Yamaha YZ450FA 2011 Owner's Service Manual page 34

6. When the engine starts running, warm it up
one or two minutes at a steady speed (of
3,000 to 5,000 r/min), and then return the
starter knob/ idle screw to its original posi-
tion.
7. Push the engine stop switch "1".
Do not warm up the engine for extended pe-
riods of time.
STARTING A WARM ENGINE
To start a warm engine, make sure that the
starter (choke) knob/idling screw is pushed in
and the throttle is closed, and then start the en-
gine by pushing the kickstarter.
If the engine fails to start, give the kickstarter 10
to 20 slow kicks at full throttle in order to clear
the engine of the rich air-fuel mixture retained in
it.
STARTING AND BREAK-IN
BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel tank
with the fuel.
2. Perform the pre-operation checks on the
machine.
3. Start and warm up the engine. Check the
idle speed, and check the operation of the
controls and the engine stop switch. Then,
restart the engine and check its operation
within no more than 5 minutes after it is re-
started.
4. Operate the machine in the lower gears at
moderate throttle openings for five to eight
minutes.
5. Check how the engine runs when the ma-
chine is ridden with the throttle 1/4 to 1/2
open (low to medium speed) for about one
hour.
6. Restart the engine and check the operation
of the machine throughout its entire operat-
ing range. Restart the machine and operate
it for about 10 to 15 more minutes. The ma-
chine will now be ready to race.
• After the break-in or before each race, you
must check the entire machine for loose
fittings and fasteners as per "TORQUE-
CHECK POINTS". Tighten all such fasten-
ers as required.
• When any of the following parts have been
replaced, they must be broken in.
CYLINDER AND CRANKSHAFT:
About one hour of break-in operation is
necessary.
PISTON, RING, VALVES, CAMSHAFTS
AND GEARS:
These parts require about 30 minutes of
break-in operation at half-throttle or less.
Observe the condition of the engine care-
fully during operation.
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