Yamaha YFM660 01 User Manual

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CHASREAR SHOCK ABSORBER AND RELAY ARM
Order Job name/Part name Q’ty Remarks
9 Self-locking nut/bolt 1/1
10 Relay arm 1
11 Spacer/oil seal/bushing 1/2/2 Refer to “INSTALLING THE RELAY ARM 
AND CONNECTING ARM”.
12 Connecting arm 1
13 Dust cover 4
14 Spacer 1
15 Spacer 1
16 Bushing 4 Refer to “INSTALLING THE RELAY ARM 
AND CONNECTING ARM”.
For installation, reverse the removal pro-
cedure. 
						

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CHASREAR SHOCK ABSORBER AND RELAY ARM
HANDLING THE REAR SHOCK ABSORBER 
AND GAS CYLINDER
WARNING
This rear shock absorber and gas cylinder
contain highly compressed nitrogen gas.
Before handling the rear shock absorber or
gas cylinder, read and make sure you
understand the following information. The
manufacturer cannot be held responsible
for property damage or personal injury that
may result from improper handling of the
rear shock absorber and gas cylinder.

Do not tamper or attempt to open the rear
shock absorber or gas cylinder.

Do not subject the rear shock absorber or
gas cylinder to an open flame or any
other source of high heat. High heat can
cause an explosion due to excessive gas
pressure.

Do not deform or damage the rear shock
absorber or gas cylinder in any way. If the
rear shock absorber, gas cylinder or both
are damaged, damping performance will
suffer.
DISPOSING OF A REAR SHOCK 
ABSORBER AND GAS CYLINDER
Gas pressure must be released before dispos-
ing of a rear shock absorber and gas cylinder.
To release the gas pressure, press on the gas
valve needle with a suitable tool as shown,
until all of the gas is released (the hissing has
stopped).
WARNING
Wear eye protection to prevent eye damage
from released gas or metal chips. 
						

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CHASREAR SHOCK ABSORBER AND RELAY ARM
REMOVING THE REAR SHOCK ABSORBER
1.Remove:

Connecting arm-to-frame bolt

Rear shock absorber upper bolt
NOTE:
While removing the connecting arm-to-frame
bolt, hold the swingarm so that it does not drop
down.
CHECKING THE REAR SHOCK ABSORBER
1.Check:

Shock absorber
Oil leaks →
 Replace the rear shock absorber
assembly.

Shock absorber rod
Bends/damage →
 Replace the rear shock
absorber assembly.

Spring
Fatigue →
 Replace the rear shock absorber
assembly.
Move the spring up and down.

Gas cylinder
Damage/gas leaks →
 Replace the rear
shock absorber assembly.
CHECKING THE RELAY ARM AND 
CONNECTING ARM
1.Check:

Relay arm

Connecting arm
Damage/wear →
 Replace.

Bushings

Spacers

Oil seals
Damage/pitting/scratches →
 Replace. 
						

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CHASREAR SHOCK ABSORBER AND RELAY ARM
INSTALLING THE RELAY ARM AND 
CONNECTING ARM
1.Install: 

Bushing 1
 
(to connecting arm)
NOTE:
Apply the lithium soap base grease on the
bushing when installing.
Installed depth of bushing a:
1 mm (0.04 in)
2.Install:

Bushing 1
 

Oil seal 2
 
(to relay arm)
NOTE:
Apply the lithium soap base grease on the
bushing when installing.
Installed depth of bushing a:
6.5 mm (0.26 in)
New
INSTALLING THE REAR SHOCK 
ABSORBER
1.Install:

Connecting arm

Relay arm

Rear shock absorber
NOTE:
When installing the rear shock absorber, lift up
the swingarm. 
						

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CHASSWINGARM AND DRIVE CHAIN
SWINGARM AND DRIVE CHAIN
Order Job name/Part name Q’ty Remarks
Removing the swingarm and drive 
chainRemove the parts in the order below.
Rear wheels and hub Refer to “REAR WHEELS, WHEEL AXLE
AND HUB”.
Rear shock absorber Refer  to  “REAR  SHOCK  ABSORBER
AND RELAY ARM”.
Left footrest and left footrest guard 
bracketRefer to “ENGINE REMOVAL” in CHAP-
TER 5.
1 Adjusting bolt/nut 2/2
2 Swingarm skid plate 1
3 Drive chain guide 1
4 Pivot shaft nut/washer 1/1
5 Pivot shaft 1
6 Swingarm 1 Refer to “REMOVING THE SWINGARM”.
7 Drive sprocket cover 1 
						

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CHASSWINGARM AND DRIVE CHAIN
Order Job name/Part name Q’ty Remarks
8Nut 1
Refer to “INSTALLING THE DRIVE 
SPROCKET”. 9 Lock washer 1
10 Drive sprocket 1
11 Drive chain 1
12 Collar 1
13 Spacer 1
14 Oil seal 1
15 Bearing 1
16 Dust cover/oil seal/washer 1/1/1
17 Spacer 1
18 Oil seal 2
19 Bushing 2
Refer to “INSTALLING THE SWING-
ARM”.
20 Bearing 2
For installation, reverse the removal pro-
cedure. 
						

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CHASSWINGARM AND DRIVE CHAIN
NOTE:
Before removing the drive chain and the
sprockets, measure the drive chain slack and
a ten link section of the drive chain.
REMOVING THE SWINGARM
1.Check: 

Swingarm free play
***********************************************
Checking steps: 

Check the tightening torque of the pivot shaft
nut.

Check the swingarm side play È
 by moving
it from side to side.
If side play is noticeable, check the collar,
spacers, bearings, bushings and frame pivot.

Check the swingarm vertical movement É
by moving it up and down.
If vertical movement is tight or rough, or if
there is binding, check the collar, spacers,
bearings, bushings and frame pivot.
***********************************************
2.Remove: 

Pivot shaft nut

Pivot shaft

Swingarm
T R..
Pivot shaft nut:
95 Nm (9.5 m  kg, 68 ft  lb)
CHECKING THE SWINGARM
1.Check:

Swingarm 
Bends/cracks/damage →
 Replace. 
						

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CHASSWINGARM AND DRIVE CHAIN
2.Check:

Pivot shaft
Roll the axle on a flat surface.
Bends →
 Replace.
WARNING
Do not attempt to straighten a bent pivot
shaft.
3.Clean:

Pivot shaft

Collar

Spacers

Bearings

Bushings
4.Check:

Spacers

Oil seals
Damage/wear →
 Replace.

Bearings

Bushings
Damage/pitting →
 Replace.
Recommended cleaning solvent:
Kerosine
CHECKING THE DRIVE CHAIN
1.Measure:

Ten-link section a
 of the drive chain
Out of specification →
 Replace the drive
chain.
NOTE:

While measuring the ten-link section, push
down on the drive chain to increase its ten-
sion.

Measure the length between drive chain
roller 1
 and A
 as shown.

Perform this measurement at two or three
different places.
Max. ten-link drive chain section:
150.1 mm (5.91 in) 
						

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CHASSWINGARM AND DRIVE CHAIN
2.Check:

Drive chain
Stiffness →
 Clean and lubricate or replace.
3.Clean:

Drive chain
***********************************************

Wipe the drive chain with a clean cloth.

Put the drive chain in kerosine and remove
any remaining dirt.

Remove the drive chain from the kerosine
and completely dry it.
CAUTION:
This machine has a drive chain with small
rubber O-rings 1 between the drive chain
side plates. Never use high-pressure water
or air, steam, gasoline, certain solvents
(e.g., benzine), or a coarse brush to clean
the drive chain. High-pressure methods
could force dirt or water into the drive
chain’s internals, and solvents will deterio-
rate the O-rings. A coarse brush can also
damage the O-rings. Therefore, use only
kerosine to clean the drive chain.
***********************************************
4.Check:

O-rings 1
Damage →
 Replace the drive chain.

Drive chain rollers 2
Damage/wear →
 Replace the drive chain.

Drive chain side plates 3
Cracks/damage/wear →
 Replace the drive
chain. 
						

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CHASSWINGARM AND DRIVE CHAIN
5.Lubricate:

Drive chain
Recommended lubricant:
Engine oil or chain lubricant
suitable for O-ring chains
6.Check:

Drive sprocket

Driven sprocket
More than 1/4 tooth a
 wear →
 Replace the
drive chain sprockets as a set.
Bent teeth →
 Replace the drive chain
sprockets as a set.
b
Correct
1Drive chain roller
2Drive chain sprocket
INSTALLING THE SWINGARM
1.Install:

Bearings 1
 

Bushings 2
 
(to swingarm)
NOTE:
Apply the lithium soap base grease on the
bearing and bushing when installing.
Installed depth of bearing:
Left a: 0 mm (0 in)
Right b: 4 mm (0.16 in)
Installed depth of bushing c:
8 mm (0.31 in)
INSTALLING THE DRIVE SPROCKET
1.Install:

Drive sprocket 1
 

Lock washer 2
 

Nut 3
 
2.Bend the lock washer tab along a flat side of
the nut.
New
T R..70 Nm (7.0 m  kg, 50 ft  lb)