2008 YAMAHA XT660Z engine

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INSTRUMENT AND CONTROL FUNCTIONS
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EAU13412
Fuel tank breather hose
1. Fuel tank breather hose
2. Clamp
Before operating the motorcycle:
●Check the fuel tank breather hose
connection.
●Check the fuel tank breather hose
for cracks or damage, and replace
it if damaged.
●Make sure that the fuel tank
breather hose is not blocked, and
clean it if necessary.

ECA11400CAUTION:
Use only unleaded gasoline. The
use of leaded gasoline will cause
severe damage to internal engine
parts, such as the valves and piston
rings, as well as to the exhaust sys-
tem.
Your Yamaha engine has been de-
signed to use premium unleaded
gasoline with a research octane num-
ber of 95 or higher. If knocking (or
pinging) occurs, use a gasoline of a
different brand. Use of unleaded fuel
will extend spark plug life and reduce
maintenance costs.
EAU13431
Catalytic converter
This model is equipped with a catalyt-
ic converter in the exhaust system.
EWA10860
WARNING0
The exhaust system is hot after op-
eration. Make sure that the exhaust
system has cooled down before
doing any maintenance work.

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INSTRUMENT AND CONTROL FUNCTIONS
3-14
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To install the seat
1. Projections
2. Seat holders
1. Insert the projections on the front of the seat into the seat holders.
2. Push the rear of the seat down.
NOTE:
Make sure that the seat is properly se-
cured before riding.

EAU13870
Seat
To remove the seat
1. Seat lock
2. Unlock
1. Insert the key into the lock, and then turn it counterclockwise.
2. Pull the seat off.

ECA10700CAUTION:
The following precautions must be
observed to prevent a fire hazard or
other damages.
●Use only unleaded gasoline.
The use of leaded gasoline will
cause unrepairable damage to
the catalytic converter.
●Never park the vehicle near
possible fire hazards such as
grass or other materials that
easily burn.
●Do not allow the engine to idle
too long.

XT660Z 01-03 ING 10-03-2008 16:11 Pagina 3-14

EWA10240
WARNING0
The vehicle must not be ridden
with the sidestand down, or if the
sidestand cannot be properly
moved up (or does not stay up),
otherwise the sidestand could con-
tact the ground and distract the
operator, resulting in a possible
loss of control. Yamaha’s ignition
circuit cut-off system has been de-
signed to assist the operator in ful-
filling the responsibility of raising
the sidestand before starting off.
Therefore, check this system regu-
larly as described below and have
a Yamaha dealer repair it if it does
not function properly.

EAU15301
Sidestand
1. Sidestand
The sidestand is located on the left
side of the frame. Raise the sidestand
or lower it with your foot while holding
the motorcycle upright.
NOTE:
The built-in sidestand switch is part of
the ignition circuit cut-off system,
which cuts the ignition in certain situa-
tions. (See further down for an expla-
nation of the ignition circuit cut-off sys-
tem.)

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INSTRUMENT AND CONTROL FUNCTIONS
3-17
EAU15312
Ignition circuit cut-off
system
The ignition circuit cut-off system
(comprising the sidestand switch,
clutch switch and neutral switch) has
the following functions.
●It prevents starting when the
transmission is in gear and the
sidestand is up, but the clutch
lever is not pulled.
●It prevents starting when the
transmission is in gear and the
clutch lever is pulled, but the side-
stand is still down.
●It cuts the running engine when
the transmission is in gear and
the sidestand is moved down.
Periodically check the operation of the
ignition circuit cut-off system accord-
ing to the following procedure.
EWA10250
WARNING0
If a malfunction is noted, have a
Yamaha dealer check the system
before riding.

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INSTRUMENT AND CONTROL FUNCTIONS
3-18
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With the engine turned off:
1. Move the sidestand down.
2. Make sure that the engine stop switch is turned on.
3. Turn the key on.
4. Shift the transmission into the neutral position.
5. Push the start switch.
Does the engine start?
With the engine still running:
6. Move the sidestand up.
7. Keep the clutch lever pulled.
8. Shift the transmission into gear.
9. Move the sidestand down.
Does the engine stall?
NOTE:
This check is most reliable if performed with a
warmed-up engine.
The neutral switch may be defective.
The motorcycle should not be ridden until checked by a
Yamaha dealer.
The sidestand switch may be defective.
The motorcycle should not be ridden until checked by a
Yamaha dealer.
The clutch switch may be defective.
The motorcycle should not be ridden until checked by a
Yamaha dealer.
After the engine has stalled:
10. Move the sidestand up.
11. Keep the clutch lever pulled.
12. Push the start switch.
Does the engine start?
The system is OK. The motorcycle can be ridden.
YES NO
NO
YES
NO
YES

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PRE-OPERATION CHECKS
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ITEM
Fuel
Engine oil
Coolant
Front brake
Rear brake
EAU15605
Pre-operation check list
CHECKS
• Check fuel level in fuel tank.
• Refuel if necessary.
• Check fuel line for leakage.
• Check oil level in oil tank.
• If necessary, add recommended oil to specified level.
• Check vehicle for oil leakage.
• Check coolant level in reservoir.
• If necessary, add recommended coolant to specified level.
• Check cooling system for leakage.
• Check operation.
• If soft or spongy, have Yamaha dealer bleed hydraulic system.
• Check brake pads for wear.
• Replace if necessary.
• Check fluid level in reservoir.
• If necessary, add recommended brake fluid to specified level.
• Check hydraulic system for leakage.
• Check operation.
• If soft or spongy, have Yamaha dealer bleed hydraulic system.
• Check brake pads for wear.
• Replace if necessary.
• Check fluid level in reservoir.
• If necessary, add recommended brake fluid to specified level.
• Check hydraulic system for leakage. PAGE
3-12
6-9
6-12
3-11, 6-21, 6-22, 6-26
3-11, 6-21, 6-22, 6-27

XT660Z 04-06 ING 11-03-2008 8:30 Pagina 2

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OPERATION AND IMPORTANT RIDING POINTS
EAU15950
EWA10270
WARNING0
●Become thoroughly familiar
with all operating controls and
their functions before riding.
Consult a Yamaha dealer re-
garding any control or function
that you do not thoroughly un-
derstand.
●Never start the engine or oper-
ate it in a closed area for any
length of time. Exhaust fumes
are poisonous, and inhaling
them can cause loss of con-
sciousness and death within a
short time. Always make sure
that there is adequate ventila-
tion.
●Before starting out, make sure
that the sidestand is up. If the
sidestand is not raised com-
pletely, it could contact the
ground and distract the opera-
tor, resulting in a possible loss
of control.

EAUB1570
Starting the engine
In order for the ignition circuit cut-off
system to enable starting, one of the
following conditions must be met:
●The transmission is in the neutral
position.
●The transmission is in gear with
the clutch lever pulled and the
sidestand up.
EWA10290
WARNING0
●Before starting the engine,
check the function of the igni-
tion circuit cut-off system ac-
cording to the procedure de-
scribed on page 3-18.
●Never ride with the sidestand
down.
1. Turn the key to “ON” and make sure that the engine stop switch is
set to “
I”.

ECAB0070CAUTION:
The following warning lights and in-
dicator lights should come on for a
few seconds, then go off.
●Neutral indicator light
●Turn signal indicator light
●High beam indicator light
●Engine trouble warning light
●Coolant temperature warning
light
●Immobilizer system indicator
light
If a warning or indicator light does
not go off, see page 3-3 for the cor-
responding warning and indicator
light circuit check.
2. Shift the transmission into the neutral position.
NOTE:
When the transmission is in the neu-
tral position, the neutral indicator light
should be on, otherwise have a Yama-
ha dealer check the electrical circuit.
5-1

XT660Z 04-06 ING 11-03-2008 8:30 Pagina 5-1

OPERATION AND IMPORTANT RIDING POINTS
3. Start the engine by pushing thestart switch.
NOTE:
If the engine fails to start, release the
start switch, wait a few seconds, and
then try again. Each starting attempt
should be as short as possible to pre-
serve the battery. Do not crank the en-
gine more than 10 seconds on any one
attempt.
ECA11040CAUTION:
For maximum engine life, never ac-
celerate hard when the engine is
cold!
NOTE:
The engine is warm when it quickly re-
sponds to the throttle.
EAU16671
Shifting
1. Shift pedal
N. Neutral position
Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing
hills, etc.
The gear positions are shown in the il-
lustration.
NOTE:
To shift the transmission into the neu-
tral position, press the shift pedal down
repeatedly until it reaches the end of its
travel, and then slightly raise it.

ECA10260CAUTION:
●Even with the transmission in
the neutral position, do not
coast for long periods of time
with the engine off, and do not
tow the motorcycle for long
distances. The transmission is
properly lubricated only when
the engine is running. Inade-
quate lubrication may damage
the transmission.
●Always use the clutch while
changing gears to avoid dam-
aging the engine, transmission,
and drive train, which are not
designed to withstand the
shock of forced shifting.
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OPERATION AND IMPORTANT RIDING POINTS
EAU16810
Tips for reducing fuel
consumption
Fuel consumption depends largely on
your riding style. Consider the follow-
ing tips to reduce fuel consumption:
●Shift up swiftly, and avoid high en-
gine speeds during acceleration.
●Do not rev the engine while shift-
ing down, and avoid high engine
speeds with no load on the en-
gine.
●Turn the engine off instead of let-
ting it idle for an extended length
of time (e.g., in traffic jams, at traf-
fic lights or at railroad crossings).
EAU16841
Engine break-in
There is never a more important peri-
od in the life of your engine than the
period between 0 and 1600 km (1000
mi). For this reason, you should read
the following material carefully.
Since the engine is brand new, do not
put an excessive load on it for the first
1600 km (1000 mi). The various parts
in the engine wear and polish them-
selves to the correct operating clear-
ances. During this period, prolonged
full-throttle operation or any condition
that might result in engine overheating
must be avoided.
EAU17100
0-1000 km (0-600 mi)
Avoid prolonged operation above
4500 r/min.
1000-1600 km (600-1000 mi)
Avoid prolonged operation above
6000 r/min.
ECA10301CAUTION:
After 1000 km (600 mi) of operation,
the engine oil must be changed and
the oil filter cartridge or element re-
placed.
1600 km (1000 mi) and beyond
The vehicle can now be operated nor-
mally.
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