This manual has been prepared by Yamaha primarily for use by Yamaha dealers and their trained
mechanics when performing maintenance procedures and repairs to Yamaha equipment. It has
been written to suit the needs of persons who have a basic understanding of the mechanical and
electrical concepts and procedures inherent in the work, for without such knowledge attempted
repairs or service to the equipment could render it unsafe or unfit for use.
Because Yamaha has a policy of continuously improving its products, models may differ in detail
from the descriptions and illustrations given in this publication. Use only the latest edition of this
manual. Authorized Yamaha dealers are notified periodically of modifications and significant
changes in specifications and procedures, and these are incorporated in successive editions of this
manual.
Important information
Particularly important information is distinguished in this manual by the following notations:
QThe Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR SAFETY IS
INVOLVED!
w
Failure to follow WARNING instructions could result in severe injury or death to the machine
operator, a bystander, or a person inspecting or repairing the outboard motor.
cC
A CAUTION indicates special precautions that must be taken to avoid damage to the outboard motor.
NOTE:
A NOTE provides key information to make procedures easier or clearer.
The format of this manual has been designed to make service procedures clear and easy to understand. Use the information below as a guide for effective and quality service.
1 Parts are shown and detailed in an exploded diagram and are listed in the components list.
2 Tightening torque specifications are provided in the exploded diagrams and after a numbered
step with tightening instructions.
3 Symbols are used to indicate important aspects of a procedure, such as the grade of lubricant
and lubrication point.
4 The components list consists of part names and quantities, as well as bolt and screw dimensions.
5 Service points regarding removal, checking, and installation are shown in individual illustrations
to explain the relevant procedure.
NOTE:
For troubleshooting procedures, see Chapter 9, “Troubleshooting.”
General information
1-
1-1
6H95G11
C
How to use this manual
Symbols
The symbols below indicate the content of a chapter.
General informationFuel systemBracket unit
GEN
INFO
SpecificationsPower unitElectrical systems
SPECPOWRELEC
Periodic checks and adjustments
CHK
ADJ
Symbols 1 to 6 indicate specific data.
123456
1 Special tool
2 Specified oil or fluid
3 Specified engine speed
4 Specified tightening torque
FUELBRKT
Lower unitTroubleshooting
LOWR
5 Specified measurement
6 Specified electrical value
(resistance, voltage, electric current)
TRBL
SHTG
1
2
3
4
5
Symbols 7 to e in an exploded diagram or illustration indicate the grade of lubricant and the lubrication point.
780qwe
7 Apply Yamaha 2-stroke motor oil
8 Apply gear oil
9 Apply water resistant grease (Yamaha grease A)
0 Apply molybdenum disulfide grease
Symbols r to o in an exploded diagram or illustration indicate the type of sealant or locking agent
and the application point.
rtyuio
r Apply Gasket Maker
t Apply Three bond 1104J
y Apply LOCTITE 271 (red)
6H95G11
9
q Apply corrosion resistant grease
(Yamaha grease D)
w Apply low temperature resistant grease
(Yamaha grease C)
e Apply injector grease
u Apply LOCTITE 242 (blue)
i Apply LOCTITE 572
o Apply silicon sealant
6
7
8
9
1-2
GEN
INFO
Safety while working
To prevent an accident or injury and to ensure
quality service, follow the safety procedures
provided below.
Fire prevention
Gasoline is highly flammable.
Keep gasoline and all flammable products
away from heat, sparks, and open flames.
General information
Parts, lubricants, and sealants
Use only genuine Yamaha parts, lubricants,
and sealants or those recommended by
Yamaha, when servicing or repairing the outboard motor.
Ventilation
Gasoline vapor and exhaust gas are heavier
than air and extremely poisonous. If inhaled
in large quantities they may cause loss of
consciousness and death within a short time.
When test running an engine indoors (e.g., in
a water tank) be sure to do so where adequate ventilation can be maintained.
Self-protection
Protect your eyes by wearing safety glasses
or safety goggles during all operations involving drilling and grinding, or when using an air
compressor.
Protect your hands and feet by wearing protective gloves and safety shoes when necessary.
Under normal conditions, the lubricants mentioned in this manual should not harm or be
hazardous to your skin. However, you should
follow these precautions to minimize any risk
when working with lubricants.
1.Maintain good standards of personal and
industrial hygiene.
2.Change and wash clothing as soon as
possible if soiled with lubricants.
3.Avoid contact with skin. Do not, for example, place a soiled rag in your pocket.
4.Wash hands and any other part of the
body thoroughly with soap and hot water
after contact with a lubricant or lubricant
soiled clothing has been made.
5.To protect your skin, apply a protective
cream to your hands before working on
the outboard motor.
1-
1-3
6H95G11
Safety while working
6.Keep a supply of clean, lint-free cloths for
wiping up spills, etc.
Good working practices
Special service tools
Use the recommended special service tools
to protect parts from damage. Use the right
tool in the right manner–do not improvise.
Tightening torques
Follow the tightening torque specifications
provided throughout the manual. When tightening nuts, bolts, and screws, tighten the
large sizes first, and tighten fasteners starting
in the center and moving outward.
Non-reusable parts
Always use new gaskets, seals, O-rings, cotter pins, circlips, etc., when installing or
assembling parts.
Disassembly and assembly
1.Use compressed air to remove dust and
dirt during disassembly.
2.Apply engine oil to the contact surfaces
of moving parts before assembly.
3.Install bearings with the manufacture
identification mark in the direction indicated in the installation procedure. In addition, be sure to lubricate the bearings liberally.
4.Apply a thin coat of water-resistant
grease to the lip and periphery of an oil
seal before installation.
5.Check that moving parts operate normally after assembly.
1
2
3
4
5
6
7
8
9
6H95G11
1-4
GEN
6F610010
YAMAHA MOTOR CO., LTD.
MADE IN JAPAN
PAYS D'ORIGINE JAPON
1
3
2
4
6B410020
6B410030
× -
a
bc
6F610030
×−
a
bc
INFO
General information
Identification
Applicable model
This manual covers the following models.
Applicable models
EK40GMH, EK40JMH, EK40JW
Serial number
The outboard motor serial number is
stamped on a label attached to the port clamp
bracket.
Propeller selection
The performance of a boat and outboard
motor will be critically affected by the size and
type of propeller you choose. Propellers
greatly affect boat speed, acceleration,
engine life, fuel economy, and even boating
and steering capabilities. An incorrect choice
could adversely affect performance and could
also seriously damage the engine.
Use the following information as a guide for
selecting a propeller that meets the operating
conditions of the boat and the outboard
motor.
Propeller size
The size of the propeller is indicated on the
outside of the propeller boss or the propeller
blade.
1 Model name
2 Approved model code
3 Transom height
4 Serial number
Model name
EK40G6F5K1006117–
EK40J6H9K1001748–
1-
1-5
ApprovedStarting
model codeserial No.
a Propeller diameter (in inches)
b Propeller pitch (in inches)
c Propeller type (propeller mark)
6H95G11
Selection
When the engine speed is at the full throttle
operating range (4,500–5,500 r/min), the
ideal propeller for the boat is one that provides maximum performance in relation to
boat speed and fuel consumption.
EK40G
Propeller size (in)Material
11 3/4 × 7 1/2 - H
11 3/4 × 8 3/4 - H
11 3/4 × 10 - H
Aluminum
11 1/2 × 11 - H
11 1/2 × 12 - H
11 1/2 × 13 - H
11 1/2 × 13 1/2 - H
EK40J
Propeller size (in)Material
12 1/4 × 9 - G
11 3/4 × 10 - G
11 5/8 × 11 - G
12 × 11 - G
11 3/8 × 12 - G
11 3/4 × 12 - G
11 1/8 × 13 - G
Aluminum
11 1/2 × 13 - G
10 1/4 × 14 - G
11 1/4 × 14 - G
10 1/4 × 15 - G
11 × 15 - G
10 1/4 × 16 - G
10 3/4 × 16 - G
10 3/4 × 17 - G
Predelivery checks
To make the delivery process smooth and
efficient, the predelivery checks should be
completed as explained below.
Propeller selection/Predelivery checks
6H910040
cC
Use pre-mixed fuel only.
Fuel and oil mixing ratio is 30:1. For
break-in period, gasoline: 25:1, kerosene:
30:1 mixture shall be used.
Checking the gear oil
1.Check the gear oil level.
6F630195
Checking the battery (W)
1. Check the capacity, electrolyte level, and
specified gravity of the battery.
Recommended battery capacity:
CCA/EN: 347 A
20HR/IEC: 40 Ah
Electrolyte specified gravity:
1.280 at 20°C (68°F)
1
2
3
4
5
6
7
8
9
Checking the fuel system
1.Check that the fuel hose is securely connected and that the fuel tank is filled with
fuel.
6H95G11
1-6
GEN
0—25mm
(0—1in.)
6B410060
a
1
a
6F610060
N
R
F
2
6F610070
b
6F610075
INFO
2. Check that the positive and negative battery leads are securely connected.
Checking the outboard motor
mounting height
1.Check that the anti-cavitation plate is
between the bottom of the boat and a
maximum of 25 mm (1 in) a below it. If
the mounting height is too high, cavitation
will occur and propulsion will be reduced.
Also, the engine speed will increase
abnormally and cause the engine to overheat. If the mounting height is too low,
water resistance will increase and reduce
engine efficiency.
General information
3. Check that the shift lever 2 is in the neu-
tral position.
NOTE:
The optimum mounting height is affected by
the combination of the boat and the outboard
motor. To determine the optimum mounting
height, test run the outboard motor at different heights
2.Check that the clamp brackets are
secured with the clamp screws.
Checking the remote control cables
(remote control model)
1.Set the remote control lever to the neutral
position and fully close the throttle lever.
2. Check that the throttle pulley 1 is in its
fully closed position, and check the pulley
is contact the fully stopper a on the
bracket.
w
The shift/throttle cable joint must be
screwed in a minimum of 8.0 mm (0.31 in)
b.
NOTE:
Check the throttle valve fully open, after setting the remote control cables.
1-
1-7
6H95G11
Predelivery checks
a
b
6F610080
6F610110
a
R
N
F
6F610120
F
N
R
a
a
6F610100
6F610090
Checking the steering system
1.Check the steering friction for proper
adjustment.
NOTE:
9 To increase the friction, turn the friction
adjusting bolt in direction a.
9 To decrease the friction, turn the friction
adjusting bolt in direction b.
2.Check that the steering operates smoothly.
Checking the gear shift and throttle
operation
1.Check that the gear shift operates
smoothly when the shift lever or remote
control lever is shifted from neutral to forward or reverse.
2.Check that the throttle operates smoothly when the throttle grip (tiller handle
model) is turned from the fully closed
position to the fully open position a.
Check that the throttle operates smoothly when the remote control lever (remote
control model) is shifted from forward or
reverse to the fully open positions a.
1
2
3
4
3.Check that there is no interference with
wires or hoses when the outboard motor
is steered.
5
6
7
8
9
6H95G11
1-8
GEN
6F610130
6F610140
6F610150
6F610170
INFO
Checking the engine start switch,
engine stop lanyard switch and
engine stop button
1.Check that the engine starts when the
engine start switch is turned to START.
(remote control model)
2.Check that the engine turns off when the
engine start switch is turned to OFF.
(remote control model)
General information
Checking the cooling water pilot
hole
1.Check that cooling water is discharged
from the cooling water pilot hole.
3.Check that the engine turns off when the
engine stop lanyard switch (and or
engine stop button) is pushed or the
engine stop lanyard is pulled from the
engine stop lanyard switch.
Test run
1.Start the engine, then check that the gear
shift operates smoothly.
2.Check the engine idle speed after the
engine has been warmed up.
3.Operate at trolling speed.
4.Run the outboard motor for 1 hour at
3,000 r/min or at half throttle, then for
another hour at 4,000 r/min or at 3/4
throttle.
5.Check that the outboard motor does not
tilt up when shifting into reverse and that
water does not flow in over the transom.
NOTE:
The test run is part of the break-in operation.
1-9
6H95G11
Predelivery checks
6F610180
0
1210
Break-in
During the test run, perform the break-in
operation in the following 5 stages.
1.10 minutes a at the lowest possible
speed. A fast idle in neutral is best.
2.50 minutes b at 1/2 throttle (approxi-
mately 3,000 r/min) or less. Vary engine
speed occasionally. On an easy-planing
boat, accelerate at full throttle onto plane,
then immediately reduce the throttle to
3,000 r/min or less.
3.1 hour c at 3/4 throttle (approximately
4,000 r/min). Vary engine speed occasionally. Run at full throttle for 1 minute,
the allow about 10 minutes of operation
at 3/4 throttle or less to let the engine
cool.
4.8 hours d at any speed, but avoid oper-
ating at full throttle for more than 5 minutes at a time. Let the engine cool
between full-throttle runs. Vary engine
speed occasionally.
After test run
1.Check for water in the gear oil.
2.Check for fuel leakage in the cowling.
3.Flush the cooling water passage with
fresh water using the flushing kit and with
the engine running at idle.
1
2
3
4
5
5.After the first 10hours. Use standard premix ratio of fuel and oil. Refer to page 1-
6.
å Hours
6
7
8
9
6H95G11
1-10
GEN
INFO
— MEMO —
1-11
6H95G11
SPEC
Specifications
General specification ................................................................................... 2-1
Maximum output kW (hp) 29.4 (40) at 5,000 r/min
Full throttle operating ranger/min 4,500–5,500
Maximum fuel consumption L (US gal,19.5 (5.2, 4.3) at 5,500 r/min
lmp gal)/hr
Engine idle speedr/min 1,050–1,150
Power unit
Engine type 2-stroke, L
Cylinder quantity2
3
Total displacement cm
Bore x stroke mm (in) 78.0 × 70.0 (3.07 × 2.76)
Compression ratio 5.00
Intake systemReed valve
Scavenging systemLoop charge
Control system Tiller handleRemote control
Starting system ManualManual and
Fuel system Carburetor
Ignition control system CDI
Maximum generator output(W) V, A(80)(80)12, 6
Starting enrichmentChoke valve
Spark plug (NGK) B7HS (NGK)
Cooling system Water
Exhaust system Under waterPropeller boss
Lubrication system Pre-mixed fuel
(cu. in) 669 (40.82)
EK40GMHEK40JMHEK40JW
Model
electric
2-1
6H95G11
General specification
ItemUnit
Fuel and oil
Fuel type Regular gasoline and kerosene
Engine oil2-stroke outboard motor oil
Engine oil grade
Gear oil type Hypoid gear oil
Gear oil grade (*1)APIGL-4
Gear shift positions F-N-R
Gear ratio 1.85 (24/13)2.00 (26/13)
Reduction gear type Spiral bevel gear
Clutch type Dog clutch
Propeller shaft type Share pinSpline
Propeller direction (rear view)Clockwise
Propeller ID mark HG
Electrical
Battery minimum capacity (*2)
CCA/EN——347
20HR/IEC——40
NMMA-certified
SAE90
3
(US oz,315 (10.65, 11.11)
lmp oz)
EK40GMHEK40JMHEK40JW
Model
TC-W3
1
2
3
4
5
(*1) Meeting both API and SAE requirements
(*2) CCA: Cold Cranking Ampere
EN: European Norm (European standard)
IEC: International Electrotechnical Commission
Main jet(M.J.)#145–140–
Main air jet(M.A.J.)ø1.70–ø1.70–
Main nozzle(M.N.)mm (in)
Pilot jet(P.J.)#90609060
Pilot air jet(P.A.J.)ø1.00ø1.20ø1.00ø1.20
Pilot screw(P.S.)turns out3/4 – 1 1/43/4 – 1 1/4
Valve seat sizemm (in)
Float heightmm (in)
This chart specifies tightening torques for
standard fasteners with a standard ISO
thread pitch. Tightening torque specifications
for special components or assemblies are
provided in applicable sections of this manual.
To avoid warpage, tighten multi-fastener
assemblies in a crisscross fashion and progressive stages until the specified torque is
reached. Unless otherwise specified, torque
specifications require clean, dry threads.
Components should be at room temperature.
Tightening torques
1
2
3
4
5
6
7
8
6H95G11
9
2-10
SPEC
— MEMO —
2-11
6H95G11
CHK
ADJ
Periodic checks and adjustments
Special service tools ................................................................................... 3-1