2002 YAMAHA YFM660R engine

7-37
CAUTION:_ Do not shift gears without releasing the throt-
tle. Damage to the engine or drive train may oc-
cur. _When slowing down or stopping, release the throt-
tle and apply the brakes smoothly and evenly. As
you slow down, shift to a lower gear. Be sure that
the engine has sufficiently slowed before engaging
a lower gear. Improper use of the brakes or shift-
ing can cause the tires to lose traction, reducing
control and increasing the possibility of an acci-
dent.
WARNING
_ Make sure the engine has sufficiently slowed
before shifting to a lower gear. Engaging a low-
er gear when the engine speed is too high
could cause the wheels to stop rotating. _
U5LP61.book Page 37 Monday, August 27, 2001 3:49 PM

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.
U5LP61.book Page 55 Monday, August 27, 2001 3:49 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.
U5LP61.book Page 1 Monday, August 27, 2001 3:49 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.)
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

8-17 1. Engine oil tank
2. Engine oil tank 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 del depósito de aceite de motor
3. Marca de nivel máximo
4. Marca de nivel mínimo
EBU01014
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 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 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.
U5LP61.book Page 17 Monday, August 27, 2001 3:49 PM

8-19
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.CAUTION:_ Make sure that the oil filler cap is securely
tightened, otherwise oil may seep out when
the engine is running. _
U5LP61.book Page 19 Monday, August 27, 2001 3:49 PM

8-21 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 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.
U5LP61.book Page 21 Monday, August 27, 2001 3:49 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 ~ 8 if the oil filter cartridge is not being
replaced. _
U5LP61.book Page 23 Monday, August 27, 2001 3:49 PM