Yamaha XT660Z 2008 User manual

SERVICE MANUAL
2008
11D-F8197-E0
XT660Z

XT660Z (2008)
SERVICE MANUAL
© 2008 by Yamaha Motor Italia S.p.A.
First edition, May 2008
All rights reserved. Any reproduction or
unauthorized use without the written
permission of Yamaha Motor Italia S.p.A.
is expressly prohibited.
Printed in Italy

EAS00020
NOTICE
This manual was produced by the Yamaha Motor Italia S.p.A. primarily for use by Yamaha dealers and
their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manu-
al. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha vehicles
should have a basic understanding of mechanics and the techniques to repair these types of vehi-
cles. Repair and maintenance work attempted by anyone without this knowledge is likely to render
the vehicle unsafe and unfit for use.
Yamaha Motor Italia S.p.A. is continually striving to improve all of its models. Modifications and sig-
nificant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers
and will appear in future editions of this manual where applicable.
NOTE:
Designs and specifications are subject to change without notice.
EAS00040
IMPORTANT MANUAL INFORMATION
Particularly important information is distinguished in this manual by the following.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR SAFE-
TY IS INVOLVED!
Failure to follow WARNING instructions could result in severe injury or death to
the motorcycle operator, a bystander or a person checking or repairing the mo-
torcycle.
A CAUTION indicates special precautions that must be taken to avoid damage
to the motorcycle.
NOTE: A NOTE provides key information to make procedures easier or clearer.
WARNING
CAUTION:

EAS20090
HOW TO USE THIS MANUAL
This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive
explanations of all installation, removal, disassembly, assembly, repair and check procedures are
laid out with the individual steps in sequential order.
• The manual is divided into chapters and each chapter is divided into sections. The current section
title “1” is shown at the top of each page.
• Sub-section titles “2” appear in smaller print than the section title.
• To help identify parts and clarify procedure steps, there are exploded diagrams “3” at the start of
each removal and disassembly section.
• Numbers “4” are given in the order of the jobs in the exploded diagram. A number indicates a dis-
assembly step.
• Symbols “5” indicate parts to be lubricated or replaced. Refer to “SYMBOLS”.
• A job instruction chart “6” accompanies the exploded diagram, providing the order of jobs, names
of parts, notes in jobs, etc.
• Jobs “7” requiring more information (such as special tools and technical data) are described
sequentially.

EAS20100
SYMBOLS
The following symbols are used in this manual
for easier understanding.
NOTE:
The following symbols are not relevant to every
vehicle.
1. Serviceable with engine mounted
2. Filling fluid
3. Lubricant
4. Special tool
5. Tightening torque
6. Wear limit, clearance
7. Engine speed
8. Electrical data
9. Engine oil
10. Gear oil
11. Molybdenum disulfide oil
12. Wheel bearing grease
13. Lithium-soap-based grease
14. Molybdenum disulfide grease
15. Apply locking agent (LOCTITE®)
16. Replace the part with a new one.
New
12 3
45
78
6
91110
12 1413
15 16

GENERAL INFORMATION
TABLE OF CONTENTS
1
SPECIFICATIONS 2
PERIODIC CHECKS AND
ADJUSTMENTS 3
CHASSIS 4
ENGINE 5
COOLING SYSTEM 6
FUEL INJECTION SYSTEM 7
ELECTRICAL SYSTEM 8
TROUBLESHOOTING 9

GENERAL INFORMATION
IDENTIFICATION............................................................................................ 1-1
VEHICLE IDENTIFICATION NUMBER..................................................... 1-1
MODEL LABEL......................................................................................... 1-1
FEATURES ..................................................................................................... 1-2
OUTLINE OF THE FI SYSTEM................................................................ 1-2
FI SYSTEM............................................................................................... 1-3
INSTRUMENT FUNCTIONS .................................................................... 1-4
IMPORTANT INFORMATION ........................................................................ 1-7
PREPARATION FOR REMOVAL AND DISASSEMBLY ........................... 1-7
REPLACEMENT PARTS .......................................................................... 1-7
GASKETS, OIL SEALS AND O-RINGS ................................................... 1-7
LOCK WASHERS/PLATES AND COTTER PINS..................................... 1-7
BEARINGS AND OIL SEALS ................................................................... 1-8
CIRCLIPS ................................................................................................. 1-8
CHECKING THE CONNECTIONS ................................................................ 1-9
SPECIAL TOOLS ...........................................................................................1-10
1

1-1
IDENTIFICATION
1
1
IDENTIFICATION
EAS00170
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number “1” is stamped
into the right side of the steering head pipe.
EAS00180
MODEL LABEL
The model label “1” is affixed to the frame under
the seat. This information will be needed to or-
der spare parts.

1-2
FEATURES
EAS00019
FEATURES
EAS00896
OUTLINE OF THE FI SYSTEM
The main function of a fuel supply system is to provide fuel to the combustion chamber at the opti-
mum air-fuel ratio in accordance with the engine operating conditions and the atmospheric temper-
ature. In a conventional carburetor system, the air-fuel ratio of the mixture that is supplied to the com-
bustion chamber is created by the volume of the intake air and the fuel that is metered by the jet used
in the respective chamber. Despite the same volume of intake air, the fuel volume requirement varies
with the engine operating conditions, such as acceleration, deceleration, or operation under a heavy
load. Carburetors that meter the fuel through the use of jets have been provided with various auxil-
iary devices, so that an optimum air-fuel ratio can be achieved to accommodate the constant changes
in the operating conditions of the engine. As the requirements for engines to deliver more perform-
ance and cleaner exhaust gases increase, it becomes necessary to control the air-fuel ratio in a more
precise and finely tuned manner. To accommodate this need, this model has adopted an electroni-
cally controlled fuel injection (FI) system in place of a conventional carburetor system. This system
can achieve an optimum air-fuel ratio required by the engine at all times by using a microprocessor
that regulates the fuel injection volume according to the engine operating conditions detected by var-
ious sensors. Adoption of the FI system has resulted in a highly precise fuel supply, improved engine
response, better fuel economy, and reduced exhaust emissions. Furthermore, the air induction sys-
tem (AI system) has been placed under computer control together with the FI system in order to re-
alize cleaner exhaust gases.
1. Fuel tank
2. Engine trouble warning light
3. Ignition coil
4. Spark plug
5. Fuel pump
6. Idling adjustment screw
7. Throttle position sensor
8. Intake air pressure sensor
9. Air filter case
10. ECU
11. Lean angle cut-off switch
12. Catalytic converter
13. Fuel injection system relay
14. Battery
15. Intake air temperature sensor
16. Coolant temperature sensor
17. Fuel injector
18. Crankshaft position sensor
19. O2 sensor
20. Air induction system solenoid
21. Air cut-off valve

1-3
FEATURES
EAS00897
FI SYSTEM
The fuel pump delivers fuel to the injector via the fuel filter. The pressure regulator maintains the fu-
el pressure that is applied to the injector at 324 kPa (3.24 kg/cm2, 46.1 psi) higher than the intake
manifold pressure. Accordingly, when the energizing signal from the ECU energizes the injector, the
fuel passage opens, causing the fuel to be injected into the intake manifold only during the time the
passage remains open. Therefore, the longer the length of time the injector is energized (injection du-
ration), the greater the volume of fuel that is supplied. Conversely, the shorter the length of time the
injector is energized (injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from
the throttle position sensor, crankshaft position sensor, intake air pressure sensor, intake air temper-
ature sensor, coolant temperature sensor and O2sensor enable the ECU to determine the injection
duration. The injection timing is determined through the signal from the crankshaft position sensor.
As a result, the volume of fuel that is required by the engine can be supplied at all times in accor-
dance with the driving conditions.
Illustration is for reference only.
1. Fuel pump
2. Pressure regulator
3. Fuel injector
4. Throttle body
5. Intake air temperature sensor
6. Throttle position sensor
7. Intake air pressure sensor
8. ECU
9. Coolant temperature sensor
10. Crankshaft position sensor
11. O2sensor
12. Catalytic converter
A. Fuel system
B. Air system
C. Control system
2
1
5
4
8
7
6
9
#
3
1
A
B
C
10
12
11

1-4
FEATURES
INSTRUMENT FUNCTIONS
EAUB1500
Multi-function display
1. Tachometer
2. Speedometer
3. Odometer
4. Tripmeters/Fuel reserve tripmeter
5. Clock
6. Fuel meter
7. “RESET” button
8. “SELECT” button
EWA12311
WARNING
Be sure to stop the vehicle before making
any setting changes to the multi-function
display.
The multi-function display is equipped with the
following:
• a speedometer (which shows the riding
speed)
• a digital tachometer (which shows engine
r/min)
• an odometer (which shows the total distance
traveled)
• two tripmeters (which show the distance
traveled since they were last set to zero)
• a fuel reserve tripmeter (which shows the
distance traveled since the bottom segment
of the fuel meter started flashing)
• a clock
• a fuel meter
• a self-diagnosis device
NOTE:
• Be sure to turn the key to "ON" before using
the "SELECT" and "RESET" buttons.
• For the U.K. only: To switch the speedometer
and odometer/tripmeter displays between
kilometers and miles, push the "SELECT"
and "RESET" buttons together and turn the
key to "ON". When the digits start flashing on
the display push the "SELECT" button to
choose kilometers or miles.
Tachometer
1. Tachometer
2. Red zone
The tachometer allows the rider to monitor the
engine speed and keep it within the ideal pow-
er range.
When the key is turned to "ON", the tachometer
needle will sweep once across the r/min range
and then return to zero r/min in order to test the
electrical circuit.
ECA10030
CAUTION:
Do not operate the engine in the tachome-
ter red zone.
Red zone: 7,500 r/min and above.

1-5
FEATURES
Tripmeter and tachometer modes
1. “SELECT” button
2. “RESET” button
Pushing the "SELECT" button switches the dis-
play between the tripmeter modes "TRIP 1" and
"TRIP 2" in the following order:
TRIP 1 6TRIP 2 6TRIP 1
When the fuel amount in the fuel tank decreas-
es to 6.7 L (1.77 US gal) (1.47 Imp.gal), the bot-
tom segment of the fuel meter will start flashing,
and the tripmeter display will automatically
change to the fuel reserve tripmeter mode “F-
TRIP” and start counting the distance traveled
from that point. In that case, pushing the "SE-
LECT" button switches the display between the
various tripmeter modes in the following order:
F-TRIP 6TRIP 1 6TRIP 2 6F-TRIP
To reset a tripmeter, select it by pushing the "SE-
LECT" button, and then push the "RESET" button
for at least four seconds. If you do not reset the fu-
el reserve tripmeter manually, it will reset itself au-
tomatically and the display will return to the prior
mode after refueling and traveling 5 km (3 mi).
Clock mode
1. Clock
2. “SELECT” button
3. “RESET” button
NOTE:
The clock is displayed even when the key is
turned to "OFF".
T
o set the clock
1. Push the "SELECT" button for at least four
seconds.
2. When the hour digits start flashing, push the
"RESET" button to set the hours.
3. Push the "SELECT" button, and the minute
digits will start flashing.
4. Push the "RESET" button to set the minutes.
5. Push the "SELECT" button and then release
it to start the clock.
Fuel meter
1. Fuel meter
With the key in the "ON" position, the fuel meter
indicates the amount of fuel in the fuel tank.
When the key is turned to "ON", all of the display
segments of the fuel meter will appear one after
the other and then disappear in order to test the
electrical circuit. The display segments of the fu-
el meter disappear towards "E" (Empty) as the
fuel level decreases. When only one segment is
left near "E" (Empty), refuel as soon as possible.

1-6
FEATURES
NOTE:
This fuel meter is equipped with a selfdiagnosis
system. If the electrical circuit is defective all
the segments will start flashing.
Self-diagnosis devices
1. Engine trouble warning light “U”
2. Immobilizer system indicator light “ ”
This model is equipped with a self-diagnosis
device for various electrical circuits.
If any of those circuits are defective, the engine
trouble warning light will start flashing.
Refer to “FUEL INJECTION SYSTEM” on page
7-16. This model is also equipped with a self-di-
agnosis device for the immobilizer system.
Turn the key to "ON". If any of the immobilizer
system circuits are defective, the immobilizer
system indicator light will flash, and it will indi-
cate an error code. Refer to “IMMOBILIZER
SYSTEM” on page 8-29. However, if the indica-
tor light slowly flashes five times, and then
quickly flashes two times repeatedly, this error
could be caused by signal interference. If this
occurs, try the following.
1. Use the code re-registering key to start the
engine.
NOTE:
Make sure there are no other immobilizer keys
close to the main switch, and do not keep more
than one immobilizer key on the same key ring!
Immobilizer system keys may cause signal in-
terference, which may prevent the engine from
starting.
2. If the engine starts, turn it off and try starting
the engine with the standard keys.
3. If one or both of the standard keys do not start
the engine, re-register the standard keys.
If the multifunction display indicates an error
code, note the code number, and then check
the vehicle. Refer to “IMMOBILIZER SYSTEM”
on page 8-29.
ECA11590
CAUTION:
If the display indicates an error code, the
vehicle should be checked as soon as pos-
sible in order to avoid engine damage.

1-7
IMPORTANT INFORMATION
EAS20180
IMPORTANT INFORMATION
EAS20190
PREPARATION FOR REMOVAL AND
DISASSEMBLY
1. Before removal and disassembly, remove all
dirt, mud, dust and foreign material.
2. Use only the proper tools and cleaning
equipment.
Refer to “SPECIAL TOOLS” on page 1-10.
3. When disassembling, always keep mated
parts together. This includes gears, cylin-
ders,pistons and other parts that have been
“mated” through normal wear. Mated parts
must always be reused or replaced as an
assembly.
4. During disassembly, clean all of the parts
and place them in trays in the order of dis-
assembly. This will speed up assembly and
allow for the correct installation of all parts.
5. Keep all parts away from any source of fire.
EAS20200
REPLACEMENT PARTS
Use only genuine Yamaha parts for all replace-
ments. Use oil and grease recommended by
Yamaha for all lubrication jobs. Other brands
may be similar in function and appearance, but
inferior in quality.
EAS20210
GASKETS, OIL SEALS AND O-RINGS
1. When overhauling the engine, replace all
gaskets, seals and O-rings. All gasket sur-
faces, oil seal lips and O-rings must be
cleaned.
2. During reassembly, properly oil all mating
parts and bearings and lubricate the oil seal
lips with grease.
1. Oil
2. Lip
3. Spring
4. Grease
EAS20220
LOCK WASHERS/PLATES AND COTTER
PINS
After removal, replace all lock washers/plates
“1” and cotter pins. After the bolt or nut has
been tightened to specification, bend the lock
tabs along a flat of the bolt or nut.

1-8
IMPORTANT INFORMATION
EAS20230
BEARINGS AND OIL SEALS
Install bearings “1” and oil seals “2” so that the
manufacturer’s marks or numbers are visible.
When installing oil seals, lubricate the oil seal
lips with a light coat of lithium-soap-based
grease. Oil bearings liberally when installing, if
appropriate.
ECA13300
CAUTION:
Do not spin the bearing with compressed
air because this will damage the bearing
surfaces.
EAS20240
CIRCLIPS
Before reassembly, check all circlips carefully
and replace damaged or distorted circlips. Al-
ways replace piston pin clips after one use.
When installing a circlip “1”, make sure the
sharp-edged corner “2” is positioned opposite
the thrust “3” that the circlip receives.

1-9
CHECKING THE CONNECTIONS
EAS20250
CHECKING THE CONNECTIONS
Check the leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect:
• Lead
• Coupler
• Connector
2. Check:
• Lead
• Coupler
• Connector
Moisture →Dry with an air blower.
Rust/stains →Connect and disconnect sev-
eral times.
3. Check:
• All connections
Loose connection →Connect properly.
NOTE:
If the pin “1” on the terminal is flattened, bend
it up.
4. Connect:
• Lead
• Coupler
• Connector
NOTE:
Make sure all connections are tight.
5. Check:
• Continuity
(with the pocket tester)
Pocket tester
90890-03112
NOTE:
• If there is no continuity, clean the terminals.
• When checking the wire harness, perform
steps (1) to (3).
• As a quick remedy, use a contact revitalizer
available at most part stores.

1-10
SPECIAL TOOLS
EAS00027
SPECIAL TOOLS
The following special tools are necessary for complete and accurate tune-up and assembly. Use only the
appropriate special tools as this will help prevent damage caused by the use of inappropriate tools or im-
provised techniques. Special tools, part numbers or both may differ depending on the country.
When placing an order, refer to the list provided below to avoid any mistakes.
Tool name/Tool No. Illustration Reference
pages
Pocket tester
90890-03112
Digital circuit tester
90890-03174
Fuel injection system tester
90890-03182
Timing light
90890-03141
Ignition checker
90890-06754
Compression gauge
90890-03081
Adaptor (Compression gauge)
90890-04082
5-58, 8-45, 8-46,
8-47, 8-48, 8-52,
8-53, 8-54, 8-55,
8-56, 8-57, 8-58,
8-59, 8-60
7-10
7-23
3-7
8-55
3-8
3-8

1-11
SPECIAL TOOLS
Tool name/Tool No. Illustration Reference
pages
Pressure gauge
90890-03153
Fuel pressure adapter
90890-03176
Radiator cap tester
90890-01325
Radiator cap tester adaptor
90890-01352
Radiator cap tester adapter
90890-01497
Radiator tester adapter
90890-01496
Thickness gauge
90890-03079
Valve spring compressor attachment
90890-01243
Valve spring compressor
90890-04019
7-8
7-8
6-2, 6-3
6-2
6-2
6-3
6-2
6-3
3-4
5-20, 5-25

1-12
SPECIAL TOOLS
Tool name/Tool No. Illustration Reference
pages
Slide hammer bolt
90890-01083
Weight
90890-01084
Piston pin puller set
90890-01304
Valve guide remover (ø 6)
90890-04064
Valve guide installer (ø 6)
90890-04065
Valve guide reamer (ø 6)
90890-04066
Valve lapper
90890-04101
Flywheel puller
90890-01362
Sheave holder
90890-01701
5-15, 5-17
5-27
5-21
5-21
5-21
-
5-53
5-53, 5-55