Yamaha YFM45FAR, YFM450FAR. Service Manual - part 12

4 - 50

ENG

PRIMARY AND SECONDARY SHEAVES

INSTALLING THE PRIMARY AND 
SECONDARY SHEAVES 

1.Install:

●

Secondary sheave assembly

●

V-belt

●

Primary sheave assembly

NOTE:

●

Tightening the bolts 

1

 will push the

secondary sliding sheave away, causing the
gap between the secondary fixed and sliding
sheaves to widen.

●

Install the V-belt so that its arrow faces the
direction show in the illustration.

2.Tighten:

●

Nut (primary sheave) 

1

 

●

Nut (secondary sheave) 

2

 

NOTE:

●

Use the sheave holder 

3

 to hold the primary

sheave.

●

First, tighten the nut (primary sheave) 

1

,

then tighten the nut (secondary sheave) 

2

.

Sheave holder:

P/N. YU-01880, 90890-01701

T

 

R

.

.

100 Nm (10.0 m • kg, 72 ft • lb)

T

 

R

.

.

100 Nm (10.0 m • kg, 72 ft • lb)

4 - 51

ENG

CLUTCH

CLUTCH

Order

Job name/Part name

Q’ty

Remarks

Removing the clutch 

Remove the parts in the order below.

Primary and secondary sheaves

Refer to “PRIMARY AND SECONDARY 
SHEAVES”.

1

Cover

1

2

Clutch housing assembly

1

Refer to “REMOVING/INSTALLING THE 
CLUTCH”.

3

Gasket/dowel pin

1/2

4

One-way clutch bearing

1

5

Nut

1

6

Clutch carrier assembly

1

For installation, reverse the removal 
procedure.

4 - 52

ENG

CLUTCH

Order

Job name/Part name

Q’ty

Remarks

Disassembling the clutch housing 

Remove the parts in the order below.

1

 Oil 

seal

1

2

 Circlip

1

3

 Bearing 

housing

1

4

 Circlip

1

5

 Bearing

1

6

 Circlip

1

7

 Bearing

1

8

 Clutch 

housing

1

For assembly, reverse the disassembly 
procedure.

4 - 53

ENG

CLUTCH

REMOVING THE CLUTCH 

1.Remove:

●

Clutch housing assembly

●

Gasket

●

Dowel pins

NOTE:

Working in crisscross pattern, loosen each bolt
1/4 of a turn. Remove them after all of them
are loosened.

2.Straighten:

●

Punched portion of the nut 

1

.

3.Remove:

●

Nut 

1

 

NOTE:

Use a clutch holding tool 

2

 to hold the clutch

carrier assembly.

CHECKING THE CLUTCH 

1.Check:

●

Clutch housing 

1

 

Heat damage/wear/damage 

→

 Replace.

●

One-way clutch bearing 

2

 

Chafing/wear/damage 

→

 Replace.

NOTE:

●

Replace the one-way clutch assembly and
clutch housing as a set.

●

The one-way clutch bearing 

2

 must be

installed with the arrow mark side facing up.

*****************************************************

Checking steps:

●

Install the one-way clutch bearing and clutch
carrier assembly to the clutch housing and
hold the clutch carrier assembly.

●

When turning the clutch carrier assembly
clockwise 

È

, the clutch carrier assembly

should turn freely.
If not, the one-way clutch assembly is faulty.
Replace it.

●

When turning the clutch carrier assembly
counterclockwise 

É

, the clutch housing and

clutch carrier assembly should be engaged.
If not, the one-way clutch assembly is faulty.
Replace it.

*****************************************************

Clutch holding tool:

P/N. YM-91042, 90890-04086

4 - 54

ENG

CLUTCH

2.Check:

●

Clutch shoe
Heat damage 

→

 Replace.

3.Measure:

●

Clutch shoe thickness
Out of specification 

→

 Replace.

Clutch shoe thickness:

1.5 mm (0.06 in)

Clutch shoe wear limit 

a

:

1.0 mm (0.04 in)

INSTALLING THE CLUTCH 

1.Install:

●

Collar

●

Clutch carrier assembly

●

Nut 

1

 

NOTE:

●

Lubricate the nut with molybdenum disulfide
oil.

●

Use a clutch holding tool 

2

 to hold the clutch

carrier assembly.

2.Lock the threads with a drift punch.

Clutch holding tool:

P/N. YM-91042, 90890-04086

New

T

 

R

.

.

140 Nm (14.0 m • kg, 100 ft • lb)

3.Install:

●

One-way clutch bearing

NOTE:

The one-way clutch bearing should be
installed in the clutch carrier assembly with the
arrow mark 

a

 facing toward the clutch

housing.

4 - 55

ENG

CLUTCH

4.Install:

●

Dowel pins

●

Gasket 

●

Clutch housing assembly

NOTE:

●

Tighten the bolts in stages, using a
crisscross pattern.

●

After tightening the bolts, check that the
clutch housing assembly to counterclockwise
rotates smoothly.

New

T

 

R

.

.

10 Nm (1.0 m • kg, 7.2 ft • lb)

4 - 56

ENG

CRANKCASE

CRANKCASE

STARTER MOTOR, TIMING CHAIN AND OIL FILTER

Order

Job name/Part name

Q’ty

Remarks

Removing the starter motor, timing 
chain and oil filter 

Remove the parts in the order below.

Engine assembly

Refer to “ENGINE REMOVAL”.

Cylinder head

Refer to “CYLINDER HEAD”.

Cylinder and piston

Refer to “CYLINDER AND PISTON”.

Recoil starter and rotor

Refer  to  “RECOIL STARTER AND A.C.
MAGNETO”.

Primary and secondary sheaves

Refer  to  “PRIMARY AND SECONDARY
SHEAVES”.

Clutch carrier assembly

Refer to “CLUTCH”.

1

Oil pump drive gear/straight key

1/1

Refer  to  “REMOVING/INSTALLING THE
OIL PUMP DRIVE GEAR”.

2

Oil pump driven gear

1

3

Timing chain guide

1

4

Timing chain

1

5

Starter motor/O-ring

1/1

4 - 57

ENG

CRANKCASE

Order

Job name/Part name

Q’ty

Remarks

6

Oil filter cartridge

1

7

Speed sensor

1

8

Shift cam stopper

1

9

Low-range switch 

1

10

High-range switch

1

11

Neutral switch

1

12

Reverse switch

1

13

Oil filler cap

1

14

Bearing cover/gasket

1/1

15

Oil delivery pipe

1

16

Oil strainer cover/O-ring

1/1

17

Compression spring

1

18

Oil strainer

1

For installation, reverse the removal 
procedure.

4 - 58

ENG

CRANKCASE

CRANKCASE

Order

Job name/Part name

Q’ty

Remarks

Separating the crankcase

Remove the parts in the order below.

1

Shift lever cover/gasket

1/1

Refer to “INSTALLING THE SHIFT 
LEVER”.

2

Shift lever 1/O-ring

1/1

3

Shift lever 2 assembly

1

4

Crankcase (left)

1

Refer to “SEPARATING/ASSEMBLING 
THE CRANKCASE”.

5

Dowel pin

2

6

Crankcase (right)

1

For installation, reverse the removal 
procedure.

4 - 59

ENG

CRANKCASE

CRANKCASE BEARING

Order

Job name/Part name

Q’ty

Remarks

Removing the crankcase bearing 

Remove the parts in the order below.

Crankshaft and oil pump

Refer to “CRANKSHAFT AND OIL 
PUMP”.

Transmission

Refer to “TRANSMISSION”.

Middle drive/driven shaft

Refer to “MIDDLE GEAR”.

1

Oil seal

2

2

Bearing retainer

2

3

Bearing

10

For installation, reverse the removal 
procedure.

4 - 60

ENG

CRANKCASE

REMOVING THE OIL PUMP DRIVE GEAR 

1.Straighten:

●

Lock washer tab

2.Remove:

●

Oil pump drive gear nut

*****************************************************

Removal steps:

●

Temporary install the clutch carrier assembly

1

.

●

Hold the clutch carrier assembly with a clutch
holding tool 

2

 and loosen the oil pump drive

gear nut.

●

Remove the clutch carrier assembly.

*****************************************************

Clutch holding tool:

P/N. YM-91042, 90890-04086

SEPARATING THE CRANKCASE 

1.Separate:

●

Left crankcase 

*****************************************************

Separation steps:

●

Remove the crankcase bolts.

NOTE:

●

Loosen each bolt 1/4 of a turn at a time and
after all the bolts are loosened, remove
them.

●

Loosen the bolts in stages, using a
crisscross pattern.

È

Left crankcase 

É

Right crankcase

È

É

4 - 61

ENG

CRANKCASE

●

Remove the left crankcase.

CAUTION:

Use a soft hammer to tap on one side of the
crankcase. Tap only on reinforced portions
of the crankcase. Do not tap on the
crankcase mating surfaces. Work slowly
and carefully. Make sure that the crankcase
halves separate evenly.

●

Remove the dowel pins.

*****************************************************

CHECKING THE TIMING CHAIN AND GUIDE 

1.Check:

●

Timing chain 
Cracks/stiff 

→

 Replace the timing chain and

camshaft sprocket as a set.

2.Check:

●

Intake side timing chain guide
Wear/damage 

→

 Replace.

CHECKING THE OIL STRAINER AND OIL 
DELIVERY PIPE 

1.Check: 

●

Oil strainer 

1

 

2.Check:

●

Oil delivery pipe
Cracks/damage 

→

 Replace.

Clogged 

→

 Blow out with compressed air.

4 - 62

ENG

CRANKCASE

CHECKING THE CRANKCASE

1.Thoroughly wash the case halves in a mild

solvent. 

2.Clean all the gasket mating surfaces and

crankcase mating surfaces thoroughly.

3.Check:

●

Crankcase 
Cracks/damage 

→

 Replace.

●

Oil delivery passages
Clogged 

→

 Blow out with compressed air.

CHECKING THE BEARINGS

1.Check: 

●

Bearing
Clean and lubricate, then rotate the inner
race with a finger.
Roughness 

→

 Replace.

ASSEMBLING THE CRANKCASE 

1.Apply:

●

Sealant (Quick Gasket

®

) 

1

 

(to the mating surfaces of both case halves)

2.Install:

●

Dowel pin 

2

 

Sealant (Quick Gasket

®

):

P/N. ACC-11001-05-01

Yamaha bond No. 1215:

P/N. 90890-85505

3.Fit the left crankcase onto the right case. Tap

lightly on the case with a soft hammer.

CAUTION:

Before installing and torquing the
crankcase holding bolts, be sure to check
whether the transmission is functioning
properly by manually rotating the shift cam
in both directions.

4 - 63

ENG

CRANKCASE

4.Tighten:

●

Crankcase bolts
(follow the proper tightening sequence)

È

Right crankcase

É

Left crankcase

NOTE:

Tighten the bolts in stages, using a crisscross
pattern.

È

É

T

 

R

.

.

10 Nm (1.0 m • kg, 7.2 ft • lb)

5.Apply:

●

4-stroke engine oil
(to the crank pin, bearing and oil delivery
hole)

6.Check:

●

Crankshaft and transmission operation
Unsmooth operation 

→

 Repair.

INSTALLING THE SHIFT LEVER 

1.Install:

●

Shift lever 2 assembly 

1

 

●

Shift lever 1 

2

 

NOTE:

When installing the shift lever 1, align the
punch mark 

a

 on the shift lever 1 with the

punch marks 

b

 on the shift lever 2.

T

 

R

.

.

14 Nm (1.4 m • kg, 10 ft • lb)

4 - 64

ENG

CRANKCASE

INSTALLING THE OIL PUMP DRIVE GEAR 

1.Install:

●

Straight key

●

Oil pump drive gear

●

Lock washer 

●

Oil pump drive gear nut

New

2.Tighten:

●

Oil pump drive gear nut

*****************************************************

Tightening steps:

●

Temporary install the clutch carrier assembly

1

.

●

Hold the clutch carrier assembly with a clutch
holding tool 

2

 and tighten the oil pump drive

gear nut.

●

Remove the clutch carrier assembly.

*****************************************************

Clutch holding tool:

P/N. YM-91042, 90890-04086

T

 

R

.

.

50 Nm (5.0 m • kg, 36 ft • lb)

3.Bend the lock washer tab.

4 - 65

ENG

CRANKSHAFT AND OIL PUMP

CRANKSHAFT AND OIL PUMP

Order

Job name/Part name

Q’ty

Remarks

Removing the crankshaft and oil 
pump 

Remove the parts in the order below.

Crankcase separation

Refer to “CRANKCASE”.

1

Washer/circlip

1/1

2

Oil pump assembly/gasket

1/1

3

Balancer

1

Refer to “REMOVING THE 
CRANKSHAFT/INSTALLING THE 
CRANKSHAFT AND BALANCER”.

4

Crankshaft seal

2

5

Crankshaft

1

For installation, reverse the removal 
procedure.