Yamaha YFM660 01 User Manual

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ENGAC MAGNETO
CHECKING THE STARTER CLUTCH
1.Check:

Starter one-way clutch 1
 
Cracks/damage →
 Replace.

Bolts 2
 (starter clutch)
Loose →
 Replace.
NOTE:
The arrow mark on the starter clutch must face
inward, away from the AC magneto rotor.
***********************************************
Checking steps:

Install the starter wheel gear to the starter
clutch, and hold the starter clutch.

When turning the starter wheel gear counter
clockwise È
, the starter clutch and the wheel
gear should be...

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ENGAC MAGNETO
INSTALLING THE AC MAGNETO ROTOR
1.Apply:

Sealant (Quick Gasket®) 1
 
(into the slit)
Sealant (Quick Gasket®):
P/N. ACC-11001-05-01
Yamaha bond No. 1215
®:
P/N. 90890-85505
2.Install:

Woodruff key

AC magneto rotor
NOTE:

Before installing the rotor, clean the outside
of the crankshaft and the inside of the rotor.

After installing the rotor, check that the rotor
rotates smoothly. If not, reinstall the key and
rotor.
3.Tighten: 

AC magneto rotor nut 1
 
NOTE:

While holding the AC...

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ENGCLUTCH
CLUTCH
Order Job name/Part name Q’ty Remarks
Removing the clutch cover
Remove the parts in the order below.
Engine assembly Refer to “ENGINE REMOVAL”.
1 Oil filter bolt 1
2 Union bolt 2
3 Copper washer 4
4 Oil delivery pipe 1 1
5 Union bolt 2
6 Copper washer 4
7 Oil delivery pipe 2 1
8 Clutch cover 1 Refer to “REMOVING/INSTALLING THE 
CLUTCH”.
9 Clutch cover gasket 1
10 Dowel pin 2
For installation, reverse the removal pro-
cedure. 

5 - 44
ENGCLUTCH
Order Job name/Part name Q’ty Remarks
Removing the pull lever shaft
Remove the parts in the order below.
1 Circlip 1
2Pull lever 1
3 Pull lever spring 1
4Bolt 1
5Pull lever shaft 1
6 Oil seal 1
7 Bearing 1
8 Bearing 1
For installation, reverse the removal pro-
cedure. 

5 - 45
ENGCLUTCH
Order Job name/Part name Q’ty Remarks
Removing the clutch
Remove the parts in the order below.
1 Clutch spring 5
Refer to “INSTALLING THE CLUTCH”. 2 Pressure plate 1
3Pull rod 1
4 Bearing 1
5 Friction plate 2 2 Inside diameter = 116 mm (4.57 in)
6 Clutch plate 7
7 Friction plate 1 6 Inside diameter = 112 mm (4.41 in)
8 Cushion spring 1
9 Lock washer 1
Refer to “REMOVING/INSTALLING THE 
CLUTCH”.
10 Clutch boss 1 

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ENGCLUTCH
Order Job name/Part name Q’ty Remarks
11 Thrust washer 1
12 Clutch housing 1 Refer to “INSTALLING THE CLUTCH”.
13 Lock washer 1
Refer to “REMOVING/INSTALLING THE 
PRIMARY DRIVE GEAR AND BAL-
ANCER DRIVEN GEAR”. 14 Balancer driven gear 1
15 Straight key 1
16 Lock washer 1
17 Primary drive gear 1
18 Balancer drive gear 1
19 Spring 16
20 Dowel pin 16
21 Plate 1
22 Straight key 1
23 Washer 1
For installation, reverse the removal pro-
cedure. 

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ENGCLUTCH
REMOVING THE CLUTCH
1.Remove:

Clutch cover
NOTE:
Loosen each bolt 1/4 of a turn at a time, in
stages and in a crisscross pattern. After all of
the bolts are fully loosened, remove them.
2.Straighten the lock washer tab.
3.Loosen:

Clutch boss nut 1
 
NOTE:
While holding the clutch boss 2
 with the clutch
holding tool 3
, loosen the clutch boss nut.
Clutch holding tool:
P/N. YM-91042, 90890-04086
REMOVING THE PRIMARY DRIVE GEAR 
AND BALANCER DRIVEN GEAR
1.Straighten the lock washer...

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ENGCLUTCH
CHECKING THE FRICTION PLATE
The following procedure applies to all of the
friction 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.
Friction plate 1 thickness:
2.74 ~ 2.86 mm (0.108 ~ 0.113 in)
: 2.6 mm (0.102 in)
Friction plate 2 thickness:
2.94 ~ 3.06 mm (0.116 ~ 0.120 in)
: 2.8 mm (0.110 in)
CHECKING...

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ENGCLUTCH
CHECKING THE CLUTCH SPRING
The following procedure applies to all of the
clutch springs.
1.Check:

Clutch spring
Damage →
 Replace the clutch springs as a
set.
2.Measure:

Clutch spring free length a
 
Out of specification →
 Replace the clutch
springs as a set.
Clutch spring free length:
42.8 mm (1.69 in)
: 40.7 mm (1.60 in)
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...

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ENGCLUTCH
CHECKING THE PULL LEVER SHAFT AND 
PULL ROD
1.Check:

Pull lever shaft pinion gear teeth a
 

Pull rod teeth b
 
Damage/wear →
 Replace the pull lever shaft
and pull rod as a set.
2.Check:

Pull rod bearing
Damage/wear →
 Replace.
CHECKING THE PRIMARY DRIVE
1.Check:

Primary drive gear 1
 

Primary driven gear 2
 
Damage/wear →
 Replace the primary drive
gear and clutch housing as a set.
Excessive noise during operation →
 Replace
the primary drive gear and clutch housing as
a set....