Installation; Mounting The Outboard Motor - Yamaha F90 Owner's Manual

Installation

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Installation
The information presented in this section is
intended as reference only. It is not possible
to provide complete instructions for every
possible boat and motor combination. Proper
mounting depends in part on experience and
the specific boat and motor combination.
EWM01591
WARNING
Overpowering a boat could cause se-
vere instability. Do not install an out-
board motor with more horsepower
than the maximum rating on the capaci-
ty plate of the boat. If the boat does not
have a capacity plate, consult the boat
manufacturer.
Improper mounting of the outboard mo-
tor could result in hazardous conditions
such as poor handling, loss of control,
or fire hazards. For permanently mount-
ed models, your dealer or other person
experienced in proper rigging should
mount the motor.
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Mounting the outboard motor

The outboard motor should be mounted so
that the boat is well balanced. Otherwise, the
boat could be hard to steer. For single-engine
boats, mount the outboard motor on the cen-
terline (keel line) of the boat.
1. Center line (keel line)
48
1
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Mounting height (boat bottom)
The mounting height of your outboard motor
affects its efficiency and reliability. If it is
mounted too high, propeller ventilation may
occur, which will reduce propulsion due to
excessive propeller slip, and the water in-
takes for the cooling system may not get an
adequate water supply, which can cause en-
gine overheating. If the engine is mounted too
low, water resistance (drag) will increase,
thereby reducing engine efficiency and per-
formance.
Most commonly, outboard motor should be
mounted so that the anti-cavitation plate is in
alignment with the bottom of the boat. The
optimum mounting height of the outboard
motor is affected by the boat/motor combi-
nation and the desired use. Test runs at dif-
ferent heights can help determine the
optimum mounting height. Consult your
Yamaha dealer or boat manufacturer for fur-
ther information on determining the proper
mounting height.
ECM01635
NOTICE
Make sure that the idle hole is high
enough to prevent water from entering
the engine even if the boat is stationary
with the maximum load.
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