Breaking In Engine; Procedure For 4-Stroke Models; Preoperation Checks; Mounting Height (Boat Bottom) - Yamaha F250 Owner's Manual

EMU26930

Mounting height (boat bottom)

To run your boat at optimum efficiency, the
water resistance (drag) of the boat and out-
board motor must be made as little as possi-
ble. The mounting height of the outboard
motor greatly affects the water resistance. If
the mounting height is too high, cavitation
tends to occur, thus reducing the propulsion;
and if the propeller tips cut the air, the engine
speed will rise abnormally and cause the en-
gine to overheat. If the mounting height is too
low, the water resistance will increase and
thereby reduce engine efficiency. Mount the
outboard motor so that the anti-cavitation
plate is in alignment with the bottom of the
boat.
NOTE:
The optimum mounting height of the out-
G
board motor is affected by the boat/motor
combination and the desired use. Test runs
at different heights can help determine the
optimum mounting height. Consult your
Yamaha dealer or boat manufacturer for
further information on determining the prop-
er mounting height.
For instructions on setting the trim angle of
G
the outboard motor, see page 41.
EMU30173
Your new engine requires a period of break-in
to allow mating surfaces of moving parts to
wear in evenly. Correct break-in will help en-
sure proper performance and longer engine
life.
ECM00800
CAUTION:
Failure to follow the break-in procedure
could result in reduced engine life or even
severe engine damage.
EMU27081

Procedure for 4-stroke models

Run the engine under load (in gear with a pro-
peller installed) for 10 hours as follows.
1. First hour:
Run the engine at 2000 r/min or at ap-
proximately half throttle.
2. Second hour:
Run the engine at 3000 r/min or at ap-
proximately three-quarter throttle.
3. Remaining eight hours:
Run the engine at any speed. However,
avoid operating at full throttle for more
than 5 minutes at a time.
ZMU01762
4. After the first 10 hours:
Operate the engine normally.
EMU27103
EWM00080
WARNING
If any item in the preoperation check is not
working properly, have it inspected and
repaired before operating the outboard
motor. Otherwise an accident could occur.
ECM00120
CAUTION:
Do not start the engine out of water. Over-
heating and serious engine damage can
occur.
Operation

Breaking in engine

Preoperation checks

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