→

 Replace the friction plates 

as a set.

2. Measure:

• Friction plate thickness

Out of specification 

→

 Replace the friction 

plates as a set.

NOTE:

Measure the friction plate at four places.

EAS25110

CHECKING THE CLUTCH PLATES

The following procedure applies to all of the 
clutch plates.
1. Check:

• Clutch plate

Damage 

→

 Replace the clutch plates as a 

set.

2. Measure:

• Clutch plate warpage

(with a surface plate and thickness gauge “1”)
Out of specification 

→

 Replace the clutch 

plates as a set.

EAS25130

CHECKING THE CLUTCH SPRING PLATE

1. Check:

• Clutch spring plate

Damage 

→

 Replace.

 

Friction plate 1, 3 thickness

2.90–3.10 mm (0.114–0.122 in)

Wear limit

2.80 mm (0.110 in)

Friction plate 2 thickness

2.92–3.08 mm (0.115–0.121 in)

Wear limit

2.82 mm (0.111 in)

2

3

A. Friction plate 1, 3
B. Friction plate 2

 

Thickness gauge

90890-03180

Feeler gauge set

YU-26900-9

 

Clutch plate thickness

1.90–2.10 mm (0.075–0.083 in)

Warpage limit

0.20 mm (0.0079 in)

A

B

CLUTCH

5-62

2. Check:

• Clutch spring plate seat

Damage 

→

 Replace.

EAS25150

CHECKING THE CLUTCH HOUSING

1. Check:

• Clutch housing dogs

Damage/pitting/wear 

→

 Deburr the clutch 

housing dogs or replace the clutch housing.

NOTE:

Pitting on the clutch housing dogs will cause er-
ratic clutch operation.

2. Check:

• Bearing

Damage/wear 

→

 Replace the bearing and 

clutch housing.

EAS25160

CHECKING THE CLUTCH BOSS

1. Check:

• Clutch boss splines

Damage/pitting/wear 

→

 Replace the clutch 

boss.

NOTE:

Pitting on the clutch boss splines will cause er-
ratic clutch operation.

EAS25170

CHECKING THE PRESSURE PLATE

1. Check:

• Pressure plate

Cracks/damage 

→

 Replace.

• Bearing

Damage/wear 

→

 Replace.

EAS25190

CHECKING THE CLUTCH PUSH RODS

1. Check:

• O-ring
• Short clutch push rod
• Long clutch push rod
• Ball

Cracks/damage/wear 

→

 Replace the defec-

tive part(s).

2. Measure:

• Long clutch push rod bending limit

Out of specification 

→

 Replace the defective 

part(s).

EAS25200

CHECKING THE PRIMARY DRIVE GEAR

1. Check:

• Primary drive gear

Damage/wear 

→

 Replace the primary drive 

and primary driven gears as a set.
Excessive noise during operation 

→

 Replace 

the primary drive and primary driven gears as 
a set.

EAS25210

CHECKING THE PRIMARY DRIVEN GEAR

1. Check:

• Primary driven gear “1”

Damage/wear 

→

 Replace the primary drive 

and primary driven gears as a set.
Excessive noise during operation 

→

 Replace 

the primary drive and primary driven gears as 
a set.

ET1D71033

CHECKING THE LEFT BALANCER GEARS

1. Check:

• Left balancer drive gear

 

Long clutch push rod bending 
limit

0.30 mm (0.0118 in)

CLUTCH

5-63

• Left balancer driven gear
• Left balancer idle gear

Burrs/chips/roughness/wear 

→

 Replace the 

defective part(s).

2. Measure:

• Left balancer driven gear inside diameter “a”

Out of specification 

→

 Replace.

3. Measure:

• Left balancer driven gear housing outside di-

ameter “a”
Out of specification 

→

 Replace.

4. Calculate:

• Left-balancer-driven-gear-to-left-balancer-

driven-gear-housing clearance
Out of specification 

→

 Replace the defective 

part(s).

NOTE:

Calculate the clearance by subtracting the left 
balancer driven gear housing outside diameter 
from the left balancer driven gear inside diame-
ter.

ET1D71022

INSTALLING THE LEFT BALANCER DRIVE 
GEAR

1. Install:

• Left balancer weight 1 “1”
• Left balancer weight 2 “2”
• Left balancer driven gear “3”

NOTE:

Make sure that the punch marks “a” on the left 
balancer driven gear are facing toward left bal-
ancer weight 2.

2. Remove:

• Generator rotor

Refer to “REMOVING THE GENERATOR” 
on page 5-74.

3. Align:

• Mark “a” on the generator drive gear of the 

crankshaft
(with the mark “b” on the generator shaft driv-
en gear)

▼▼▼

▼

▼ ▼▼▼

▼

▼ ▼▼▼

▼

▼ ▼▼▼

▼

▼ ▼▼▼

▼

▼ ▼▼▼

▼

▼▼▼

a. Turn the crankshaft.
b. When the front and rear pistons are near 

TDC, align the mark “a” on the generator 
drive gear of the crankshaft with the mark “b” 
on the generator shaft driven gear.

 

Left balancer driven gear inside 
diameter “a”

59.010–59.028 mm (2.323–2.324 
in)

Limit

59.100 mm (2.327 in)

 

Left balancer driven gear hous-
ing outside diameter “a”

58.925–58.960 mm (2.320–2.321 
in)

Limit

58.900 mm (2.318 in)

a

a

 

Left-balancer-driven-gear-to-left-
balancer-driven-gear-housing 
clearance

0.050–0.103 mm (0.0020–0.0041 
in)

T

 

R

.

 

Left balancer weight bolt

10 Nm (1.0 m·kg, 7.2 ft·lb)
LOCTITE

®

2

3

a

1