2003 YAMAHA YFM660R radiator cap

5-19
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. _
EBU00498
Chain
Check the general condition of the chain and
check the chain slack before every ride. Lubricate
and adjust the chain as necessary. (See pages
8-81–8-87 for details.)
U5LP62.book Page 19 Wednesday, May 8, 2002 11:24 AM

8-33 1. Coolant reservoir cap
2. Maximum level mark
3. Minimum level mark
1. Bouchon 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
EBU01015
Cooling system
1. Check the coolant level in the coolant reser-
voir when the engine is cold as the coolant
level will vary with engine temperature. The
coolant level should be between the maxi-
mum and minimum marks.
2. If the level is low, remove the coolant reser-
voir cap, and then add coolant or distilled wa-
ter 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 auto-
matic. It is switched on or off according to the
coolant temperature in the radiator.
_If your ATV overheats, see page 8-124 for details.Coolant reservoir capacity:
0.29 L
U5LP62.book Page 33 Wednesday, May 8, 2002 11:24 AM

8-35 1. Coolant drain bolt
1. Boulon de vidange du liquide de refroidissement
1. Perno de drenaje de refrigerante
1. Radiator cap
1. Bouchon de radiateur
1. Tapa del radiador
EBU01024
Changing the coolant
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. _1. Place the ATV on a level surface.
2. Remove panel A. (See page 8-15 for panel
removal and installation procedures.)
3. Place a container under the engine, and then
remove the coolant drain bolt.
4. Remove the radiator cap.
U5LP62.book Page 35 Wednesday, May 8, 2002 11:24 AM

8-41
CAUTION:_ Hard water or salt water is harmful to the en-
gine. You may use soft water if you cannot get
distilled water. _12. Install the radiator cap and the coolant reser-
voir cap.
13. Start the engine and let it idle for several min-
utes. 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 ra-
diator.
14. Check the coolant level in the reservoir. If it is
low, add coolant to the maximum level mark.
15. Start the engine and then check for coolant
leakage.NOTE:_ If any leakage is found, have a Yamaha dealer
check the cooling system. _16. Install the panel.
U5LP62.book Page 41 Wednesday, May 8, 2002 11:24 AM

8-124
Engine overheatingNOTE: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.
U5LP62.book Page 124 Wednesday, May 8, 2002 11:24 AM

10-3
Radiator capacity (including all routes) 1.3 L
Air filter Wet element
Fuel:
Type
Tank capacity
Reserve amountUnleaded gasoline only
For Europe: Regular unleaded gasoline only with a
research octane number of 91 or higher
12 L
2.6 L
Carburetor:
Type
× quantity
ManufacturerBSR33
× 1
MIKUNI
Spark plug:
Type/manufacturer
GapDPR8EA-9/NGK
0.8–0.9 mm
Clutch:
Type
OperationWet, multiple-disc
Left hand operation
Transmission:
Primary Reduction System
Primary Reduction Ratio
Secondary Reduction System
Secondary Reduction Ratio
Transmission type
OperationSpur gear
71/34 (2.088)
Chain drive
40/13 (3.076)
Constant mesh, 5-speed forward, 1-speed reverse
Left foot operation MODEL YFM660R
U5LP62.book Page 3 Wednesday, May 8, 2002 11:24 AM