Yamaha 20D User manual

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Read this manual carefully before operating this
outboard motor.
OWNER’S MANUAL
20D
25N
6L3-28199-7C-E0

EMU25052
Read this manual carefully before operating this outboard motor. Keep this
manual onboard in a waterproof bag when boating. This manual should stay
with the outboard motor if it is sold.

Important manual information
EMU25105
To the owner
Thank you for choosing a Yamaha outboard
motor. This Owner’s Manual contains infor-
mation needed for proper operation, mainte-
nance and care. A thorough understanding
of these simple instructions will help you ob-
tain maximum enjoyment from your new
Yamaha. If you have any question about the
operation or maintenance of your outboard
motor, please consult a Yamaha dealer.
In this Owner’s Manual particularly important
information is distinguished in the following
ways.
: This is the safety alert symbol. It is
used to alert you to potential personal injury
hazards. Obey all safety messages that fol-
low this symbol to avoid possible injury or
death.
WARNING
EWM00781
A WARNING indicates a hazardous situa-
tion which, if not avoided, could result in
death or serious injury.
NOTICE
ECM00701
A NOTICE indicates special precautions
that must be taken to avoid damage to the
outboard motor or other property.
T
IP:
A TIP provides key information to make pro-
cedures easier or clearer.
Yamaha continually seeks advancements in
product design and quality. Therefore, while
this manual contains the most current prod-
uct information available at the time of print-
ing, there may be minor discrepancies
between your machine and this manual. If
there is any question concerning this manu-
al, please consult your Yamaha dealer.
To ensure long product life, Yamaha recom-
mends that you use the product and perform
the specified periodic inspections and main-
tenance by correctly following the instruc-
tions in the owner’s manual. Any damage
resulting from neglect of these instructions is
not covered by warranty.
Some countries have laws or regulations re-
stricting users from taking the product out of
the country where it was purchased, and it
may be impossible to register the product in
the destination country. Additionally, the
warranty may not apply in certain regions.
When planning to take the product to another
country, consult the dealer where the prod-
uct was purchased for further information.
If the product was purchased used, please
consult your closest dealer for customer re-
registration, and to be eligible for the speci-
fied services.
T
IP:
The 20DMHO, 20DWO, 25NMHO and the
standard accessories are used as a base for
the explanations and illustrations in this
manual. Therefore some items may not ap-
ply to every model.
EMU25121
20D, 25N
OWNER’S MANUAL
©2009 by Yamaha Motor Co., Ltd.
1st Edition, April 2009
All rights reserved.
Any reprinting or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd.
is expressly prohibited.
Printed in Japan

Table of contents
Safety information............................. 1
Outboard motor safety .................... 1
Propeller............................................ 1
Rotating parts.................................... 1
Hot parts ........................................... 1
Electric shock.................................... 1
Engine shut-off cord (lanyard)........... 1
Gasoline............................................ 1
Gasoline exposure and spills ............ 1
Carbon monoxide.............................. 1
Modifications ..................................... 2
Boating safety ................................. 2
Alcohol and drugs ............................. 2
Personal flotation devices ................. 2
People in the water ........................... 2
Passengers ....................................... 2
Overloading....................................... 2
Avoid collisions ................................. 2
Weather ............................................ 3
Passenger training ............................ 3
Boating safety publications ............... 3
Laws and regulations ........................ 3
General information .......................... 4
Identification numbers record.......... 4
Outboard motor serial number .......... 4
Key number....................................... 4
EC Declaration of Conformity
(DoC) ............................................. 4
CE Marking ..................................... 4
Read manuals and labels................ 6
Warning labels .................................. 6
Specifications and requirements..... 9
Specifications .................................. 9
Installation requirements ............... 10
Boat horsepower rating................... 10
Mounting motor ............................... 10
Remote control requirements........ 10
Battery requirements..................... 11
Battery specifications ...................... 11
Mounting battery ............................. 11
Multiple batteries............................. 11
Without a rectifier or Rectifier
Regulator ...................................... 11
Propeller selection......................... 11
Start-in-gear protection ................. 12
Engine oil requirements ................ 12
Fuel requirements......................... 12
Gasoline .......................................... 12
Muddy or acidic water................... 12
Anti-fouling paint ........................... 13
Motor disposal requirements......... 13
Emergency equipment.................. 13
Components .................................... 14
Components diagram.................... 14
Fuel tank ......................................... 14
Fuel joint.......................................... 15
Fuel gauge ...................................... 15
Fuel tank cap...................................15
Air vent screw..................................15
Remote control box ......................... 15
Remote control lever ....................... 15
Neutral interlock trigger ................... 16
Neutral throttle lever........................16
Choke switch ................................... 16
Tiller handle..................................... 16
Gear shift lever................................16
Throttle grip ..................................... 17
Throttle indicator ............................. 17
Throttle friction adjuster...................17
Engine shut-off cord (lanyard) and
clip................................................. 18
Engine stop button .......................... 18
Choke knob for pull type .................19
Manual starter handle .....................19
Main switch ..................................... 19
Steering friction adjuster .................19
Trim tab with anode......................... 20
Trim rod (tilt pin) .............................. 20
Shallow water lever ......................... 20
Tilt lock mechanism......................... 21
Tilt support bar ................................ 21
Cowling lock lever(s) (turn type)...... 21
2-pin connector ............................... 22
Battery charging information ........... 22
Alert indicator .................................. 22
Engine control system ................... 23
Alert system .................................. 23
Overheat alert ................................. 23
Oil level alert and oil filter clogging
alert ............................................... 23

Table of contents
Installation ....................................... 25
Installation ..................................... 25
Mounting the outboard motor.......... 25
Clamping the outboard motor ......... 26
Operation ......................................... 28
First-time operation ....................... 28
Breaking in engine .......................... 28
Getting to know your boat ............... 28
Checks before starting engine ...... 28
Fuel level......................................... 29
Remove cowling.............................. 29
Fuel system..................................... 29
Controls........................................... 29
Engine shut-off cord (lanyard)......... 30
Oil.................................................... 30
Engine............................................. 30
Operation after long period of
storage.......................................... 30
Install cowling.................................. 31
Battery............................................. 31
Filling fuel and engine oil............... 32
Filling fuel for portable tank............. 32
Filling oil for manual starter
model ............................................ 33
Oil level indicator operation............. 34
Operating engine........................... 34
Sending fuel (portable tank)............ 34
Starting engine................................ 35
Checks after starting engine ......... 40
Cooling water .................................. 40
Warming up engine ....................... 41
Choke start models ......................... 41
Checks after engine warm-up ....... 41
Shifting ............................................ 41
Stop switches.................................. 41
Shifting .......................................... 41
Stopping boat ................................ 42
Stopping engine ............................ 43
Procedure ....................................... 43
Trimming outboard motor.............. 44
Adjusting trim angle for manual tilt
models .......................................... 44
Adjusting boat trim .......................... 45
Tilting up and down ....................... 46
Procedure for tilting up (manual tilt
models) ......................................... 46
Procedure for tilting down (manual
tilt models)..................................... 47
Shallow water................................ 48
Cruising in shallow water (manual
tilt models)..................................... 48
Cruising in other conditions........... 49
Maintenance .................................... 50
Transporting and storing outboard
motor ........................................... 50
Clamp screw mounting models ....... 50
Storing outboard motor ...................50
Procedure........................................ 51
Lubrication (oil injection models).....52
Cleaning the outboard motor........... 52
Checking painted surface of
motor............................................. 52
Periodic maintenance ................... 52
Replacement parts .......................... 53
Severe operating conditions............ 53
Maintenance chart 1........................ 54
Maintenance chart 2........................ 56
Greasing.......................................... 57
Cleaning and adjusting spark
plug ............................................... 57
Checking fuel filter........................... 58
Inspecting idling speed.................... 58
Checking water in engine oil tank ...59
Checking wiring and connectors ..... 59
Checking propeller .......................... 59
Removing propeller ......................... 60
Installing propeller ........................... 60
Changing gear oil ............................ 61
Cleaning fuel tank ...........................62
Inspecting and replacing
anode(s)........................................ 62
Checking battery (for electric start
models) ......................................... 63
Connecting the battery .................... 63
Disconnecting the battery................ 64
Trouble Recovery............................ 65
Troubleshooting ............................ 65
Temporary action in emergency ... 68
Impact damage ............................... 68
Replacing fuse ................................ 68

Table of contents
Starter will not operate .................... 69
Emergency starting engine ............. 69
Treatment of submerged motor..... 71

1
Safety information
EMU33622
Outboard motor safety
Observe these precautions at all times.
EMU36501
Propeller
People can be injured or killed if they come
in contact with the propeller. The propeller
can keep moving even when the motor is in
neutral, and sharp edges of the propeller can
cut even when stationary.
●
Stop the engine when a person is in the
water near you.
● Keep people out of reach of the propeller,
even when the engine is off.
EMU33630
Rotating parts
Hands, feet, hair, jewelry, clothing, PFD
straps, etc. can become entangled with inter-
nal rotating parts of the engine, resulting in
serious injury or death.
Keep the top cowling in place whenever pos-
sible. Do not remove or replace the cowling
with the engine running.
Only operate the engine with the cowling re-
moved according to the specific instructions
in the manual. Keep hands, feet, hair, jewel-
ry, clothing, PFD straps, etc. away from any
exposed moving parts.
EMU33640
Hot parts
During and after operation, engine parts are
hot enough to cause burns. Avoid touching
any parts under the top cowling until the en-
gine has cooled.
EMU33650
Electric shock
Do not touch any electrical parts while start-
ing or operating the engine. They can cause
shock or electrocution.
EMU33671
Engine shut-off cord (lanyard)
Attach the engine shut-off cord so that the
engine stops if the operator falls overboard
or leaves the helm. This prevents the boat
from running away under power and leaving
people stranded, or running over people or
objects.
Always attach the engine shut-off cord to a
secure place on your clothing or your arm or
leg while operating. Do not remove it to leave
the helm while the boat is moving. Do not at-
tach the cord to clothing that could tear
loose, or route the cord where it could be-
come entangled, preventing it from function-
ing.
Do not route the cord where it is likely to be
accidentally pulled out. If the cord is pulled
during operation, the engine will shut off and
you will lose most steering control. The boat
could slow rapidly, throwing people and ob-
jects forward.
EMU33810
Gasoline
Gasoline and its vapors are highly flam-
mable and explosive. Always, refuel ac-
cording to the procedure on page 34 to
reduce the risk of fire and explosion.
EMU33820
Gasoline exposure and spills
Take care not to spill gasoline. If gasoline
spills, wipe it up immediately with dry rags.
Dispose of rags properly.
If any gasoline spills onto your skin, immedi-
ately wash with soap and water. Change
clothing if gasoline spills on it.
If you swallow gasoline, inhale a lot of gaso-
line vapor, or get gasoline in your eyes, get
immediate medical attention. Never siphon
fuel by mouth.
EMU33900
Carbon monoxide
This product emits exhaust gases which
contain carbon monoxide, a colorless, odor-
less gas which may cause brain damage or

Safety information
2
death when inhaled. Symptoms include nau-
sea, dizziness, and drowsiness. Keep cock-
pit and cabin areas well ventilated. Avoid
blocking exhaust outlets.
EMU33780
Modifications
Do not attempt to modify this outboard mo-
tor. Modifications to your outboard motor
may reduce safety and reliability, and render
the outboard unsafe or illegal to use.
EMU33740
Boating safety
This section includes a few of the many im-
portant safety precautions that you should
follow when boating.
EMU33710
Alcohol and drugs
Never operate after drinking alcohol or tak-
ing drugs. Intoxication is one of the most
common factors contributing to boating fatal-
ities.
EMU33720
Personal flotation devices
Have an approved personal flotation device
(PFD) on board for every occupant. Yamaha
recommends that you must wear a PFD
whenever boating. At a minimum, children
and non-swimmers should always wear
PFDs, and everyone should wear PFDs
when there are potentially hazardous boat-
ing conditions.
EMU33731
People in the water
Always watch carefully for people in the wa-
ter, such as swimmers, skiers, or divers,
whenever the engine is running. When
someone is in the water near the boat, shift
into neutral and stop the engine.
Stay away from swimming areas. Swimmers
can be hard to see.
The propeller can keep moving even when
the motor is in neutral. Stop the engine when
a person is in the water near you.
EMU33751
Passengers
Consult your boat manufacturer’s instruc-
tions for details about appropriate passenger
locations in your boat and be sure all pas-
sengers are positioned properly before ac-
celerating and when operating above an idle
speed. Standing or sitting in non-designated
locations may result in being thrown either
overboard or within the boat due to waves,
wakes, or sudden changes in speed or direc-
tion. Even when people are positioned prop-
erly, alert your passengers if you must make
any unusual maneuver. Always avoid jump-
ing waves or wakes.
EMU33760
Overloading
Do not overload the boat. Consult the boat
capacity plate or boat manufacturer for max-
imum weight and number of passengers. Be
sure that weight is properly distributed ac-
cording to the boat manufacturers instruc-
tions. Overloading or incorrect weight
distribution can compromise the boats han-
dling and lead to an accident, capsizing or
swamping.
EMU33772
Avoid collisions
Scan constantly for people, objects, and oth-
er boats. Be alert for conditions that limit your
visibility or block your vision of others.
ZMU06025

Safety information
3
Operate defensively at safe speeds and
keep a safe distance away from people, ob-
jects, and other boats.
●
Do not follow directly behind other boats or
waterskiers.
●
Avoid sharp turns or other maneuvers that
make it hard for others to avoid you or un-
derstand where you are going.
●
Avoid areas with submerged objects or
shallow water.
● Ride within your limits and avoid aggres-
sive maneuvers to reduce the risk of loss
of control, ejection, and collision.
● Take early action to avoid collisions. Re-
member, boats do not have brakes, and
stopping the engine or reducing throttle
can reduce the ability to steer. If you are
not sure that you can stop in time before
hitting an obstacle, apply throttle and turn
in another direction.
EMU33790
Weather
Stay informed about the weather. Check
weather forecasts before boating. Avoid
boating in hazardous weather.
EMU33880
Passenger training
Make sure at least one other passenger is
trained to operate the boat in the event of an
emergency.
EMU33890
Boating safety publications
Be informed about boating safety. Additional
publications and information can be obtained
from many boating organizations.
EMU33600
Laws and regulations
Know the marine laws and regulations where
you will be boating- and obey them. Several
sets of rules prevail according to geographic
location, but all are basically the same as the
International Rules of the Road.

4
General information
EMU25171
Identification numbers record
EMU25183
Outboard motor serial number
The outboard motor serial number is
stamped on the label attached to the port
side of the clamp bracket.
Record your outboard motor serial number in
the spaces provided to assist you in ordering
spare parts from your Yamaha dealer or for
reference in case your outboard motor is sto-
len.
EMU25190
Key number
If a main key switch is equipped with the mo-
tor, the key identification number is stamped
on your key as shown in the illustration.
Record this number in the space provided for
reference in case you need a new key.
EMU37290
EC Declaration of Conformity
(DoC)
This outboard motor conforms to certain por-
tions of the European Parliament directive
relating to machinery.
Each conformed outboard motor accompa-
nied with EC DoC.EC DoC contains the fol-
lowing information;
●
Name of Engine Manufacture
● Model name
●
Product code of model (Approved model
code)
● Code of conformed directives
EMU25203
CE Marking
Outboard motors affixed with this “CE”mark-
ing conform with the directives of; 98/37/EC,
94/25/EC - 2003/44/EC and 2004/108/EC.
1. Outboard motor serial number location
1. Key number

General information
5
1. CE marking location
ZMU03683
1
ZMU06040

General information
6
EMU33520
Read manuals and labels
Before operating or working on this motor:
●
Read this manual.
●
Read any manuals supplied with the boat.
● Read all labels on the outboard motor and the boat.
If you need any additional information, contact your Yamaha dealer.
EMU33831
Warning labels
If these labels are damaged or missing, contact your Yamaha dealer for replacements.
20D, 25N
ZMU06146
1
2
3

General information
7
EMU33912
Contents of labels
The above warning labels mean as follows.
1
WARNING
EWM01691
Emergency starting does not have start-
in-gear protection. Ensure shift control is
in neutral before starting engine.
2
WARNING
EWM01681
● Keep hands, hair, and clothing away
from rotating parts while the engine is
running.
● Do not touch or remove electrical parts
when starting or during operation.
3
WARNING
EWM01671
●
Read Owner’s Manuals and labels.
● Wear an approved personal flotation
device (PFD).
●
Attach engine shut-off cord (lanyard) to
your PFD, arm, or leg so the engine
stops if you accidentally leave the
helm, which could prevent a runaway
boat.
ZMU05706
12
3

General information
8
EMU33843
Symbols
The following symbols mean as follows.
Notice/Warning
Read Owner’s Manual
Hazard caused by continuous rotation
Electrical hazard
Remote control lever/gear shift lever operat-
ing direction, dual direction
Engine start/ Engine cranking
ZMU05696
ZMU05664
ZMU05665
ZMU05666
ZMU05667
ZMU05668

9
Specifications and requirements
EMU31480
Specifications
T
IP:
“(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.
EMU2821E
Dimension:
Overall length:
20DMHO 936 mm (36.9 in)
20DWO 615 mm (24.2 in)
25NMHO 936 mm (36.9 in)
Overall width:
20DMHO 358 mm (14.1 in)
20DWO 304 mm (12.0 in)
25NMHO 358 mm (14.1 in)
Overall height S:
1068 mm (42.0 in)
Overall height L:
1195 mm (47.0 in)
Transom height S:
419 mm (16.5 in)
Transom height L:
546 mm (21.5 in)
Weight (AL) S:
20DMHO 49.0 kg (108 lb)
20DWO 50.5 kg (111 lb)
25NMHO 49.0 kg (108 lb)
Weight (AL) L:
20DMHO 50.5 kg (111 lb)
20DWO 52.0 kg (115 lb)
25NMHO 50.5 kg (111 lb)
Performance:
Full throttle operating range:
5000–6000 r/min
Maximum output:
20DMHO 14.7 kW@5500 r/min (20
HP@5500 r/min)
20DWO 14.7 kW@5500 r/min (20
HP@5500 r/min)
25NMHO 18.4 kW@5500 r/min (25
HP@5500 r/min)
Idling speed (in neutral):
750 ± 50 r/min
Engine:
Type:
2-stroke L
Displacement:
395.0 cm
3
Bore × stroke:
67.0 × 56.0 mm (2.64 × 2.20 in)
Ignition system:
CDI
Spark plug with resistor (NGK):
BR7HS-10
Spark plug gap:
0.9–1.0 mm (0.035–0.039 in)
Control system:
20DMHO Tiller
20DWO Remote control
25NMHO Tiller
Starting system:
20DMHO Manual
20DWO Manual and electric
25NMHO Manual
Starting carburetion system:
Choke valve
Min. cold cranking amps (CCA/EN):
20DWO 347.0 A
Min. rated capacity (20HR/IEC):
20DWO 40.0 Ah
Alternator output:
20DMHO 80 W
25NMHO 80 W
Maximum generator output:
20DWO 6 A
Drive unit:
Gear positions:

Specifications and requirements
10
Forward-neutral-reverse
Gear ratio:
2.08 (27/13)
Trim and tilt system:
Manual tilt
Propeller mark:
F
Fuel and oil:
Recommended fuel:
Regular unleaded gasoline
Min. research octane:
90
Fuel tank capacity:
25 L (6.60 US gal, 5.50 Imp.gal)
Recommended engine oil:
YAMALUBE 2-stroke outboard motor
oil
Lubrication:
Oil injection
Engine oil tank capacity:
0.7 L (0.74 US qt, 0.62 Imp.qt)
Recommended gear oil:
Hypoid gear oil SAE#90
Gear oil quantity:
0.370 L (0.391 US qt, 0.326 Imp.qt)
Tightening torque for engine:
Spark plug:
25.0 Nm (2.55 kgf-m, 18.4 ft-lb)
Propeller nut:
35.0 Nm (3.57 kgf-m, 25.8 ft-lb)
Noise and vibration level:
Operator sound pressure level (ICOMIA
39/94 and 40/94):
91.1 dB(A)
Sound power level (ICOMIA 39/94 and
40/94):
98.0 dB(A)
Vibration on tiller handle (ICOMIA 38/94):
Vibration on tiller handle is under 2.5
m/s
2
EMU33554
Installation requirements
EMU33563
Boat horsepower rating
WARNING
EWM01560
Overpowering a boat can cause severe
instability.
Before installing the outboard motor(s), con-
firm that the total horsepower of your mo-
tor(s) does not exceed the boats maximum
horsepower rating. See the boat’s capacity
plate or contact the manufacturer.
EMU33571
Mounting motor
WARNING
EWM01570
●
Improper mounting of the outboard mo-
tor could result in hazardous condi-
tions such as poor handling, loss of
control, or fire hazards.
●
Because the motor is very heavy, spe-
cial equipment and training is required
to mount it safely.
Your dealer or other person experienced in
proper rigging should mount the motor using
correct equipment and complete rigging in-
structions. For further information, see page
25.
EMU33581
Remote control requirements
WARNING
EWM01580
●
If the engine starts in gear, the boat can
move suddenly and unexpectedly, pos-
sibly causing a collision or throwing
passengers overboard.
●
If the engine ever starts in gear, the
start-in-gear protection device is not
working correctly and you should dis-
continue using the outboard. Contact

Specifications and requirements
11
your Yamaha dealer.
The remote control unit must be equipped
with a start-in-gear protection device(s). This
device prevents the engine from starting un-
less it is in neutral.
EMU25694
Battery requirements
EMU25721
Battery specifications
The engine cannot be started if battery volt-
age is too low.
EMU36290
Mounting battery
Mount the battery holder securely in a dry,
well-ventilated, vibration-free location in the
boat. WARNING! Do not put flammable
items, or loose heavy or metal objects in
the same compartment as the battery.
Fire, explosion or sparks could result.
[EWM01820]
EMU36300
Multiple batteries
To connect multiple batteries, such as for
multiple engine configurations or for an ac-
cessory battery, consult your Yamaha dealer
about battery selection and correct wiring.
EMU25730
Without a rectifier or Rectifier
Regulator
NOTICE
ECM01090
A battery cannot be connected to models
that do not have a rectifier or Rectifier
Regulator.
If you wish to use a battery with the models
without a rectifier or Rectifier Regulator, in-
stall an optional Rectifier Regulator.
Using a maintenance-free battery with the
above models can shorten the life of the bat-
tery significantly.
Install an optional Rectifier Regulator or use
accessories rated to withstand 18 volts or
higher with the above models. Consult your
Yamaha dealer for details on installing an
optional Rectifier Regulator.
EMU34192
Propeller selection
Next to selecting an outboard, choosing the
right propeller is one of the most important
purchasing decisions a boater can make.
The type, size, and design of your propeller
have a direct impact on acceleration, top
speed, fuel economy, and even engine life.
Yamaha designs and manufactures propel-
lers for every Yamaha outboard motor and
every application.
Your outboard motor came with a Yamaha
propeller chosen to perform well over a
range of applications, but there may be uses
where a different propeller would be more
appropriate.
Your Yamaha dealer can help you select the
right propeller for your boating needs. Select
a propeller that will allow the engine to reach
the middle or upper half of the operating
range at full throttle with the maximum boat-
load. Generally, chose a larger pitch propel-
ler for a smaller operating load and a smaller
pitch propeller for a heavier load. If you carry
loads that vary widely, chose the propeller
that lets the engine run in the proper range
for your maximum load but remember that
you may need to reduce your throttle setting
to stay within the recommended engine
speed range when carrying lighter loads.
For instructions on propeller removal and in-
stallation, see page 59.
Minimum cold cranking amps (CCA/EN):
20DWO 347.0 A
Minimum rated capacity (20HR/IEC):
20DWO 40.0 Ah

Specifications and requirements
12
EMU25770
Start-in-gear protection
Yamaha outboard motors or Yamaha-ap-
proved remote control units are equipped
with start-in-gear protection device(s). This
feature permits the engine to be started only
when it is in neutral. Always select neutral
before starting the engine.
EMU25651
Engine oil requirements
If the recommended engine oil is not avail-
able, another 2-stroke engine oil with an
NMMA-certified TC-W3 rating may be used.
EMU36360
Fuel requirements
EMU36802
Gasoline
Use a good quality gasoline that meets the
minimum octane rating. If knocking or ping-
ing occurs, use a different brand of gasoline
or premium unleaded fuel.
NOTICE
ECM01981
● Do not use leaded gasoline. Leaded
gasoline can seriously damage the en-
gine.
● Avoid getting water and contaminants
in the fuel tank. Contaminated fuel can
cause poor performance or engine
damage. Use only fresh gasoline that
has been stored in clean containers.
EMU36880
Muddy or acidic water
Yamaha strongly recommends that you have
your dealer install the optional chromium-
plated water pump kit if you use the outboard
motor in muddy or acidic water conditions.
However, depending on the model it might
not be required.
1. Propeller diameter in inches
2. Propeller pitch in inches
3. Type of propeller (propeller mark)
1. Propeller diameter in inches
2. Propeller pitch in inches
3. Type of propeller (propeller mark)
ZMU04604
-
x
123
ZMU04605
-
x
123
Recommended engine oil:
YAMALUBE 2-stroke outboard motor
oil
Recommended gasoline:
Regular unleaded gasoline with a min-
imum octane rating of 90 (Research
Octane Number).

Specifications and requirements
13
EMU36330
Anti-fouling paint
A clean hull improves boat performance. The
boat bottom should be kept as clean of ma-
rine growth as possible. If necessary, the
boat bottom can be coated with an anti-foul-
ing paint approved for your area to inhibit
marine growth.
Do not use anti-fouling paint which includes
copper or graphite. These paints can cause
more rapid engine corrosion.
EMU36341
Motor disposal requirements
Never illegally discard (dump) the motor.
Yamaha recommends consulting the dealer
about discarding the motor.
EMU36351
Emergency equipment
Keep the following items onboard in case
there is trouble with the motor.
● A tool kit with assorted screwdrivers, pli-
ers, wrenches (including metric sizes), and
electrical tape.
● Waterproof flashlight with extra batteries.
●
An extra engine shut-off cord (lanyard)
with clip.
● Spare parts, such as an extra set of spark
plugs.
Consult your Yamaha dealer for details.

14
Components
EMU2579M
Components diagram
T
IP:
* May not be exactly as shown; also may not be included as standard equipment on all mod-
els.
20D, 25N
EMU25802
Fuel tank
If your model was equipped with a portable
fuel tank, its function is as follows.
WARNING
EWM00020
The fuel tank supplied with this engine is
its dedicated fuel reservoir and must not
4
1
2
3
1
2
5
6
7
8
8
9
17
18
15
16
13
12
10
11
14
20
19
21
ZMU06147
1. Manual starter handle
2. Choke knob
3. 2-pin connector*
4. Gear shift lever*
5. Tiller handle*
6. Throttle friction adjuster*
7. Engine stop button/Engine shut-off switch*
8. Transom clamp handle
9. Tilt lock lever
10. Trim rod
11. Cooling water inlet
12. Propeller
13. Trim tab (anode)
14. Anti-cavitation plate
15. Clamp bracket
16. Restraint cable attachment
17. Shallow water lever
18. Top cowling
19. Remote control box (side mount type)*
20. Fuel tank
21. Clip*