Page 57 of 97
1
2
3
4
5
6
7
8
9
10
PERIODIC MAINTENANCE AND MINOR REPAIR
6-15
To clean the air filter check hose
1. Air filter check hose
2. Check hose cap
1. Check the hose on the side of theair filter case for accumulated dirt
or water.
2. If dirt or water is visible, remove the hose, clean it, and then install
it.
EAU44730
Checking the engine idling
speed
1. Idle adjusting screw
a. Increasing the engine idling speed
b. Decreasing the engine idling speed
The engine idling speed must be
checked as follows and, if necessary,
adjusted by a Yamaha dealer at the in-
tervals specified in the periodic main-
tenance and lubrication chart.
Start the engine and warm it up for
several minutes at 1000-2000 r/min
while occasionally revving it to 4000-
5000 r/min.
Engine idling speed:1400-1600 r/min
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-15
Page 58 of 97

PERIODIC MAINTENANCE AND MINOR REPAIR
6-16
1
2
3
4
5
6
7
8
9
10
EAU21640
Tires
To maximize the performance, durabil-
ity, and safe operation of your motor-
cycle, note the following points regard-
ing the specified tires.
Tire air pressure
The tire air pressure should be
checked and, if necessary, adjusted
before each ride.
EWA10500
WARNING0
●The tire air pressure must be
checked and adjusted on cold
tires (i.e., when the tempera-
ture of the tires equals the am-
bient temperature).
●The tire air pressure must be
adjusted in accordance with
the riding speed and with the
total weight of rider, passenger,
cargo, and accessories ap-
proved for this model.
EAU21382
Checking the throttle cable
free play
1. Throttle cable free play
The throttle cable free play should
measure 3.0-5.0 mm (0.12-0.20 in) at
the throttle grip. Periodically check the
throttle cable free play and, if neces-
sary, have a Yamaha dealer adjust it.
EAU21401
Valve clearance
The valve clearance changes with
use, resulting in improper air-fuel mix-
ture and/or engine noise. To prevent
this from occurring, the valve clear-
ance must be adjusted by a Yamaha
dealer at the intervals specified in the
periodic maintenance and lubrication
chart.
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-16
Page 59 of 97

1
2
3
4
5
6
7
8
9
10
PERIODIC MAINTENANCE AND MINOR REPAIR
6-17
EWA11020
WARNING0
Because loading has an enormous
impact on the handling, braking,
performance and safety character-
istics of your motorcycle, you
should keep the following precau-
tions in mind.
●NEVER OVERLOAD THE MO-
TORCYCLE! Operation of an
overloaded motorcycle may re-
sult in tire damage, loss of con-
trol, or severe injury. Make sure
that the total weight of rider,
passenger, cargo, and acces-
sories does not exceed the
specified maximum load for the
vehicle.
●Do not carry along loosely
packed items, which can shift
during a ride.
●Securely pack the heaviest
items close to the center of the
motorcycle and distribute the
weight evenly on both sides.
Tire air pressure
(measured on cold tires):Up to 90 kg (198 lb):
Front:210 kPa (30 psi) (2.1 kgf/cm
2)
Rear: 230 kPa (33 psi) (2.3 kgf/cm
2)
90 kg (198 lb) to maximum load:
Front: 230 kPa (33 psi) (2.3 kgf/cm
2)
Rear: 250 kPa (36 psi) (2.5 kgf/cm
2)
Off-road riding:
Front: 200 kPa (29 psi) (2.0 kgf/cm
2)
Rear: 200 kPa (29 psi) (2.0 kgf/cm
2)
High-speed riding:
Front: 210 kPa (30 psi) (2.1 kgf/cm
2)
Rear: 230 kPa (33 psi) (2.3 kgf/cm
2)
Maximum load*: 190 kg (419 lb)
* Total weight of rider, passenger, cargo and accessories
●Adjust the suspension and tire
air pressure with regard to the
load.
●Check the tire condition and air
pressure before each ride.
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-17
Page 60 of 97
PERIODIC MAINTENANCE AND MINOR REPAIR
6-18
1
2
3
4
5
6
7
8
9
10
Tire information
This motorcycle is equipped with tube
tires.
EWA10460
WARNING0
●The front and rear tires should
be of the same make and de-
sign, otherwise the handling
characteristics of the vehicle
cannot be guaranteed.
●After extensive tests, only the
tires listed below have been
approved for this model by
Yamaha Motor Co., Ltd.
Tire inspection
1. Tire sidewall
2. Tire tread depth
The tires must be checked before
each ride. If the center tread depth
reaches the specified limit, if the tire
has a nail or glass fragments in it, or if
the sidewall is cracked, have a Yama-
ha dealer replace the tire immediately.
NOTE:
The tire tread depth limits may differ
from country to country. Always com-
ply with the local regulations.
Minimum tire tread depth
(front and rear): 1.6 mm (0.06 in)
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-18
Page 61 of 97

1
2
3
4
5
6
7
8
9
10
PERIODIC MAINTENANCE AND MINOR REPAIR
6-19
Front tire:Size:90/90-21M/C 54S
90/90-21M/C 54T
Manufacturer/model: METZELER/TOURANCE
FRONT MICHELIN/SIRAC
Rear tire: Size:130/80-17M/C 65S
130/80-17M/C 65T
Manufacturer/model: METZELER/TOURANCE
MICHELIN/SIRAC A
EWA10570
WARNING0
●Have a Yamaha dealer replace
excessively worn tires. Besides
being illegal, operating the mo-
torcycle with excessively worn
tires decreases riding stability
and can lead to loss of control.
●The replacement of all wheel-
and brake-related parts, in-
cluding the tires, should be left
to a Yamaha dealer, who has
the necessary professional
knowledge and experience.
●It is not recommended to patch
a punctured tube. If unavoid-
able, however, patch the tube
very carefully and replace it as
soon as possible with a high-
quality product.
EAU21940
Spoke wheels
To maximize the performance, durabil-
ity, and safe operation of your motor-
cycle, note the following points regard-
ing the specified wheels.
●The wheel rims should be
checked for cracks, bends or
warpage, and the spokes for
looseness or damage before
each ride. If any damage is found,
have a Yamaha dealer replace the
wheel. Do not attempt even the
smallest repair to the wheel. A de-
formed or cracked wheel must be
replaced.
●The wheel should be balancedwhenever either the tire or wheel
has been changed or replaced.
An unbalanced wheel can result
in poor performance, adverse
handling characteristics, and a
shortened tire life.
●Ride at moderate speeds afterchanging a tire since the tire sur-
face must first be "broken in" for it
to develop its optimal characteris-
tics.
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-19
Page 62 of 97

PERIODIC MAINTENANCE AND MINOR REPAIR
6-20
1
2
3
4
5
6
7
8
9
10
NOTE:
If the specified clutch lever free play
could be obtained as described above,
tighten the locknut and skip the rest of
the procedure, otherwise proceed as
follows. 3. Fully turn the adjusting bolt at the clutch lever in direction (a) to
loosen the clutch cable.
4. Loosen the locknut at the crankcase.
1. Locknut
2. Clutch lever free play adjusting nut(crankcase)
5. To increase the clutch lever free
play, turn the adjusting nut in di-
rection (a). To decrease the clutch
lever free play, turn the adjusting
nut in direction (b).
6. Tighten the locknut at the clutch lever and the crankcase.
1
b
a
2
EAU22041
Adjusting the clutch lever
free play
1. Locknut
2. Adjusting bolt
3. Clutch lever free play
The clutch lever free play should mea-
sure 10.0-15.0 mm (0.39-0.59 in) as
shown. Periodically check the clutch
lever free play and, if necessary, ad-
just it as follows.1. Loosen the locknut at the clutch lever.
2. To increase the clutch lever free play, turn the adjusting bolt in di-
rection (a). To decrease the clutch
lever free play, turn the adjusting
bolt in direction (b).
31
2
b
a
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-20
Page 63 of 97

1
2
3
4
5
6
7
8
9
10
PERIODIC MAINTENANCE AND MINOR REPAIR
6-21
EAU22390
Checking the front and rear
brake pads
The front and rear brake pads must be
checked for wear at the intervals spec-
ified in the periodic maintenance and
lubrication chart.
EAU22420
Front brake pads
1. Front brake pad wear indicator groove
Each front brake pad is provided with
a wear indicator groove, which allows
you to check the brake pad wear with-
out having to disassemble the brake.
To check the brake pad wear, check
the wear indicator groove. If a brake
pad has worn to the point that the
wear indicator groove has almost dis-
appeared, have a Yamaha dealer re-
place the brake pads as a set.
EAU22500
Rear brake pads
1. Rear brake pad lining thickness
Check each rear brake pad for dam-
age and measure the lining thickness.
If a brake pad is damaged or if the lin-
ing thickness is less than 1.0 mm
(0.04 in), have a Yamaha dealer re-
place the brake pads as a set.
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-21
Page 64 of 97

PERIODIC MAINTENANCE AND MINOR REPAIR
6-22
1
2
3
4
5
6
7
8
9
10
Insufficient brake fluid may allow air to
enter the brake system, possibly caus-
ing it to become ineffective.
Before riding, check that the brake flu-
id is above the minimum level mark
and replenish if necessary.
A low brake fluid level may indicate
worn brake pads and/or brake system
leakage. If the brake fluid level is low,
be sure to check the brake pads for
wear and the brake system for leak-
age.
Observe these precautions:
●When checking the fluid level,
make sure that the top of the
brake fluid reservoir is level.
●Use only the recommended qual-
ity brake fluid, otherwise the rub-
ber seals may deteriorate, caus-
ing leakage and poor braking
performance.
●Refill with the same type of brake
fluid. Mixing fluids may result in a
harmful chemical reaction and
lead to poor braking performance.
●Be careful that water does not en-
ter the brake fluid reservoir when
refilling. Water will significantly
lower the boiling point of the fluid
and may result in vapor lock.
●Brake fluid may deteriorate paint-
ed surfaces or plastic parts. Al-
ways clean up spilled fluid imme-
diately.
●As the brake pads wear, it is nor-
mal for the brake fluid level to
gradually go down. However, if
the brake fluid level goes down
suddenly, have a Yamaha dealer
check the cause.
Recommended brake fluid: DOT 4
EAU22580
Checking the brake fluid
level
Front brake
1. Minimum level mark
Rear brake
1. Minimum level mark
XT660Z 04-06 ING 11-03-2008 8:31 Pagina 6-22