Yamaha F 25 Manual

							Basic components
16
EMU26450Carrying handle
A carrying handle is provided on the rear of
the outboard motor. It enables you to carry the
outboard motor easily with one hand.
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							Operation
17
EMU26901
Installation
CAUTION:
ECM00110
Incorrect engine height or obstructions to
smooth water flow (such as the design or
condition of the boat, or accessories such
as transom ladders or depth finder trans-
ducers) can create airborne water spray
while the boat is cruising. Severe engine
damage may result if the motor is operat-
ed continuously in the presence of air-
borne water spray.
NOTE:
During water testing check the buoyancy of
the boat, at rest, with its maximum load.
Check that the static water level on the ex-
haust housing is low enough to prevent water
entry into the powerhead, when water rises
due to waves when the outboard is not run-
ning.
EMU26910Mounting the outboard motor
WARNING
EWM00820

Overpowering a boat could cause se-
vere instability. Do not install an out-
board motor with more horsepower than
the maximum rating on the capacity
plate of the boat. If the boat does not
have a capacity plate, consult the boat
manufacturer.

The information presented in this sec-
tion is intended as reference only. It is
not possible to provide complete in-
structions for every possible boat and
motor combination. Proper mounting
depends in part on experience and the
specific boat and motor combination.
WARNING
EWM00830
Improper mounting of the outboard motor
could result in hazardous conditions such
as poor handling, loss of control, or fire
hazards. Observe the following:

For permanently mounted models, your
dealer or other person experienced in
proper rigging should mount the motor.
If you are mounting the motor yourself,
you should be trained by an experienced
person.

For portable models, your dealer or oth-
er person experienced in proper out-
board motor mounting should show you
how to mount your motor.
Mount the outboard motor on the center line
(keel line) of the boat, and ensure that the
boat itself is well balanced. Otherwise the
boat will be hard to steer. For boats without a
keel or which are asymmetrical, consult your
dealer.
EMU26920Mounting height
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
1. Center line (keel line)
ZMU017601
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							Operation
18
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 between the bottom of the boat and a
level 25 mm (1 in.) below it.
NOTE:

The optimum mounting height of the out-
board motor is affected by the boat and mo-
tor 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 25.
EMU26970Clamping the outboard motor
1. Place the outboard motor on the transom
so that it is positioned as close to the cen-
ter as possible. Tighten the transom
clamp screws evenly and securely. Oc-
casionally check the clamp screws for
tightness during operation of the out-
board motor because they could become
loose due to engine vibration.
WARNING
EWM00640
Loose clamp screws could allow the out-
board motor to fall off or move on the tran-
som. This could cause loss of control and
serious injury. Make sure the transom
screws are tightened securely. Occasion-
ally check the screws for tightness during
operation.
2. If the engine restraint cable attachment is
equipped on your engine, an engine re-
straint cable or chain should be used. At-
tach one end to the engine restraint cable
attachment and the other to a secure
mounting point on the boat. Otherwise
the engine could be completely lost if it
accidentally falls off the transom.
3. Secure the clamp bracket to the transom
using the bolts provided with the out-
board (if packed). For details, consult
your Yamaha dealer.
ZMU02012
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							Operation
19
WARNING
EWM00650
Avoid using bolts, nuts or washers other
than those contained in the engine pack-
aging. If used, they must be of at least the
same quality of material and strength and
must be tightened securely. After tighten-
ing, test run the engine and check their
tightness.
EMU30173
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.
EMU27081Procedure 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.
4. After the first 10 hours:
Operate the engine normally.
EMU27102
Preoperation checks
WARNING
EWM00080
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.
CAUTION:
ECM00120
Do not start the engine out of water. Over-
heating and serious engine damage can
occur.
EMU31500Fuel

Check to be sure you have plenty of fuel for
your trip.

Make sure there are no fuel leaks or gaso-
line fumes.
EMU27130Controls

Check throttle, shift, and steering for proper
operation before starting the engine.

The controls should work smoothly, without
binding or unusual free play.

Look for loose or damaged connections.

Check operation of the starter and stop
switches when the outboard motor is in the
water.
EMU27140Engine

Check the engine and engine mounting.

Look for loose or damaged fasteners.

Check the propeller for damage.EMU30212Checking the engine oil level
1. Put the outboard motor in an upright po-
sition (not tilted).
2. Check the oil level using the oil level
check window to be sure the level falls
between the upper and lower marks. Fill
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							Operation
20
with oil if it is below the lower mark, or
drain to the specified level if it is above
the upper mark.
EMU30850
Filling fuel for built-in tank
WARNING
EWM00060
Gasoline and its vapors are highly flam-
mable and explosive. Keep away from
sparks, cigarettes, flames, or other sourc-
es of ignition.
1. With the outboard motor tilted down (in
the vertical running position), remove the
fuel tank cap.
2. Use a funnel if the nozzle on the fuel can
or pump is not small enough or long
enough to fit into the mouth of the fuel
tank.3. Fill the fuel tank carefully.
4. Securely close the cap after refueling.
Wipe up any spilled fuel.
EMU27270Ring Free Fuel Additive
Gasoline is a precise blend of many different
substances, each chosen to give certain char-
acteristics. Gasoline blends have been
changing in recent years in response to con-
cerns about pollution and resulting emissions
regulations. One of the most obvious changes
has been the elimination of lead from most fu-
els.
As gasoline has changed, the amount of addi-
tives such as aromatics and oxygenates has
increased. These additives are important for
the engines in passenger cars, but they can
have detrimental effects in marine engines,
because of increased deposits in the combus-
tion chamber. When enough deposits collect,
piston rings begin sticking. Performance
drops and engine wear increases dramatical-
ly.
While many additives available may reduce
deposits, Yamaha recommends the use of
Ring Free Fuel Additive, available from your
Yamaha dealer. Ring Free Fuel Additive
has repeatedly proven its ability to clean com-
bustion deposits from inside the engine, nota-
bly the critical piston-ring-land area, and fuel
system components. Follow product labeling
for use instructions.
1. Oil level check window
1. Lower level mark
2. Upper level mark
Fuel tank capacity:
0.9 L (0.24 US gal) (0.20 Imp.gal)
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							Operation
21
EMU27450
Operating engineEMU31510Feeding fuel
WARNING
EWM00420

Before starting the engine, make sure
that the boat is tightly moored and that
you can steer clear of any obstructions.
Be sure there are no swimmers in the
water near you.

When the air vent screw is loosened,
gasoline vapor will be released. Gaso-
line is highly flammable, and its vapors
are flammable and explosive. Refrain
from smoking, and keep away from
open flames and sparks while loosening
the air vent screw.

This product emits exhaust gases which
contain carbon monoxide, a colorless,
odorless gas which could cause brain
damage or death when inhaled. Symp-
toms include nausea, dizziness, and
drowsiness. Keep cockpit and cabin ar-
eas well ventilated. Avoid blocking ex-
haust outlets.
1. Loosen the air vent screw on the fuel tank
cap by one turn.
2. Open the fuel cock.
EMU27490Starting engineEMU27522Manual start models
1. Place the gear shift lever in neutral.
WARNING
EWM00110
Always start the engine in neutral to avoid
accidentally moving the boat.
2. If the engine stop switch lanyard is
equipped, attach it to a secure place on
your clothing, or your arm or leg. Then in-
stall the lock plate on the other end of the
lanyard into the engine stop switch.
WARNING
EWM00120

Attach the engine stop switch lanyard to
a secure place on your clothing, or your
arm or leg while operating.
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							Operation
22

Do not attach the lanyard to clothing
that could tear loose. Do not route the
lanyard where it could become entan-
gled, preventing it from functioning.

Avoid accidentally pulling the lanyard
during normal operation. Loss of engine
power means the loss of most steering
control. Also, without engine power, the
boat could slow rapidly. This could
cause people and objects in the boat to
be thrown forward.
3. Place the throttle grip in the “”
(start) position.
4. Place the choke knob in the “”
(start) position. After the engine starts, re-
turn the knob to the “” (run) position.
NOTE:

When restarting a warm engine, place the
choke knob in the “” (run) position.

If the choke knob is left in the “” (start)
position while the engine is running, the en-
gine will run poorly or stall.
5. Pull the manual starter handle slowly until
you feel resistance. Then give a strong
pull straight out to start the engine. Re-
peat if necessary.
6. After the engine starts, slowly return the
manual starter handle to the original posi-
tion before releasing it.
7. Slowly return the throttle grip to the fully
closed position.
NOTE:

When the engine is cold, it needs to be
warmed up. For further information, see
page 23.
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							Operation
23

If the engine does not start on the first try,
repeat the procedure. If the engine fails to
start after 4 or 5 tries, open the throttle a
small amount (between 1/8 and 1/4) and try
again. Also if the engine is warm and fails to
start, open the throttle a same amount and
try to start the engine again. If the engine
still fails to start, see page 45.
EMU27670
Warming up engineEMU27732Manual start models
1. After starting the engine, return the choke
knob to the halfway position. For approx-
imately the first 5 minutes after starting,
warm up the engine by operating at one
fifth throttle or less. After the engine has
warmed up, push the choke knob in fully.
Failure to do so will shorten engine life.
NOTE:

If the choke knob is left pulled out after the
engine starts, the engine will stall.

In temperatures of -5°C or less, leave the
choke knob pulled out fully for approximate-
ly 30 seconds after starting.
2. Check for a steady flow of water from the
cooling water pilot hole.
CAUTION:
ECM00511
A continuous flow of water from the cool-
ing water pilot hole shows that the water
pump is pumping water through the cool-
ing passages. If water is not flowing out of
the hole at all times while the engine is
running, overheating and serious damage
could occur. Stop the engine and check
whether the cooling water inlet on the low-
er case or the cooling water pilot hole isblocked. Consult your Yamaha dealer if
the problem cannot be located and cor-
rected.
EMU27740
Shifting
WARNING
EWM00180
Before shifting, make sure there are no
swimmers or obstacles in the water near
you.
CAUTION:
ECM00220
To change the boat direction or shifting
position from forward to reverse or vice-
versa, first close the throttle so that the en-
gine idles (or runs at low speeds).
EMU27764Forward (tiller handle and remote con-
trol models)
Tiller handle models
1. Place the throttle grip in the fully closed
position.
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							Operation
24
2. Move the gear shift lever quickly and firm-
ly from neutral to forward.
Remote control models
Pull up the neutral interlock trigger (if
equipped) and move the remote control lever
quickly and firmly from neutral to forward.
EMU27811Reverse
WARNING
EWM00190
When operating in reverse, go slowly. Do
not open the throttle more than half. Other-
wise the boat could become unstable,
which could result in loss of control and
an accident.
1. Place the throttle grip in the fully closed
position.2. Turn the outboard motor around 180°,
and then move the tiller handle so that it
is facing toward the bow.
NOTE:
The outboard motor can be turned a full 360°
in its bracket (full-pivot system).
3. Move the gear shift lever quickly and firm-
ly from neutral to forward.
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							Operation
25
EMU27820
Stopping engine
Before stopping the engine, first let it cool off
for a few minutes at idle or low speed. Stop-
ping the engine immediately after operating at
high speed is not recommended.
EMU31520Procedure
1. Push and hold the engine stop button un-
til the engine comes to a complete stop.
2. After stopping the engine, tighten the air
vent screw on the fuel tank cap and set
the fuel cock to the closed position.
NOTE:
The engine can also be stopped by pulling the
lanyard and removing the lock plate from the
engine stop switch.
EMU27861
Trimming outboard motor
The trim angle of the outboard motor helps
determine the position of the bow of the boat
in the water. Correct trim angle will help im-
prove performance and fuel economy while
reducing strain on the engine. Correct trim an-
gle depends upon the combination of boat,
engine, and propeller. Correct trim is also af-
fected by variables such as the load in the
boat, sea conditions, and running speed.
WARNING
EWM00740
Excessive trim for the operating condi-
tions (either trim up or trim down) can
cause boat instability and can make steer-
ing the boat more difficult. This increases
the possibility of an accident. If the boat
begins to feel unstable or is hard to steer,
slow down and/or readjust the trim angle.
1. Trim operating angle
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