Page 4 of 414
EBU00009
INTRODUCTION
Congratulations on your purchase of the Yamaha
YFM660R. It represents the result of many years
of Yamaha experience in the production of fine
sporting, touring, and pacesetting racing ma-
chines. With the purchase of this Yamaha, you can
now appreciate the high degree of craftsmanship
and reliability that have made Yamaha a leader in
these fields.
This manual will provide you with a good basic un-
derstanding of the features and operation of this
machine.
This manual includes important safe-
ty information. It provides information about
special techniques and skills necessary to ride
your machine. It also includes basic maintenance
and inspection procedures. If you have any ques-
tions regarding the operation or maintenance of
your machine, please consult a Yamaha dealer.
U5LP61.book Page 2 Monday, August 27, 2001 3:49 PM
Page 15 of 414

OPERATION ...........................................6-1
Starting a cold engine ..........................6-3
Starting a warm engine ........................6-9
Warming up ..........................................6-9
Reverse knob operation and
reverse driving .................................6-11
Shifting ................................................6-15
To start out and accelerate ................6-17
To decelerate .....................................6-21
Engine break-in ..................................6-23
Parking ...............................................6-27
Parking on a slope ..............................6-29
Accessories and loading ....................6-31
Accessories ........................................6-31
Loading ..............................................6-33
RIDING YOUR ATV..................................7-1
Getting to know your ATV .....................7-3
Ride with care and good judgement .....7-5
Be careful where you ride ...................7-27
Turning your ATV ................................7-39
Climbing uphill.....................................7-45
Riding downhill ....................................7-55
Crossing a slope .................................7-59
Crossing through shallow water ..........7-63
Riding over rough terrain ....................7-67
Sliding and skidding ............................7-69
67
What to do if ... ................................... 7-73
What to do ... ...................................... 7-73
PERIODIC MAINTENANCE AND
ADJUSTMENT ........................................ 8-1
Owner’s manual and tool kit ................ 8-3
Periodic maintenance/lubrication ......... 8-7
Panel removal and installation ........... 8-15
Engine oil and oil filter cartridge ......... 8-17
Cooling system ................................... 8-31
Changing the coolant.......................... 8-33
Spark plug inspection ......................... 8-41
Air filter element cleaning .................. 8-45
Carburetor adjustment ....................... 8-51
Idle speed adjustment ....................... 8-53
Throttle lever adjustment ................... 8-55
Valve clearance adjustment .............. 8-57
Front and rear brake pad inspection... 8-59
Inspecting the brake fluid level ........... 8-61
Brake fluid replacement ...................... 8-65
Front brake adjustment ...................... 8-67
Rear brake adjustment ....................... 8-69
Parking brake adjustment ................... 8-71
Adjusting the rear brake light switch ... 8-75
Clutch lever free play adjustment ...... 8-77
Drive chain slack check ..................... 8-79
Drive chain slack adjustment .............. 8-81
8
U5LP61.book Page 2 Monday, August 27, 2001 3:49 PM
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Lubricating the drive chain ................ 8-83
Cable inspection and lubrication ....... 8-87
Brake and shift pedal/brake and
clutch lever lubrication ..................... 8-87
Front upper and lower arm pivot
lubrication ......................................... 8-89
Rear arm pivot lubrication .................. 8-91
Wheel removal .................................. 8-95
Wheel installation .............................. 8-97
Battery ............................................... 8-99
Battery maintenance ....................... 8-103
Fuse replacement ............................ 8-105
Replacing a headlight bulb ............... 8-107
Tail/brake light bulb replacement ..... 8-117
Troubleshooting ............................... 8-119
Troubleshooting chart ...................... 8-121
CLEANING AND STORAGE .................. 9-1
A. CLEANING ...................................... 9-1
B. STORAGE ...................................... 9-7
9
SPECIFICATIONS ................................ 10-1
CONVERSION TABLE .......................... 11-1
1011
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Page 42 of 414
2-5
Never attempt wheelies, jumps, or other stunts.
Always inspect your ATV each time you use it
to make sure it is in safe operating condition.
Always follow the inspection and maintenance
procedures and schedules described in this
manual.
Always keep both hands on the handlebars
and both feet on the footboards of the ATV dur-
ing operation.
Always go slowly and be extra careful when op-
erating on unfamiliar terrain. Always be alert to
changing terrain conditions when operating the
ATV.
Never operate on excessively rough, slippery
or loose terrain until you have learned and
practiced the skills necessary to control the
ATV on such terrain. Always be especially cau-
tious on these kinds of terrain.
U5LP61.book Page 5 Monday, August 27, 2001 3:49 PM
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5-4
WARNING
Always inspect your ATV each time you use it to make sure the ATV is in safe operating condition.
Always follow the inspection and maintenance procedures and schedules described in the
Owner’s Manual. Failure to inspect increases the possibility of an accident or equipment damage.
AVERTISSEMENT
_ Toujours effectuer ces contrôles avant chaque départ afin de s’assurer que le VTT peut être utilisé en toute sécu-
rité. Toujours respecter les procédés et intervalles de contrôle et d’entretien repris dans ce manuel. Omettre ces
contrôles accroît les risques d’accident ou d’endommagement du véhicule. _
ADVERTENCIA
Inspeccionar siempre el ATV cada vez que vaya a utilizarse, para asegurarse de que está en condicio-
nes de funcionar sin peligro.
Seguir siempre los procedimientos y programas de inspección y mantenimiento descritos en el Manual
del Usuario. Si no se inspecciona la máquina, aumenta el riesgo de accidente o avería.U5LP61.book Page 4 Monday, August 27, 2001 3:49 PM
Page 256 of 414
8-1
EBU00516
PERIODIC MAINTENANCE AND
ADJUSTMENTPeriodic inspection, adjustment and lubrication will
keep your machine in the safest and most efficient
condition possible. Safety is an obligation of the
machine owner. The most important points of ma-
chine inspection, adjustment and lubrication are
explained on the following pages.
WARNING
Never service an engine while it is running.
Moving parts can catch clothing or parts of the
body, causing injury. Electrical components
can cause shocks or can start fires. Turn off
the engine when performing maintenance un-
less otherwise specified. Have a Yamaha deal-
er perform service if you are not familiar with
machine service.
U5LP61.book Page 1 Monday, August 27, 2001 3:49 PM
Page 258 of 414

8-3 1. Owner’s manual
2. Owner’s tool kit
3. Low-pressure tire gauge
1. Manuel du propriétaire
2. Trousse à outils
3. Manomètre basse pression pour pneus
1. Manual del usuario
2. Equipo de herramientas
3. Comprobador de la presión de los neumáticos
EBU00258
Owner’s manual and tool kit
You are recommended to put this owner’s manual
and low-pressure tire gauge in the vinyl bag and
always carry them along with the owner’s tool kit
under the seat. The service information included in
this manual is intended to provide you, the owner,
with the necessary information for completing your
own preventive maintenance and minor repairs.
The tools provided in the Owner’s tool kit are suffi-
cient for this purpose, except that a torque wrench
is also necessary to properly tighten nuts and
bolts.NOTE:If you do not have a torque wrench available dur-
ing a service operation requiring one, take your
machine to a Yamaha dealer to check the torque
settings and adjust them as necessary.
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8-7
EBU00262
PERIODIC MAINTENANCE/LUBRICATION
ITEM ROUTINEINITIAL EVERY
1
month3
months6
months6
months1
year
Valves*•Check valve clearance.
•Adjust if necessary.
Cooling system•Check coolant leakage.
•Repair if necessary.
•Replace coolant every 24 months.Spark plug•Check condition.
•Adjust gap and clean.
•Replace if necessary.Air filter element•Clean.
•Replace if necessary.Every 20~40 hours
(More often in wet or dusty areas.)
Carburetors*•Check starter (choke) operation.
•Adjust engine idling speed and synchronization.Crankcase breather
system*•Check breather hose for cracks or damage.
•Replace if necessary.Exhaust system*•Check for leakage.
•Tighten if necessary.
•Replace gasket if necessary.Fuel line*•Check fuel hose for cracks or damage.
•Replace if necessary.Engine oil
•Replace (Warm engine before draining.)Engine oil filter cartridge
•Replace if necessary.Drive chain
•Check and adjust slack/alignment/clean/lube.Front brake•Check free play/operation/fluid leakage/
See NOTE Page 8-8.
•Correct if necessary.Rear brake*•Check operation/fluid leakage/See NOTE Page 8-8.
•Correct if necessary.U5LP61.book Page 7 Monday, August 27, 2001 3:49 PM