2004 YAMAHA YFM50S engine

6-3
EBU14410
Starting a cold engine
w
Always make sure all control cables work
smoothly before you begin riding in cold
weather. If the control cables are froze or do
not work smoothly, you could be unable to
control the ATV, which could lead to an acci-
dent or collision.
1. Set the parking brake.
2. Turn the fuel cock to “ON”.
3. Turn the main switch to “ON” and the
engine stop switch to “RUN”.
4. Shift the transmission into neutral.
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6-5
NOTE:
This model is equipped with an ignition circuit
cut-off system.
The engine can be started under the following
conditions.
a. When the transmission is in neutral. At this
time the neutral indicator light should come
on. If the light does not come on, ask a
Yamaha dealer to inspect it.
b. When the transmission is in the drive posi-
tion and the rear brake lever is applied.
However, it is recommended to shift into
neutral before starting the engine.
5. Use the choke lever in reference to the fig-
ure:
Position 1: Cold engine start–
ambient temperature below 30° C.
Position 2: Warming up position.
Position 3: Cold engine start–
ambient temperature above 25° C
and warm engine start position.
CHOKE
ONOFF
0°10°20°30°
°C
a
3 1
1
23
1. Fully open “ON”2. Half open (warming up position)
3. Closed “OFF”a. Choke lever
1. Pleine course “ON”2. Mi-course (position de chauffe)3. Fermé “OFF”a. Levier de choke
1. Abierto completamente “ON”
2. Semiabierto (posición de calentamiento)
3. Cerrado “OFF”a. Palanca del starter AMBIENT TEMP. / CHOKE LEVER POSITION
POSITION DE LEVIER DE STARTER / TEMP. AMBIANTEPOSICION DEL MANDO DEL STARTER / TEMP. AMBIENTE
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6-7
6. Completely close the throttle lever and
start the engine by pushing the start
switch.
NOTE:
If the engine fails to start, release the start
switch, then push it again. Pause a few seconds
before the next attempt. Each cranking should
be as short as possible to preserve battery ener-
gy. Do not crank the engine more than 10 sec-
onds on each attempt.
7. If the engine is started with the starter
(choke) in position 1, the choke lever
should be returned to position 2to warm
up the engine. If the engine is started with
the starter (choke) in position 2, keep the
starter (choke) in this position to warm up
the engine.
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6-9
8. Continue warming up the engine until it
idles smoothly and return the choke lever
to position 3before riding.
cC
See the “Engine break-in” section prior to
operating engine for the first time.
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6-11
EBU00181
Starting a warm engine
To start a warm engine, refer to the “Starting a
cold engine” section. The choke lever should not
be used. The throttle should be opened slightly.
EBU00184
Warming up
To get maximum engine life, always warm up
the engine before starting off. Never accelerate
hard with a cold engine! To see whether or not
the engine is warm, check if it responds to the
throttle normally with the choke lever turned off.
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6-13
1
2
1. Shift lever 2. Drive position1. Levier de sélecteur 2. Vitesse de marche1. Palanca del cambio 2. Posición de marcha
EBU14400
To start out and accelerate:
1. Release the throttle lever.
cC
Always close the throttle before shifting the
transmission into the drive position.
Otherwise, damage to the engine and drive
train may result.
2. Apply the parking brake. (See page 6-23.)
3. Shift the transmission into the drive posi-
tion.
NOTE:
Before shifting the transmission into the drive
position, be sure to apply the parking brake. The
engine will stop if you attempt to shift into drive
without applying the parking brake first.
5YF-9-60 6 4/24/03 6:36 PM Page 12

6-17
EBU00208
To decelerate:
When slowing down or stopping, release the
throttle 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 shifting can cause the tires to lose
traction, reducing control and increasing the
possibility of an accident.
w
Make sure the engine has sufficiently slowed
before shifting to a lower gear. Engaging a
lower gear when the engine speed is too
high could make the wheels stop rotating.
This could cause loss of control, an accident
and injury. It could also cause engine or
drive train damage.
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6-19
EBU02091
Engine break-in
There is never a more important period in the
life of your machine than the period between
zero and 20 hours.
For this reason, we ask that you carefully read
the following material. Because the engine is
brand new, you must not put an excessive load
on it for the first several hours of running. During
the first 20 hours, the various parts in the engine
wear and polish themselves to the correct oper-
ating clearances.
During this period, prolonged full throttle opera-
tion or any condition which might result in exces-
sive engine heating must be avoided. However,
momentary (2–3 seconds maximum) full throttle
operation under load does not harm the engine.
5YF-9-60 6 4/24/03 6:36 PM Page 18