Breaking in engine, Procedure for 4-stroke models, Operation – Yamaha F250 LF250 User Manual
Page 35
Operation
29
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-
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
the outboard motor, see page 35.
EMU30172
Breaking in engine
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.
CAUTION:
ECM00800
Failure to follow the break-in procedure
could result in reduced engine life or even
severe engine damage.
EMU27080
Procedure for 4-stroke models
Run the engine under load (in gear with a pro-
peller installed) as follows.
1.
For the first hour of operation:
Run the engine at 2000 r/min or at ap-
proximately half throttle.
2.
For the second hour of operation:
Run the engine at 3000 r/min or at ap-
proximately three-quarter throttle.
3.
For the next eight hours of operation:
Avoid continuous operation at full throttle
for more than five minutes at a time.
4.
After the first 10 hours:
Operate the engine normally.
1. Center line (keel line)
ZMU01762
U6P212E0.book Page 29 Monday, June 6, 2005 4:23 PM