2008 YAMAHA XT660Z engine

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PERIODIC MAINTENANCE AND MINOR REPAIR
6-41
Engine overheatingEWA10400
WARNING0
●Do not remove the radiator cap when the engine and radiator are hot. Scalding hot fluid and steam may be
blown out under pressure, which could cause serious injury. Be sure to wait until the engine has cooled.
●After removing the radiator cap retaining bolt, place a thick rag, like a towel, over the radiator cap, a\
nd then
slowly rotate the cap counterclockwise to the detent to allow any residual pressure to escape. When the hiss-
ing sound has stopped, press down on the cap while turning it counterclockwise, and then remove the cap.

NOTE:
If coolant is not available, tap water can be temporarily used instead, provided that it is changed to the recommended
coolant as soon as possible.
Wait until the
engine has cooled.Check the coolant level
in the reservoir and radiator.
The coolant level is low.
Check the cooling
system for leakage.
The coolant level
is OK.
There is
leakage.
There is no
leakage.
Have a Yamaha dealer check
and repair the cooling system.
Start the engine. If the engine overheats again, have
a Yamaha dealer check and repair the cooling system.
Add coolant. (See NOTE.)

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MOTORCYCLE CARE AND STORAGE
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EAU26000
Care
While the open design of a motorcycle
reveals the attractiveness of the tech-
nology, it also makes it more vulnera-
ble. Rust and corrosion can develop
even if high-quality components are
used. A rusty exhaust pipe may go un-
noticed on a car, however, it detracts
from the overall appearance of a mo-
torcycle. Frequent and proper care
does not only comply with the terms of
the warranty, but it will also keep your
motorcycle looking good, extend its
life and optimize its performance.
Before cleaning 1. Cover the muffler outlet with a plastic bag after the engine has
cooled down.
2. Make sure that all caps and cov- ers as well as all electrical cou-
plers and connectors, including
the spark plug cap, are tightly in-
stalled. 3. Remove extremely stubborn dirt,
like oil burnt onto the crankcase,
with a degreasing agent and a
brush, but never apply such prod-
ucts onto seals, gaskets, sprock-
ets, the drive chain and wheel
axles. Always rinse the dirt and
degreaser off with water.
Cleaning
ECA10770CAUTION:
●Avoid using strong acidic
wheel cleaners, especially on
spoked wheels. If such prod-
ucts are used on hard-to-re-
move dirt, do not leave the
cleaner on the affected area
any longer than instructed. Al-
so, thoroughly rinse the area
off with water, immediately dry
it, and then apply a corrosion
protection spray.
●Improper cleaning can damage
windshields, cowlings, panels
and other plastic parts. Use on-
ly a soft, clean cloth or sponge
with mild detergent and water
to clean plastic.
●Do not use any harsh chemical
products on plastic parts. Be
sure to avoid using cloths or
sponges which have been in
contact with strong or abrasive
cleaning products, solvent or
thinner, fuel (gasoline), rust re-
movers or inhibitors, brake flu-
id, antifreeze or electrolyte.
●Do not use high-pressure
washers or steam-jet cleaners
since they cause water seep-
age and deterioration in the fol-
lowing areas: seals (of wheel
and swingarm bearings, fork
and brakes), electric compo-
nents (couplers, connectors,
instruments, switches and
lights), breather hoses and
vents.

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MOTORCYCLE CARE AND STORAGE
7-2
●For motorcycles equipped with
a windshield: Do not use strong
cleaners or hard sponges as
they will cause dulling or
scratching. Some cleaning
compounds for plastic may
leave scratches on the wind-
shield. Test the product on a
small hidden part of the wind-
shield to make sure that it does
not leave any marks. If the
windshield is scratched, use a
quality plastic polishing com-
pound after washing.
After nor
mal use
Remove dirt with warm water, a mild
detergent, and a soft, clean sponge,
and then rinse thoroughly with clean
water. Use a toothbrush or bottlebrush
for hard-to-reach areas. Stubborn dirt
and insects will come off more easily if
the area is covered with a wet cloth for
a few minutes before cleaning. After r
iding in the rain, near the sea
or on salt-sprayed roads
Since sea salt or salt sprayed on roads
during winter are extremely corrosive
in combination with water, carry out
the following steps after each ride in
the rain, near the sea or on salt-
sprayed roads.
NOTE:
Salt sprayed on roads in the winter
may remain well into spring.
1. Clean the motorcycle with cold water and a mild detergent, after
the engine has cooled down.
ECA10790CAUTION:
Do not use warm water since it in-
creases the corrosive action of the
salt.
2. Apply a corrosion protection spray on all metal, including
chrome- and nickel-plated, sur-
faces to prevent corrosion. After cleaning
1. Dry the motorcycle with a chamois or an absorbing cloth.
2. Immediately dry the drive chain and lubricate it to prevent it from
rusting.
3. Use a chrome polish to shine chrome, aluminum and stainless-
steel parts, including the exhaust
system. (Even the thermally in-
duced discoloring of stainless-
steel exhaust systems can be re-
moved through polishing.)
4. To prevent corrosion, it is recom- mended to apply a corrosion pro-
tection spray on all metal, includ-
ing chrome- and nickel-plated,
surfaces.
5. Use spray oil as a universal clean- er to remove any remaining dirt.
6. Touch up minor paint damage caused by stones, etc.
7. Wax all painted surfaces.
8. Let the motorcycle dry completely before storing or covering it.

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MOTORCYCLE CARE AND STORAGE
7-4
Long-term
Before storing your motorcycle for sev-
eral months:1. Follow all the instructions in the “Care” section of this chapter.
2. Fill up the fuel tank and add fuel stabilizer (if available) to prevent
the fuel tank from rusting and the
fuel from deteriorating.
3. Perform the following steps to protect the cylinder, piston rings,
etc. from corrosion.a. Remove the spark plug cap and spark plug.
b. Pour a teaspoonful of engine oil into the spark plug bore.
c. Install the spark plug cap onto the spark plug, and then place
the spark plug on the cylinder
head so that the electrodes
are grounded. (This will limit
sparking during the next step.)
d. Turn the engine over several times with the starter. (This will
coat the cylinder wall with oil.)
e. Remove the spark plug cap from the spark plug, and then
install the spark plug and the
spark plug cap.EWA10950
WARNING0
To prevent damage or injury from
sparking, make sure to ground the
spark plug electrodes while turning
the engine over.
4. Lubricate all control cables and the pivoting points of all levers
and pedals as well as of the side-
stand/centerstand.
5. Check and, if necessary, correct the tire air pressure, and then lift
the motorcycle so that both of its
wheels are off the ground. Alter-
natively, turn the wheels a little
every month in order to prevent
the tires from becoming degraded
in one spot.
6. Cover the muffler outlets with plastic bags to prevent moisture
from entering them.

7. Remove the battery and fullycharge it. Store it in a cool, dry
place and charge it once a month.
Do not store the battery in an ex-
cessively cold or warm place [less
than 0 °C (30 °F) or more than 30
°C (90 °F)]. For more information
on storing the battery, see
page 6-31.
NOTE:
Make any necessary repairs before
storing the motorcycle.

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SPECIFICATIONS
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Engine oil:Type: SAE10W30 or SAE10W40 or SAE15W40
or SAE20W40 or SAE20W50
Recommended engine oil grade: API service SE, SF, SG type or higher
Engine oil quantity: Without oil filter element replacement:2.50 L (2.64 US qt) (2.19 Imp.qt)
With oil filter element replacement: 2.60 L (2.73 US qt) (2.26 Imp.qt)
Total amount (dry engine): 2.90 L (3.07 US qt) (2.55 Imp.qt)
Cooling system:Radiator capacity (including all routes): 1.2 L (1.26 US qt) (1.05 Imp.qt) (Radiator) +
0.5 L (0.52 US qt) (0.44 Imp.qt)
(Coolant reservoir)
Coolant reservoir capacity (up to the
maximum level mark): 0.50 L (0.52 US qt) (0.44 Imp.qt)
From low to full level: 0.30 L (0.32 US qt) (0.26 Imp.qt)
Air filter:Air filter element:Paper
Fuel:Recommended fuel:Premium unleaded gasoline only
Fuel tank capacity: 23.0 L (6.07 US gal) (5.06 Imp.gal)
Fuel reserve amount: 6.7 L (1.76 US gal) (1.46 Imp.gal)
Fuel injection:Manufacturer:DENSO
Model: 297500-0390
Spark plug:Manufacturer/model:NGK/CR7EGap:0.7-0.8 mm (0.028-0.032 in)
Clutch:Clutch type:Wet, multiple-disc
Transmission:Primary reduction system:Spur gear
Primary reduction ratio: 75/36 (2.083)
Secondary reduction system: Chain drive
Secondary reduction ratio: 45/15 (3.00)
Transmission type: Constant mesh 5-speed
Dimensions:Overall length:2246 mm (88.42 in)
Overall width: 864 mm (34.01 in)
Overall height: 1477 mm (58.14 in)
Seat height: 896 mm (35.27 in)
Wheelbase: 1500 mm (59.05 in)
Ground clearance: 260 mm (10.23 in)
Minimum turning radius: 1958 mm (77.08 in)
Basic weight:With oil and fuel:208.5 kg (459 lb)
Engine:Engine type:Liquid cooled 4-stroke, SOHC
Cylinder arrangement: Forward-inclined single cylinder
Displacement: 660.0 cm
3(40.27 cu.in)
Bore x stroke: 100.0 x 84.0 mm (3.94 x 3.31 in)
Compression ratio: 10.00 : 1
Starting system: Electric starter
Lubrication system: Dry sump
-20 -10 0 10 20 30 40 50 °C
SAE 10W-30
SAE 10W-40
SAE 20W-40
SAE 20W-50
SAE 15W-40

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SPECIFICATIONS
8-3
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Rear suspension:
Type: Swingarm (link suspension)
Spring/damper type: Coil spring/gas-oil damper, spring
preload adjustable
Wheel travel: 200 mm (7.87 in)
Electrical system:
Ignition system:Transistorized coil ignition (digital)
Charging system: A.C. magneto
Battery:
Model:GT9B-4
Voltage, capacity: 12 V, 8 Ah
Headlight:
Bulb type:Halogen bulb
Bulb voltage, wattage x quantity:Headlight:12 V, 55 W x 2
Auxiliary light: 12 V, 5 W x 2
Tail/brake light: LED
Front turn signal light: 12 V, 10 W x 2
Rear turn signal light: 12 V, 10 W x 2
Meter lighting: LED (backlight) Neutral indicator light:
LED
Turn signal indicator light: LED
High beam indicator light: LED
Coolant temperature warning light: LED
Engine trouble warning light: LED
Immobilizer system indicator light: LED
Fuses:Main fuse:
30 A
Headlight fuse: 20 A
Signaling system fuse: 10 A
Ignition fuse: 10 A
Parking lighting fuse: 10 A
Radiator fan fuse: 7.5 A
Fuel injection system fuse: 10 A
Backup fuse (for odometer, clock and immobilizer):
10 A

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INDEX
AAir filter element, cleaning the check hose....................................6-14
Air filter element, replacing ..............6-14
Anti-theft alarm (optional)...................3-8
Auxiliary light bulb, replacing............6-35
B Battery ..............................................6-30 To access the battery ...................6-30
To charge the battery....................6-30
To store the battery.......................6-31
Brake and clutch levers, checking and lubricating ...............6-26
Brake fluid ........................................6-22 Changing ......................................6-23
Checking fluid level .......................6-22
Brake lever .......................................3-11
Brake pads, checking .......................6-21
Brake pedal ......................................3-11 Lubricating ....................................6-27
C Cables, checking and lubricating .....6-25
Care and storage ...............................7-1
Catalytic converter ...........................3-13
Checking and lubricating the brake and clutch levers .................6-26
Checking and lubricating the brake pedal ...................................6-27
Checking and lubricating the cables ...........................................6-25 Checking and lubricating the
sidestand ......................................6-27
Checking and lubricating the throttle grip and cable ...................6-26
Checking the sidestand switch .........3-18
Clock mode ........................................3-7
Clutch lever ......................................3-10
Clutch lever free play, adjusting .......6-20
Consumer information ........................9-1
Controls and instruments ...................2-3
Function ..........................................3-1
Coolant .............................................6-12
Coolant temperature warning light .....3-4
D Description .........................................2-1 Controls and instrument .................2-3
Left view..........................................2-1
Right view .......................................2-2
Dimmer switch....................................3-9
Drive chain, cleaning and lubricating .....................................6-25
Drive chain slack ..............................6-23 Adjusting .......................................6-23
Checking .......................................6-23
Cleaning and lubricating ...............6-25
E Engine break-in ..................................5-3
Engine idling speed, adjusting .........6-15
Engine oil and oil filter element ..........6-9
Engine oil filter element....................6-10 Engine stop switch .............................3-9
Engine trouble warning light...............3-4
F Front fork ..........................................3-15 Adjusting .......................................3-15
Checking .......................................6-28
Front wheel ......................................6-36 Installing........................................6-37
Removing......................................6-36
Fuel ..................................................3-12
Fuel consumption, tips for reducing ...5-3
Fuel meter ..........................................3-7
Fuel tank breather hose ...................3-13
Fuel tank cap ...................................3-11
Fuses, replacing ...............................6-31
H Handlebar switches ............................3-9 Dimmer switch ................................3-9
Engine stop switch ..........................3-9
Hazard switch ...............................3-10
Horn switch .....................................3-9
Pass switch .....................................3-9
Start switch .....................................3-9
Turn signal switch ...........................3-9
Headlight bulb, replacing..................6-33
High beam indicator light ...................3-4
Horn switch ........................................3-9
I Identification numbers ........................9-1
Idling speed, checking .....................6-15

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INDEX
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Ignition circuit cut-off system............3-17 Checking operation procedure......3-18
Immobilizer system ............................3-1
Immobilizer system indicator light ......3-4
Indicator and warning lights ...............3-3 Coolant temperature warning
light .................................................3-4
Engine trouble warning light ...........3-4
High beam indicator light ................3-4
Immobilizer system indicator light...3-4
Neutral indicator light ......................3-4
Turn signal indicator light ................3-3
Instruments ........................................2-3
Instrument and control functions........3-1
K Key identification number ...................9-1
Keys ...................................................3-1
L License plate light bulb, replacing ....6-35
Lubricating the brake and clutch levers ..................................6-26
Lubricating the brake pedal..............6-27
Lubricating the cables ......................6-25
Lubricating the drive chain ...............6-25
Lubricating the sidestand .................6-27
Lubricating the throttle grip and cable .............................................6-26
Lubricating the swingarm pivots.......6-28
M Main switch/steering lock ...................3-2 Model label .........................................9-2
Multi-function display..........................3-5
Clock mode .....................................3-7
Self-diagnosis devices ....................3-7
Tachometer .....................................3-6
Tripmeter and tachometer modes ...3-6
N Neutral indicator light .........................3-4
O Oil filter element ...............................6-10
Operation and important riding points ..............................................5-1
Owner’s tool kit...................................6-1
P Panels, removing and installing .........6-6
Parking ...............................................5-4
Pass switch ........................................3-9
Periodic maintenance and lubrication chart ..............................6-2
Periodic maintenance and minor repair...............................................6-1
Pre-operation check list......................4-2
Pre-operation checks .........................4-1
R Rear suspension, lubricating............6-27
Rear wheel .......................................6-38 Installing........................................6-39
Removing......................................6-38
Record the identification numbers .....9-1 S
Safety information ..............................1-1
Seat ..................................................3-14
Self-diagnosis devices .......................3-7
Shift pedal ........................................3-10
Shifting ...............................................5-2
Shock absorber assembly (adjusting) .....................................3-16
Sidestand .........................................3-17
Sidestand, checking and lubricating .....................................6-27
Sidestand switch, checking ..............3-18
Spark plug, checking..........................6-8
Specifications .....................................8-1
Spoke wheels ...................................6-19
Start switch ........................................3-9
Starting the engine.............................5-1
Steering, checking............................6-29
Steering lock ......................................3-2
Storage...............................................7-3
Supporting the motorcycle ...............6-36
Swingarm, lubricating the pivots ......6-28
T Tachometer ........................................3-6
Tail/brake light ..................................6-34
Throttle cable free play, checking.....6-16
Throttle grip and cable, checking and lubricating ..............................6-26
Tips for reducing fuel consumption ....5-3
Tires .................................................6-16 Air pressure ..................................6-16

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