check engine YAMAHA YFM660R 2001 Manuale de Empleo (in Spanish)
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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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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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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. 
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EBU00783
Cooling system
1. Check  the  coolant  level  in  the  coolant  res-
ervoir when the engine is cold as the cool-
ant level will vary with engine temperature.
The  coolant  level  should  be  between  the
maximum and minimum marks.
2. Remove  the  coolant  reservoir  cap,  and
then add coolant or distilled water to raise
it to the specified level.
CAUTION:
Hard water or salt water is harmful to the en-
gine.  You  may  use  soft  water  if  you  can’t  get
distilled water. 
NOTE:
If  water  is  added,  have  a  Yamaha  dealer
check the antifreeze content of the coolant
as soon as possible. 
The radiator fan operation is completely au-
tomatic. It is switched on or off according to
the coolant temperature in the radiator. 
If your ATV overheats, see page 8-120 for details.Coolant reservoir capacity:
0.29 L
1. Coolant reservoir cap
2. Maximum level mark
3. Minimum level mark
1. Cache du vase d’expansion
2. Repère de niveau maximum
3. Repère de niveau minimum
1. Tapa del depósito de líquido refrigerante
2. Marca de nivel máximo
3. Marca de nivel mínimo 
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CAUTION:
Hard water or salt water is harmful to the en-
gine. You may use soft water if you cannot get
distilled water. 
11.  Install the radiator cap.
12.  Start  the  engine  and  let  it  idle  for  several
minutes. Stop the engine, and then check
the coolant level in the radiator. If it is low,
add  more  coolant  until  it  reaches  the  top
of the radiator.
13.  Fill  the  coolant  reservoir  with  coolant  up
to the maximum level.
14.  Install the coolant reservoir cap and check
for coolant leakage.
NOTE:
If any leakage is found, have a Yamaha dealer
check the cooling system. 
15. Install the panel. 
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1. Check hose
1. Flexible de contrôle
1. Manguito de comprobación
1. Air filter case cover 2. Holder (× 6)
1. Couvercle du boîtier de filtre à air 2. Support (× 6)
1. Tapa de la caja del filtro 2. Soporte (× 6)
EBU00818
Air filter element cleaning
NOTE:
There  is  a  check  hose  at  the  bottom  of  the  air
filter case. If dust or water collects in this hose,
empty the hose and clean the air filter element
and air filter case. 
1. Remove  the  seat.  (See  page  8-15  for  seat
removal procedure.)
2. Remove  the  air  filter  case  cover  by  un-
hooking the holders.
3. Remove the air filter element and remove
it from its frame.
4. Wash  the  element  gently  but  thoroughly
in solvent.
WARNING
Always use parts cleaning solvent to clean the
air filter element. Never use low flash point sol-
vents or gasoline to clean the air filter element
because the engine could catch fire or explode.  
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NOTE:
The  air  filter  element  should  be  cleaned  every
20  ~  40  hours.  It  should  be  cleaned  and  lubri-
cated more often if the machine is operated in
extremely dusty areas. Each time the filter ele-
ment  maintenance  is  performed,  check  the  air
inlet  to  the  filter  case  for  obstructions.  Check
the  air  cleaner  rubber  joint  to  the  carburetor
and manifold fittings for an airtight seal. Tight-
en  all  fittings  securely  to  avoid  the  possibility
of unfiltered air entering the engine. 
CAUTION:
Never operate the engine with the air filter el-
ement  removed.  This  will  allow  unfiltered  air
to enter, causing rapid engine wear and possi-
ble  engine  damage.  Additionally,  operation
without  the  filter  element  will  affect  carbure-
tor jetting with subsequent poor performance
and possible engine overheating.
1. Hose
1. Flexible
1. Manguera 
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EBU00724
Troubleshooting chart
Starting problems or poor engine performance
1. Fuel
Check if there is fuel
in the fuel tank.There is fuel.Turn the fuel cock
lever to “OFF”.No fuel.Fuel cock is
clogged.
Clean the 
fuel cock. Some fuel.Turn the fuel cock
lever to “RES”.Restart the engine.
No fuel.Supply fuel.
2. Compression
Use the electric
starter to see if 
there is compression.There is compression.
Compression normal.
No compression.Ask a Yamaha dealer to
inspect.
3. Ignition
Remove the 
spark plug and 
check electrodes.WetWipe clean with dry cloth.
DryAttach spark plug cap and
ground to chassis.Use the
electric starter.Spark is good.Ignition system is
normal.
Spark is weak.
Adjust the spark plug gap
or replace the spark plug. No spark.
Ask a Yamaha dealer to
inspect. 4. Battery
Use the electric starter.Engine turns over
quickly.Battery is good.
Engine turns over
slowly.Check the connections.Check the 
fuel flow.
Turn the fuel cock
lever to “ON”.
Remove the fuel hose
from the fuel cock.  
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Engine overheating
NOTE:
If it is difficult to get the recommended coolant, tap water can be temporarily used, provided that it
is changed to the recommended coolant as soon as possible. 
WARNING
Wait for the engine and radiator to cool before removing the radiator cap. You could be burned by
hot fluid and steam blown out under pressure. Always put a thick rag over the cap when opening.
Allow any remaining pressure to escape before completely removing the cap. 
Wait until the 
engine has cooled.Check the coolant level in the 
reservoir tank and/or radiator.
Level is OK.
Level is low, check the 
cooling system for leakage.
No
leakage.
Leakage.Ask a Yamaha dealer to inspect 
and repair the cooling system.
Add coolant. (See NOTE.)
Restart the engine. If the engine overheats again, ask a 
Yamaha dealer to inspect and/or repair the cooling system.