Page 6 of 444
EBU00946
1-INTRODUCTION
Congratulations on your purchase of the Yamaha
YFM660FS. 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 understanding of the features and op-
eration of this ATV.
This manual includes impor-
tant safety information. It provides information
about special techniques and skills necessary
to ride your ATV. It also includes basic mainte-
nance and inspection procedures. If you have any
questions regarding the operation or maintenance
of your ATV, please consult a Yamaha dealer.
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Tire wear limit......................................5-31
OPERATION ............................................6-1
Starting a cold engine ...........................6-3
Starting a warm engine .........................6-9
Warming up...........................................6-9
Drive select lever operation and
reverse driving ..................................6-11
Engine break-in ...................................6-17
Parking ................................................6-19
Parking on a slope ..............................6-21
Accessories and loading .....................6-23
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 ....................7-69
Sliding and skidding ............................7-71
What to do if ........................................7-75
What to do...........................................7-75
67
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 ......... 8-33
Final gear oil ....................................... 8-47
Differential gear oil.............................. 8-51
Cooling system ................................... 8-57
Changing the coolant.......................... 8-61
Axle boots ........................................... 8-69
Spark plug inspection ......................... 8-71
Air filter element cleaning ................... 8-77
Carburetor adjustment ........................ 8-85
Idle speed adjustment ........................ 8-87
Valve clearance adjustment ............... 8-89
Throttle lever adjustment .................... 8-89
Front brake pad check ........................ 8-91
Rear brake pad inspection.................. 8-91
Inspecting the brake fluid level ........... 8-93
Brake fluid replacement ...................... 8-97
Front brake lever free play.................. 8-99
Rear brake lever and pedal
adjustment ...................................... 8-101
Adjusting the rear brake light
switch ............................................. 8-105
Cable inspection and lubrication....... 8-107
8
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Brake lever and brake pedal
lubrication ....................................... 8-109
Rear knuckle upper and lower
pivot lubrication .............................. 8-111
Wheel removal ................................. 8-113
Wheel installation ............................. 8-115
Battery .............................................. 8-117
Battery maintenance ........................ 8-121
Fuse replacement............................. 8-123
Replacing a headlight bulb ............... 8-127
Headlight beam adjustment.............. 8-131
Tail/brake light bulb replacement ..... 8-131
Troubleshooting................................ 8-133
Troubleshooting chart....................... 8-135
CLEANING AND STORAGE ................... 9-1
A. Cleaning ........................................... 9-1
B. Storage ............................................ 9-7
SPECIFICATIONS ................................. 10-1
CONVERSION TABLE .......................... 11-1
91011EE.book Page 3 Tuesday, April 1, 2003 12:23 PM
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2-5
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.
Always follow proper procedures for turning as
described in this manual. Practice turning at
low speeds before attempting to turn at faster
speeds. Do not turn at excessive speed.
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Page 127 of 444
5-2
5
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 Own-
er’s Manual. Failure to inspect increases the possibility of an accident or equipment damage.EE.book Page 2 Tuesday, April 1, 2003 12:23 PM
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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.
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Page 272 of 444

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 propietario
2. Juego de herramientas del propietario
3. Manómetro de baja presión
EBU00563
Owner’s manual and tool kit
You are recommended to put this owner’s manual
in the vinyl bag and always carry it in the storage
box. Put the owner’s tool kit and low-pressure tire
gauge in the space beside the battery.
The service information included in this manual is
intended to provide you, the owner, with the nec-
essary information for completing your own pre-
ventive maintenance and minor repairs. The tools
provided in the Owner’s tool kit are sufficient 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. _
EE.book Page 3 Tuesday, April 1, 2003 12:23 PM
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8-7
EBU00262
PERIODIC MAINTENANCE/LUBRICATION
ITEM ROUTINEWhichever
comes firstINITIAL EVERY
km 320 1,200 2,400 2,400 4,800
hours 20 75 150 150 300
Valves*Check valve clearance.
Adjust if necessary.
Cooling systemCheck coolant leakage.
Repair if necessary.
Replace coolant every 24 months.Spark plugCheck condition.
Adjust gap and clean.
Replace if necessary.Air filter elementClean.
Replace if necessary.Every 20–40 hours
(More often in wet or dusty areas.)
Carburetor*Check starter (choke) operation.
Adjust engine idling speed.Crankcase breather
system*Check breather hose for cracks or damage.
Replace if necessary.Exhaust system*Check for leakage.
Tighten if necessary.
Replace gasket(s) 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.Final gear oil
Check oil level/oil leakage.
Replace.Differential gear oil
Front brake*Check 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.V-belt*Check operation.
Check for cracks or damage.Wheels*Check balance/damage/runout.
Repair if necessary.EE.book Page 7 Tuesday, April 1, 2003 12:23 PM