engine YAMAHA YFM660R 2001 Repair Manual

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1. Locknut 2. Adjusting bolt
a. Throttle lever free play
1. Contre-écrou 2. Boulon de réglage
a. Jeu du levier d’accélération
1. Contratuerca 2. Perno de ajuste
a. Juego libre de la palanca del acelerador
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Throttle lever adjustment
NOTE:
Adjust the engine idling speed before adjust-
ing the throttle lever free play.
1. Loosen the locknut.
2. Turn the adjusting bolt until the throttle le-
ver free play is 3 ~ 5 mm.
3. Tighten the locknut.

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2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive chain with
a special O-ring chain lubricant.
CAUTION:
Do not use engine oil or any other lubricants
for the drive chain, as they may contain sub-
stances that could damage the O-rings.

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Cable inspection and lubrication
WARNING
Inspect cables frequently and replace if dam-
aged. Corrosion can result when the outer
covering of control cables becomes damaged.
Cables can also become frayed or kinked. Op-
eration of controls could be restricted, which
could cause an accident or injury.
Lubricate the inner cables and the cable ends.
If the cables do not operate smoothly, ask a
Yamaha dealer to replace them.
EBU00737
Brake and shift pedal/brake and clutch lever
lubrication
Lubricate the pivoting parts of each lever and
pedal.Recommended lubricant:
Engine oil
Recommended lubricant:
Lithium-soap-based grease
(all-purpose grease)

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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.

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CLEANING AND STORAGE
A. CLEANING
Frequent, thorough cleaning of your machine
will not only enhance its appearance but will
improve its general performance and extend
the useful life of many components.
1. Before cleaning the machine:
a. Block off the end of the exhaust pipe to
prevent water entry. A plastic bag and
strong rubber band may be used.
b. Make sure the spark plug and all filler caps
are properly installed.
2. If the engine case is excessively greasy,
apply degreaser with a paint brush. Do
not apply degreaser to the chain, sprock-
ets or wheel axles.
3. Rinse the dirt and degreaser off with a
garden hose. Use only enough pressure
to do the job.

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8. Automotive type wax may be applied to
all painted and chrome plated surfaces.
Avoid combination cleaner-waxes. Many
contain abrasives which may mar the
paint or protective finish. When finished,
start the engine and let it idle for several
minutes.
WARNING
Wet brakes may have reduced stopping abili-
ty, increasing the chance of an accident. Test
the brakes after washing. Apply the brakes
several times at slow speeds to let friction dry
out the linings.

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B. STORAGE
Long term storage (60 days or more) of your
machine will require some preventive proce-
dures to guard against deterioration. After
thoroughly cleaning the machine, prepare for
storage as follows:
1. Fill the fuel tank with fresh fuel and add
fuel stabilizer (if available).
NOTE:
Use of fuel stabilizer eliminates the need to
drain the fuel system. Consult a Yamaha dealer
if the fuel system is to be drained instead.
2. Remove the spark plug, pour about one
tablespoon of SAE 10W30 or 20W40 mo-
tor oil in the spark plug hole and reinstall
the spark plug. Ground the spark plug
wire and turn the engine over several
times to coat the cylinder wall with oil.
3. Clean the drive chain thoroughly and lu-
bricate it. (See page 8-81.)
4. Lubricate all control cables.

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SPECIFICATIONS
MODEL YFM660R
Dimension:
Overall length
Overall width
Overall height
Seat height
Wheel base
Ground clearance
Minimum turning radius1,830 mm
1,100 mm
1,150 mm
860 mm
1,245 mm
265 mm
3,300 mm
Basic weight:
With oil and full fuel tank 193 kg
Engine:
Type
Cylinder arrangement
Displacement
Bore× Stroke
Compression ratio
Starting system
Lubrication systemLiquid-cooled, 4-stroke, SOHC
Single cylinder, forward inclined
660 cm
3
100
× 84 mm
9.2 : 1
Electric starter
Dry sump

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ER
10
10
10
10
10
10
10
10
10
10
101
Engine oil:
Type-20°-10°0°10°20°30°40°50°C
5W/30
10W/30
10W/40
20W/50
20W/40
15W/40
Recommended engine oil classification API Service SE, SF, SG type or higher
Quantity:
Periodic oil change
With oil filter cartridge replacement
Total amount1.9 L
1.95 L
2.3 L MODEL YFM660R
CAUTION:
Be sure to use motor oils that do not contain anti-
friction modifiers. Passenger car motor oils (often
labeled “Energy Conserving”) contain anti-friction
additives which will cause clutch and/or starter
clutch slippage, resulting in reduced component
life and poor engine performance.