Yamaha V STAR 950 User manual

Fix it like a Pro
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©2007 Repairpro Manuals

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.
TIP
The following symbols are not relevant to every vehicle.
SYMBOL DEFINITION SYMBOL DEFINITION
Serviceable with engine
mounted Gear oil
Filling fluid Molybdenum disulfide oil
Lubricant Brake fluid
Special tool Wheel bearing grease
Tightening torque Lithium-soap-based grease
Wear limit, clearance Molybdenum disulfide grease
Engine speed Silicone grease
Electrical data Apply locking agent (LOC-
TITE®).
Engine oil Replace the part with a new
one.

1
2
3
4
5
6
7
8
EAS20110 TABLE OF CONTENTS
GENERAL INFORMATION
SPECIFICATIONS
PERIODIC CHECKS AND ADJUSTMENTS
CHASSIS
ENGINE
FUEL SYSTEM
ELECTRICAL SYSTEM
TROUBLESHOOTING

1
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 .......................................................................1-6
PREPARATION FOR REMOVAL AND DISASSEMBLY..........................1-6
REPLACEMENT PARTS.........................................................................1-6
GASKETS, OIL SEALS AND O-RINGS..................................................1-6
LOCK WASHERS/PLATES AND COTTER PINS ...................................1-6
BEARINGS AND OIL SEALS .................................................................1-7
CIRCLIPS ...............................................................................................1-7
CHECKING THE CONNECTIONS ...............................................................1-8
SPECIAL TOOLS..........................................................................................1-9

IDENTIFICATION
1-1
EAS20130
IDENTIFICATION
EAS20140
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number “1” is
stamped into the right side of the steering
head pipe.
EAS20150
MODEL LABEL
The model label “1” is affixed to the frame. This
information will be needed to order spare
parts.
2
3
1
1

FEATURES
1-2
EAS20170
FEATURES
EAS5S71022
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 tempera-
ture. In the conventional carburetor system, the air-fuel ratio of the mixture that is supplied to the
combustion chamber is created by the volume of the intake air and the fuel that is metered by the jet
used in the respective carburetor.
Despite the same volume of intake air, the fuel volume requirement varies by the engine operating
conditions, such as acceleration, deceleration, or operating under a heavy load. Carburetors that
meter the fuel through the use of jets have been provided with various auxiliary devices, so that an
optimum air-fuel ratio can be achieved to accommodate the constant changes in the operating con-
ditions of the engine.
As the requirements for the engine to deliver more performance and cleaner exhaust gases
increase, it becomes necessary to control the air-fuel ratio in a more precise and finely tuned man-
ner. To accommodate this need, this model has adopted an electronically controlled fuel injection
(FI) system, in place of the 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 various sensors.
The adoption of the FI system has resulted in a highly precise fuel supply, improved engine
response, better fuel economy, and reduced exhaust emissions.
1. Air temperature sensor
2. Intake air pressure sensor
3. Engine trouble warning light
4. Fuel pump
5. Front cylinder injector
6. Rear cylinder injector
7. Throttle position sensor
8. Spark plug
9. Speed sensor
10.Relay unit (fuel pump relay)
11.ECU (engine control unit)
12.O2sensor
13.Lean angle sensor
14.ISC (idle speed control) unit
15.Crankshaft position sensor
16.Rear cylinder ignition coil
17.Front cylinder ignition coil
18.Engine temperature sensor

FEATURES
1-3
EAS5S71020
FI SYSTEM
The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the
fuel pressure that is applied to the fuel injector at only 392 kPa (3.92 kg/cm², 56.9 psi). Accordingly,
when the energizing signal from the ECU energizes the fuel injector, the fuel passage opens, caus-
ing 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 fuel injector is energized (injection duration), the greater
the volume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is ener-
gized (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, air temperature
sensor, engine temperature sensor, lean angle sensor, speed sensor and O2sensor enable the
ECU to determine the injection duration. The injection timing is determined through the signals 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 accordance with the driving conditions.
Illustration is for reference only.
15
A
1
2
3
C
12
13
14
B
9
11
4
8
7
65
Front
Rear
10
16
1. Fuel pump
2. Fuel injector
3. Ignition coil
4. ECU (engine control unit)
5. Air temperature sensor
6. Lean angle sensor
7. ISC (idle speed control) unit
8. Throttle position sensor
9. O2sensor
10.Engine temperature sensor
11.Catalytic converter
12.Crankshaft position sensor
13.Intake air pressure sensor
14.Throttle body
15.Air filter case
16.Speed sensor
A. Fuel system
B. Air system
C. Control system

FEATURES
1-4
EAS5S71021
INSTRUMENT FUNCTIONS
Multi-function meter unit
WARNING
EWA5S71001
Be sure to stop the vehicle before making
any setting changes to the multi-function
meter unit.
The multi-function meter unit is equipped with
the following:
• a speedometer (which shows the riding
speed)
• an odometer (which shows the total distance
traveled)
• two tripmeters (which show the distance trav-
eled since they were last set to zero)
• a fuel reserve tripmeter (which shows the
distance traveled on the fuel reserve)
•aclock
• a self-diagnosis device
• a brightness control mode
TIP
Be sure to turn the key to “ON” before using
the “SELECT” switch and “RESET” switch,
except for setting the brightness control mode.
Speedometer
The speedometer shows the riding speed.
When the key is turned to “ON”, the speedom-
eter needle will sweep once across the speed
range and then return to zero in order to test
the electrical circuit.
Clock
To set the clock:
1. Push the “SELECT” switch and the
“RESET” switch together for at least three
seconds.
2. When the hour digits start flashing, push
the “RESET” switch to set the hours.
3. Push the “SELECT” switch, and the minute
digits will start flashing.
4. Push the “RESET” switch to set the min-
utes.
5. Push the “SELECT” switch and then
release it to start the clock.
1. Speedometer
2. Odometer/tripmeter/fuel reserve tripmeter/
clock
1. “SELECT” switch
2. “RESET” switch
1
2
1
2
1. Speedometer
1. Clock
1
1

FEATURES
1-5
Odometer, tripmeter, and fuel reserve trip-
meter modes
Push the “SELECT” switch to change the dis-
play between the odometer mode “ODO”, the
tripmeter modes “TRIP A” and “TRIP B” in the
following order:
ODO →TRIP A →TRIP B →ODO
If the fuel level warning light comes on, the
odometer display will automatically change to
the fuel reserve tripmeter mode “TRIP F” and
start counting the distance traveled from that
point. In that case, push the “SELECT” switch
to change the display between the various trip-
meter and odometer modes in the following
order:
TRIP F →TRIP A →TRIP B →ODO →TRIP
F
To reset a tripmeter, select it by pushing the
“SELECT” switch, and then push the “RESET”
switch for at least one second. If you do not
reset the fuel reserve tripmeter manually, it will
reset itself automatically, and the display will
return to the prior mode after refueling and
traveling 5 km (3 mi).
Self-diagnosis device
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 come on, and then the
odometer/tripmeter/clock display will indicate a
two-digit error code (e.g., 12, 13, 14).
If the odometer/tripmeter/clock display indi-
cates any error codes, note the code number,
and then check the vehicle. Refer to “FUEL
INJECTION SYSTEM” on page 7-27.
ECA5S71001
If the display indicates an error code, the
vehicle should be checked as soon as pos-
sible in order to avoid engine damage.
Brightness control mode
This function allows you to adjust the bright-
ness of the multi-function meter unit panel to
suit the outside lighting conditions.
To set the brightness:
1. Turn the key to “OFF”.
2. Push and hold the “SELECT” switch.
3. Turn the key to “ON”, and then release the
“SELECT” switch after five seconds.
4. Adjust the multi-function meter unit panel
brightness level by pushing the “SELECT”
switch.
5. Push the “RESET” switch.
The odometer/tripmeter/clock display will
return to the prior mode.
1. Odometer/tripmeter/fuel reserve tripmeter
1. Error code display
1
1
1. Brightness level
1

IMPORTANT INFORMATION
1-6
EAS20180
IMPORTANT INFORMATION
EAS20190
PREPARATION FOR REMOVAL AND DISAS-
SEMBLY
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 1-9.
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.
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. Oil
2. Lip
3. Spring
4. Grease

IMPORTANT INFORMATION
1-7
EAS20230
BEARINGS AND OIL SEALS
Install bearings and oil seals so that the manu-
facturer’s marks or numbers are visible. When
installing oil seals “1”, lubricate the oil seal lips
with a light coat of lithium-soap-based grease.
Oil bearings liberally when installing, if appro-
priate.
ECA13300
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.
Always 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.

CHECKING THE CONNECTIONS
1-8
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
several times.
3. Check:
• All connections
Loose connection →Connect properly.
TIP
If the pin “1” on the terminal is flattened, bend
it up.
4. Connect:
• Lead
• Coupler
• Connector
TIP
Make sure all connections are tight.
5. Check:
•Continuity
(with the pocket tester)
TIP
• 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.
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C

SPECIAL TOOLS
1-9
EAS20260
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 inappropri-
ate tools or improvised 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.
TIP
• For U.S.A. and Canada, use part numbers starting with “YM-”, “YU-”, or “ACC-”.
• For others, use part numbers starting with “90890-”.
Tool name/Tool No. Illustration Reference
pages
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
1-8, 7-79, 7-80,
7-81, 7-85, 7-
86, 7-87, 7-88,
7-89, 7-90, 7-
91, 7-92, 7-93,
7-94, 7-95
Thickness gauge
90890-03180
Feeler gauge set
YU-26900-9
3-7
Vacuum gauge
90890-03094
Carburetor synchronizer
YU-44456
3-9
Timing light
90890-03141
Inductive clamp timing light
YU-03141
3-5
Compression gauge
90890-03081
Engine compression tester
YU-33223
5-22
YU-44456

SPECIAL TOOLS
1-10
Extension
90890-04136
5-22
Extension
90890-04082
5-22
Oil filter wrench
90890-01426
YU-38411
3-24
Belt tension gauge
90890-03170
Rear drive belt tension gauge
YM-03170
3-18
Steering nut wrench
90890-01403
Exhaust flange nut wrench
YU-A9472
3-20, 4-58
Damper rod holder
90890-01460
4-51, 4-53
T-handle
90890-01326
T-handle 3/8" drive 60 cm long
YM-01326
4-51, 4-53
Fork seal driver
90890-01442
Adjustable fork seal driver (36–46 mm)
YM-01442
4-53, 4-54
Tool name/Tool No. Illustration Reference
pages

SPECIAL TOOLS
1-11
Rotor holding tool
90890-01235
Universal magneto & rotor holder
YU-01235
5-13, 5-17, 5-18
Slide hammer bolt
90890-01083
Slide hammer bolt 6 mm
YU-01083-1
5-14
Weight
90890-01084
YU-01083-3
5-14
Valve spring compressor
90890-04019
YM-04019
5-25, 5-30
Valve spring compressor attachment
90890-01243
Valve spring compressor adapter (26 mm)
YM-01253-1
5-25, 5-30
Valve guide remover (ø6)
90890-04064
Valve guide remover (6.0 mm)
YM-04064-A
5-27
Tool name/Tool No. Illustration Reference
pages
YU-01083-3

SPECIAL TOOLS
1-12
Valve guide installer (ø6)
90890-04065
Valve guide installer (6.0 mm)
YM-04065-A
5-27
Valve guide reamer (ø6)
90890-04066
Valve guide reamer (6.0 mm)
YM-04066
5-27
Piston pin puller set
90890-01304
Piston pin puller
YU-01304
5-33
Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
5-41, 5-42, 5-
48, 5-50
Flywheel puller set
90890-01468
Heavy duty puller
YU-33270-B
5-41
Yamaha bond No. 1215
90890-85505
(Three Bond No.1215®)
5-42, 5-63
Tool name/Tool No. Illustration Reference
pages
YU-01304

SPECIAL TOOLS
1-13
Universal clutch holder
90890-04086
YM-91042
5-48, 5-51
Pressure gauge
90890-03153
YU-03153
6-9, 6-11
Fuel pressure adapter
90890-03176
YM-03176
6-11
Digital circuit tester
90890-03174
Model 88 Multimeter with tachometer
YU-A1927
5-57, 6-12
Ignition checker
90890-06754
Opama pet-4000 spark checker
YM-34487
7-88
Digital tachometer
90890-06760
YU-39951-B
3-5, 3-9
Tool name/Tool No. Illustration Reference
pages