2008 YAMAHA XT660Z engine

PERIODIC MAINTENANCE AND MINOR REPAIR
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1. Air filter element
ECA10480CAUTION: ● Make sure that the air filter ele-
ment is properly seated in the
air filter case.
● The engine should never be op-
erated without the air filter ele-
ment installed, otherwise the
piston(s) and/or cylinder(s) may
become excessively worn.
5. Install the air filter case cover by installing the screws.
6. Install the seat.
1
EAUB1480
Replacing the air filter
element and cleaning the
check hose
The air filter element should be re-
placed at the intervals specified in the
periodic maintenance and lubrication
chart. Replace the air filter element
more frequently if you are riding in un-
usually wet or dusty areas. In addition,
the air filter check hose must be fre-
quently checked and cleaned if neces-
sary. To replace the air filter element
1. Air filter case
2. Screws
1. Remove the seat. (See page 3-
14.)
2. Remove the air filter case cover by removing the screws.
3. Pull the air filter element out.
4. Insert a new air filter element into the air filter case as shown.
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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

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PERIODIC MAINTENANCE AND MINOR REPAIR
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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.

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PERIODIC MAINTENANCE AND MINOR REPAIR
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1. Wheel axle
2. Drive chain slack adjusting bolt
3. Locknut
4. Alignment marks
ECA10570
CAUTION:
Improper drive chain slack will
overload the engine as well as oth-
er vital parts of the motorcycle and
can lead to chain slippage or break-
age. To prevent this from occurring,
keep the drive chain slack within
the specified limits.
3. Tighten the locknuts, then the axle nut to their specified torques.
Tightening torques:
Locknut:16 Nm (1.6 m·kgf, 11 ft·lbf)
Axle nut: 105 Nm (10.5 m·kgf, 75 ft·lbf)
EAU34311
To adjust the drive chain slack1. Loosen the axle nut and the lock- nut on each side of the swingarm.
2. To tighten the drive chain, turn the adjusting bolt on each side of the
swingarm in direction (a). To
loosen the drive chain, turn the
adjusting bolt on each side of the
swingarm in direction (b), and
then push the rear wheel forward.
NOTE:
Using the alignment marks on each
side of the swingarm, make sure that
both chain pullers are in the same po-
sition for proper wheel alignment.
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-25
EAU23022
Cleaning and lubricating
the drive chain
The drive chain must be cleaned and
lubricated at the intervals specified in
the periodic maintenance and lubrica-
tion chart, otherwise it will quickly
wear out, especially when riding in
dusty or wet areas. Service the drive
chain as follows.
ECA10581CAUTION:
The drive chain must be lubricated
after washing the motorcycle and
riding in the rain.
1. Clean the drive chain with kerosene and a small soft brush.
ECA11120CAUTION:
To prevent damaging the O-rings,
do not clean the drive chain with
steam cleaners, high-pressure
washers or inappropriate solvents. 2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive
chain with a special O-ring chain
lubricant.
ECA11110CAUTION:
Do not use engine oil or any other
lubricants for the drive chain, as
they may contain substances that
could damage the O-rings.
EAU23100
Checking and lubricating
the cables
The operation of all control cables and
the condition of the cables should be
checked before each ride, and the ca-
bles and cable ends should be lubri-
cated if necessary. If a cable is dam-
aged or does not move smoothly, have
a Yamaha dealer check or replace it.
Recommended lubricant: Engine oil
EWA10720
WARNING0
Damage to the outer sheath may in-
terfere with proper cable operation
and will cause the inner cable to
rust. Replace a damaged cable as
soon as possible to prevent unsafe
conditions.

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PERIODIC MAINTENANCE AND MINOR REPAIR
6-29
EAU23280
Checking the steering
Worn or loose steering bearings may
cause danger. Therefore, the opera-
tion of the steering must be checked
as follows at the intervals specified in
the periodic maintenance and lubrica-
tion chart.1. Place a stand under the engine to raise the front wheel off the
ground.
EWA10750
WARNING0
Securely support the motorcycle so
that there is no danger of it falling
over.

2. Hold the lower ends of the frontfork legs and try to move them for-
ward and backward. If any free
play can be felt, have a Yamaha
dealer check or repair the steering.EAU23290
Checking the wheel bearings
The front and rear wheel bearings
must be checked at the intervals spec-
ified in the periodic maintenance and
lubrication chart. If there is play in the
wheel hub or if the wheel does not turn
smoothly, have a Yamaha dealer
check the wheel bearings.

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PERIODIC MAINTENANCE AND MINOR REPAIR
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To service the rear wheel
Raise the rear wheel off the ground by
using a motorcycle stand or, if a mo-
torcycle stand is not available, by plac-
ing a jack either under each side of the
frame in front of the rear wheel or un-
der each side of the swingarm.EAU24360
Front wheelEAUB1440To remove the front wheel
EWA10820
WARNING0
●It is advisable to have a Yama-
ha dealer service the wheel.
●Securely support the motorcy-
cle so that there is no danger of
it falling over.
1. Wheel axle
2. Brake caliper bolts
A. Front wheel axle pinch bolt
B. Front wheel axle pinch bolt

A
2
B
1

EAU24350
Supporting the motorcycle
Since this model is not equipped with
a centerstand, follow these precau-
tions when removing the front and rear
wheel or performing other mainte-
nance requiring the motorcycle to
stand upright. Check that the motorcy-
cle is in a stable and level position be-
fore starting any maintenance. A
strong wooden box can be placed un-
der the engine for added stability.
To service the front wheel 1. Stabilize the rear of the motorcy- cle by using a motorcycle stand
or, if an additional motorcycle
stand is not available, by placing a
jack under the frame in front of the
rear wheel.
2. Raise the front wheel off the ground by using a motorcycle
stand.

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PERIODIC MAINTENANCE AND MINOR REPAIR
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EAU42130Troubleshooting charts
Starting problems or poor engine performanceEWA10840
WARNING0
Keep away open flames and do not smoke while checking or working on the \
fuel system.

1. Fuel
2. Compression
3. Ignition
4. Battery
Check the fuel level in the
fuel tank.
Operate the electric
starter.
Remove the spark plug
and check the electrodes.
Operate the electric
starter.
There is enough
fuel.
There is
compression.
Wet.
The engine turns
over quickly.
There is no fuel.
There is no
compression.
Dry.
The engine turns
over slowly.
Check the
compression.
Check the ignition.
Wipe off with a dry cloth and correct
the spark plug gap, or replace the
spark plug.
The battery is good.
Have a Yamaha dealer check the
vehicle.
Check the battery lead connections,
and charge the battery if necessary.
Open the throttle halfway and
operate the electric starter.
The engine does not start.
Check the battery.
The engine does
not start. Have a
Yamaha dealer
check the vehicle.
Supply fuel.
Have a Yamaha dealer check
the vehicle.
The engine does not start.
Check the compression.

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