Yamaha EK40G User manual

EK40J
SERVICE MANUAL
6H9-28197-5G-11
EK40G
A4Cover6H9 04.7.6 9:31 Page 1

NOTICE
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 out-
board motor.
NOTE:
A NOTE provides key information to make procedures easier or clearer.
EK40G/EK40J
SERVICE MANUAL
©2004 by Yamaha Motor Co., Ltd.
1st Edition, August 2004
All rights reserved.
Any reprinting or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd.
is expressly prohibited.
Printed in Japan
A4Cover6H9 04.7.6 9:31 Page 2

Specifications
General information
Periodic checks and adjustments
Fuel system
Power unit
Bracket unit
Electrical systems
Troubleshooting
Index
Contents
Lower unit
9
8
7
6
2
1
GEN
INFO
SPEC
CHK
ADJ
FUEL
POWR
LOWR
BRKT
ELEC
TRBL
SHTG
3
4
5
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6H95G11 1-
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General information
How to use this manual ............................................................................... 1-1
Manual format .......................................................................................... 1-1
Symbols ................................................................................................... 1-2
Safety while working ................................................................................... 1-3
Fire prevention ......................................................................................... 1-3
Ventilation ................................................................................................ 1-3
Self-protection ......................................................................................... 1-3
Parts, lubricants, and sealants ................................................................ 1-3
Good working practices ........................................................................... 1-4
Disassembly and assembly ..................................................................... 1-4
Identification ................................................................................................. 1-5
Applicable model ..................................................................................... 1-5
Serial number .......................................................................................... 1-5
Propeller selection ....................................................................................... 1-5
Propeller size ........................................................................................... 1-5
Selection .................................................................................................. 1-6
Predelivery checks ...................................................................................... 1-6
Checking the fuel system ........................................................................ 1-6
Checking the gear oil level ...................................................................... 1-6
Checking the battery (W) ......................................................................... 1-6
Checking the outboard motor mounting height ....................................... 1-7
Checking the remote control cables (remote control model) .................. 1-7
Checking the steering system ................................................................. 1-8
Checking the gear shift and throttle operation ........................................ 1-8
Checking the engine start switch, engine stop lanyard switch and engine
stop button ............................................................................................... 1-9
Checking the cooling water pilot hole ...................................................... 1-9
Test run .................................................................................................... 1-9
Break-in ................................................................................................. 1-10
After test run .......................................................................................... 1-10
GEN
INFO
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GEN
INFO
1- 6H95G11
General information
1-1
How to use this manual
Manual format
The format of this manual has been designed to make service procedures clear and easy to under-
stand. Use the information below as a guide for effective and quality service.
1Parts are shown and detailed in an exploded diagram and are listed in the components list.
2Tightening torque specifications are provided in the exploded diagrams and after a numbered
step with tightening instructions.
3Symbols are used to indicate important aspects of a procedure, such as the grade of lubricant
and lubrication point.
4The components list consists of part names and quantities, as well as bolt and screw dimensions.
5Service points regarding removal, checking, and installation are shown in individual illustrations
to explain the relevant procedure.
NOTE:
For troubleshooting procedures, see Chapter 9, “Troubleshooting.”
LOWR Lower unit
6-5 62Y5A11
Lower unit
No. Part name Q’ty Remarks
1 Lower unit 1
2 Plastic tie 1 Not reusable
3Hose 1
4 Check screw 1
5 Gasket 2 Not reusable
6 Dowel pin 2
7 Bolt 4 M10 40 mm
8 Drain screw 1
9Grommet 1
10 Bolt 1 M10 45 mm
11 Bolt 1 M8 60 mm
12 Thrust washer 1
13 Propeller 1
14 Washer 1
15 Washer 1
16 Cotter pin 1 Not reusable
17 Propeller nut 1
18 Trim tab 1
LOWR Lower unit
6-19 62Y5A11
Removing the drive shaft
1. Remove the drive shaft assembly and
pinion, and then pull out the forward
gear.
Disassembling the drive shaft
1. Install the pinion nut , tighten it finger
tight, and then remove the drive shaft
bearing using a press.
CAUTION:
• Do not press the drive shaft threads
directly.
Do not reuse the bearing, always
replace it with a new one.
Disassembling the forward gear
1. Remove the taper roller bearing from the
forward gear using a press.
CAUTION:
Do not reuse the bearing, always replace
it with a new one.
2. Remove the needle bearing from the for-
ward gear.
CAUTION:
Do not reuse the bearing, always replace
it with a new one.
Drive shaft holder 4 : 90890-06518
Pinion nut holder : 90890-06505
Socket adapter 2 : 90890-06507
Bearing inner race attachment :
90890-06639
S62Y6850K
Bearing separator : 90890-06534
Stopper guide plate : 90890-06501
Stopper guide stand :
90890-06538
Bearing puller : 90890-06535
Bearing puller claw 1 :
90890-06536
S62Y6740K
321
1
2
3
3
2
3
4
5
1
4
5
a
×
×
×
1
2
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6H95G11
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1-2
GEN
INFO
Symbols
The symbols below indicate the content of a chapter.
General information Fuel system Bracket unit
Specifications Power unit Electrical systems
Periodic checks and adjustments Lower unit Troubleshooting
Symbols 1to 6indicate specific data.
1Special tool
2Specified oil or fluid
3Specified engine speed
4Specified tightening torque
5Specified measurement
6Specified electrical value
(resistance, voltage, electric current)
Symbols 7to ein an exploded diagram or illustration indicate the grade of lubricant and the lubri-
cation point.
7Apply Yamaha 2-stroke motor oil
8Apply gear oil
9Apply water resistant grease (Yamaha grease A)
0Apply molybdenum disulfide grease
qApply corrosion resistant grease
(Yamaha grease D)
wApply low temperature resistant grease
(Yamaha grease C)
eApply injector grease
Symbols rto oin an exploded diagram or illustration indicate the type of sealant or locking agent
and the application point.
rApply Gasket Maker
tApply Three bond 1104J
yApply LOCTITE 271 (red)
uApply LOCTITE 242 (blue)
iApply LOCTITE 572
oApply silicon sealant
FUEL BRKT
SPEC POWR ELEC
CHK
ADJ LOWR TRBL
SHTG
123456
C
78 0qwe
rtyuio
How to use this manual
9
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GEN
INFO
1- 6H95G11
General information
1-3
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.
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 ade-
quate ventilation can be maintained.
Self-protection
Protect your eyes by wearing safety glasses
or safety goggles during all operations involv-
ing drilling and grinding, or when using an air
compressor.
Protect your hands and feet by wearing pro-
tective gloves and safety shoes when neces-
sary.
Parts, lubricants, and sealants
Use only genuine Yamaha parts, lubricants,
and sealants or those recommended by
Yamaha, when servicing or repairing the out-
board motor.
Under normal conditions, the lubricants men-
tioned 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 exam-
ple, 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.
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1-4
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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 tight-
ening 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, cot-
ter 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 indicat-
ed in the installation procedure. In addi-
tion, be sure to lubricate the bearings lib-
erally.
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 normal-
ly after assembly.
Safety while working
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GEN
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1- 6H95G11
General information
1-5
Identification
Applicable model
This manual covers the following models.
Serial number
The outboard motor serial number is
stamped on a label attached to the port clamp
bracket.
1Model name
2Approved model code
3Transom height
4Serial number
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.
aPropeller diameter (in inches)
bPropeller pitch (in inches)
cPropeller type (propeller mark)
6F610010
YAMAHA MOTOR CO., LTD.
MADE IN JAPAN
PAYS D'ORIGINE JAPON
1
3
2
4
6B410020
6B410030
×-
abc
6F610030
×−
abc
Applicable models
EK40GMH, EK40JMH, EK40JW
Model name Approved Starting
model code serial No.
EK40G 6F5K 1006117–
EK40J 6H9K 1001748–
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1-6
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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 pro-
vides maximum performance in relation to
boat speed and fuel consumption.
EK40G
EK40J
Predelivery checks
To make the delivery process smooth and
efficient, the predelivery checks should be
completed as explained below.
Checking the fuel system
1. Check that the fuel hose is securely con-
nected and that the fuel tank is filled with
fuel.
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.
Checking the battery (W)
1. Check the capacity, electrolyte level, and
specified gravity of the battery.
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
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
6H910040
6F630195
Propeller selection/Predelivery checks
Recommended battery capacity:
CCA/EN: 347 A
20HR/IEC: 40 Ah
Electrolyte specified gravity:
1.280 at 20°C (68°F)
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GEN
INFO
1- 6H95G11
General information
1-7
2. Check that the positive and negative bat-
tery 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) abelow 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 over-
heat. If the mounting height is too low,
water resistance will increase and reduce
engine efficiency.
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 differ-
ent 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 1is in its
fully closed position, and check the pulley
is contact the fully stopper aon the
bracket.
3. Check that the shift lever 2is in the neu-
tral position.
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 set-
ting the remote control cables.
0—25mm
(0—1in.) 6B410060
a
1
a
6F610060
N
RF
2
6F610070
b
6F610075
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6H95G11 1-8
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Predelivery checks
Checking the steering system
1. Check the steering friction for proper
adjustment.
NOTE:
9To increase the friction, turn the friction
adjusting bolt in direction a.
9To decrease the friction, turn the friction
adjusting bolt in direction b.
2. Check that the steering operates smooth-
ly.
3. Check that there is no interference with
wires or hoses when the outboard motor
is steered.
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 for-
ward or reverse.
2. Check that the throttle operates smooth-
ly 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 smooth-
ly when the remote control lever (remote
control model) is shifted from forward or
reverse to the fully open positions a.
a
b
6F610080
6F610110
a
RN
F
6F610120
F
N
R
a
a
6F610100
6F610090
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GEN
INFO
1-9 6H95G11
General information
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)
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.
Checking the cooling water pilot
hole
1. Check that cooling water is discharged
from the cooling water pilot hole.
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.
6F610130
6F610140
6F610150
6F610170
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6H95G11 1-10
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Break-in
During the test run, perform the break-in
operation in the following 5 stages.
1. 10 minutes aat the lowest possible
speed. A fast idle in neutral is best.
2. 50 minutes bat 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 cat 3/4 throttle (approximately
4,000 r/min). Vary engine speed occa-
sionally. 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 dat any speed, but avoid oper-
ating at full throttle for more than 5 min-
utes at a time. Let the engine cool
between full-throttle runs. Vary engine
speed occasionally.
5. After the first 10hours. Use standard pre-
mix ratio of fuel and oil. Refer to page 1-
6.
åHours
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.
Predelivery checks
6F610180
012 10
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GEN
INFO
1-11 6H95G11
—MEMO —
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6H95G11
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SPEC
Specifications
General specification ................................................................................... 2-1
Maintenance specification .......................................................................... 2-3
Power unit ................................................................................................ 2-3
Lower unit ................................................................................................ 2-5
Electrical .................................................................................................. 2-5
Dimensions .............................................................................................. 2-7
Tightening torques ....................................................................................... 2-9
Specified torques ..................................................................................... 2-9
General torques ..................................................................................... 2-10
6H95G11_02 04.8.19 9:35 Page 1

Item Unit Model
EK40GMH EK40JMH EK40JW
Dimensions
Overall length mm (in) 997 (39.3) 692 (27.2)
Overall width mm (in) 484 (19.1) 363 (14.3)
Overall height
(S) mm (in) 1,215 (47.8) 1,208 (47.6)
(L) mm (in) 1,342 (52.8) 1,335 (52.6) –
Boat transom height
(S) mm (in) 381 (15.0)
(L) mm (in) 508 (20.2) –
Weight
(with aluminum propeller)
(S) kg (lb) 65.0 (143) 70.0 (154)
(L) kg (lb) 68.0 (150) 72.0 (159) –
Performance
Maximum output kW (hp) 29.4 (40) at 5,000 r/min
Full throttle operating range r/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 speed r/min 1,050–1,150
Power unit
Engine type 2-stroke, L
Cylinder quantity 2
Total displacement cm3(cu. in) 669 (40.82)
Bore x stroke mm (in) 78.0 ×70.0 (3.07 ×2.76)
Compression ratio 5.00
Intake system Reed valve
Scavenging system Loop charge
Control system Tiller handle Remote control
Starting system Manual Manual and
electric
Fuel system Carburetor
Ignition control system CDI
Maximum generator output (W) V, A (80) (80) 12, 6
Starting enrichment Choke valve
Spark plug (NGK) B7HS (NGK)
Cooling system Water
Exhaust system Under water Propeller boss
Lubrication system Pre-mixed fuel
SPEC
2-1 6H95G11
Specifications
General specification
6H95G11_02 04.8.19 9:35 Page 2

6H95G11 2-2
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General specification
Item Unit Model
EK40GMH EK40JMH EK40JW
Fuel and oil
Fuel type Regular gasoline and kerosene
Engine oil 2-stroke outboard motor oil
Engine oil grade
NMMA-certified TC-W3
Gear oil type Hypoid gear oil
Gear oil grade (*1) API GL-4
SAE 90
Gear oil quantity cm3(US oz, 315 (10.65, 11.11)
lmp oz)
Bracket unit
Trim angle Degree 8, 12, 16, 20, 24
(at 12° boat transom)
Tilt-up angle Degree 67
Steering angle Degree 45 + 45
Drive unit
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 pin Spline
Propeller direction (rear view) Clockwise
Propeller ID mark H G
Electrical
Battery minimum capacity (*2)
CCA/EN — — 347
20HR/IEC — — 40
(*1) Meeting both API and SAE requirements
(*2) CCA: Cold Cranking Ampere
EN: European Norm (European standard)
IEC: International Electrotechnical Commission
6H95G11_02 04.8.19 9:35 Page 3

SPEC
2-3 6H95G11
Specifications
Maintenance specification
Power unit
Item Unit Model
EK40GMH EK40JMH EK40JW
Power unit
Minimum compression kPa 400 (4.0, 58)
pressure (*1) (kgf/cm2, psi)
Cylinder head
Warpage limit mm (in) 0.1 (0.0039)
(lines indicate straightedge
position)
Cylinders
Bore size mm (in) 78.000–78.020 (3.0709–3.0716)
Wear limit mm (in) 78.100 (3.0700)
Taper limit mm (in) 0.08 (0.0032)
Out-of-round limit mm (in) 0.05 (0.0020)
Pistons
Piston diameter (D) mm (in) 77.940–77.965 (3.0685–3.0695)
Measuring point (H) mm (in) 10.0 (0.39)
Piston-to-cylinder clearance mm (in) 0.055–0.060 (0.0022–0.0024)
(limit) 0.110 (0.0043)
Piston pin boss bore mm (in) 19.904–19.915 (0.7836–0.7841)
Oversize piston
1st mm (in) 0.25 (0.010)
2nd mm (in) 0.50 (0.020)
Oversize piston diameter
1st mm (in) 78.190–78.215 (3.0783–3.0793)
2nd mm (in) 78.440–78.465 (3.0882–3.0892)
Piston pins
Outside diameter mm (in) 19.895–19.900 (0.7833–0.7835)
(*1) Measuring conditions:
Ambient temperature 20°C (68°F), wide open throttle, with spark plugs removed from all cylinders.
The figures are for reference only.
6H95G11_02 04.8.19 9:35 Page 4