Yamaha YFM660FS Manual

LIT-11616-17-14 5KM-28197-E2
YFM660FS
SUPPLEMENTARY
SERVICE MANUAL

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and data for the
YFM660FS. For complete service information procedures it is necessary to use this Supplementary
Service Manual together with the following manual.
YFM660FP SERVICE MANUAL: LIT-11616-15-01 (5KM-28197-E0)
YFM660FR SUPPLEMENTARY SERVICE MANUAL: LIT-11616-16-34 (5KM-28197-E1)
YFM660FS
SUPPLEMENTARY
SERVICE MANUAL
©2003 by Yamaha Motor Corporation, U.S.A.
First Edition, April 2003
All rights reserved.
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor Corporation, U.S.A.
is expressly prohibited.
Printed in U.S.A.
LIT-11616-17-14

EB001000
NOTICE
This manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers
and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one
manual, so it is assumed that anyone who uses this book to perform maintenance and repairs on
Yamaha machine has a basic understanding of the mechanical ideas and the procedures of
machine repair. Repairs attempted by anyone without this knowledge are likely to render the
machine unsafe and unfit for use.
Yamaha Motor Company, Ltd. is continually striving to improve all 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.
N
OTE:
Designs and specifications are subject to change without notice.
IMPORTANT INFORMATION
Particularly important information is distinguished in this manual by the following notations.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED!
Failure to follow WARNING instructions could result in severe injury or death
to the machine operator, a bystander or a person inspecting or repairing the
machine.
A CAUTION indicates special precautions that must be taken to avoid dam-
age to the machine.
A NOTE provides key information to make procedures easier or clearer.
WARNING
CAUTION:
NOTE:

EB002000
HOW TO USE THIS MANUAL
MANUAL ORGANIZATION
This manual consists of chapters for the main categories of subjects. (See “Illustrated symbols”)
1st title 1: This is the title of the chapter with its symbol in the upper right corner of each page.
2nd title 2: This title indicates the section of the chapter and only appears on the first page of each
section. It is located in the upper left corner of the page.
3rd title 3: This title indicates a sub-section that is followed by step-by-step procedures accompa-
nied by corresponding illustrations.
EXPLODED DIAGRAMS
To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each
removal and disassembly section.
1. An easy-to-see exploded diagram 4is provided for removal and disassembly jobs.
2. Numbers 5are given in the order of the jobs in the exploded diagram. A number that is enclosed
by a circle indicates a disassembly step.
3. An explanation of jobs and notes is presented in an easy-to-read way by the use of symbol marks
6. The meanings of the symbol marks are given on the next page.
4. A job instruction chart 7accompanies the exploded diagram, providing the order of jobs, names
of parts, notes in jobs, etc.
5. For jobs requiring more information, the step-by-step format supplements 8are given in addition
to the exploded diagram and the job instruction chart.

EB003000
ILLUSTRATED SYMBOLS
Illustrated symbols 1to 0are printed on the
top right of each page and indicate the subject
of each chapter.
1General information
2Specifications
3Periodic checks and adjustments
4Engine
5Cooling system
6Carburetion
7Drive train
8Chassis
9Electrical
0Troubleshooting
Illustrated symbols Ato Hare used to identify
the specifications appearing in the text.
ACan be serviced with engine mounted
BFilling fluid
CLubricant
DSpecial tool
ETorque
FWear limit, clearance
GEngine speed
HΩ, V, A
Illustrated symbols Ito Nin the exploded
diagrams indicate the types of lubricants and
lubrication points.
IApply engine oil
JApply gear oil
KApply molybdenum disulfide oil
LApply wheel bearing grease
MApply lightweight lithium-soap-based grease
NApply molybdenum disulfide grease
Illustrated symbols Oto Pin the exploded
diagrams indicate where to apply a locking
agent Oand when to install a new part P.
OApply the locking agent (LOCTITE)
PReplace
12
34
56
78
90
AB
CD
EF
GH
IJK
LMN
OP
GEN
INFO SPEC
CHK
ADJ ENG
COOL CARB
DRIV
CHAS
–+
ELEC TRBL
SHTG
T
R
.
.
EGM
BLS M
LT
New

CONTENTS
GENERAL INFORMATION ..............................................................................1
FEATURES ...............................................................................................1
OVERRIDE SWITCH (DEACTIVATING THE SPEED LIMITER
WHEN THE DIFFERENTIAL IS LOCKED) ...........................................1
SPECIFICATIONS ............................................................................................3
GENERAL SPECIFICATIONS ..................................................................3
MAINTENANCE SPECIFICATIONS .........................................................4
ENGINE ................................................................................................4
CHASSIS ..............................................................................................5
ELECTRICAL ........................................................................................5
CHASSIS ..........................................................................................................6
STEERING SYSTEM ................................................................................6
INSTALLING THE REAR BRAKE LEVER ............................................6
ELECTRICAL ...................................................................................................7
CHECKING THE SWITCH ........................................................................7
CHECKING THE SWITCH CONTINUITY .............................................7
SIGNAL SYSTEM .....................................................................................9
CIRCUIT DIAGRAM ..............................................................................9
YFM660FS WIRING DIAGRAM

GEN
INFO
–1 –
GENERAL INFORMATION
FEATURES
OVERRIDE SWITCH
(DEACTIVATING THE SPEED LIMITER WHEN THE DIFFERENTIAL IS LOCKED)
This model is equipped with a speed limiter system (35 km/h [22 mph]) that operates when the dif-
ferential is locked and the ATV is traveling forward. If additional engine power is required (e.g., to
free the ATV from mud) when the ATV is traveling forward and the differential is locked, the speed
limiter can be temporarily deactivated by pressing the override switch.
N
OTE:
The speed limiter is deactivated only while the override switch is being pressed.
1Override switch
When the override switch is pressed, the segments of the speedometer digits are displayed as fol-
lows.
N
OTE:
●When the front differential gear is locked and the drive select lever is in the “L”, “H”, “N”, or “P”
position, the display changes when the override switch is pressed. (The speedometer display is
not displayed at this time.)
●When the front differential gear is not locked or the drive select lever is in the “R”position, the dis-
play does not change even if the override switch is pressed.
mph
ODOTRIP AB CLOCKHOUR
E
F
F
F
OFF
LOCK
0.2s 0.2s
0.2s 0.2s
0.2s 0.2s
FEATURES

GEN
INFO
–2 –
FEATURES
CAUTION:
If the segments of the speedometer digits show the override display when the override
switch is not pressed, the speed limiter system is malfunctioning. Check the override switch
and ignition system, and then repair if necessary.

–3 –
SPEC
SPECIFICATIONS
GENERAL SPECIFICATIONS
Item Standard
Model code: 5KMH
5KMM
5KMN
5KMP
Transmission:
Primary reduction system V-belt
Secondary reduction system Shaft drive
Secondary reduction ratio 41/21 ×24/18 ×33/9 (9.544)
Transmission type V-belt automatic
Operation Left hand operation
Single speed automatic 2.45 ~ 0.70 : 1
Sub transmission ratio low 35/17 (2.058)
high 26/21 (1.238)
Reverse gear 25/17 (1.471)
GENERAL SPECIFICATIONS

–4 –
SPEC
MAINTENANCE SPECIFICATIONS
ENGINE
Item Standard Limit
Carburetor:
I. D. mark 5KMA 10 ----
Main jet (M.J) #153.8 ----
Main air jet (M.A.J) #70 ----
Jet needle (J.N) 6JPH9-53-2 ----
Needle jet (N.J) O-0M ----
Pilot air jet (P.A.J.1) #60 ----
Pilot air jet (P.A.J.2) 1.5 ----
Pilot outlet (P.O) 1.1 ----
Pilot jet (P.J) #40 ----
Bypass 1 (B.P.1) 0.8 ----
Bypass 2 (B.P.2) 0.8 ----
Bypass 3 (B.P.3) 0.8 ----
Valve seat size (V.S) 3.0 ----
Starter jet (G.S.1) #55 ----
Starter jet (G.S.2) 0.8 ----
Throttle valve size (Th.V) #105 ----
Float height (F.H) 13 mm (0.51 in) ----
Fuel level (F.L) 4.5 mm (0.18 in) ----
Engine idle speed 1,450 ~ 1,550 r/min ----
Intake vacuum 30.7 ~ 33.3 kPa
(230 ~ 250 mmHg, 9.07 ~ 9.83 inHg)
----
MAINTENANCE SPECIFICATIONS

–5 –
SPEC
CHASSIS
ELECTRICAL
Item Standard Limit
Front suspension:
Shock absorber travel 86 mm (3.39 in) ----
Fork spring free length 296.5 mm (11.67 in) 290.6 mm
(11.44 in)
Spring fitting length 237 mm (9.33 in) ----
Spring rate (K1) 20 N/mm
(2.04 kg/mm, 114.2 lb/in)
----
Stroke (K1) 0 ~ 86 mm (0 ~ 3.39 in) ----
Optional spring No ----
Rear suspension:
Shock absorber travel 95 mm (3.74 in) ----
Spring free length 278.5 mm (10.96 in) ----
Spring fitting length 237 mm (9.33 in) ----
Spring rate (K1) 36.4 N/mm
(3.71 kg/mm, 207.84 lb/in)
----
Stroke (K1) 0 ~ 95 mm (0 ~ 3.74 in) ----
Optional spring No ----
Item Standard Limit
C.D.I.:
Magneto model/manufacturer F4T469/MITSUBISHI ----
Pickup coil resistance/color 459 ~ 561 Ωat 20 °C (68 °F)/
White/Red –White/Green
----
Rotor rotation direction sensing coil resis-
tance/color
0.063 ~ 0.077 Ωat 20 °C (68 °F)/
Red –White/Blue
----
C.D.I. unit model/manufacturer F8T40372/MITSUBISHI ----
Charging system:
Type A.C. magneto generator ----
Model/manufacturer F4T469/MITSUBISHI ----
Nominal output 14 V 21 A at 5,000 r/min ----
Charging coil resistance/color 0.32 ~ 0.43 Ωat 20 °C (68 °F)/
White –White
----
MAINTENANCE SPECIFICATIONS

–6 –
CHAS
STEERING SYSTEM
CHASSIS
STEERING SYSTEM
INSTALLING THE REAR BRAKE LEVER
1.Install:
●Handlebar switch 1
●Rear brake lever
●Lever bracket 2
N
OTE:
Install the lever bracket as shown.
a74.5 mm (2.9 in)

–7 –
–+
ELEC
CHECKING THE SWITCH
ELECTRICAL
CHECKING THE SWITCH
CHECKING THE SWITCH CONTINUITY
Refer to “CHECKING THE SWITCH”in CHAPTER 9 (Manual No.: 5KM-28197-E0) and check for
continuity between lead terminals.
Poor connection, no continuity →Correct or replace.
*The coupler locations are circled.
L
B
Y
G
Br
L/B
1
5
6
B
7
23
PUSH
Br L Y G B
R/W
L/BL/G
Br/L BrR
L/R Sb Br Gy G/R B
R/BL/B
2WD
4WD
LOCK
L/G
L/B
L/R
Sb
Gy
Br
G/R
B
(BLACK) (GRAY)
P
L
Gy W
ON
OFF
R Br Br/L
Br Y
(BLACK)
8
BB
(BLACK)
9
0A
BB
4
PUSH
B
Lg R/BR/W
Lg

–8 –
–+
ELEC
CHECKING THE SWITCH
1Light switch
2Engine stop switch
3Start switch
4Override switch
5On-command four-wheel drive switch and differential gear lock switch
6Main switch
7Rear brake light switch
8Front brake light switch
9Rear brake switch
0Gear position switch
AReverse switch
BFuse

–9 –
–+
ELEC
SIGNAL SYSTEM
EB806000
SIGNAL SYSTEM
CIRCUIT DIAGRAM
2WD
4WD
LOCK
ON
OFF
B
B
RR
L/WL/B
R/B L/W
W/R
B/Y
R
O
W/G
B
Sb
G/WW/B
G/R
(BLACK) (BLACK)
(BLACK)
(BLACK)
(GRAY)
(GRAY) (BLACK)
(BLACK)
(BLACK)
R
W/G
W/LW/R
W/G
R
W/RW/G
L/G
L/B
L/R
Sb
R/Y
L/B
L
B
Y
G
L/G
L/B
L/R
Sb
L
B
Y
G
Br
L/B
Gy
Br
G/R
B
Gy
Br
G/R
B
Sb
W
L/WB/RW/L
G/L
Sb
L/W
B/RW/L
W
G/L
L/Y
G/YL/RW/R
W/BR/W
P
L
Gy
W
Sb
L/R
L/WW/R
(BLACK)
Br
G/Y
L/R
L/YW/B
W/R
W
WW
W
WW
BR
WWW
(BLACK)
B/Y
B
LB BL
OB
O
B
G
W/B
PB
Br
YBr
Y
Br YBB
(DARK GRAY)
(GRAY) (GRAY)
G/Y
B
(BLACK)(BLACK)
(BLACK) (BLACK)
Br/B
WL
B
L/Y
W
B
G/RR/G
B
G/R R/G
B
GY
B
YG
B
GY
B
YG
B
R/BR/W
Lg
R/WR/B
Lg
W W
W WBR
RR R
B B
R
B
P
L
L
B B
B P
Y
Y
G
Y GY G
B B
B
O O
B B
W
W/R
W/B
L/W
R
W/G
Y/B
R/B
B/Y B/Y
G/W G/W
L/W
L/B
Br/L
Br/L
Br
Br
Br
L/Y
W
B
B
B
B
Br
L L
B
B
L/Y
G/R
B/R
Lg
G/W
Sb
WIRE HARNESS
IGNITION COIL LEAD
C
WIRE HARNESS
B
WIRE HARNESS
SUB-WIRE HARNESS SUB-WIRE HARNESS
A
B
B/R
W/B
W/B
B
B/R
C
C
1
8
4
56
7
A
9
C
B
D
E
GH I JK LM
O
N
P
Q
R
a
]
`
g
3
Br/L
cde
Br/L
Br/L
b
U
V
\
Z
L/B
R/BBr/B
Br
B/Y
Sb
L/B
R/BBr/B
Br
B/Y
Sb
R
W/R
W/G W/G
W W 2
R
R/G
R
R
Br Br
Br/L
R
Br/L
=
G/L
B/Y L/R
Y/B
R/B R/B
L/W
L/W
L/R
L/R
W/R W/R
Sb
Sb
B
L/B
Sb
Br
B
T
S
X
Y
B
L
R/B
Br/L
Br/R
Br/R
Br/B
Br/R
Br/RL/G
B
Br/R
Br/R
Br/B
B
L/G
W
Br/R Br/R
B/Y
B
L/R
G/R
Gy
Gy
L/G
(BLACK)
B/Y
Br/R
Br/RL/R
B
(BLACK)
Y/B
L/RBr/R
Gy
(BLACK) (GRAY)
(GRAY)(BLACK)
B
B BB B
B B B B
B
A
A
A
L/R
L/B
L/B
B/Y B/YB/RB/R B/R
Br/B
Br/B Br/B
W/B
W/B W/B
L/BSb
Sb
Br Br
Sb
Br
R/G
B/R
W/B
R/W
W/L
W/L W/L
G/R
G/Y G/Y
G/L
W
ff
i
h
R/Y R/W R/Y R/B L/BR/W
R/W
j
Y
Y
PUSH PUSH
OFF
R
Lg
F
L/R
B
Br
W
B/R
Lg
Y/B G/L
R
W/BB/YB/R
B

–10 –
–+
ELEC
SIGNAL SYSTEM
3Main switch
4Backup fuse
5Battery
6Main fuse
9Reverse switch
0CDI unit
DSpeed sensor
FMulti-function meter
GDifferential gear lock indicator light
HCoolant temperature indicator light
IReverse indicator light
JNeutral indicator light
KPark indicator light
LHigh-range indicator light
MLow-range indicator light
NGear position switch
PFuel sender
QThermo switch 1
YOn-command four-wheel drive switch and differential gear lock switch
ZGear motor
]Ignition fuse
eOverride switch
gSignaling system fuse
hRear brake light switch
iFront brake light switch
jTail/brake light

YAMAHA MOTOR CO., LTD.
2500 SHINGAI IWATA SHIZUOKA JAPAN
PRINTED IN U.S.A.

YFM660FS WIRING DIAGRAM
2WD
4WD
LOCK
ON
OFF
B
B
RR
L/WL/B
R/B L/W
W/R
B/Y R
O
W/G
B
Sb
G/WW/B
G/R
(BLACK) (BLACK)
(BLACK)
(BLACK)
(GRAY)
(GRAY) (BLACK)
(BLACK)
(BLACK)
R W/G
W/LW/R
W/G R
W/RW/G
L/G
L/B
L/R
Sb
R/Y
L/B
L
B
Y
G
L/G
L/B
L/R
Sb
L
B
Y
G
Br
L/B
Gy
Br
G/R
B
Gy
Br
G/R
B
Sb
W
L/WB/RW/L
G/L
Sb
L/W
B/RW/L
W G/L
L/Y
G/YL/RW/R
W/BR/W
P
L
Gy
W
Sb
L/R
L/WW/R
(BLACK)
Br
G/Y
L/R
L/YW/B
W/R
W
WW
W
WW
BR
WWW
(BLACK)
B/Y
B
LB BL
OB
O B
G W/B
PB
Br
YBr
Y
Br YBB
(DARK GRAY)
(GRAY) (GRAY)
G/Y
B
(BLACK)(BLACK)
(BLACK) (BLACK)
Br/BB/RW/BB/Y
WL
B
L/Y W
B
G/RR/G
B
G/R R/G
B
GY
B
YG
B
GY
B
YG
B
R/BR/W
Lg
R/WR/B
Lg
W
W
W
WBR
RR
R
B
B
R
B
P
L
L
B B
B
P
Y
Y
G
Y GY G
B
B
B
O O
B B
W
W/R
W/B
L/W
R
W/G
Y/B
R/B
B/Y
B/Y
G/W
G/W
L/W
L/B
Br/L
Br/L
Br
Br
Br
L/Y
W
B
B
B
B
Br
L
L
B
B
L/Y
G/R
B/R
Lg
G/W
Sb
WIRE HARNESS IGNITION COIL LEAD
C
WIRE HARNESS
B
WIRE HARNESS
SUB-WIRE HARNESS SUB-WIRE HARNESS
A
B
B/R
W/B
W/B
B
B/R
C
C
1
8
4
56
7
A
9
C
B
D
E
GH I JK LM
O
N
P
Q
R
a
]
`
g
3
[
Br/L
c e
Br/L
Br/L
b
U
V
\
Z
L/B
R/BBr/B
Br
B/Y
Sb
L/B
R/BBr/B
Br
B/Y
Sb
R
W/R
W/G
W/G
W W 2
R
R/G
R
R Br Br Br/L
R Br/L
=
G/L
B/Y L/R
Y/B
R/B
R/B
L/W
L/W
L/R
L/R
W/R
W/R
Sb
Sb
B
L/B
Sb
Br
B
T
S
X
Y
B
L R/B
Br/L
Br/R
Br/R
Br/B
Br/R
Br/RL/G
B
Br/R
Br/R
Br/B
B
L/G
W
Br/R Br/R
B/Y
B
L/R
G/R
Gy
Gy
L/G
(BLACK)
B/Y
Br/R
Br/RL/R
B
(BLACK)
Y/B
L/RBr/R
Gy
(BLACK) (GRAY)
(GRAY)(BLACK)
B
B
BB
B
B B B B
B
A
A
A
L/R
L/B
L/B
B/Y
B/YB/RB/R B/R
Br/B
Br/B Br/B
W/B
W/B W/B
L/BSb
Sb
Br
Br
Sb
Br
R/G
B/R
W/B
R/W
W/L
W/L
W/L
G/R
G/Y
G/Y
G/L
W
ff
i
h
R/Y R/W
R/Y R/B L/BR/W
R/W
j
Y
Y
PUSH PUSH
OFF
R
Lg
F
L/R
B
Br
W
B/R Lg
Y/B
G/L
R
B
1AC magneto
2Rectifier/regulator
3Main switch
4Backup fuse
5Battery
6Main fuse
7Starter relay
8Starter motor
9Reverse switch
0CDI unit
ARear brake switch
BIgnition coil
CSpark plug
DSpeed sensor
EMeter assembly
FMulti-function meter
GDifferential gear lock indicator light
HCoolant temperature indicator light
IReverse indicator light
JNeutral indicator light
KPark indicator light
LHigh-range indicator light
MLow-range indicator light
NGear position switch
ODiode
PFuel sender
QThermo switch 1
RCircuit breaker (fan motor)
SThermo switch 2
TFan motor
UFour-wheel drive fuse
VFour-wheel drive relay 1
WFour-wheel drive relay 2
XFour-wheel drive relay 3
YOn-command four-wheel drive switch and
differential gear lock switch
ZGear motor
[Auxiliary DC jack fuse
\Auxiliary DC jack
]Ignition fuse
^Headlight fuse
aHandlebar switch (left)
bLight switch
cEngine stop switch
dStart switch
eOverride switch
fHeadlight
gSignaling system fuse
hRear brake light switch
iFront brake light switch
jTail/brake light
COLOR CODE
B ............Black
Br...........Brown
G............Green
L.............Blue
Lg...........Light green
O............Orange
P ............Pink
R............Red
Sb ..........Sky blue
Gy ..........Gray
W ...........White
Y ............Yellow
B/R.........Black/Red
B/Y.........Black/Yellow
Br/B........Brown/Black
Br/L ........Brown/Blue
Br/R .......Brown/Red
G/L.........Green/Blue
G/R ........Green/Red
G/W........Green/White
G/Y.........Green/Yellow
L/B .........Blue/Black
L/G .........Blue/Green
L/R .........Blue/Red
L/W ........Blue/White
L/Y .........Blue/Yellow
R/B.........Red/Black
R/G ....... Red/Green
R/W....... Red/White
R/Y........ Red/Yellow
W/B ....... White/Black
W/G....... White/Green
W/L ....... White/Blue
W/R....... White/Red
Y/B ........ Yellow/Black