2004 YAMAHA YFM660R engine

7-55
RIDING DOWNHILL
When riding your ATV downhill, shift your weight
as far to the rear and uphill side of the ATV as pos-
sible. Move back on the seat and sit with your
arms straight. Choose a low gear which will allow
the engine compression to do most of the braking
for you. Improper braking may cause a loss of trac-
tion.
Use caution while descending a hill with loose or
slippery surfaces. Braking ability and traction may
be adversely affected by these surfaces. Improper
braking may also cause a loss of traction.
Whenever possible, ride your ATV straight down-
hill. Avoid sharp angles which could allow the ATV
to tip or roll over. Carefully choose your path and
ride no faster than you will be able to react to ob-
stacles which may appear.
U5LP63.book Page 55 Monday, March 10, 2003 2:06 PM

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.
U5LP63.book Page 1 Monday, March 10, 2003 2:06 PM

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.)
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 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.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.Clutch* Check operation.
 Adjust if necessary.Wheels* Check balance/damage/runout.
 Replace if necessary.E-8.fm Page 7 Tuesday, March 11, 2003 2:06 PM

8-17 1. Engine oil tank
2. Engine oil tank filler cap
3. Dipstick
4. Maximum level mark
5. Minimum level mark
1. Réservoir d’huile de moteur
2. Bouchon de remplissage de l’huile de moteur
3. Jauge
4. Repère de niveau maximum
5. Repère de niveau minimum
1. Depósito de aceite de motor
2. Tapa de relleno del depósito de aceite de motor
3. Varilla de medición
4. Marca de nivel máximo
5. Marca de nivel mínimo
EBU12381
Engine oil and oil filter cartridge
The engine oil level should be checked before
each ride. In addition, the oil must be changed and
the oil filter cartridge replaced at the intervals
specified in the periodic maintenance and lubrica-
tion chart.
To check the engine oil level
1. Place the ATV on a level surface.
2. Start the engine, warm it up until the engine
oil has reached a normal temperature of
60°C, let it continue to idle for twenty to thirty
seconds. During this period, rev the engine
two or three times to approximately
3,000 r/min, and then turn the engine off.NOTE:_ To achieve the proper engine oil temperature for
an accurate oil level reading, the engine must
have first completely cooled down, and then
warmed up again for several minutes to normal
operating temperature. _
U5LP63.book Page 17 Monday, March 10, 2003 2:06 PM

8-19
3. Wait a few minutes until the oil settles, re-
move the engine oil tank filler cap, wipe the
dipstick clean with a clean rag, insert it back
into the filler hole (without screwing it in), and
then remove it again to check the oil level.NOTE:_ The engine oil should be between the minimum
and maximum level marks. _4. If the engine oil is below the minimum level
mark, add sufficient oil of the recommended
type to raise it to the correct level.NOTE:_ When adding oil, be careful not to overfill the en-
gine oil tank; the oil level rises faster starting from
the half-level-portion on the dipstick. _5. Insert the dipstick into the oil filler hole, and
then tighten the oil filler cap.
U5LP63.book Page 19 Monday, March 10, 2003 2:06 PM

8-21 1. Engine guard 2. Bolt (× 6)
1. Protège-carter 2. Boulon (× 6)
1. Protector del motor 2. Perno (× 6)
CAUTION:_ Make sure that the oil filler cap is securely
tightened, otherwise oil may seep out when
the engine is running. _To change the engine oil (with or without oil fil-
ter cartridge replacement)
1. Remove the engine guard by removing the
bolts.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Place an oil pan under the engine to collect
the used oil.
U5LP63.book Page 21 Monday, March 10, 2003 2:06 PM

8-23 1. Crankcase engine oil drain bolt
1. Boulon de vidange d’huile du carter
1. Perno de drenaje de aceite de motor del cárter
1. Engine oil tank drain bolt
1. Boulon de vidange du réservoir d’huile de moteur
1. Perno de drenaje del depósito aceite de motor
4. Remove the crankcase engine oil drain bolt.
5. Remove the engine oil tank filler cap and the
oil tank drain bolt.
6. Check the washers for damage, and replace
if necessary.NOTE:_ Skip steps 7–9 if the oil filter cartridge is not being
replaced. _
U5LP63.book Page 23 Monday, March 10, 2003 2:06 PM

8-25 1. Oil filter cartridge
2. Oil filter wrench
1. Cartouche du filtre à huile
2. Clé pour filtre à huile
1. Cartucho del filtro de aceite
2. Llave para filtros de aceite
1. O-ring
1. Joint torique
1. Junta tórica
7. Remove the oil filter cartridge with an oil filter
wrench.NOTE:_ An oil filter wrench is available at a nearby
Yamaha dealer. _8. Apply a thin coat of engine oil to the O-ring of
the new oil filter cartridge.NOTE:_ Make sure that the O-ring is properly seated. _9. Install a new oil filter cartridge with an oil filter
wrench, and then tighten it to the specified
torque with a torque wrench.
10. Install the crankcase engine oil drain bolt and
the engine oil tank drain bolt, and then tighten
them to the specified torques. Tightening torque:
Oil filter cartridge:
17 Nm (1.7 m·kgf)
U5LP63.book Page 25 Monday, March 10, 2003 2:06 PM