Yamaha 50G User manual

6H2-28197-Z9-11
SERVICE
MANUAL
50G, 60F, 70B,
75C, 90A

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NOTICE
This manual has been prepared by the Yamaha Motor Company Ltd. 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 the Yamaha Motor Company Ltd. has a policy of continuously improving its prod-
ucts, models may differ in detail from the descriptions and illustrations given in this publica-
tion. 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.
A10001-0*
50G, 60F, 70B, 75C, 90A
SERVICE MANUAL
 1999 Yamaha Motor Co., Ltd.
1st Edition, February 1999
No part of this publication may be
reproduced or transmitted in any form or by
any means including photocopying and
recording without the written permission of
the copyright holder. Such written
permission must also be obtained before
any part of this publication is stored in a
retrieval system of any nature.

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A50000-0
HOW TO USE THIS MANUAL
MANUAL FORMAT
This manual provides the mechanic with descriptions of the operations of disassembly,
repair, assembly, adjustment and inspection, each of which is presented in a sequential, step-
by-step procedure.
To assist you to find your way about this manual, the Section Title and Major Heading is
given at the head of every page.
An Index to contents is provided on the first page of each section.
MODEL INDICATION
Multiple models are shown in this manual. These indications are noted as follows.
THE ILLUSTRATIONS
Some illustrations in this manual may differ from the model you have. This is because the
procedure described may relate to several models, though only one may be illustrated. (The
name of the model described will be mentioned in the description.)
To help you identify components and understand the correct procedures of disassembly and
assembly, exploded diagrams are provided. Steps in the procedures are numbered thus: 1),
2), 3). Parts shown in the illustrations are identified thus: 1 , 2 , 3 .
REFERENCES
These have been kept to a minimum, however, when you are referred to another section of
the manual, you are told the page number to go to.
Model name 50GETO 60FEHTO 60FED 60FEDO 60FET 60FETO 70BEDO 70BETO
USA and
Canada name — P60TH C60ER — C60TR — — 70TR
Indication 50GETO 60FEHTO 60FED 60FEDO 60FET 60FETO 70BEDO 70BETO
Model name 75CET 75CETO 75CEHTO 80AETO 90AEHD 90AED 90AET 90AETO
USA and
Canada name C75TR 75TR P75TH — — — C90TR 90TR B90TR
Indication 75CET 75CETO 75CEHTO 80AETO 90AEHD 90AED 90AET 90AETO

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SPECIFICATIONS
These are given in bold type at each procedure. It is not necessary to leave the section deal-
ing with the procedure in order to look up the specifications.
It is important to note the differences in specifications of models. Where a procedure relates
to more than one model, the main differences in specifications will be shown in the following
table.
WARNINGS, CAUTIONS AND NOTES
Attention is drawn to the various Warnings, Cautions and Notes which distinguish important
information in this manual in the following ways.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR SAFETY IS
INVOLVED!
WARNING
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.
CAUTION:
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.
Model name 50GETO 60FEHTO 60FED 60FEDO 60FET 60FETO 70BEDO 70BETO
USA and
Canada name — P60TH C60ER — C60TR — — 70TR
Control system Remote
control
Manual
control Remote control
Tilt system Power trim and tilt Manual tilt Power trim and tilt Manual tilt Power trim
and tilt
Lubrication
system Oil injection Pre-mixed Oil injection Pre-mixed Oil injection
Model name 75CET 75CETO 75CEHTO 80AETO 90AEHD 90AED 90AET 90AETO
USA and
Canada name C75TR 75TR P75H — — — C90TR 90TR B90TR
Control system Remote control Manual
control
Remote
control
Manual
control Remote control
Tilt system Power trim and tilt Manual tilt Power trim and tilt
Lubrication
system Pre-mixed Oil injection Pre-mixed Oil injection

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A50001-1-4
SYMBOLS
Symbols 1 to 9 are designed as thumb-
tabs to indicate the content of a chapter.
1 General Information
2 Specifications
3 Periodic Inspection and Adjustment
4 Fuel System
5 Power Unit
6 Lower Unit
7 Bracket Unit
8 Electrical Systems
9 Trouble Analysis
Symbols 0 to F indicates specific data:
0 Special service tool
A Specified liquid
B Specified grease
C Specified engine speed
D Specified torque
E Specified measurement
F Specified electrical value
[Resistance ( Ω ), Voltage (V),
Electric current (A)]
Symbol G to J in an exploded diagram
indicate grade of lubricant and location of
lubrication point:
G Apply engine oil
H Apply gear oil
I Apply molybdenum disulfide oil
J Apply water resistant grease (Yamaha
marine grease A, Yamaha marine grease)
Symbols K to N in an exploded diagram
indicate grade of sealing or locking agent,
and location of application point:
K Apply Gasket Maker

L Apply LOCTITE

No. 271 (Red LOCTITE)
M Apply LOCTITE

No. 242 (Blue LOCTITE)
NApply LOCTITENo. 572
NOTE:
In this manual, the above symbols may not
be used in every case.
12
34
56
78
90
AB
CD
EF
GH
IJ
KL
MN
GEN
INFO SPEC
INSP
ADJ FUEL
POWR
LOWR
BRKT –+
ELEC
TRBL
ANLS
T
R
.
.
EG
MA
GM
271
LT
242
LT
572
LT

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INDEX
GENERAL INFORMATION
1
SPECIFICATIONS
2
SPEC
PERIODIC INSPECTION AND
ADJUSTMENT
3
FUEL SYSTEM
4
FUEL
POWER UNIT
5
POWR
LOWER UNIT
6
LOWR
BRACKET UNIT
7
BRKT
ELECTRICAL SYSTEMS
8
ELEC
TROUBLE ANALYSIS
9
GEN
INFO
INSP
ADJ
–+
TRBL
ANLS
A30000-0

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1
2
3
4
5
6
7
8
9
GEN
INFO
CHAPTER 1
GENERAL INFORMATION
IDENTIFICATION ............................................................................................ 1-1
SERIAL NUMBER..................................................................................... 1-1
STARTING SERIAL NUMBERS ............................................................... 1-1
SAFETY WHILE WORKING ............................................................................ 1-2
FIRE PREVENTION................................................................................... 1-2
VENTILATION........................................................................................... 1-2
SELF-PROTECTION.................................................................................. 1-2
OILS, GREASES AND SEALING FLUIDS................................................ 1-2
GOOD WORKING PRACTICES................................................................ 1-3
DISASSEMBLY AND ASSEMBLY........................................................... 1-4
SPECIAL TOOLS ............................................................................................. 1-5
MEASURING ............................................................................................ 1-6
REMOVAL AND INSTALLATION ............................................................ 1-8

1-1
GEN
INFO
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IDENTIFICATION
A60000-1*
IDENTIFICATION
SERIAL NUMBER
The serial number of the outboard motor is
stamped on a plate attached to the port side
of the clamp bracket.
1 Serial number
NOTE:
For USA model:
As an anti-theft measure, a special label on
which the outboard motor serial number is
stamped is bonded to the port side of the
clamp bracket. The label is specially treated
so that peeling it off causes cracks across
the serial number.
1 Model name
2 Approved model No.
3 Transom height
4 Serial number
STARTING SERIAL NUMBERS
The starting serial number blocks are as fol-
lows:
Model Approved
model No.
Serial
number
Model Approved
model No.
Serial
number
World-
wide USA Canada World-
wide USA Canada
50GETO — — 62F L: 400805 ~ 70BEDO — —
6H3
L: 402029 ~
60FEHTO P60TH P60TH
6H2
L: 551924 ~ 70BETO 70TR 70TR L: 491824 ~
X: 750186 ~ X: 731262 ~
60FED — C60ER S: 001118 ~ 75CET C75TR C75TR
6H0
L: 001251 ~
L: 305624 ~ 75CETO — 75TR L: 951540 ~
60FEDO — — S: 100850 ~ 75CEHTO P75TH — L: 900371 ~
L: 407212 ~ 80AETO — — L: 457543 ~
60FET C60TR C60TR
S: 050474 ~ X: 851331 ~
L: 357665 ~ 90AEHD — —
6H1
L: 320132 ~
X: 710231 ~ 90AED — — L: 401108 ~
60FETO — —
S: 150756 ~ 90AET C90TR C90TR L: 354053 ~
L: 472180 ~ 90AETO 90TR
B90TR 90TR L: 498690 ~
X: 732000 ~ X: 856313 ~

1-2
GEN
INFO
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SAFETY WHILE WORKING
SAFETY WHILE WORKING
The procedures given in this manual are
those recommended by Yamaha to be fol-
lowed by Yamaha dealers and their
mechanics.
FIRE PREVENTION
Gasoline (petrol) is highly flammable.
Petroleum vapor is explosive if ignited.
Do not smoke while handling and keep it
away from heat, sparks, and open flames.
VENTILATION
Petroleum vapor is heavier than air and if
inhaled in large quantities will not support
life. Engine exhaust gases are harmful to
breathe. When test-running an engine
indoors, maintain good ventilation.
SELF-PROTECTION
Protect your eyes with suitable safety
glasses or safety goggles when using com-
pressed air, when grinding or when doing
any operation which may cause particles to
fly off.
Protect hands and feet by wearing safety
gloves or protective shoes if appropriate to
the work you are doing.
OILS, GREASES AND SEALING
FLUIDS
Use only genuine Yamaha oils, grease and
sealing fluids or those recommended by
Yamaha.

1-3
GEN
INFO
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SAFETY WHILE WORKING
Under normal conditions of use, there
should be no hazards from the use of the
lubricants mentioned in this manual. How-
ever, safety is all-important and by adopt-
ing good safety practices, any risk is
minimized.
A summary of the most important precau-
tions is as follows:
1. While working, maintain good stan-
dards of personal and industrial
hygiene.
2. Clothing which has become contami-
nated with lubricants should be
changed as soon as practicable, and
laundered before further use.
3. Avoid skin contact with lubricants; do
not, for example, place a soiled wiping-
rag in one’s pocket.
4. Hands, and any other part of the body
which have been in contact with lubri-
cants or lubricant-contaminated cloth-
ing, should be thoroughly washed with
hot water and soap as soon as practica-
ble.
5. To protect the skin, the application of a
suitable barrier cream to the hands
before working is recommended.
6. A supply of clean, lint-free cloths should
be available for wiping purposes.
GOOD WORKING PRACTICES
1. The right tools
Use the special tools that are advised to
protect parts from damage. Use the
right tool in the right manner - don’t
improvise.
2. Tightening torque
Follow the torque tightening instruc-
tions. When tightening bolts, nuts and
screws, tighten the larger sizes first, and
tighten inner-positioned fixings before
outer-positioned ones.

1-4
GEN
INFO
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SAFETY WHILE WORKING
3. Non-reusable items
When reassembling, always use new
gaskets, packing, O-rings, oil seals,
split-pins and circlips, etc.
DISASSEMBLY AND ASSEMBLY
1. Clean parts with compressed-air when
disassembling them.
2. Oil the contact surfaces of moving parts
before assembly.
3. After assembly, check that moving parts
operate normally.
4. Install bearings with the manufacturer’s
markings on the side exposed to view
and liberally oil the bearings.
5. When installing oil seals, apply a light
coating of water-resistant grease to the
outside circumference.

1-5
GEN
INFO
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SPECIAL TOOLS
A80000-0*
SPECIAL TOOLS
The use of correct special tools recommended by Yamaha will aid the work and enable accu-
rate assembly and tune-up. Improvisations and use of improper tools can cause damage to
the equipment.
NOTE:
●
For USA and Canada, use part numbers starting with “YB-”, “YM-”, “YU-” or “YW-”.
●
For others, use part numbers starting with “90890-”.

1-6
GEN
INFO
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SPECIAL TOOLS
MEASURING
Tool name
Tool No.
Use for:
USA and
Canada a
Except for
USA and
Canada b
1 Tachometer YU-08036-A 90890-06760 Idle speed
2 Dynamic spark tester YM-34487 90890-06754 Ignition system
3 CDI tester YU-91022-B N.A. Ignition system
4 Mity Vac YB-35956 90890-06756 Fuel joint
5 Pressure tester YB-35956 90890-06762 Lower case
6 Dial gauge YU-03097 90890-01252 Backlash
7 Backlash indicator YB-06265 90890-06706 Backlash
8 Magnet base YU-34481 90890-06705 Backlash
9 Backlash adjusting plate YB-07003 N.A. Backlash
10 Thickness gauge YU-26900-8 N.A. Shimming
11 Pinion height gauge N.A. 90890-06702 Pinion shimming
12 Digital caliper N.A. 90890-06704 Pinion
shimming
Forward
shimming
13 Gauge block YB-34432-9 N.A. Pinion shimming
14 Adapter plate YB-34432-10 N.A. Pinion shimming
15 Gauge base YB-34432-11 N.A. Pinion shimming
16 Clamp YB-34432-17 N.A. Pinion shimming
17 Shimming plate N.A. 90890-06701 Forward shimming
18 Base plate YB-34446-1 N.A. Forward shimming
19 Compression spring YB-34446-3 N.A. Forward shimming
20 Press plate YB-34446-5 N.A. Forward shimming
21 Gauge pin YB-34446-7 N.A. Forward shimming
22 Digital multimeter YU-34899-A 90890-06752 Electrical
23 Pocket tester YU-03112 90890-03112 Electrical
24 Pressure gauge YB-06181 N.A. PTT unit
25 Shimming gauge YB-34468-3
YB-34468-5 N.A. Reverse shimming
26 3 pins test harness YB-06443 90890-06757 Peak voltage measurement

1-7
GEN
INFO
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SPECIAL TOOLS

1-8
GEN
INFO
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SPECIAL TOOLS
REMOVAL AND INSTALLATION
Tool name
Tool No.
Use for:
USA and
Canada a
Except for
USA and
Canada b
1 Small end bearing installer YB-06107
YB-06287 90890-06527 Connecting rod
2 Piston slider YU-33294 90890-06530 Cylinder piston
3 Slide hammer set YB-06096 N.A.
Water pump housing oil seal
Reverse gear bearing
Propeller shaft housing oil seal
Drive shaft outer bearing
Forward gear outer bearing
4 Stopper guide plate N.A. 90890-06501
Water pump housing oil seal
Bearing housing
Reverse gear bearing
Propeller shaft housing oil seal
Drive shaft outer bearing
5 Bearing puller N.A. 90890-06535
Water pump housing oil seal
Reverse gear bearing
Propeller shaft housing oil seal
Drive shaft outer bearing
6 Stopper guide stand N.A. 90890-06538
Water pump housing oil seal
Reverse gear bearing
Propeller shaft housing oil seal
Drive shaft outer bearing
7 Ring nut wrench YB-06048
YB-34447
90890-06510
90890-06511 Ring nut
8 Extension N.A. 90890-06513 Ring nut
9 Claw YB-06207 90890-06502
90890-06503 Propeller shaft housing
10 Universal puller YB-06117 N.A. Propeller shaft housing
11 Center bolt N.A. 90890-06504 Propeller shaft housing
12 Drive rod YB-06071 90890-06602 Propeller shaft housing oil seal
Drive shaft needle bearing
13 Needle bearing attachment YB-06153 90890-06612 Propeller shaft housing bearing
14 Drive shaft holder YB-06049
YB-06151
90890-06518
90890-06519 Pinion nut
15 Pinion nut holder N.A. 90890-06505 Pinion nut
16 Bearing outer race puller N.A. 90890-06523 Forward gear outer bearing
17 Needle bearing attachment YB-06155 90890-06611 Drive shaft needle bearing
18 Bearing separator YB-06219 90890-06534
Crank shaft bearing
Reverse gear bearing
Forward gear bearing
19 Drive rod YB-06071 90890-06604 Propeller shaft needle bearing
20 Needle bearing attachment YB-06153 90890-06612
90890-06614 Propeller shaft needle bearing

1-9
GEN
INFO
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SPECIAL TOOLS

1-10
GEN
INFO
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SPECIAL TOOLS
Tool name
Tool No.
Use for:
USA and
Canada a
Except for
USA and
Canada b
21 Bearing depth plate N.A. 90890-06603 Propeller shaft needle bearing
Drive shaft needle bearing
22 Oil seal attachment YB-06269 N.A. Propeller shaft oil seal
23 Needle bearing depth stop YB-34473 N.A. Drive shaft needle bearing
24 Driver rod YB-06071 90890-06606 Drive shaft outer bearing
25 Bearing outer race attach-
ment YB-06156 90890-06626 90890-06627 Drive shaft outer bearing
26 Driver rod YB-06071 90890-06605 Forward gear outer bearing
27 Bearing outer race attach-
ment YB-06276-B 90890-06621 90890-06622 Forward gear outer bearing
28 Bearing inner race attach-
ment N.A. 90890-06640 90890-06662 Forward gear inner bearing
29 Shift rod wrench YB-06052 N.A. Shift rod
30 Cylinder end screw wrench YB-06175-1A N.A. PTT
31 Cylinder end screw wrench YB-06175-2B 90890-06544
90890-06548 PTT
32 Flywheel holder YB-06139 90890-06522 Flywheel
33 Flywheel puller YB-06117 90890-06521 Flywheel