Starting And Break-In - Yamaha 2011 YZ250FA Owner's Service Manual

STARTING AND BREAK-IN

FUEL
Always use the recommended fuel as stated
below. Also, be sure to use new gasoline the
day of a race.
Recommended fuel:
Premium unleaded gasoline only
with a research octane number of
95 or higher.
Use only unleaded gasoline. The use of
leaded gasoline will cause severe damage
to the engine internal parts such as valves,
piston rings, and exhaust system, etc.
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 ar-
ea. The exhaust fumes are poisonous; they
can cause loss of consciousness and death
in a very short time. Always operate the ma-
chine in a well-ventilated area.
• The carburetor on this machine has a
built-in accelerator pump. Therefore, when
starting the engine, 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 because 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, perform the
checks in the pre-operation check list.
STARTING AND BREAK-IN
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 ele-
ment. (Excess oil in the element may adversely
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 kicking the
kickstarter crank. Otherwise, the kickstarter
crank may kick back.
6. Return the cold starter knob to its original
position and run the engine at 3,000–5,000
r/min for 1 or 2 minutes.
Since this model is equipped with an accelera-
tor 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 extended pe-
riods of time.
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