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YAMAHA YZ250F(Y) Owner's Service Manual Page 19

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If knocking or pinging occurs, use a
different brand of gasoline or higher
octane grade.
• For refueling, be sure to stop the
engine and use enough care not
to spill any fuel. Also be sure to
avoid refueling close to a fire.
• Refuel after the engine, exhaust
pipe, etc. have cooled off.
HANDLING NOTE
Never start or run the engine in a
closed area. The exhaust fumes
are poisonous; they can cause
loss of consciousness and death
in a very short time. Always oper-
ate the machine in a well-ventilated
area.
• The carburetor on this machine
has a built-in accelerator pump.
Therefore, when starting the en-
gine, do not operate the throttle
or the spark plug will foul.
• Unlike a two-stroke engine, this
engine cannot be kick started
when the throttle is open be-
cause the kickstarter may kick
back. Also, if the throttle is open
the air/fuel mixture may be too
lean for the engine to start.
• Before starting the machine, per-
form the checks in the pre-opera-
tion check list.
AIR FILTER MAINTENANCE
According to "CLEANING THE AIR
FILTER ELEMENT" section in the
CHAPTER 3, apply the foam-air-filter
oil or its equivalent to the element.
(Excess oil in the element may ad-
versely affect engine starting.)
STARTING A COLD ENGINE
1. Inspect the coolant level.
2. Turn the fuel cock to "ON".
3. Shift the transmission into neutral.
4. Fully open the cold starter knob
"1".
5. Kick the kickstarter crank.
Do not open the throttle while kick-
ing the kickstarter crank. Other-
wise, the kickstarter crank may
kick back.
6. Return the cold starter knob to its
original position and run the en-
gine at 3,000–5,000 r/min for 1 or
2 minutes.
Since this model is equipped with an
accelerator pump, if the engine is
raced (the throttle opened and
closed), the air/fuel mixture will be too
rich and the engine may stall. Also
unlike a two-stroke engine, this model
can idle.
Do not warm up the engine for ex-
tended periods of time.
STARTING A WARM ENGINE
Do not operate the cold starter knob
and throttle. Pull the hot starter lever
"1" and start the engine by kicking
the kickstarter crank forcefully with a
firm stroke. As soon as the engine
starts, release the hot starter lever to
close the air passage.
Restarting an engine after a fall
Pull the hot starter lever and start the
engine. As soon as the engine starts,
release the hot starter lever to close
the air passage.
1-9
STARTING AND BREAK-IN
The engine fails to start
Pull the hot starter lever all the way
out and while holding the lever, kick
the kickstarter crank 10 to 20 times to
clear the engine. Then, restart the en-
gine. Refer to "Restarting an engine
after a fall".
Air tem-
perature =
less than
5 °C (41
°F)
Air tem-
perature =
more than
5 °C (41
°F)
Star
ting
Air tem-
a
perature
cold
(normal
en-
tempera-
gine
ture) = be-
tween 5
°C (41 °F)
and 25 °C
(77 °F)
Air tem-
perature =
more than
25 °C (77
°F)
Starting an en-
gine after a long
period of time
Restarting a
warm engine
Restarting an
engine after a
fall
* Operate the throttle grip before kick
starting.
Observe the following break-in
procedures during initial operation
to ensure optimum performance
and avoid engine damage.
Thrott
Cold
Hot
le
start-
start-
grip
er
er le-
oper-
knob
ver
ation*
Open
3 or 4
ON
OFF
times
None
ON
OFF
ON/
None
OFF
OFF
None OFF OFF
None
ON
OFF
None OFF
ON
None OFF
ON

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This manual also for:

Yz250f 2009, Yz250fy 2009

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  • Dave May 30, 2016 02:21:
    Really good really good really goodj