Yamaha YFM660 01 User Manual

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ENGCLUTCH
INSTALLING THE PRIMARY DRIVE GEAR 
AND BALANCER DRIVEN GEAR
1.Install:

Dowel pin

Spring

Balancer drive gear
(onto the primary drive gear)
NOTE:
Align the punch mark a
 on the balancer drive
gear with the punch mark b
 on the primary
drive gear.
2.Install:

Primary drive gear

Balancer driven gear
NOTE:
Align the punch mark a
 on the balancer driven
gear with the punch mark b
 on the primary
drive gear.
3.Tighten:

Balancer driven gear nut 1
 

Primary drive gear nut 2
 
NOTE:

Place an aluminum plate 3
 between the
teeth of the balancer drive gear 4
 and bal-
ancer driven gear 5
.

Apply the molybdenum disulfide grease to
the thread of axles and nuts.
4.Bend the lock washer tabs along the bal-
ancer driven gear nut.
5.Bend the lock washer tabs along a flat side
of the primary drive gear nut.
T R..140 Nm (14.0 m  kg, 100 ft  lb)
T R..150 Nm (15.0 m  kg, 110 ft  lb) 
						

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ENGCLUTCH
INSTALLING THE CLUTCH
1.Install:

Clutch housing 1
 
NOTE:

Make sure that the primary driven gear teeth
and primary drive gear teeth mesh correctly.

Make sure that the oil pump drive gear teeth
and oil pump driven gear teeth mesh cor-
rectly.
2.Tighten:

Clutch boss nut 1
 
NOTE:
While holding the clutch boss 2
 with the clutch
holding tool 3
, tighten the clutch boss nut.
3.Bend the lock washer tab along a flat side of
the nut.
Clutch holding tool:
P/N. YM-91042, 90890-04086
T R..90 Nm (9.0 m  kg, 65 ft  lb)
4.Install:

Pressure plate 1
 
NOTE:
Align the punch mark a
 on the pressure plate
with the punch mark b
 on the clutch boss. 
						

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ENGCLUTCH
5.Install:

Clutch spring
NOTE:
Tighten the bolts in stages, using a crisscross
pattern.
T R..8 Nm (0.8 m  kg, 5.8 ft  lb)
6.Install:

Clutch cover
NOTE:
Be sure to mesh the pull lever shaft with the
pull rod teeth to ensure that the mark a
 on pull
lever 1
 is at the closest position to stationary
pointer b
 onto the clutch cover when the
clutch is engaged.
7.Install:

Clutch cable holder 1
 

Bolts
2Bolt:   = 25 mm
3Bolt:   = 30 mm
4Bolt:   = 35 mm
5Bolt:   = 50 mm
NOTE:
Tighten the bolts in stages, using a crisscross
pattern.
T R..10 Nm (1.0 m  kg, 7.2 ft  lb) 
						

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ENGOIL PUMP
OIL PUMP
Order Job name/Part name Q’ty Remarks
Removing the oil pump
Remove the parts in the order below.
Clutch Refer to “CLUTCH”.
1 Circlip 1
2 Oil pump driven gear 1
3 Oil pump 1
4 Oil pump gasket 1
5 O-ring 2
For installation, reverse the removal pro-
cedure. 
						

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ENGOIL PUMP
Order Job name/Part name Q’ty Remarks
Disassembling the oil pump
Remove the parts in the order below.
1
Oil pump housing 1/oil seal 1/1
2
Oil pump outer rotor 1 1
3
Dowel pin 1
4
Oil pump inner rotor 1 1
5
Oil pump housing cover/oil seal 1/1
6
Dowel pin 2
7
Oil pump shaft 1
8
Dowel pin 1
9
Oil pump inner rotor 2 1
Refer to “ASSEMBLING THE OIL 
PUMP”.
0
Oil pump outer rotor 2 1
A
Oil pump housing 2 1
For assembly, reverse the disassembly
procedure. 
						

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ENGOIL PUMP
CHECKING THE OIL PUMP
1.Check:

Oil pump driven gear

Oil pump housings

Oil pump housing cover
Cracks/wear/damage →
 Replace.
2.Measure:

Tip clearance a
 
(between the inner rotor 1
 and the outer
rotor 2
)

Side clearance b
 
(between the outer rotor 2
 and the pump
housing 3
)
Out of specification →
 Replace the oil pump.
Tip clearance a:
0.12 mm (0.005 in)
: 0.2 mm (0.008 in)
Side clearance b:
0.03 ~ 0.08 mm (0.001 ~ 0.003 in)
3.Check:

Oil pump operation
Unsmooth →
 Repeat steps (1) and (2) or
replace the defective parts.
ASSEMBLING THE OIL PUMP
1.Install:

Oil pump inner rotor 2

Oil pump outer rotor 2
NOTE:
Align the match mark a
 on the inner rotor 2
with the match mark b
 on the outer rotor 2. 
						

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ENGSHIFT SHAFT
SHIFT SHAFT
Order Job name/Part name Q’ty Remarks
Removing the shift shaft
Remove the parts in the order below.
Clutch Refer to “CLUTCH”.
1 Shift arm 1
Refer to “INSTALLING THE SHIFT 
SHAFT”. 2 Shift shaft 1
3 Shift shaft spring 1
4Collar 1
5Roller 1
6 Stopper lever 1
Refer to “INSTALLING THE STOPPER 
LEVER”. 7 Stopper lever spring 1
8Roller 1 
						

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ENGSHIFT SHAFT
Order Job name/Part name Q’ty Remarks
9 Shift guide 1
Refer to “INSTALLING THE SHIFT 
LEVER”. 10 Shift lever 1
11 Pawl 2
12 Pawl pin 2
13 Spring 2
14 Segment 1
15 Oil seal 1
For installation, reverse the removal pro-
cedure. 
						

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ENGSHIFT SHAFT
CHECKING THE SHIFT SHAFT
1.Check:

Shift shaft 1
 
Bends/damage/wear →
 Replace.

Shift shaft spring 2
 
Damage/wear →
 Replace.
CHECKING THE STOPPER LEVER
1.Check:

Stopper lever 1
 
Bends/damage →
 Replace.
Roller turns roughly →
 Replace the stopper
lever.

Stopper spring 2
 
Damage →
 Replace.
CHECKING THE SHIFT GUIDE AND SHIFT 
LEVER
1.Check:

Shift guide 1
 

Shift lever 2
 

Pawl 3
 

Pawl pin 4
 

Spring 5
 
Damage/wear →
 Replace.
CHECKING THE SEGMENT
1.Check:

Segment
Damage/wear →
 Replace.
INSTALLING THE SHIFT LEVER
1.Install:

Segment 1
 

Segment bolt
NOTE:
Align the notch a
 on the segment with the pin
b
 on the shift cam.
T R..30 Nm (3.0 m  kg, 22 ft  lb) 
						

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ENGSHIFT SHAFT
2.Install:

Springs 1
 

Pawl pins 2
 

Pawls 3
 

Shift guide 4
 
(to the shift lever)
3.Install:

Shift lever assembly 1
 

Shift guide 2
 
NOTE:
The shift lever assembly is installed at the
same time as the shift guide.
INSTALLING THE STOPPER LEVER
1.Install:

Roller

Stopper lever spring 1
 

Stopper lever 2
 
NOTE:

Hook the ends of the stopper lever spring
onto the stopper lever and the crankcase
boss.

Mesh the stopper lever with the shift drum
segment.