Yamaha F 25 Manual

							Operation
26
EMU27872Adjusting trim angle for manual tilt 
models
There are 4 or 5 holes provided in the clamp
bracket to adjust the outboard motor trim an-
gle.
1. Stop the engine.
2. Tilt the outboard motor up, and then re-
move the trim rod from the clamp bracket.
3. Reposition the rod in the desired hole.
To raise the bow (“trim-out”), move the rod
away from the transom.
To lower the bow (“trim-in”), move the rod to-
ward the transom.
Make test runs with the trim set to different an-
gles to find the position that works best for
your boat and operating conditions.
WARNING
EWM00400

Stop the engine before adjusting the
trim angle.

Use care to avoid being pinched when
removing or installing the rod.

Use caution when trying a trim position
for the first time. Increase speed gradu-
ally and watch for any signs of instability
or control problems. Improper trim an-
gle can cause loss of control.
NOTE:
The outboard motor trim angle can be
changed approximately 4 degrees by shifting
the trim rod one hole.
EMU27911Adjusting boat trim
When the boat is on plane, a bow-up attitude
results in less drag, greater stability and effi-
ciency. This is generally when the keel line of
the boat is up about 3 to 5 degrees. With the
bow up, the boat may have a greater tenden-
cy to steer to one side or the other. Compen-
sate for this as you steer. The trim tab can
also be adjusted to help offset this effect.
When the bow of the boat is down, it is easier
to accelerate from a standing start onto plane.
Bow Up
Too much trim-out puts the bow of the boat
too high in the water. Performance and econ-
omy are decreased because the hull of the
boat is pushing the water and there is more air
drag. Excessive trim-out can also cause the
propeller to ventilate, which reduces perfor-
mance further, and the boat may “porpoise”
(hop in the water), which could throw the op-
erator and passengers overboard.
1. Trim rod
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							Operation
27
Bow Down
Too much trim-in causes the boat to “plow”
through the water, decreasing fuel economy
and making it hard to increase speed. Operat-
ing with excessive trim-in at higher speeds
also makes the boat unstable. Resistance at
the bow is greatly increased, heightening the
danger of “bow steering” and making opera-
tion difficult and dangerous.
NOTE:
Depending on the type of boat, the outboard
motor trim angle may have little effect on the
trim of the boat when operating.
EMU27921
Tilting up and down
If the engine will be stopped for some time or
if the boat is moored in shallows, the outboard
motor should be tilted up to protect the propel-
ler and casing from damage by collision with
obstructions, and also to reduce salt corro-
sion.
WARNING
EWM00220
Be sure all people are clear of the out-
board motor when tilting up and down,
also be careful not to pinch any body parts
between the drive unit and engine bracket.
WARNING
EWM00230
Leaking fuel is a fire hazard. Tighten the
air vent screw and place the fuel cock in
the closed position if the outboard motor
will be tilted for more than a few minutes.
Otherwise fuel may leak.
CAUTION:
ECM00231

Before tilting the outboard motor, follow
the procedure under “Stopping engine”
in this chapter. Never tilt the outboard
motor while the engine is running. Se-
vere damage from overheating can re-
sult.

Do not tilt up the engine by pushing the
tiller handle because this could break
the handle.

Keep the power unit higher than the pro-
peller at all times. Otherwise water could
run into the cylinder and cause damage.

The outboard motor cannot be tilted
when in reverse or when the outboard
motor is turned 180° (facing the rear).
U69M15E0.book  Page 27  Wednesday, April 5, 2006  4:48 PM 
						

							Operation
28
EMU27964Procedure for tilting up (manual tilt 
models)
1. Place the gear shift lever in neutral (if
equipped) and face the outboard motor
forward.
2. On full-pivot system models, tighten the
steering friction adjuster by turning it
clockwise to prevent the motor from turn-
ing freely.
3. Tighten the air vent screw. On models
equipped with a fuel joint, disconnect the
fuel line from the outboard motor.
4. Close the fuel cock.5. Tilt support bar equipped models: Hold
the rear of the top cowling or the rear han-
dle (if equipped) with one hand and tilt the
outboard motor up fully until the tilt sup-
port bar automatically locks.
6. Tilt support knob equipped models: Hold
the rear of the top cowling with one hand,
fully tilt the outboard motor up, and push
the tilt support knob into the clamp brack-
et.
7. Tilt support lever equipped models: Hold
the rear handle and tilt the engine up fully
until the tilt support lever automatically
locks.
NOTE:
Tilt support lever/bar equipped models: If the
motor is not facing forward, the tilt support le-
ver/bar cannot automatically turn to the
U69M15E0.book  Page 28  Wednesday, April 5, 2006  4:48 PM 
						

							Operation
29
locked position. If the tilt support lever/bar
does not automatically lock, swing the motor
a little to the left and right.
EMU28032Procedure for tilting down (manual tilt 
models)
1. Slightly tilt the outboard motor up.
2. If equipped with the tilt support bar: Slow-
ly tilt the outboard motor down while pull-
ing the tilt support bar lever up.
3. If equipped with the tilt support knob: Pull
the knob out, and then slowly tilt the out-
board motor down.
4. If equipped with the tilt support lever:
Slowly tilt the outboard motor down while
pulling the tilt support lever up.
5. Loosen the steering friction adjuster by
turning it counterclockwise, and adjust
the steering friction according to operator
preference.
WARNING
EWM00720
If there is too much resistance it could be
difficult to steer, which could result in an
accident.
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							Maintenance
30
EMU31480
Specifications
NOTE:
“(AL)” stated in the specification data below
represents the numerical value for the alumi-
num propeller installed.
Likewise, “(SUS)” represents the value for
stainless steel propeller installed and “(PL)”
for plastic propeller installed.
EMU28218
Dimension:
Overall length:
623 mm (24.5 in)
Overall width:
345 mm (13.6 in)
Overall height S:
1021 mm (40.2 in)
Transom height S:
432 mm (17.0 in)
Weight (AL) S:
17.0 kg (37 lb)
Performance:
Full throttle operating range:
5250–5750 r/min
Maximum output:
1.8 kW@5500 r/min (2.5 HP@5500 r/min)
Idling speed (in neutral):
1900 ±100 r/min
Engine:
Type:
4-stroke S
Displacement:
72.0 cm³ (4.39 cu.in)
Bore × stroke:
54.0 × 31.5 mm (2.13 × 1.24 in)
Ignition system:
TCI
Spark plug (NGK):
BR6HS
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
Control system:
Tiller
Starting system:
ManualStarting carburetion system:
Choke valve
Valve clearance (cold engine) IN:
0.08–0.12 mm (0.0032–0.0047 in)
Valve clearance (cold engine) EX:
0.08–0.12 mm (0.0032–0.0047 in)
Drive unit:
Gear positions:
Forward-neutral
Gear ratio:
2.08 (27/13)
Trim and tilt system:
Manual tilt
Propeller mark:
BS
Fuel and oil:
Recommended fuel:
Regular unleaded gasoline
Min. pump octane:
86
Fuel tank capacity (built in type):
0.9 L (0.24 US gal) (0.20 Imp.gal)
Recommended engine oil:
4-stroke outboard motor oil
Engine oil grade API:
API SE, SF, SG, SH, SJ, SL
Engine oil type SAE:
SAE10W30 or SAE10W40
Lubrication:
Wet sump
Engine oil quantity (excluding oil filter):
0.35 L (0.37 US qt) (0.31 Imp.qt)
Recommended gear oil:
Hypoid gear oil SAE#90
Gear oil quantity:
75.0 cm³ (2.54 US oz) (2.65 Imp.oz)
Tightening torque for engine:
Spark plug:
25.0 Nm (18.4 ft-lb) (2.55 kgf-m)
Engine oil drain bolt:
18.0 Nm (13.3 ft-lb) (1.84 kgf-m)
U69M15E0.book  Page 30  Wednesday, April 5, 2006  4:48 PM 
						

							Maintenance
31
EMU28222
Transporting and storing out-
board motor
WARNING
EWM00690

Leaking fuel is a fire hazard. When trans-
porting and storing the outboard motor,
close the air vent screw and fuel cock to
prevent fuel from leaking.

USE CARE when transporting fuel tank,
whether in a boat or car.

DO NOT fill fuel container to maximum
capacity. Gasoline will expand consider-
ably as it warms up and can build up
pressure in the fuel container. This can
cause fuel leakage and a potential fire
hazard.
WARNING
EWM00700
Never get under the lower unit while it is
tilted, even if a motor support bar is used.
Severe injury could occur if the outboard
motor accidentally falls.
CAUTION:
ECM00660
Do not use the tilt support lever or knob
when trailering the boat. The outboard mo-
tor could shake loose from the tilt support
and fall. If the motor cannot be trailered in
the normal running position, use an addi-
tional support device to secure it in the tilt
position.
The outboard motor should be trailered and
stored in the normal running position. If there
is insufficient road clearance in this position,
then trailer the outboard motor in the tilt posi-
tion using a motor support device such as a
transom saver bar. Consult your Yamaha
dealer for further details.
EMU28235Clamp screw mounting models
When transporting or storing the outboard
motor while removed from a boat, keep the
outboard motor in the attitude shown.
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							Maintenance
32
NOTE:
Place a towel or something similar under the
outboard motor to protect it from damage.
EMU28241Storing outboard motor
When storing your Yamaha outboard motor
for prolonged periods of time (2 months or
longer), several important procedures must
be performed to prevent excessive damage.
It is advisable to have your outboard motor
serviced by an authorized Yamaha dealer pri-
or to storage. However, you, the owner, with a
minimum of tools, can perform the following
procedures.
CAUTION:
ECM01080

To prevent problems which can be
caused by oil entering the cylinder from
the sump, keep the outboard motor in
the attitude shown when transporting
and storing it. If storing or transporting
the outboard motor on its side (not up-
right), put it on a cushion after draining
the engine oil.

Do not place the outboard motor on its
side before the cooling water has
drained from it completely, otherwise
water may enter the cylinder through the
exhaust port and cause engine trouble.

Store the outboard motor in a dry, well-
ventilated place, not in direct sunlight.
EMU28302ProcedureEMU28372Flushing in a test tank
1. Wash the outboard motor body using
fresh water. For further information, see
page 33.
2. Fill the fuel tank with fresh fuel and add
one ounce of “Yamaha Fuel Conditioner
and Stabilizer” (Part No. LUB-FUELC-12-
00) to each gallon of fuel.
NOTE:
The use of “Yamaha Fuel Conditioner and
Stabilizer” eliminates the need to drain the
fuel system. Consult your Yamaha dealer or
other qualified mechanic if the fuel system is
to be drained instead.
3. Remove the engine top cowling and si-
lencer cover.
4. Install the outboard motor on the test
tank.
5. Fill the tank with fresh water to above the
level of the anti-cavitation plate.
1. Water surface
2. Lowest water level
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							Maintenance
33
CAUTION:
ECM00300
Do not run the engine without supplying it
with cooling water. Either the engine water
pump will be damaged or the engine will
be damaged from overheating. Before
starting the engine, be sure to supply wa-
ter to the cooling water passages.
CAUTION:
ECM00290
If the fresh water level is below the level of
the anti-cavitation plate, or if the water
supply is insufficient, engine seizure may
occur.
6. Cooling system flushing is essential to
prevent the cooling system from clogging
up with salt, sand, or dirt. In addition, fog-
ging of the engine is mandatory to pre-
vent excessive engine damage due to
rust. Perform the flushing and fogging at
the same time.
WARNING
EWM00090

Do not touch or remove electrical parts
when starting or during operation.

Keep hands, hair, and clothes away from
the flywheel and other rotating parts
while the engine is running.
7. Run the engine at a fast idle for 10–15
minutes in neutral position.
8. Just prior to turning off the engine, quickly
spray “Yamaha Stor-Rite Engine Fogging
Oil” (Part No. LUB-STRRT-12-00) alter-
nately into each carburetor or the fogging
hole of the silencer cover, if equipped.
When properly done, the engine will
smoke excessively and almost stall.
9. Remove the outboard motor from the test
tank.10. Drain the cooling water completely out of
the motor. Clean the body thoroughly.
11. Install the silencer cover/cap and top
cowling.
EMU28400Lubrication (except oil injection mod-
els)
1. Grease the spark plug threads and install
the spark plug(s) and torque to proper
specification. For information on spark
plug installation, see page 36.
2. Change the gear oil. For instructions, see
page 42. Inspect the oil for the presence
of water that indicates a leaky seal. Seal
replacement should be performed by an
authorized Yamaha dealer prior to use.
3. Grease all grease fittings. For further de-
tails, see page 36.
EMU28421Cleaning and anticorrosion measures
1. Wash down the exterior of the outboard
motor with fresh water and dry off com-
pletely.
2. Spray the outboard motor exterior with
“Yamaha Silicone Protectant” (Part No.
LUB-SILCNE-13-00).
3. Wax the cowling with a non-abrasive wax
such as “Yamaha Silicone Wax” (Part No.
ACC-11000-15-02).
EMU28450Cleaning the outboard motor
After use, wash the exterior of the outboard
motor with fresh water. Flush the cooling sys-
tem with fresh water.
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							Maintenance
34
NOTE:
For cooling system flushing instructions, see
page 31.
EMU28460Checking painted surface of motor
Check the motor for scratches, nicks, or flak-
ing paint. Areas with damaged paint are more
likely to corrode. If necessary, clean and paint
the areas. A touch-up paint is available from
your Yamaha dealer.
EMU28486
Periodic maintenance
WARNING
EWM01070
Be sure to turn off the engine when you
perform maintenance unless otherwise
specified. If you or the owner is not famil-
iar with machine servicing, this work
should be done by your Yamaha dealer or
other qualified mechanic.
Maintenance, replacement, or repair of the
emission control devices and systems
may be performed by any marine engine
repair establishment or individual. All war-
ranty repairs, however, including those to
the emission control system, must be per-
formed by an authorized Yamaha marine
dealership.
A service manual is available for purchase
through your Yamaha dealer for owners who
have the mechanical skills, tools, and other
equipment necessary to perform mainte-
nance not covered by this owner’s manual.
EMU28510Replacement parts
If replacement parts are necessary, use only
genuine Yamaha parts or parts of the same
type and of equivalent strength and materials.
Any part of inferior quality may malfunction,
and the resulting loss of control could endan-
ger the operator and passengers. Yamaha
genuine parts and accessories are available
from your Yamaha dealer.
U69M15E0.book  Page 34  Wednesday, April 5, 2006  4:48 PM 
						

							Maintenance
35
EMU28522Maintenance chart
Frequency of maintenance operations may be adjusted according to the operating conditions,
but the following table gives general guidelines. Refer to the sections in this chapter for expla-
nations of each owner-specific action.
NOTE:
When operating in salt water, turbid or muddy water, the engine should be flushed with clean
water after each use.
The “” symbol indicates the check-ups which you may carry out yourself.
The “” symbol indicates work to be carried out by your Yamaha dealer.
Item ActionsInitial Every
10 hours 
(1 month)50 hours 
(3 months)100 hours 
(6 months)200 hours 
(1 year)
Anode(s) (external)Inspection / replace-
ment
Anode(s) (internal)Inspection / replace-
ment
Cooling water passag-
esCleaning
Cowling clamp Inspection
Fuel filter (inside built-
in fuel tank)Inspection / cleaning
Fuel system Inspection
Fuel tank (built-in tank) Inspection / cleaning
Gear oil Change
Greasing points Greasing
Idling speed (carbure-
tor models)Inspection
Propeller and cotter pinInspection / replace-
ment
Shift link / shift cable Inspection / adjustment
ThermostatInspection / replace-
ment
Throttle link / throttle 
cable / throttle pick-up 
timingInspection / adjustment
Water pumpInspection / replace-
ment
Engine oil Inspection / change
Spark plug(s)Cleaning / adjustment / 
replacement
Valve clearance (OHC, 
OHV)Inspection / adjustment
U69M15E0.book  Page 35  Wednesday, April 5, 2006  4:48 PM