engine YAMAHA YFM660R 2001 Service Manual

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RIDING DOWNHILL
When riding your ATV downhill, shift your
weight as far to the rear and uphill side of the
ATV as possible. 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 traction.
Use caution while descending a hill with loose
or slippery surfaces. Braking ability and trac-
tion may be adversely affected by these surfac-
es. Improper braking may also cause a loss of
traction.
Whenever possible, ride your ATV straight
downhill. Avoid sharp angles which could al-
low the ATV to tip or roll over. Carefully choose
your path and ride no faster than you will be
able to react to obstacles which may appear.

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EBU00516
PERIODIC MAINTENANCE AND
ADJUSTMENT
Periodic inspection, adjustment and lubrica-
tion will keep your machine in the safest and
most efficient condition possible. Safety is an
obligation of the machine owner. The most im-
portant points of machine inspection, adjust-
ment 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 unless
otherwise specified. Have a Yamaha dealer
perform service if you are not familiar with
machine service.

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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 and adjust idle speed/starter operation.
• Adjust if necessary.
Crankcase breather
system*• Check breather hose for cracks or damage.
• Replace if necessary.
Exhaust system*• Check for leakage.
• Retighten 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.
Brakes*• Check operation/fluid leakage/See NOTE Page 8-8.
• Correct if necessary.
Clutch*• Check operation.
• Adjust if necessary.

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1. Engine oil tank
2. Engine oil filler cap
3. Maximum level mark
4. Minimum level mark
1. Réservoir d’huile de moteur
2. Bouchon de remplissage de l’huile de moteur
3. Repère de niveau maximum
4. Repère de niveau minimum
1. Depósito de aceite de motor
2. Tapa de relleno de aceite de motor
3. Marca de nivel máximo
4. Marca de nivel mínimo
EBU00812
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 inter-
vals specified in the periodic maintenance and
lubrication chart.
To check the engine oil level
1. Place the ATV on a level surface.
2. Start the engine, warm it up until the en-
gine oil has reached a normal tempera-
ture of 60˚C, let it continue to idle for ten
seconds, 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.
3. Wait a few minutes until the oil settles, re-
move the engine oil tank filler cap, wipe
the dipstick clean, insert it back into the
filler hole (without screwing it in), and
then remove it again to check the oil level.

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NOTE:
The engine oil should be between the mini-
mum and maximum level marks.
4. If the engine oil is below the minimum
level mark, add sufficient oil of the recom-
mended type to raise it to the correct lev-
el.
NOTE:
When adding oil, be careful not to overfill the
engine; 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.
CAUTION:
Make sure that the oil filler cap is securely
tightened, otherwise oil may seep out when
the engine is running.

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1. Engine guard 2. Bolt (
× 6)
1. Protège-carter 2. Boulon (
× 6)
1. Protector del motor 2. Perno (
× 6)
To change the engine oil (with or without oil
filter cartridge replacement)
1. Remove the engine guard by removing
the bolts.
2. Start the engine, warm it up for several
minutes, and then turn it off.
3. Place an oil pan under the engine to col-
lect the used oil.

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1. Engine oil crankcase drain bolt
1. Boulon de vidange du carter d’huile de moteur
1. Perno de drenaje de aceite de motor del cárter
4. Remove the crankcase drain bolt.
5. Check the washer for damage, and re-
place it if necessary.
6. Remove the engine oil tank filler cap and
the drain bolt.
NOTE:
Skip steps 7–8 if the oil filter cartridge is not be-
ing replaced.
1. Engine oil tank drain bolt
1. Boulon de vidange du réservoir d’huile de moteur
1. Perno de drenaje de aceite de motor del motor

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1. Engine oil filter cartridge
2. Oil filter wrench
1. Cartouche du filtre à huile de moteur
2. Clé pour filtre à huile
1. Cartucho del filtro de aceite de motor
2. Llave para filtros de aceite
7. Remove the oil filter cartridge with an oil
filter wrench.
NOTE:
An oil filter wrench is available at a nearby
Yamaha dealer.
8. Install a new oil filter cartridge and tighten
it to the specified torque with an oil filter
wrench.
9. Install the crankcase engine oil drain bolt
and the engine oil tank drain bolt, then
tighten them to the specified torques. Tightening torque:
Oil filter cartridge:
17 Nm (1.7 m·kg)
Tightening torques:
Crankcase engine oil drain bolt:
30 Nm (3.0 m·kg)
Engine oil tank drain bolt:
25 Nm (2.5 m·kg)

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10. Add sufficient oil of the recommended
type to raise it to the correct level, and
then install and tighten the oil tank filler
cap.
CAUTION:
In order to prevent clutch slippage (since
the engine oil also lubricates the clutch),
do not mix any chemical additives with
the oil or use oils of a higher grade than
“CD”. In addition, do not use oils labeled
“ENERGY CONSERVING II” or higher.
Make sure that no foreign material enters
the crankcase. Recommended engine oil:
See page 10-2.

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11. Start the engine, and then let it idle for
several minutes while checking it for oil
leakage. If oil is leaking, immediately turn
the engine off and check for the cause.
12. Turn the engine off, and then check the oil
level and correct it if necessary.