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:
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 outboard motor.
NOTE:
A NOTE provides key information to make procedures easier or clearer.
After test run ..............................................................................................1-9
3
4
5
6
7
6D81G11
8
9
GEN
INFO
General information
How to use this manual
Manual format
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 part 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.”
1
40 mm
10 45 mm
60 mm
3
LOWR
Lower unit
No.Part nameQ’tyRemarks
1 Lower unit1
2 Plastic tie1
3Hose1
4 Check screw1
5 Gasket2
6 Dowel pin2
7 Bolt4 M10
8 Drain screw1
9Grommet1
10 Bolt1 M
11 Bolt1 M8
12 Thrust washer1
13 Propeller1
14 Washer1
15 Washer1
16 Cotter pin1
17 Propeller nut1
18 Trim tab1
6-5
Lower unit
Not reusable
Not reusable
Not reusable
4
2
62Y5A11
1
LOWR
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 1, tighten it finger
tight, and then remove the drive shaft
bearing 2 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.
The symbols below are designed to indicate the content of a chapter.
How to use this manual
General information
GEN
INFO
Specifications
SPEC
Periodic checks and adjustments
CHK
ADJ
Symbols 1 to 6 indicate specific data.
123456
Fuel system
FUEL
Power unit
POWR
Lower unit
LOWR
Bracket unit
BRKT
Electrical systems
ELEC
Troubleshooting
–+
TRBL
SHTG
1
2
3
4
Special tool
1
Specified oil or fluid
2
Specified engine speed
3
Specified tightening torque
4
Symbols 7 to C in an exploded diagram indicate the grade of lubricant and the lubrication point.
7890ABC
AM
EG
Apply Yamaha 4-stroke motor oil
7
Apply gear oil
8
Apply water resistant grease (Yamaha grease A)
9
Apply molybdenum disulfide grease
0
Symbols D to H in an exploded diagram indicate the type of sealant or locking agent and the application point.
DEFGH
GM
LT
271
Specified measurement
5
Specified electrical value
6
(resistance, voltage, electric current)
CI
Apply corrosion resistant grease
A
(Yamaha grease D)
Apply low temperature resistant grease
B
(Yamaha grease C)
Apply injector grease
C
LT
242
LT
572
SS
5
6
7
8
9
Apply Gasket Maker
D
Apply LOCTITE 271 (red)
E
Apply LOCTITE 242 (blue)
F
6D81G11
Apply LOCTITE 572
G
Apply silicon sealant
H
1-2
GEN
INFO
General information
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 adequate ventilation can be maintained.
1
Parts, lubricants, and sealants
Use only genuine Yamaha parts, lubricants,
and sealants or those recommended by
Yamaha, when servicing or repairing the outboard motor.
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.
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.
1-3
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.
6D81G11
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
6D81G11
1-4
GEN
INFO
General information
Identification
Applicable model
This manual covers the following model.
Applicable model
F90TR
Serial number
The outboard motor serial number is
stamped on a label attached to the port
clamp bracket.
S6D81010
1
Propeller selection
1
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
propeller boss end, on the side of the propeller boss.
When the engine speed is at the full throttle
operating range (5,000–6,000 r/min), the
ideal propeller for the boat is one that provides maximum performance in relation to
boat speed and fuel consumption.
Propeller size (in)Material
12 5/8 × 21 - K
13 × 19 - K
13 × 23 - K
13 × 25 - K
Aluminum
13 1/4 × 17 - K
13 1/2 × 15 - K
13 5/8 × 13 - K
1
2
3
14 × 11 - K
13 × 17 - K
13 × 19 - K
13 × 21 - K
13 × 23 - K
13 × 25 - K
13 1/2 × 14 - K
13 1/2 × 16 - K
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 hoses are securely
connected and that the fuel tank is full
with fuel.
Stainless
S6D81020
CAUTION:
This is a 4-stroke engine. Never use premixed fuel.
Checking the engine oil level
1.Check the engine oil level.
1
a
4
5
6
b
S60C1150
NOTE:
If the engine oil is below the minimum level
mark b, add sufficient oil until the level is
between a and b.
7
8
6D81G11
Recommended engine oil:
4-stroke motor oil
API: SE, SF, SG, SH, or SJ
SAE: 10W-30 or 10W-40
Engine oil quantity:
Without oil filter replacement:
4.3 L (4.55 US qt, 3.78 Imp qt)
9
1-6
GEN
INFO
General information
Checking the gear oil level
1.Check the gear oil level.
S60C1140
Checking the battery
1.Check the capacity, electrolyte level, and
specified gravity of the battery.
Recommended battery capacity:
CCA/SAE: 380 A
MCA/ABYC: 502 A
RC/SAE: 124 Minute
Electrolyte specified gravity:
1.280 at 20 °C (68 °F)
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 bolts.
Checking the remote control cables
1.Set the remote control lever to the neutral position and fully close the throttle
lever.
2.Check that the stopper 1 on the throttle
cam contacts the fully closed stopper
on the cylinder block.
2
2
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
aligned with the bottom of the boat. 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.
1
S6D81030
3.Check that the alignment mark a on the
bushing is aligned with the alignment
mark b on the bracket.
a
b
S6D81040
1-7
6D81G11
Predelivery checks
N
F
R
c
WARNING
The shift/throttle cable joint must be
screwed in a minimum of 8.0 mm (0.31 in)
.
c
Checking the steering system
1.Check the steering friction for proper
adjustment.
2.Check that the steering operates
smoothly.
S69J3370
a
a
S69J1210
Checking the power trim and tilt
system
1.Check that the outboard motor tilts up
and down smoothly when operating the
power trim and tilt unit.
2.Check that there is no abnormal noise
produced when the outboard motor is
tilted up or down.
3.Check that there is no interference with
wires or hoses when the tilted-up outboard motor is steered.
4.Check that the trim meter points down
when the outboard motor is tilted all the
way down.
1
2
3
4
5
S60C1200
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 remote control lever
is shifted from neutral to forward or
reverse.
2.Check that the throttle operates smoothly
when the remote control lever is shifted
from forward or reverse to the fully open
position a.
Checking the engine start switch and
engine stop lanyard switch
1.Check that the engine starts when the
engine start switch is turned to START.
2.Check that the engine turns off when the
engine start switch is turned to OFF.
S60V1070
6
7
8
9
6D81G11
1-8
GEN
INFO
General information
3.Check that the engine turns off when 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.
Break-in
During the test run, perform the break-in
operation in the following three stages.
1.One hour a at 2,000 r/min or at approximately half throttle
2.One hour b at 3,000 r/min or 3/4 throttle
and 1 minute out of every 10 at full throttle
3.Eight hours c at any speed, however,
avoid running at full speed for more than
5 minutes
È
ab
0
1
210
c
Test run
1.Start the engine, and 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
2,000 r/min or at half throttle, then for
another hour at 3,000 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.
S69J1240
Hour
È
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.
NOTE:
The test run is part of the break-in operation.
1-9
6D81G11
SPEC
Specifications
General specifications...................................................................................2-1
Piston diameter (D)mm (in)78.928–78.949 (3.1074–3.1082)
Measuring point (H)mm (in)13.0 (0.51)
Piston clearancemm (in)0.070–0.080 (0.0028–0.0031)
Over size piston diametermm (in)79.178–79.199 (3.1172–3.1181)
Piston rings
Top ring
Dimension Bmm (in)1.17–1.19 (0.0461–0.0469)
Dimension Tmm (in)2.80–3.00 (0.1102–0.1181)
End gapmm (in)0.15–0.30 (0.0059–0.0118)
Side clearancemm (in)0.04–0.08 (0.0016–0.0031)
2nd piston ring
Dimension Bmm (in)1.47–1.49 (0.0579–0.0587)
Dimension Tmm (in)3.00–3.20 (0.1181–0.1260)
End gapmm (in)0.70–0.90 (0.0276–0.0354)
Side clearancemm (in)0.03–0.07 (0.0012–0.0028)
(*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.
(*2)
The figures are for reference only.
Model
F90TR
860 (8.6, 124.7)
2
2-3
6D81G11
Maintenance specification
ItemUnit
Oil ring
Dimension Bmm (in)2.38–2.48 (0.0937–0.0976)
Dimension T
End gapmm (in)0.20–0.70 (0.0079–0.0276)
Side clearancemm (in)0.03–0.15 (0.0012–0.0059)
Valve lifter outside diametermm (in)27.965–27.980 (1.1010–1.1016)
Valve lifter-to-cylinder head
clearance
Valve shims
Valve shim thickness
(in 0.025 mm increments)
Connecting rods
Big end inside diametermm (in)47.025–47.045 (1.8514–1.8522)
Big end side clearancemm (in)0.14–0.28 (0.0055–0.0110)
Crankpin oil clearancemm (in)0.024–0.044 (0.0009–0.0017)
Big-end bearing thickness
Apron screwM640.43.0
Flywheel magnet nutM2421521.5158.6
Starter motor boltM8292.921.4
Spark plug wire cover screwM640.43.0
Starter relay lead boltM640.43.0
Starter relay holder screwM630.32.2
Main and fuel pump relay screwM630.32.2
Oil pressure switch—80.85.9
Oil pressure switch lead boltM420.21.5
PTT relay lead nutM640.43.0
PTT motor lead boltM640.43.0
Positive battery lead nutM890.96.6
Timing belt tensioner boltM10393.928.8
Drive sprocket nutM4026526.5195.5
Driven sprocket boltM10606.044.3
Gear oil drain screw—90.96.6
Gear oil check screw—90.96.6
Lower case mounting bolt (L-transom model)M10393.928.8
Lower case mounting nut (X-transom model)—393.928.8
Propeller nutM16343.425.1
Ring nut—10310.376.0
Cooling water inlet cover screw—50.53.7
Pinion nutM16939.368.6
Bracket unit
Shift rod detent bolt—181.813.3
Shift position switch screwM410.10.7
Flushing hose adapter screwM620.21.5
Oil pump boltM6101.07.4
Upper mounting nut—515.137.6
Lower mounting nut—515.137.6
Grease nipple—30.32.2
Oil pump cover screwM640.43.0
Oil seal housing screwM640.43.0
Upper mount boltM8282.820.7
Muffler assembly boltM8202.014.8
Engine oil drain boltM14272.720.0
Oil strainer boltM6101.07.4
Oil pan boltM6111.18.1
Exhaust manifold boltM6111.18.1
1st
2nd303.022.1
3rd90°
1st
2nd121.28.9
1st
2nd282.820.7
1st
2nd60°
1st
2nd80°
M8
M10
M6
M8
M10
M8
Tightening torques
N·mkgf·mft·lb
141.410.3
151.511.1
60.64.4
141.410.3
191.914.0
181.813.3
1
2
3
4
5
6
7
8
9
6D81G11
2-12
SPEC
Specifications
Part to be tightenedThread size
Steering arm stud boltM10202.014.8
Self-locking nut—151.511.1
Trim sensor cam screwM620.21.5
Power trim and tilt unit
Reservoir cap—70.75.2
PTT motor boltM640.43.0
Gear pump boltM550.53.7
Gear pump housing boltM550.53.7
Relief valve cap bolt
Lever boltM320.21.5
Manual valve—20.21.5
Gear pump bracket bolt
Trim cylinder end screw—909.066.4
Tilt cylinder end screw—808.059.0
Tilt piston boltM12858.562.7
M440.43.0
M550.53.7
M320.21.5
M540.43.0
Tightening torques
N·mkgf·mft·lb
General torques
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.
Checking the anodes...............................................................................3-14
Checking the battery................................................................................3-14
Lubricating the outboard motor................................................................3-15
6
7
8
9
6D81G11
CHK
ADJ
Periodic checks and adjustments
Special service tools
Digital tachometer
YU-39951-B
Battery powered timing light
YM-33277-A
3
Pressure/vacuum tester
YB-35956-A
Oil filter wrench
YU-38411
3-1
6D81G11
Special service tools / Maintenance interval chart
Maintenance interval chart
Use the following chart as a guideline for general maintenance.
Adjust the maintenance intervals according to the operating conditions of the outboard motor.
InitialEvery
ItemRemarks
Anodes (external)Check/replace3-14
Anodes (internal)Check/replace3-14
BatteryCheck/charge3-14
Cooling water passagesClean3-8
Top cowlingCheck3-3
Fuel filter