Yamaha EK25BMH Service manual

EK25BMH

SSSSEEEERRRRVVVVIIIICCCCE E E E MMMMAAAANNNNUUUUAAAALLLL

290404

69T-28197-ZA-11

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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.

EK25BMH

SERVICE MANUAL

©2000 Yamaha Motor Co., Ltd.

1st Edition, October 2000

All rights reserved. Any reprinting or unauthorized use without the written permission of Yamaha Motor Co., Ltd. is expressly prohibited.

Printed in Japan

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HOW TO USE THIS MANUAL

MANUAL FORMAT

All of the procedures in this manual are organised in a sequential, step-by-step format. The information has been compiled to provide the mechanic with an easy to read, handy reference that contains comprehensive explanations of all disassembly, repair, assembly, and inspection operations.

In this revised format, the condition of a faulty component will precede an arrow symbol and the course of action required will follow the symbol, e.g.,

• Bearings

Pitting/scratches

→

Replace.

To assist you in finding your way through this manual, the section title and major heading is given at the top of every page.

MODEL INDICATION

Multiple models are referred to in this manual and their model indications are noted as follows.

Model name

Indication

EK25BMH

EK25BMH

ILLUSTRATIONS

The illustrations within this service manual represent all of the designated models.

CROSS REFERENCES

The cross references have been kept to a minimum. Cross references will direct you to the appropriate section or chapter.

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IMPORTANT INFORMATION

In this Service Manual particularly important information is distinguished 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 outboard motor.

NOTE:

A NOTE provides key information to make procedures easier or clearer.

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HOW TO USE THIS MANUAL

1

The main points regarding removing/installing and disassembling/assembling procedures are shown in the exploded views.

2

The numbers in the exploded views indicate the required sequence of the procedure and should be observed accordingly.

3

Symbols are used in the exploded views to indicate important aspects of the procedure.

A list of meanings for these symbols is provided on the following page.

4 It is important to refer to the job instruction charts at the same time as the exploded views.

These charts list the sequence that the procedures should be carried out in, as well as providing explanations on part names, quantities, dimensions and important points relating to each relevant task.

5 In addition to tightening torques, the dimensions of the bolts and screws are also mentioned.

Example:

Bolt and screw size 10

×

25 mm : bolt and screw diameter (D)

× lenght (L)

6 In addition to the exploded views and job instruction charts, this manual provides individual illustrations when further explanations are required to explain the relevant procedure.

1

2

3

5

4

2

6

13

15

.

T

R

.

17

A

19

21

23

25

LT

271

LT

572

D

GM

5

1

GEN

INFO

3

CHK

ADJ

POWR

7

BRKT

9

TRBL

ANLS

11

16

20

22

24

18

E

C

M

4

LT

242

26

2

SPEC

4

FUEL

6

LOWR

8

ELEC

– +

10

12

14

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SYMBOLS

Symbols

1 to

9 are designed as thumbtabs to indicate the content of a chapter.

1

General information

2 Specifications

3 Periodic check and adjustments

4

Fuel system

5

Power unit

6 Lower unit

7 Bracket unit

8

Electrical systems

9

Trouble analysis

Symbols

10 to

15 indicate specific data.

10 Special tool

11 Specified liquid

12

Specified engine speed

13

Specified torque

14 Specified measurement

15 Specified electrical value

[Resistance (

Ω

), Voltage (V), Electric current

(A)]

Symbol

16 to

20 in an exploded diagram indicate the grade of lubricant and the location of the lubrication point.

16

Apply Yamaha 2-stroke motor oil

17

Apply water resistant grease

(Yamaha grease A, Yamaha marine grease)

18 Apply water resistant grease

(Yamaha grease C, Yamaha marine grease)

19 Apply water resistant grease

(Yamaha grease D, Yamaha marine grease)

20

Apply molybdenum disulfide grease

Symbols

21 to

26 in an exploded diagram indicate the grade of the sealing or locking agent and the location of the application point.

21 Apply Gasket Maker

®

22

Apply Yamabond #4

(Yamaha bond number 4)

23

Apply LOCTITE

®

No.271 (Red LOCTITE)

24 Apply LOCTITE

®

No.242 (Blue LOCTITE)

25 Apply LOCTITE

®

No.572

26

Apply silicon sealant

CONTENTS

GENERAL INFORMATION

SPECIFICATIONS

PERIODIC CHECK AND

ADJUSTMENT

FUEL SYSTEM

RECOIL STARTER

LOWER UNIT

BRACKET UNIT

ELECTRICAL SYSTEM

TROUBLE ANALYSIS

E

POWR

5

LOWR

6

BRKT

7

– +

ELEC

8

TRBL

ANLS

9

GEN

INFO

1

SPEC

2

CHK

ADJ

3

FUEL

4

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 ........................................................................................... 1-5

REMOVING AND INSTALLING ............................................................... 1-7

FEATURES AND BENEFITS ........................................................................... 1-9

POWER UNIT ........................................................................................... 1-9

IGNITION SYSTEM ............................................................................... 1-10

COOLING SYSTEM ................................................................................1-11

TILLER HANDLE .................................................................................... 1-13

BRACKET AND BOTTOM COWLING ................................................... 1-14

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3

4

5

1

2

8

9

6

7

GEN

INFO

IDENTIFICATION

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1

IDENTIFICATION

SERIAL NUMBER

The outboard motor ’s serial number is stamped on a label which is attached to the port clamp bracket.

NOTE:

As an antitheft measure, a special label on which the outboard motor’s serial number is stamped is bonded to the port clamp bracket. The label is specially treated so that peeling it off causes cracks across the serial number.

1

2

3

4

Model name

Approval model code

Transom height

Serial number

STARTING SERIAL NUMBERS

The starting serial number blocks are as follows:

Model name

Worldwide

EK25BMH

Approval model code

62C

Starting serial number

S:100101

L:400101

Y:750101

1-1

GEN

INFO

SAFETY WHILE WORKING

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The procedures given in this manual are those recommended by Yamaha to be foll o w e d b y Ya m a h a d e a l e r s a n d t h e i r mechanics.

FIRE PREVENTION

Gasoline (petrol) is highly flammable.

Petroleum vapor is explosive if ignited.

Do not smoke while handling gasoline and keep it away from heat, sparks and open flames.

VENTILATION

Petroleum vapor is heavier than air and is deadly if inhaled in large quantities. Engine exhaust gases are harmful to breathe.

When test-running an engine indoor s, maintain good ventilation.

SELF-PROTECTION

Protect your eyes with suitable safety glasses or safety goggles, 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, greases and sealing fluids or those recommended by

Yamaha.

1-2

GEN

INFO


E

Under normal conditions or use, there should be no hazards from the use of the lubricants mentioned in this manual, but safety is all-important, and by adopting good safety practices, any risk is minimized.

A summary of the most important precautions is as follows:

1. While working, maintain good stand a r d s o f p e r s o n a l a n d i n d u s t r i a l hygiene.

2. Clothing which has become contamin a t e d w i t h l u b r i c a n t s s h o u l d b e changed as soon as practicable, and laundered before further use.

3. Avoid skin contact with lubricants; do not, for example, place a soiled wipingrag in your pocket.

4. Hands and any other part of the body which have been in contact with lubricants or lubricant-contaminated clothing, should be thoroughly washed with hot water and soap as soon as practicable.

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 recommended special tools to protect parts from damage. Use the right tool in the right manner - do not improvise.

2. Tightening torque

Follow the tightening torque instructions. When tightening bolts, nuts and screws, tighten the large sizes first, and tighten inner-positioned fixings before outer-positioned ones.

1-3

GEN

INFO


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3. Non-reusable items

Always use new gaskets, packings, Orings, split-pins, circlips, etc., on reassembly.

DISASSEMBLY AND ASSEMBLY

1. Clean parts with compressed air when disassembling.

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 diameter.

1-4

1

3

5

7

9

11

2

4

6

8

10

12

GEN

INFO

SPECIAL TOOLS

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SPECIAL TOOLS

Using the correct special tools recommended by Yamaha, will aid the work and enable accurate assembly and tune-up.

Improvising and using improper tools can damage the equipment.

MEASURING

1

2

3

4

5

6

7

8

9

10

11

12

Dial gauge set

P/N. 90890-01252

Crank stand alignment

P/N. 90890-03107

Pocket tester

P/N. 90890-03112

Timing light

P/N. 90890-03141

Compression Gauge

P/N. 90890-03160

Peak voltage adaptor

P/N. 90890-03172

Digital circuit tester

P/N. 90890-03174

Ignition tester

P/N. 90890-06754

Vacuum/pressure pump gauge set

P/N. 90890-06756

Digital tachometer

P/N. 90890-06760

Leakage tester

P/N. 90890-06762

Digital caliper

P/N. 90890-06704

1-5

13

GEN

INFO

15

17

19

SPECIAL TOOLS

14

16

18

20

13

14

15

16

17

18

19

20

21

Cylinder gauge

P/N. 90890-06759

Outside micrometer

P/N. 90890-03006

P/N. 90890-03008

Inside micrometer

P/N. 90890-03010

Thickness gauge

P/N. 90890-03079

Shimming plate

P/N. 90890-06701

Pinion height gauge

P/N. 90890-06702

Magnet base

P/N. 90890-06705

Backlash indicator

P/N. 90890-06706

Magnet base plate

P/N. 90890-07003

21

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1-6

9

11

13

3

5

7

15

17

19

1

GEN

INFO

SPECIAL TOOLS

2

4

6

8

10

12

14

16

18

20

REMOVING AND INSTALLING

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Flywheel puller

P/N. 90890-06521

Flywheel holder

P/N. 90890-06522

Small end bearing installer

P/N. 90890-06527

Bearing separator

P/N. 90890-06534

Stopper guide plate

P/N. 90890-06501

Bearing housing puller claw

P/N. 90890-06564

Center bolt

P/N. 90890-06504

Drive shaft holder 3

P/N. 90890-06517

Bearing puller ass’y

P/N. 90890-06535

Stopper guide stand

P/N. 90890-06538

Driver rod LL

P/N. 90890-06605

Driver rod LS

P/N. 90890-06606

Driver rod L3

P/N. 90890-06652

Driver rod SL

P/N. 90890-06602

Driver rod SS

P/N. 90890-06604

Bearing depth plate

P/N. 90890-06603

Needle bearing attachment

P/N. 90890-06608

P/N. 90890-06611

P/N. 90890-06615

Ball bearing attachment

P/N. 90890-06633

Bearing inner race attachment

P/N. 90890-06643

P/N. 90890-06644

P/N. 90890-06645

Bearing outer race attachment

P/N. 90890-06622

P/N. 90890-06628

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1-7

21

GEN

INFO

23

25

27

29

31

33

35

SPECIAL TOOLS

22

24

26

28

30

32

34

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

Crank jig ass’y

P/N. 90890-02421

Frange

P/N. 90890-02351

Body

P/N. 90890-02352

Bolt

P/N. 90890-02353

Washer

P/N. 90890-02354

Bushing-5 (D25)

P/N. 90890-02359

Bushing-12 (D35)

P/N. 90890-02366

Height ring-13 (H57)

P/N. 90890-02379

Pressure Plate

P/N. 90890-02384

Press body

P/N. 90890-02385

Plate A

P/N. 90890-02386

Plate B

P/N. 90890-02387

Pressure pin B

P/N. 90890-02390

Bearing pressure B

P/N. 90890-02392

Bearing pressure C

P/N. 90890-02393

Support

P/N. 90890-02394

Spacer B

P/N. 90890-02396

Bushing-14

P/N. 90890-02419

36

37

1-8

E

GEN

INFO

FEATURES AND BENEFITS


POWER UNIT

E

The EK25B is designed to provide superior fuel economy, serviceability, and durability.

They are based on the previous EK25A with newly designed linkage to control both throttle opening and ignition timing mechanically and simultaneously.

Special attention was paid on the crankshaft bearings. Collar is now added to the upper main journal of the crankshaft. Roller bearing is applied for the center bearing.

The collar added on the upper main journal contributes to get and better serviceability.

Fig. 1

Fig. 2

1-9

GEN

INFO

IGNITION SYSTEM


E

Ignition system on the EK25B consists of flywheel magnet, charge coil, pulser coil, CDI unit, and ignition coil.

Similar to the previous EK25A, the engine has the mechanical ignition timing advance system that works by way of the linkage.

Superior fuel economy is attained by the modified ignition timing control arrangement.

Also the system restricts the ignition timing advance to prevent engine kickback when the shift is in neutral.

Fig. 3

1-10

GEN

INFO

COOLING SYSTEM


E

New structure applied to the cooling system provides additional cooling capacity in the upper casing.

With additional cooling water passage (indicated by ), water walls contained in the new upper casing contribute to the reduction of outer surface temperature.

Fig. 4

1-11

GEN

INFO

COOLING SYSTEM


E

Fig. 5

1-12

GEN

INFO

TILLER HANDLE


E

For the throttle grip on the steering handle of the EK25B, 100 degrees of opening angle covers all ranges from full-closed to wide-open positions.

Also, new steering handle parts were developed to assume the long use. Inner diameter of the steering handle engagement area, and both inner and outer diameters of steering bracket are increased.

Please note that if the new steering handle is installed on the previous models, Steering handle 2, Steering bracket, Collar, and Washer must be replaced.

Fig. 6

Fig. 7

1-13

GEN

INFO


BRACKET AND BOTTOM COWLING

E

The Bracket 1 is modified on the EK25B, and newly designed rubber seal is added to provide better sealing ability for the bottom cowling.

Fig. 8

1-14

SPEC

CHAPTER 2

SPECIFICATIONS

GENERAL SPECIFICATIONS ......................................................................... 2-1

MAINTENANCE SPECIFICATIONS ............................................................... 2-3

POWER UNIT ........................................................................................... 2-3

LOWER UNIT ........................................................................................... 2-5

ELECTRICAL ............................................................................................ 2-6

DIMENSIONS .......................................................................................... 2-8

DIMENSIONS .......................................................................................... 2-9

TIGHTENING TORQUES ............................................................................. 2-11

SPECIFIED TORQUES ........................................................................... 2-11

GENERAL TORQUES ............................................................................ 2-12

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3

4

5

1

2

8

9

6

7

SPEC

GENERAL SPECIFICATIONS

2


Item Unit

Worldwide

DIMENSIONS

Overall length

Overall width

Overall height

(S)

(L)

(Y) mm (in) mm (in) mm (in) mm (in) mm (in)

Boat transom height

(S)

(L)

(Y)

WEIGHT

(S)

(L)

(Y) mm (in) mm (in) mm (in)

PERFORMANCE

Maximum output (ISO)

Full throttle operating range kW (hp)

@5,000 r/min r/min

Maximum fuel consumption L (US gal,

Imp gal)

@5,500 r/min

POWER UNIT

Type

Number of cylinders

Displacement

Bore and stroke

Compression ratio

Compression pressure

<Minimum> cm kg (lb) kg (lb) kg (lb)

3

(cu. in) mm (in) kPa

(kgf/cm

2

, psi) kPa

(kgf/cm

2

, psi) kPa

(kgf/cm

2

, psi)

Spark plug(NGK)

Number of carburetor

Enrichment system

Intake system

Induction system

Exhaust system

2-1

Model

EK25BMH

843 (33.2)

399 (15.7)

1,146 (45.1)

1,273 (50.1)

1,320 (52.0)

381 (15.0)

508 (20.0)

559 (22.0)

53.0 (116.9)

54.5 (120.2)

55.0 (121.3)

18.4 (25.0)

4,500 - 5,500

13.8 (3.6, 3.0)

Gasoline / Kerosene

2 stroke

2

496 (30.3)

72.0

×

61.0 (2.83

×

2.40)

#1: 5.3 (0.05, 0.8), #2: 5.7 (0.06, 0.8)

#1: 680 (6.8, 98.6), #2: 730 (7.3, 105.9)

#1: 540 (5.4, 78.3), #2: 580 (5.8, 84.1)

B7HS-10

1

Chock valve

Reed valve

Loop charge

Through propeller boss

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SPEC


Item

Worldwide

Lubrication system

Cooling system

Ignition control system

Alternator output

POWER UNIT

Starting system

Control system

Advanced system

CARBURETOR

ID mark

FUEL AND OIL

Fuel type

(Main)

Mixing ratio

(Sub)

Mixing ratio

Engine oil type

Engine oil grade

Gear oil

Gear oil grade

Gear oil capacity

Unit

V - W cm

3

(US oz,

Imp oz)

BRACKET

Tilt angle

Tilt-up angle

Shallow water angle from transom

Steering angle

DRIVE UNIT

Gear shift positions

Gear ratio

Gear type

Propeller direction

(rear view)

Propeller drive system

Propeller mark

Degree

Degree

Degree

Degree

Manual

Mechanical

Mechanical

69T00

Kerosene

30 : 1

Unleaded regular gasoline

50 : 1

2 stroke outboard engine oil

TC - W3

Hypoid gear oil

SAE #90 (API GL - 4)

320 (10.8, 11.3)

4, 8, 12, 16, 20

76

Tilt angle + 20

40 + 40

F - N - R

2.08 (27/13)

Spiral bevel

Clockwise

Spline

F

E

Model

EK25BMH

Mixed (Gasoline and oil, Kerosene and oil)

Water

CDI

12 - 80

2-2

SPEC

MAINTENANCE SPECIFICATIONS


POWER UNIT

Item

Worldwide

Unit

Model

EK25BMH

CYLINDER HEAD

Warpage limit mm (in) 0.1 (0.004)

E

(lines indicate straightedge position)

CYLINDERS

Bore size

Wear limit

Taper limit

Out-of-round limit

PISTON

Piston side "D"

Measuring point "H" mm (in) mm (in) mm (in) mm (in) mm (in) mm (in)

72.00 - 72.02 (2.8346 - 2.8354)

72.10 (2.8386)

0.08 (0.0031)

0.05 (0.0020)

71.94 - 71.96 (2.8323 - 2.8331)

10.0 (0.3937)

Piston-cylinder clearance

<Limit>

Oversize piston diameter

1st

2nd

Pin boss inside diameter

PISTON PINS

Outside diameter

PISTON RING (1st)

Type

(B)

(T)

End gap

(installed)

<Limit>

Side clearance

<Limit> mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in)

2-3

0.060 - 0.065 (0.0024 - 0.0026)

0.1 (0.0039)

72.25 (2.8445)

72.50 (2.8543)

19.904 - 19.915 (0.7836 - 0.7841)

19.895 - 19.900 (0.7833 - 0.7835)

Keystone

2.0 (0.079)

3.0 (0.118)

0.20 - 0.35 (0.008 - 0.014)

0.35 (0.014)

0.03 - 0.05 (0.0012 - 0.0020)

0.05 (0.0020)

SPEC


Item

Worldwide

PISTON RING (2nd)

Type

(B)

(T)

End gap

(installed)

<Limit>

Side clearance

<Limit>

CRANKSHAFT

Crank width (A)

(B)

(C)

Unit mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in)

Model

EK25BMH

Plain

2.0 (0.079)

3.0 (0.118)

0.20 - 0.35 (0.0079 - 0.0137)

0.35 (0.014)

0.03 - 0.07 (0.0012 - 0.0028)

0.07 (0.0028)

56.90 - 56.95 (2.2401 - 2.2421)

153.7 - 154.0 (6.0512 - 6.0630)

39.9 - 40.1 (1.5709 - 1.5787)

E

Runout limit (D)

Side clearance (E)

Maximum axial play (F)

CONNECTING ROD

Small end diameter

CARBURETOR

Main jet

Main air jet

Main nozzle

Pilot jet

Pilot air jet

Pilot screw

(M.J.)

(M.A.J.)

(M.N.)

(P.J.)

(P.A.J.)

(P.S.)

Valve seat size (V.S.)

Float height mm (in) mm (in) mm (in) mm (in)

#

φ mm (in)

φ mm (in)

# mm (in) turns out mm (in) mm (in)

0.03 (0.0012)

0.2 - 0.7 (0.0079 - 0.0276)

2.0 (0.079)

23.904 - 23.917 (0.941 - 0.942)

Kerosene carburetor Gasoline carburetor

155

1.3 (0.051)

2.8 (0.110)

50

0.92 (0.036)

1/2 + 2

1/2 - 1/2

1.4 (0.055)

18 (0.079)

—

—

—

48

0.90 (0.035)

1 - 1/2 ± 1/2

1.2 (0.047)

—

Float arm height

Idle speed mm (in) r/min

2-4

—

1,300 ± 50

3 (0.118)

SPEC


Item

Worldwide

REED VALVES

Thickness

Valve stopper height

(Standard)

(for Sri Lanka)

Valve bending limit

THERMOSTAT

Valve opening

temperature

Full-open temperature

Minimum valve lift

LOWER UNIT

Unit mm (in) mm (in) mm (in)

°C (°F)

°C (°F) mm (in)

Model

EK25BMH

0.2 (0.008)

3.46 - 3.50 (0.136 - 0.138)

4.20 - 4.60 (0.165 - 0.181)

0.2 (0.008)

48 - 52 (118 - 126)

60 (140)

3 (0.12)

Unit

Model

EK25BMH

Item

Worldwide

GEAR BACKLASH

Pinion - forward gear

Pinion - reverse gear

Pinion gear shims

Forward gear shims

Reverse gear shims

PROPELLER

Material

No. of blades

×

diameter

× pitch

Test propeller mm (in) mm (in) mm mm mm in

P/N.

0.31 - 0.72 (0.012 - 0.028)

0.93 - 1.65 (0.037 - 0.065)

0.7 / 1.0 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6

1.0 / 1.1 / 1.2 / 1.3 / 1.4

1.0 / 1.1 / 1.2 / 1.3

Aluminium

3

×

9 - 7/8

×

11 - 1/4

3

×

9 - 7/8

×

8

3

×

9 - 7/8

×

9

3

×

9 - 7/8

×

10 - 1/2

3

×

9 - 7/8

×

12

3

×

9 - 7/8

×

13

3

×

9 - 7/8

×

14

90890-01629

E r/min 5,250 - 5,450

2-5

SPEC


ELECTRICAL

Item Unit

Worldwide

IGNITION SYSTEM

Ignition timing

(Full retard)

(Full advanced)

Spark plug gap

Ignition spark gap

(Minimum)

Degree

Degree mm (in) mm (in)

Ignition coil resistance

(Primary)

(Secondary)

Charge coil resistance

(Br - L)

Charge coil output peak voltage (Br - L)

@ cranking 1

*1

@ cranking 2

*1

@ 1,500 r/min k

Ω

Ω

Ω

*1

@ 3,500 r/min

Pulser coil resistance

(W/R - B , W/B - B)

Pulser coil output peak voltage (W/R - B , W/B - B)

@ cranking 1

*1

@ cranking 2

*1

@ 1,500 r/min

@ 3,500 r/min

CDI unit resistance

CDI unit output peak voltage

(B/O - B , B/W - B)

@ cranking 1

*1

@ cranking 2

*1

@ 1,500 r/min

@ 3,500 r/min

V

V

V

V

Ω

V

V

V

V

Ω

V

V

V

V

Cranking 1: Open circuit.

Cranking 2: Related parts are connected.

Model

EK25BMH

ATDC 2 ± 2

BTDC 22 ± 2

0.9 - 1.0 (0.035 - 0.039)

8.0 (0.31)

0.18 - 0.24

2.70 - 3.70

342 - 418

146

146

150

150

311 - 381

6.8

6.7

16.0

26.0

Refer to the "CDI UNIT" on page 8-10

5.5

130.0

135.0

135.0

E

2-6

SPEC


Item Unit

Worldwide

CHARGING SYSTEM

Lighting coil resistance

(G - G)

Lighting coil output peak voltage (G - G)

@ cranking 1

*1

@ cranking 2

*1

@ 1,500 r/min

@ 3,500 r/min

@ 1,500 r/min

(Open circuit)

@ 3,500 r/min

(Open circuit)

*1

Ω

V

V

V

V

V

V

Cranking 1: Open circuit.

Cranking 2: Related parts are connected.

Model

EK25BMH

0.31 - 0.37

4.6

—

—

—

14.7

30.0

E

2-7

SPEC

DIMENSIONS


E

2-8

SPEC


W2

W3

W4

W5

W6

A1

A2

C1

C2

H7

H8

H9

H10

W1

DIMENSIONS

L1

L2

L3

L4

L5

Symbol

L6

L7

L8

L10

H1

H2

H3

H4

H5

H6

Worldwide

(S)

(L)

(Y)

(S)

(L)

(Y)

(S)

(L)

(Y)

(S)

(L)

(Y)

(S)

(L)

(Y)

Unit mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in)

Degree

Degree mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in)

Model

EK25BMH

597 (23.50)

466 (18.35)

621 (24.45)

701 (27.60)

730 (28.74)

118 (4.65)

30 (1.18)

596 (23.46)

40.3 (1.59)

166 (6.54)

233 (9.17)

148 (5.83)

192 (7.56)

302 (11.89)

472 (18.58)

40

68

35 (1.38)

65 (2.56)

429 (16.89)

180 (7.09)

420 (16.54)

385 (15.16)

61 (2.40)

83 (3.27)

83 (3.27)

736 (28.98)

854 (33.62)

897 (35.31)

405 (15.94)

195 (7.68)

74.2 (2.92)

707 (27.83)

834 (32.83)

881 (34.68)

439 (17.28)

144 (5.67)

423 (16.65)

550 (21.65)

2-9

E

SPEC


E

Symbol

B1

B2

B3

B4

B5

B6

B11

B12

D1

Worldwide

Unit mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in) mm (in)

φ mm (in)

2-10

Model

EK25BMH

89 (3.50)

140 (5.51)

112.5 (4.43)

96.5 (3.80)

122.5 (4.82)

176 (6.93)

85 (3.35)

51 (2.01)

8.5 (0.33)

SPEC

TIGHTENING TORQUES


SPECIFIED TORQUES

Part to be tightened

Part name

POWER UNIT

Recoil starter mounting

Recoil starter center boit

Recoil starter center Nut

Flywheel magnet

Power unit mounting

Intake manifold mounting

1st

2nd

1st

2nd

Spark plug

Cylinder head mounting

Exhaust cover mounting

Crankcase mounting

1st

2nd

1st

2nd

1st

2nd

Bolt

Bolt

Nut

Nut

Bolt

Bolt

—

Bolt

Bolt

Bolt

LOWER UNIT

Propeller

Lower unit mounting

Propeller shaft housing

Pinion gear nut

Water inlet

BRACKET

Shift actuator mounting

Bolt

Nut

Shift lever Bolt

Mount rubber(side upper) Nut

Mount rubber(lower front) Bolt

Steering bracket mounting

Clamp bracket nylon

Bolt

Nut

Nut

Bolt

Nut

Bolt

Nut

Bolt

ELECTRICAL

CDI unit

Ignition coil

Engine stop switch

Bolt

Bolt

Nut

* Do not apply too much torque.

Thread size

Q’ty

M6

M12

—

M12

M8

M6

M14

M8

M6

M8

M6

M10

M6

M10

M8

M6

—

—

M10

M10

M6

M8

M5

M6

M6

M16

9

2

11

3

1

1

1

6

15

10

4

2

1

2

4

1

2

2

1

2

1

6

6

2

2

1

E

Tightening torques

N

• m kgf

• m ft

• lb

Remarks

11

17

11

17

17

11

45

4

8

35

4

8

15

30

8

25

15

30

12

15

10

140

11

22

4

11

50

5

35

37

37

D

1.1

1.7

1.1

1.7

1.7

1.1

4.5

0.4

0.8

3.5

0.4

0.8

1.5

3.0

0.8

2.5

1.5

3.0

1.2

1.5

1.0

14

1.1

2.2

0.4

3.5

3.7

3.7

1.1

5.0

0.5

8.1

13

8.1

13

13

8.1

33

3.0

5.9

26

3.0

5.9

11

22

5.9

18

11

22

8.9

11

7.4

103

8.1

16

3.0

26

27

27

8.1

37

3.7

2-11

SPEC

Nut (A) Bolt (B)

8 mm

10 mm

12 mm

14 mm

17 mm

M5

M6

M8

M10

M12


General torque specifications

N

• m kgf

• m ft

• lb

5

8

18

36

43

0.5

0.8

1.8

3.6

4.3

3.7

5.9

13

27

32

E

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 multifastener assemblies in a crisscross fashion and progressive stages until the specified tightening torque is reached. Unless otherwise specified, tightening torque specifications require clean, dry threads.

Components should be at room temperature.

A

B

2-12

CHK

ADJ

CHAPTER 3

PERIODIC CHECK AND ADJUSTMENT

MAINTENANCE INTERVAL CHART .............................................................. 3-1

TOP COWLING ............................................................................................... 3-2

CHECKING THE TOP COWLING FIT ....................................................... 3-2

FUEL SYSTEM ................................................................................................ 3-2

CHECKING THE FUEL LINE .................................................................... 3-2

CHECKING THE FUEL FILTER ................................................................. 3-3

CHECKING THE FUEL PUMP ................................................................. 3-3

CHECKING THE FUEL JOINT ................................................................. 3-3

CONTROL SYSTEM ....................................................................................... 3-4

ADJUSTING THE IGNITION TIMING ..................................................... 3-4

ADJUSTING THE ENGINE IDLE SPEED .............................................. 3-15

ADJUSTING THE START-IN-GEAR PROTECTION DEVICE ................. 3-17

POWER UNIT ............................................................................................... 3-18

MEASURING THE COMPRESSION PRESSURE .................................. 3-18

COOLING SYSTEM ...................................................................................... 3-19

CHECKING THE COOLING WATER DISCHARGE ................................ 3-19

LOWER UNIT ................................................................................................ 3-19

CHECKING THE GEAR OIL LEVEL ....................................................... 3-19

CHANGING AND CHECKING THE GEAR OIL ..................................... 3-19

CHECKING THE LOWER UNIT (FOR AIR LEAKS) ............................... 3-20

GENERAL ..................................................................................................... 3-21

CHECKING THE ANODE ....................................................................... 3-21

CHECKING THE SPARK PLUGS ........................................................... 3-22

CHECKING THE PROPELLER ................................................................ 3-23

CHECKING BOLTS AND NUTS ............................................................ 3-23

LUBRICATION POINTS ......................................................................... 3-24

E

3

4

5

1

2

8

9

6

7

CHK

ADJ

MAINTENANCE INTERVAL CHART

E

3

MAINTENANCE INTERVAL CHART

Frequency of maintenance operations may be adjusted according to the operating conditions, but the following table gives general guidelines.

The mark (

@) indicates the check-ups which maybe carried out by owner.

The mark (

:) indicates work to be carried out by Yamaha dealer.

Item Remarks

Initial

10 hours

Every

50 hours

(3 months)

100 hours

(6 months)

200 hours

(1 year)

FUEL SYSTEM

Fuel filter

Fuel system

Clean

Check

Clean Fuel tank

POWER UNIT

Carburetor setting

Water leakage

CONTROL SYSTEM

Check

Adjust

Cooling water passage Clean

Exhaust leakage Check

Check

Ignition timing

Idle speed

Check

Adjust

Check

Adjust

LOWER UNIT

Gear oil

Propeller

GENERAL

Spark plug

Change

Check

Clean

Adjust

Replace

Wiring and connectors Check

Greasa points

Bolts and nuts

Anode

Motor exterior

Grease

Retighten

Check

Check

@

:

:

@

:

:

:

:

@

@

@

@

:

:

:

@

:

:

:

@

@

@

:

:

:

@

:

:

:

@

:

:

:

:

:

@

@

:

@

@

@

:

@

:

:

:

@

:

Refer page

3-3

3-2

—

3-15

3-15

—

—

—

3-4

3-4

3-15

3-15

3-19

3-23

3-22

3-22

3-22

—

3-24

3-23

3-21

—

NOTE:

Cooling water passages:

When operating in salt water, turbid or muddy water, the engine should be flushed with clean water after each use.

3-1

CHK

ADJ

TOP COWLING/FUEL SYSTEM

TOP COWLING

CHECKING THE TOP COWLING FIT

Check:

• Top cowling

Cracks/damage

→

Replace.

• Hook

Bent

→

Correct.

• Rivet

Damage

→

Repair.

• Rubber of trim

Peel/tear

→

Repair.

NOTE:

Hooks and latches are unadjustable.

E

3-2

FUEL SYSTEM

CHECKING THE FUEL LINE

Check:

• Fuel hose

Cracks/damage/leak

→

Replace.

Refer to "FUEL JOINT, FUEL FILTER,

AND FUEL PUMP" on page 4-1.

CHK

ADJ

FUEL SYSTEM

CHECKING THE FUEL FILTER

Check:

• Fuel filter element

1

Foreign matter

→

Clean.

• Fuel filter cup

2

Cracks/damage/leak

→

Replace.

• O-ring

3

Cracks/damage

→

Replace.

E

CHECKING THE FUEL PUMP

Check:

• Fuel pump

Cracks/damage/leak

→

Repair/replace.

Refer to "DISASSEMBLING THE

FUEL PUMP" on page 4-4.

NOTE:

Observe pump with naked eyes.

3-3

CHECKING THE FUEL JOINT

Check:

• Fuel joint

1

Cracks/damage/leak

→

Replace.

• Seal

2

Cracks/damage

→

Replace.

CHK

ADJ

CONTROL SYSTEM

CONTROL SYSTEM

ADJUSTING THE IGNITION TIMING

E

CAUTION:

Ignition timing adjustment on the running engine must be performed in the test tank with a te st propeller installed on the engine.

Test propeller

90890-01629

WARNING

While checking the engine, do not touch the rotating part (flywheel), CDI unit, ignition coil, and any other hazardous areas.

1. Check:

• Ignition timing

Out of specification

→

Adjust.

Ignition timing (at idle)

ATDC 2° ± 2°

Ignition timing (at full advance)

BTDC 22° ± 2°

Engine idle speed

1,300 ± 50 r/min

Full throttle operating range

5,350 ± 100 r/min

Checking steps

(1) Install the timing light a

onto the spark plug lead of cylinder #1.

(2) Install the digital tachometer b


(3) Press the position key "C" on the digital tachometer.

(4) Start the engine and allow it to warm up for a few minutes.

Timing light ...................................

90890-03141

Digital tachometer ........................

90890-06760

a b

3-4

CHK

ADJ

CONTROL SYSTEM

E

(5) Set the shift lever

1

in forward position.

(6) Fully open the throttle by moving the throttle

2

to the “FAST” position.

Full throttle operating range

5,350 ± 100 r/min

(7) Check the ignition timing by pointing the timing light at the timing indicator on the starter case.


BTDC 22° ± 2°

3-5

(8) Move the throttle

2

to full-close position.


1,300 ± 50 r/min

(9) Check the ignition timing by pointing the timing light at the timing indicater on the starter case.

Ignition timing (at idle)

ATDC 2° ± 2°

NOTE:

• Ignition timing adjustment is not required if the timing indicator reading falls within the specification.

• If the reading is out of specification, adjust the timing by the following procedure.

CHK

ADJ

CONTROL SYSTEM

E

2. Adjustment with full-open throttle:

• Magnet base stopper

CAUTION:

• Make sure that engine is not running.

• Remove the plug caps.

Adjustment steps


1



2

to full-open position.

(3) Slowly turn the flywheel clockwise to align the full advanced timing mark with the specified position on the timing indicator.


BTDC 22° ± 2°

(4) Turn the magnet base

3

until the timcomes in line with the ignition mark on the rotor.

b

4

(5) Check that the magnet base stopper

4 is in contact with the stopper on the engine body (full-open end stopper)

5

.

5

3-6

CHK

ADJ

6

CONTROL SYSTEM

E

(6) If they are not in contact, loosen the set bolt

6

, adjust until they are correctly in contact with each other, and secure the bolt again.

3. Adjusting the carburetor control link:

• Accelerator cam

• Carburetor control link



1



2


4

3

(3) Make sure that the magnet base stopper

3

is in contact with the stopper on the engine body (full-open end stopper)

4

.

(4) Check to see that the full-open marking

"C" on the accelerator cam aligns with the center of the cam roller.

3-7

CHK

ADJ

CONTROL SYSTEM

E

(5) "Loosen the bolt, and align the fullopen marking "C" with the center of carburetor throttle roller, and tighten the set-bolt."

NOTE:

Remove the manual starter before adjusting.

(6) "Loosen the rod tightening screw a

.

While pushing the rod with your finger, tighten the screw so that the throttle is full-open (the full-open stopper b

is pushed against the stopper c

), and lock the screw."

NOTE:

After adjustment, open and close the throttle repeatedly for several times to reassure that the full-open position of the accelerator cam and the positioning of the carburetor control link stopper are correct.

4. Adjustment with full-closed throttle:

• Accelerator cam

• Carburetor control link



1



2


3-8

CHK

ADJ

CONTROL SYSTEM

3

E


3

is in contact with the stopper on the engine body (full-close end stopper)

4

.

4

(4) Make sure that the lever is in contact with the carburetor throttle stop screw.

(5) Correct adjustment has been established if the cam roller is not in contact with the accelerator cam.

3-9

(6) If the lever is not in contact with the throttle stop screw move the plate cam to the left so that the lever comes to contact with the throttle stop screw.

NOTE:

• When shifting the plate cam slightly, do not shift it more than 2 mm (0.079 in) to the left from the point at which the marking line of the full-open mark "C" aligns with the centerline of the roller cam at full-throttle.

• After adjustment, open and close the throttle for several times, and reassure that the lever is in contact with the throttle stop screw on the carburetor, and that the cam roller is not in contact with the accelerator cam.

CHK

ADJ

CONTROL SYSTEM

E

5. Adjusting the throttle cable

• Throttle cable

Adjusting steps

NOTE:

After adjustment, open and close the throttle for several times for reassurance.


1



2


4

3



4

.

(4) If the stoppers come in contact before the throttle is fully open, loosen the lock nut

6

on the throttle-opening cable, turn-in the adjusting nut

5

until the cerrect positioning is attained, and then secure it by the lock nut

6

.

(5) If the stoppers do not come in contact at full-open throttle, then turn-out the adjusting nut

5

on the throttle-opening cable until the correct positioning is attained, and secure it by the lock nut

6

.

3-10

CHK

ADJ

CONTROL SYSTEM

E

(6) After confirming the positive contact of stoppers at full-open throttle position, turn the adjusting nut

7

on the throttle-closing cable so that the cable has a little slack, and then secure it by the lock

(7) Once the adjustment under full-open throttle is completed, move the throttle

2


4

3


3

is in contact with the stopper on the engine body (full-close end stopper)

4

.


2


3-11

(10) In this condition, make sure that the full-open stopper is in contact with the stopper.

NOTE:

If they are not in contact, adjust the carburetor control link.

Refer to "Adjusting the carburetor control link:" on page 3-7.

CHK

ADJ

CONTROL SYSTEM

E


2


(12) At this point, make sure that the throttle lever is in contact with the throttle stop screw on the carburetor.

NOTE:

• After adjustment, open and close the throttle for several times for reassurance.

• If they are not in contact, adjust the carburetor control link.


6. Adjusting the throttle control lever:

• Throttle control lever



1

at the forward position.


2


3-12

CHK

ADJ

CONTROL SYSTEM

3

E



4

.

4

(4) Check that the throttle control lever

5 is in contact with the stopper

6

on the bottom cowling.

4

3

3-13

(5) If they are not in contact, adjust the throttle control lever seats on the stopper on the bottom cowling.

NOTE:

After adjustment, open and close the throttle repeatedly for several times to reassure the correct positioning.



4

.

NOTE:

If they are not in contact, perform the adjustment with full-open throttle.

Refer to "Adjustment with full-open throttle:" on page 3-6.

(7) In this condition, make sure that the full-open stopper is in contact with the stopper.

NOTE:

If they are not in contact, adjust the carburetor control link.


CHK

ADJ

CONTROL SYSTEM

E

7. Adjusting the engine idle speed:

• Engine idle speed


(1) Adjust the pilot screw.

Pilot screw turn-out

Gasoline carburetor::::

1 - 1/2 ± 1/2

Kerosene carburetor:

1/2 + 2

1/2 - 1/2

(2) Adjust the idling stop screw


1,300 ± 50 r/min

Refer to "ADJUSTING THE ENGINE IDLE

SPEED" on page 3-15.

3-14

CHK

ADJ

CONTROL SYSTEM

E

ADJUSTING THE ENGINE IDLE SPEED

NOTE:

• The engine should be warmed up for the adjustment. Correct adjustment cannot be obtained when the engine is cold.

• Make sure that the pilot screw adjustment is normal before implementing idling stop screw adjustment.

1. Measure:



→

Adjust.


1,300 ± 50 r/min

3-15

CAUTION:

Install the engine in the test tank to check the engine idle speed.

Measuring steps


(2) Install the digital tachometer

1


(3) "Press the position key "C" on the digital tachometer."

Digital Tachometer........................

90890-06760

1

2. Adjust:

• Carburetor pilot screw

CAUTION:

Do not adjust the carburetor when it is operating properly. Excessive adjustment may cause the engine poor performance.


(1) Turn in the pilot screw (

1

:Gasoline,

2

:Kerosene) until they are lightly seated.

(2) Turn out the pilot screws by specified number of turns.


Gasoline carburetor::::

1 - 1/2 ± 1/2

Kerosene carburetor:

1/2 + 2

1/2 - 1/2

CHK

ADJ

CONTROL SYSTEM

E

(3) Make sure that the idle speed is stable when the throttle is opened and closed for several times.

NOTE:

If the idle speed is not stable, disassemble and readjust the carburetor.

3. Adjust:



(1) Turn the idling stop screw

2

of carburetor in direction a

or b

until the specified engine idle speed is obtained.

Direction a

Direction b n c e a s e s d e c ea s e s....

(2) Check the engine idling stability by opening and closing the throttle for several times. If engine idling is unstable, adjust the pilot screw.

NOTE:

After adjustment, open and close the throttle for several times and keep it idling for at least 15 seconds. Check if engine idle speed is stable.

3-16

CHK

ADJ

2

1

CONTROL SYSTEM

E

ADJUSTING THE START-IN-GEAR

PROTECTION DEVICE

CAUTION:

• Make sure that the engine is not running.

• Remove the plug caps.

1. Check:

• Start-in-gear protection device

Checking steps


1

in forward or reverse position.

(2) Check that the starter rope

2

cannot be pulled out.

(3) If the starter rope can be pulled out, perform the adjustment.

2. Adjust:



1

in neutral position.

c b a b

(2) Turn in or out the adjusting nut c

on the starter stop wire so that the starter stopper end a

is aligned with the hole on the starter case b

.

NOTE:

• Check again that the starter rope can not be pulled out when the shift is engaged.

• Check again that the starter rope can be pulled out when the shift is in neutral.

3-17

CHK

ADJ

1

POWER UNIT

2

3-18

E

POWER UNIT

MEASURING THE COMPRESSION

PRESSURE

NOTE:

The engine should be warmed up before measuring the compression pressure. Correct measurement cannot be obtained when the engine is cold.

1. Measure:

• Compression pressure

Below minimum compression pressure

→

Check or replace piston, piston rings, cylinder head, and cylinder head gasket.

Compression pressure

(reference value)

#1: 680 kPa (6.8 kgf/cm

2

, 98.6 psi)

#2: 730 kPa (7.3 kgf/cm

2

, 105.9 psi)

Minimum compression pressure

#1: 540 kPa (5.4 kgf/cm

2

, 78.3 psi)

#2: 580 kPa (5.8 kgf/cm

2

, 84.1 psi)

Measuring steps

(1) Remove the spark plug

1

.

CAUTION:

Before removing the spark plug, clean the spark plug well arec to prevent any dirt from falling into the cylinder that is being checked.

(2) Install the compression gauge

2

into the spark plug hole.

Compression gauge

90890-03160

(3) Fully open the throttle.

(4) Fully open the choke. (Make the choke valve ineffective.)

(5) Crank the engine by means of recoil starter (MH model) or starter motor (W,

WC, and WH models) until the compression gauge gives stable reading.

(6) Remove the compression gauge

2

.

(7) Install the spark plug

1

.

.

T

R

.

Spark plug

25 N

•

m (2.5 kgf

•

m, 18 ft

•

lb)

CHK

ADJ

COOLING SYSTEM/LOWER UNIT

E

COOLING SYSTEM

CHECKING THE COOLING WATER

DISCHARGE

Check:

• Pilot water

Does not flow

→

Clean and check the cooling water passage.

Checking steps

(1) Place the lower unit in water.

(2) Start the engine.

(3) Check that water flows from the pilot water outlet.

LOWER UNIT

CHECKING THE GEAR OIL LEVEL

Check:

• Gear oil level

Level is low

→

Add gear oil to the proper level.

3-19

CHANGING AND CHECKING THE

GEAR OIL

1. Check:

• Gear oil

Milky oil

→

Replace the oil seal.

Slug oil

→

Check the oil gears, bearings, and clutch dog.

Checking steps

(1) Tilt up the outboard slightly.

(2) Place a container under the gear oil drain screw

1

.

(3) Remove the gear oil drain screw and gear oil level check screw

2

.

CHK

ADJ

LOWER UNIT

3-20

E

2. Fill:

• Gear oil

(with the specified amount of the recommended gear oil.)

Recommended gear oil

Hypoid gear oil, SAE #90 (API GL-4)

Oil capacity

320 cm

3

(10.8 US oz, 11.3 lmp oz)

Filling steps

(1) Place the outboard in an upright position.

(2) Insert the gear oil tube into the drain hole and slowly fill the gear oil until oil flows out of the check hole and no air bubbles are visible.

(3) Install the gear oil level check screw and then quickly install the gear oil drain screw.

CHECKING THE LOWER UNIT

(FOR AIR LEAKS)

Check:

• Lower unit holding pressure

Pressure drops

→

Check the seal and components.

Lower unit holding pressure

100 kPa (1.0 kg/cm

2

, 14.5 psi) for

10 seconds

Checking steps

CAUTION:

Do not ove rpressurize the lower unit.

Excessive pressure may damage the oil seals.

(1) Remove the gear oil level check screw.

(2) Install the pressure tester into the check hole.

Leakage tester

90890-06762

(3) Apply the specified pressure.

(4) The lower unit should hold the specified pressure for 10 seconds.

CHK

ADJ

GENERAL

E

GENERAL

CHECKING THE ANODE

Check:

• Anodes

Scales

→

Clean.

Oil/grease

→

Clean.

Excessive wear

→

Replace.

CAUTION:

Do not oil, grease, or paint the anode, or it will not operate properly.

3-21

CHK

ADJ

GENERAL

E

CHECKING THE SPARK PLUGS

1. Check:

• Electrodes

1

Cracks/excessive wear

→

Replace.

• Insulator color

2

Distinctly different color

→

Check the engine condition.

Color guide:

Medium to light tan color

Normal

Whitish color

• Lean fuel mixture

• Plugged jet (s)

• Wrong setting

Blackish color

• Rich mixture

• Excessive oil usage

• Defective ignition system

• Defective spark plug

2. Clean:

• Spark plug

(use a spark plug cleaner or wire brush)

3. Check:

• Spark plug type

1

Incorrect

→

Replace.

Standard spark plug

NGK B7HS-10

4. Measure:

• Spark plug gap a


→

Replace.

Spark plug gap

0.9-1.0 mm (0.035-0.039 in)

3-22

CHK

ADJ

GENERAL

E

5. Tighten:

• Spark plug

.

T

R

.

Spark plug

25 N

•

m (2.5kgf

•

m, 18 ft

•

lb)

NOTE:

• Before installing the spark plug, clean the gasket surface and spark plug surface. Also, it it suggested to apply a thin film of anti-seize compound to the spark plug threads to prevent thread seizure.

• If a torque wrench is not available, a good estimate of the correct tightening torque is to finger tighten a

the spark plug and then tighten it another 1/4 to

1/2 of a turn b

.

CHECKING THE PROPELLER

Check:

• Propeller

• Spline

Wear/cracks/damage

→

Replace.

CHECKING BOLTS AND NUTS

Check:

• Power unit mount bolt

• Flywheel nut

Loose bolts / nuts

→

Tighten to the specified torque.

.

T

R

.

Power unit mount bolt

1st 11 N

•

m (1.1 kgf

•

m, 8.1 ft

•

lb)

2nd 22 N

•

m (2.2 kgf

•

m, 16 ft

•

lb)

Flywheel nut

140 N

•

m (14 kgf

•

m, 103 ft

•

lb)

3-23

CHK

ADJ

GENERAL

E

LUBRICATION POINTS

1. Apply:

• Yamaha grease A

NOTE:

Using a grease gun, fill in the grease until it comes out of the bushing.

NOTE:

Use a grease gun.

NOTE:


NOTE:


NOTE:

Use a grease gun.

3-24

CHK

ADJ

GENERAL

NOTE:

Use a grease gun.

E

NOTE:

Grease the area where shift rod, shift connector, and the nut are fastened.

NOTE:

Grease the sliding face of the choke knob.

NOTE:

Grease the inner cable and the lock nut.

2. Apply:

• Yamaha grease D

3-25

FUEL

CHAPTER 4

FUEL SYSTEM

FUEL JOINT, FUEL FILTER, AND FUEL PUMP ............................................. 4-1

REMOVING THE FUEL JOINT, FUEL FILTER AND FUEL PUMP ........... 4-1

CHECKING THE FUEL JOINT ................................................................. 4-3

CHECKING THE FUEL FILTER ................................................................. 4-3

ASSEMBLING THE FUEL FILTER ........................................................... 4-3

FUEL PUMP .................................................................................................... 4-4

DISASSEMBLING THE FUEL PUMP ...................................................... 4-4

CHECKING THE FUEL PUMP ................................................................. 4-6

ASSEMBLING THE FUEL PUMP ............................................................ 4-7

CARBURETOR ................................................................................................ 4-9

REMOVING THE CARBURETOR ............................................................. 4-9

DISASSEMBLING THE CARBURETOR ................................................ 4-10

CHECKING THE CARBURETOR ............................................................ 4-16

ASSEMBLING THE CARBURETOR ...................................................... 4-17

INSTALLING THE CARBURETOR ......................................................... 4-20

E

3

4

5

1

2

8

9

6

7

FUEL

FUEL JOINT, FUEL FILTER, AND FUEL PUMP

4


REMOVING THE FUEL JOINT, FUEL FILTER AND FUEL PUMP

E

Step Job/Parts

1 Clip

2 Fuel hose (fuel pump to carburetor)

3 Clip

4 Fuel hose (fuel pump to carburetor)

5 Clip

6 Fuel hose (fuel filter to fuel pump)

7 Clip

8 Fuel hose (fuel filter to fuel pump)

9 Clip

10 Fuel hose (fuel joint to fuel filter)

11 Clip

12 Fuel hose (fuel joint to fuel filter)

13 Bolt

4-1

Q’ty

2

1 Gasoline

2

1 Kerosene

2

1 Gasoline

2

1 Kerosene

2

1 Gasoline

2

1 Kerosene

2

Remarks

Continued on next page.

FUEL


E

Step

14 Fuel pump

15 Gasket

16 Nut

17 Fuel filter

18 Fuel filter

19 Bolt

20 Bolt

21 Filter bracket

22 Bolt

23 Fuel joint

24 Seal

Job/Parts

4-2

Q’ty

1

1

1

1

1

1

Not reusable

2

1 Gasoline

1 Kerosene

1

1

Remarks

FUEL


E

CHECKING THE FUEL JOINT

1. Check:

• Fuel joint

1

Cracks/damage/leak

→

Replace.

• Seal

2

Cracks/damage

→

Replace.

2. Measure:

• Fuel joint operation

Impossible to maintain the specified pressure for 10 sec.

→

Replace.

Measuring steps

(1) Attach the vacuum/pressure pump gauge.

Vacuum/pressure pump gauge set

90890-06756

(2) Apply the specified pressure.

Specified pressure

50 kPa (0.5 kg/cm

2

, 7.25 psi)

4-3

CHECKING THE FUEL FILTER

Check:

• Filter cap

1

Cracks/damage

→

Replace.

• Filter element

2

Cracks/damage/leak

→

Replace.

• O-ring

3

Cracks/damage

→

Replace.

• Cup

4

Foreign matter

→

Clean.

ASSEMBLING THE FUEL FILTER

(1) Install filter element to cap.

(2) Install O-ring to filter cup.

(3) Assemble cap and filter cup.

NOTE:

Start the engine and confirm the proper function.

FUEL

FUEL PUMP

FUEL PUMP

DISASSEMBLING THE FUEL PUMP

E

Step Job/Part Q’ty

1 Screw (with washer) 3

2 Body 1

3 Diaphragm 1

4 Gasket 1

Not reusable

5 Body 1

6 Diaphragm gasket

7 Diaphragm

2

1

8 Body 1

Not reusable

9 Screw

10 Seat valve

11 Nut

12 Screw

13 Washer

2

2

2

3

3

Remarks


4-4

FUEL

FUEL PUMP

E

Step Job/Part

14 Body

15 Diaphragm

16 Diaphragm gasket

Q’ty

1

1

1

Remarks

4-5

FUEL

FUEL PUMP

CHECKING THE FUEL PUMP

1. Check:

• Body

1

• Body

2

• Body

3

• Body

4

Cracks/damage/leak

→

Replace.

Foreign matters

→

Clean.

• Seat valve

5

Cracks/ damage

→

Replace.

• Diaphragm

6

Damage

→

Replace.

E

4-6

2. Check:

• Fuel pump

Reverse air flow

→

Replace.

Checking steps

NOTE:

Do not overpressurize the fuel pump. Excessive pressure may cause air to leak out.

(1) Install the Vacuum/pressure pump gauge set onto the fuel pump as shown.

Vacuum/pressure pump gauge set

90890-06756

(2) Apply the specified pressure with the

Vacuam/pressure pump gauge set.

Fuel pump pressure

50 kPa (0.5 kg/cm

2

, 7.25 psi)

NOTE:

• Make sure no air comes out of the opposite side of the fuel pump.

• Start the engine and confirm the proper function.

FUEL

FUEL PUMP

2

ASSEMBLING THE FUEL PUMP

NOTE:

Clean all parts before assembly.

Assembly steps

(1) Assemble Body

1

and seat valve.

E

(2) Insert the diaphragm between the diaphragm gaskets, and set them on Body

2

.

1

(3) Set Body

1

on the diaphragm gasket.

3

(4) Fit diaphragm and gasket on Body

3

.

1

3

(5) Assemble Body

3

as has been fitted in

(4) to Body

1

.

4-7

FUEL

4

FUEL PUMP

E

(6) Assemble body

4

, diaphragm, and diaphragm gasket in this order.

4

1

4 fasten them with the screw.

1

4-8

FUEL

CARBURETOR

CARBURETOR

REMOVING THE CARBURETOR

E

Step

1 Rod

2 Bolt

3 Intake silencer

4 O-ring

5 Nut

6 Carburetor

7 Gasket

Job/Part Q’ty

1

2

1

1

Not reusable

2

1

1

Not reusable

Remarks

4-9

FUEL

CARBURETOR

DISASSEMBLING THE CARBURETOR

E

Step Job/Part

1 Drain screw

2 Drain gasket

3 Drain screw

4 Drain gasket

5 Drain screw

6 Packing

7 Steel ball seat

8 Steel ball

9 Check valve spring

10 Check valve seat packing

11 Rod

12 Lever joint

13 Hose

4-10

Q’ty

1

1

1

2

1

1

1

Not reusable

1

1

Not reusable

1

1

Not reusable

1

1

Remarks


FUEL

CARBURETOR

E

Step Job/Part

14 Bolt

15 Bolt

16 Float chamber

17 Float chamber packing

18 Chamber packing

19 Starter jet

20 Check valve

21 O-ring

22 Pump spring

23 Pump plunger

24 Float

25 Pilot jet

26 Pin

4-11

Q’ty

1

1

1

1

1

4

3

1

1

1

1

1

1

Not reusable

Remarks


FUEL

CARBURETOR

E

Step

27 Float arm

28 Needle valve

29 Chamber cover

30 Set screw

31 Washer

32 Pump lever

33 Coller

34 Pin

35 Float

36 Needle valve

37 Valve seat

38 Packing

39 Main jet

Job/Part

4-12

Q’ty

1

1

1

1

1

1

1

1

1

1

1

1

Not reusable

1

Remarks


FUEL

CARBURETOR

E

Step Job/Part

40 Main nozzle

41 Steel ball seat

42 Steel ball

43 Check valve spring

44 Check valve seat packing

45 Screw

46 Rod

47 Lever joint

48 Nut

49 Spring washer

50 Coller

51 Accel arm

52 Cotter pin

4-13

Q’ty Remarks

1

1

1

1

1

1

1

1

1

1

1

1

1

Not reusable


FUEL

CARBURETOR

E

Step Job/Part

53 Washer

54 Accel roller

55 Accel link shaft

56 Coller

57 Pilot screw

58 Spring

59 Pilot screw

60 Spring

61 Idling stop screw

62 Spring

63 Bolt

64 Plate

65 Damper

4-14

Q’ty

1

1

3

1

1

1

1

1

1

1 Kerosene

1

1 Gasoline

1

Remarks


FUEL

CARBURETOR

E

Step Job/Part

66 Hose

67 Hose

68 Cover plate

69 Cover plate packing

70 Plunger spring

71 Guide screw

72 Starter lever

73 Starter plunger

74 Pilot jet

75 Drain screw

76 O-ring

77 Carburetor body

4-15

Q’ty

1

1

1

1

1

1

1

1

1

1

1

Not reusable

1

Remarks

FUEL

CARBURETOR

25B-4-19

E

CHECKING THE CARBURETOR

CAUTION:

Do not use steel-wire to clean the jets. This may enlarge the jet diameters and seriously affect performance.

Check:

• Carburetor body

1

Cracks/damage

→

Replace.

Contamination

→

Clean.

• Needle valve

2

Grooved wear

→

Replace.

• Pilot screw

3

Bent/wear

→

Replace.

• Main jet

Contamination

→

Clean.

• Pilot jet

Contamination

→

Clean.

• Main nozzle

Contamination

→

Clean.

• Float

Cracks/damage

→

Replace.

• Pump plunger

4

Cracks/damage

→

Replace.

• Fuel passage

Clog

→

Clean.

• Air passage

Clog

→

Clean.

NOTE:

Use a suitable cleaning solvent and blow out clogged passages with compressed air.

WARNING

Protect your eyes with suitable safety spectacles or safety goggles when using compressed air.

4-16

FUEL

CARBURETOR

E

ASSEMBLING THE CARBURETOR

1. Install:

• Main nozzle

1

• Main jet

2

• Valve seat

3

• Needle valve

4

• Float

5

• Float pin

6

NOTE:

When installing the float into the carburetor, place the needle valve into the needle valve seat.

4-17

FUEL

CARBURETOR

E

2. Measure:

• Float height a


→

Replace

Float height

18.0 mm (0.709 in)

NOTE:

• The float should be resting on the needle valve, but not compressing the needle valve.

• Take measurement at the top of the float flange opposite to its pivoted side.

• Float height which is out of specification cannot be adjust. Replace the float with a new one.

3. Install:

• Float chamber packing

1

• Float chamber

2

4. Install:

• Accel arm

1

• Accel link shaft

2

4-18

5. Install:

• Pilot screw

1

(Gasoline)

• Pilot screw

2

(Kerosene)

CAUTION:

Do not cause damage to the tip of the pilot screw by over-tightening it.

FUEL

CARBURETOR

6. Install:

• Cover plate

1

• Damper

2

E

4-19

7. Install:

• Float arm

1

• Pin

2

• Needle valve

3

8. Measure:

• Float arm height a


→

Adjust

Float arm height

3.0 mm (0.118 in)

NOTE:

Adjust the heights of both float arms so that they are on the same level.

FUEL

CARBURETOR

E

9. Install:

• Pump plunger

1

• Float

2

• Chamber packing

3

NOTE:

Make sure the plunger seal is not turned up.

INSTALLING THE CARBURETOR

1. Install:

• Gasket

1

• Carburetor

2

• Nut

3

• O-ring

4

• Intake silencer

5

• Bolt

6

NOTE:

Insert the projection of choke lever

7

into the choke knob hole

8

.

4-20

2. Adjust:

• Pilot screw

Adjusting steps

(1) Turn in all of the pilot screw until they are lightly seated.

(2) Turn out the pilot screws to specified number of turns.


Gasoline carburetor :

1 – 1/2 ± 1/2

Kerosene carburetor :

1/2 + 2

1/2 - 1/2

(3) Make sure that the idle speed is stable when the throttle is opened and closed for several times.

FUEL

CARBURETOR

E

3. Measure:



→

adjust.


1,300 ± 50 r/min

Measuring steps


(2) Install the Digital tachometer

1


Digital Tachometer

90890-06760

4-21

POWR

CHAPTER 5

RECOIL STARTER

RECOIL STARTER .......................................................................................... 5-1

REMOVIING THE RECOIL STARTER ...................................................... 5-1

DISASSEMBLING THE RECOIL STARTER ............................................. 5-2

CHECKING THE RECOIL STARTER ........................................................ 5-4

ASSEMBLING THE RECOIL STARTER ................................................... 5-6

INSTALLING THE RECOIL STARTER ...................................................... 5-9

FLYWHEEL MAGNET ................................................................................... 5-10

REMOVIING THE FLYWHEEL MAGNET ............................................... 5-10

INSTALLING THE FLYWHEEL MAGNET .............................................. 5-11

POWER UNIT ............................................................................................... 5-12

DISCONNECTING THE LEADS AND STAYS ........................................ 5-12

REMOVING THE POWER UNIT ............................................................ 5-14

MAGNET BASE AND CONTROL LEVER .................................................... 5-15

REMOVING THE MAGNET BASE AND MAGNET CONTROL LEVER 5-15

INTAKE MANIFOLD AND REED VALVES ................................................... 5-17

REMOVING THE INTAKE MANIFOLD AND REED VALVES ................ 5-17

CHECKING THE REED VALVES ............................................................ 5-18

INSTALLING THE INTAKE MANIFOLD ................................................ 5-18

CYLINDER HEAD ......................................................................................... 5-19

REMOVING THE CYLINDER HEAD ...................................................... 5-19

CHECKING THE CYLINDER HEAD ....................................................... 5-20

CHECKING THE THERMOSTAT ............................................................ 5-21

INSTALLING THE CYLINDER HEAD AND CYLINDER HEAD COVER . 5-22

INSTALLING THE THERMOSTAT ......................................................... 5-22

EXHAUST COVER ........................................................................................ 5-23

REMOVING THE EXHAUST COVER ..................................................... 5-23

CHECKING THE EXHAUST COVER ...................................................... 5-24

INSTALLING THE EXHAUST COVER ................................................... 5-24

CRANKCASE ................................................................................................ 5-25

REMOVING THE CRANKCASE ............................................................. 5-25

ASSEMBLING THE OIL SEAL HOUSING ............................................. 5-26

IINSTALLING THE CRANKCASE .......................................................... 5-26

CRANKSHAFT AND CYLINDER BODY ....................................................... 5-28

REMOVING THE CRANKSHAFT AND CYLINDER BODY .................... 5-28

CHECKING THE CYLINDER BODY ....................................................... 5-29

CHECKING THE PISTON ....................................................................... 5-30

E

POWR

CALCULATING THE PISTON-TO-CYLINDER CLEARANCE ................. 5-31

CHECKING THE PISTON PINS AND SMALL-END BEARINGS ........... 5-32

CHECKING THE PISOTN RINGS .......................................................... 5-33

CHECKING THE CRANKSHAFT ............................................................ 5-34

INSTALLING THE PISTON AND PISTON RINGS ................................. 5-37

INSTALLING THE CRANKSHAFT AND PISTON .................................. 5-37

CHECKING THE ANODE ....................................................................... 5-38

CRANK SHAFT ............................................................................................. 5-39

DISASSEMBLING THE CRANKSHAFT ................................................ 5-39

REMOVING THE CRANKSHAFT BEARING ......................................... 5-41

ASSEMBLING THE CRANKSHAFT ...................................................... 5-44

INSTALLING CRANKSHAFT BEARING ................................................ 5-50

CHECKING THE CRANKSHAFT ............................................................ 5-51

E

3

4

5

1

2

8

9

6

7

POWR

RECOIL STARTER

5

RECOIL STARTER

REMOVIING THE RECOIL STARTER

E

Step Job/Parts

1 Starter stop wire

2 Bolt (with washer)

3 Nut

4 Recoil starter

5 Collar

Q’ty

1

3

2

1

2

Remarks

5-1

POWR

RECOIL STARTER

DISASSEMBLING THE RECOIL STARTER

E

Step Job/Parts

1 Starter stop wire

2 Starter stop plunger

3 Spring

4 Cover

5 Starter handle-grip

6 Damper


8 Rope guide

9 Nut

10 Center bolt

11 Thrust washer

12 Friction plate

13 Collar 1

5-2

Q’ty

2

1

1

1

1

1

1

1

1

1

1

1

1

Remarks


POWR

RECOIL STARTER

E

Step

14 Friction spring

15 Drive pawl

16 Return spring

17 Bushing

18 Sheave drum

19 Starter rope

20 Spiral spring

21 Thrust washer

22 Starter case

Job/Parts Q’ty

1

1

1

1

1

1

1

1

1

5-3

Remarks

v

POWR

RECOIL STARTER

E

CHECKING THE RECOIL STARTER

1. Remove:

• Cover

1

• Starter handle-grip

2

NOTE:

Undo the knot in the starter rope, and wind the rope around the sheave drum.

CAUTION:

Be careful not to touch the sheave drum which is rotating at high speeds.

2. Remove:

• Sheave drum

1

NOTE:

When removing the sheave drum from the starter case, hold down the spiral spring with screwdriver inserted into the hole in the sheave drum, so that the spiral spring will not spring out.

WARNING

When removing the sheave drum, be sure t o se t th e spring fr ee a nd re mov e the sheave retainer bolt. Otherwise, the spiral spring may jump out, endangering other person.

5-4

3. Remove:

• Spiral spring

1

NOTE:

Hold the spring with one hand, and unfold the spring from its center with the other hand. Be careful so that the spring does not jump out.

POWR

RECOIL STARTER

E

WARNING

When removing or installing the spiral spring, use care not to injure your hand. It is advisable to wear gloves.

4. Check:

• Bushing

1

Cracks/damage/wear

→

Replace.

5. Check:

• Spiral spring

1

Bent/broken/damage

→

Replace.

6. Check:

• Starter rope

1

Damage/frays/wear

→

Replace.

7. Check:

• Sheave drum

1

• Starter case

2

Cracks/damage/wear

→

Replace.

5-5

POWR

RECOIL STARTER

8. Check:

• Drive pawl

1

Cracks/damage/wear

→

Replace.

• Return spring

2

• Friction spring

3

Bent/broken/damage

→

Replace.

E

ASSEMBLING THE RECOIL STARTER

CAUTION:

New spiral springs come held in a steel hoop. To install, hook the outer end onto the spring pin first, place into the starter case, and then remove the steel hoop.

1. Install:

• Starter case

1

• Thrust washer

2

• Spiral spring

3

NOTE:

Hook the outer end

4

of the spiral spring onto the spring pin attached to the starter case, and put the spring into the starter case by winding it counterclockwise.

WARNING

When removing or installing the spiral spring, use care not to injure your hand. It is advisable to wear gloves.

5-6

POWR

RECOIL STARTER

E

2. Install:

• Starter rope

1

• Sheave drum

2

NOTE:

• Insert the rope through the rope hole and knot the end as shown.

• Wind the rope 1-1/2 turns counterclockwise onto the sheave drum.

• Place the rope at the cutaway

3

.

WARNING

• Do not use a damaged starter rope, it could cause injury.

1

1

2

3. Install:

• Bushing

1

NOTE:

Mount the bushing on the starter case shaft.

5-7

4. Install:

• Sheave drum

1

NOTE:

While turning the sheave drum, fit the sheave drum shaft slot into the spiral spring hook, and then place the sheave drum shaft into the starter case boss.

5. Install:

• Return spring

1

• Drive pawl

2

NOTE:

Hook the end of the return spring onto the drive pawl, and check to see that the drive pawl returns smoothly.

POWR

3

2

1

RECOIL STARTER

6. Install:

• Friction plate

1

• Collar 1

2

• Friction spring

3

7. Install:

• Friction plate

1

(with friction spring etc.)

• Center bolt

2

• Nut

3

.

T

R

.

Center bolt

15 N

•

m (1.5 kgf

•

m, 11 ft

•

lb)

Nut

10 N

•

m (1.0 kgf

•

m, 7.4 ft

•

lb)

E

8. Install:

• Starter rope

1

• Damper

2

• Starter handle-grip

3

• Cover

4

5-8

POWR

RECOIL STARTER

E

NOTE:

• Set the sheave drum so that the cut in the sheave drum is diametrically opposite the starter handle-grip.

• Pass the rope through the starter handle-grip, and make a knot in the end of the rope as shown.

• After assembling, wind the rope 3 turns counterclockwise around the sheave drum to contract the spring.

• By pulling out the rope, check the operation of the starter.

INSTALLING THE RECOIL STARTER

Install:

• Recoil starter

1

• Starter stop wire

2

Refer to the "ADJUSTING THE START-

IN-GEAR PROTECTION DEVICE" on page 3-17.

5-9

POWR

FLYWHEEL MAGNET

FLYWHEEL MAGNET

REMOVIING THE FLYWHEEL MAGNET

E

Step Job/Part

1 Bolt

2 Starter pulley

3 Nut

4 Washer

5 Flywheel magnet

6 Woodruf key

Q’ty

3

1

1

1

1

1

Remarks

5-10

POWR

FLYWHEEL MAGNET

Remove:

• Flywheel magnet

Removing steps

(1) Remove the starter pulley

(2) Remove the flywheel magnet nut.

Flywheel holder

90890-06522

E

NOTE:

The major load should be applied in the direction of the arrows. If the load is not applied as shown, the flywheel holder may easily slip off of the flywheel magnet.

(3) Remove the flywheel magnet.

Flywheel puller

90890-06521

NOTE:

• The major load should be applied in the direction of the arrows.

• Apply the load until the flywheel magnet comes off the tapered portion of the crankshaft.

CAUTION:

To prevent damage to the engine or tools, screw in the flywheel puller set-bolts evenly and completely so that the puller plate is parallel to the flywheel magnet.

5-11

INSTALLING THE FLYWHEEL MAGNET

Install:

• Flywheel magnet

Flywheel holder

90890-06522

NOTE:

The major load should be applied in the direction of the arrows. If the load is not applied as shown, the flywheel holder may easily slip off of the flywheel magnet.

POWR

POWER UNIT

POWER UNIT

DISCONNECTING THE LEADS AND STAYS

E

Step

1 Bolt

2 Washer

3 Bolt

4 Electrical unit

5 Bolt

6 Earth lead

7 Bolt

8 Bolt

9 Stay

10 Bolt

11 Stay

12 Bolt

13 Stay

Job/Part

5-12

Q’ty

2

1

1

1

4

2

1

1

1

2

1

1

1

Remarks


POWR

POWER UNIT

E

Step

14 Bolt

15 CDI unit

16 Bolt

17 Ignition coil

18 Bracket

19 Pipe

20 Damper

21 Grommet

Job/Part Q’ty

2

2

2

1

1

4

4

1

Remarks

5-13

POWR

POWER UNIT

REMOVING THE POWER UNIT

E

Step Job/Part

1 Cotter pin

2 Washer

3 Wavewasher

4 Throttle cable 1

5 Throttle cable 2


7 Power unit

8 Dowel pin

9 Gasket

5-14

Q’ty

1

1

6

1

1

Not reusable

1

1

2

1

Not reusable

Remarks

POWR

MAGNET BASE AND CONTROL LEVER


REMOVING THE MAGNET BASE AND MAGNET CONTROL LEVER

E

Step Job/Part

1 Clamp

2 Joint link

3 Bolt

4 Magnet base

5 Screw

6 Change coil

7 Screw

8 Lighting coil

9 Screw

10 Pulser coil

11 Screw

12 Magnet base retainer 2

13 Magnet base retainer 1

5-15

Q’ty

2

1

2

1

1

1

4

1

4

2

4

1

1

Remarks


POWR


E

Step Job/Part

14 Magnet base friction plate

15 Joint link


17 Collar

18 Magneto control lever


20 Throttle cable stay


22 Collar

23 Arm

5-16

Q’ty

1

1

1

1

1

1

1

1

1

1

Remarks

POWR

INTAKE MANIFOLD AND REED VALVES


REMOVING THE INTAKE MANIFOLD AND REED VALVES

E

Step Job/Part



3 Clamp (Fuel hose)


5 Intake manifold

6 Intake manifold gasket

7 Reed valve

8 Gasket

Q’ty

1

2

1

6

1

1

Not reusable

1

1

Not reusable

Remarks

5-17

POWR


CHECKING THE REED VALVES

1. Check:

• Reed valve

1

Cracks/damage

→

Replace.

E

2. Measure:

• Valve bending a


→

Replace.

Valve bending limit

0.2 mm (0.008 in)

3. Measure:

• Valve stopper height b


→

Replace.

Valve stopper height

Standard:

3.46 - 3.50 mm (0.136 - 0.138 in) for Sri Lanka:

4.20 - 4.60 mm (0.165 - 0.181 in)

INSTALLING THE INTAKE MANIFOLD

Install:

• Intake manifold

NOTE:

• Tighten the intake manifold mounting bolts in two steps of torque.

• Apply LOCTITE

®

No.572 on the bolts.

.

T

R

.

Intake manifold mounting bolt

1st: 4 N

•

m (0.4 kgf

•

m, 3.0 ft

•

lb)

2nd: 8 N

•

m (0.8 kgf

•

m, 5.9 ft

•

lb)

5-18

POWR

CYLINDER HEAD

CYLINDER HEAD

REMOVING THE CYLINDER HEAD

E

Step Job/Part

1 Spark plug

2 Hose


4 Thermostat cover

5 Gasket

6 Plain washer

7 Thermostat



10 Cylinder head cover

11 Head cover gasket

12 Cylinder head

13 Cylinder head gasket

5-19

Q’ty

2

1

3

1

1

Not reusable

1

1

11

2

1

1

Not reusable

1

1

Not reusable

Remarks

POWR

CYLINDER HEAD

E

CHECKING THE CYLINDER HEAD

1. Check:

• Combustion chamber

Carbon deposits

→

Clean.

• Water jacket

Mineral deposits/rust

→

Clean.

CAUTION:

Do not scratch the contacting surface of the cylinder head and cylinder head cover.

2. Measure:

• Cylinder head warpage

(use a straightedge and thickness gauge)


→

Resurface/ replace.

Warpage limit

0.1 mm (0.004 in)

Resurfacing steps

(1) Place a 400 – 600 grit wet sandpaper on the surface plate.

(2) Resurface the cylinder head by moving it in a figure-eight motion along the sandpaper.

NOTE:

Rotate the cylinder head several times to ensure an even surface.

5-20

POWR

CYLINDER HEAD

CHECKING THE THERMOSTAT

1. Check:

• Thermostat

Damage/stick

→

Replace.

E

2. Measure:

• Valve opening temperature

• Valve lift


→

Replace.

W a e r e

B e o w m p

48

1 1 8 – 1 2

A b o v

1 40 e

–

V a ve lifffftttt

0 mm n .

1

3

2 m m

Measuring steps

(1) Suspend the thermostat in a container filled with water.

(2) Place a thermometer in the water.

(3) Slowly heat the water.

(4) While stirring the water, check that the thermostat opens at the specified temperature.

5-21

POWR

CYLINDER HEAD

E

INSTALLING THE CYLINDER HEAD

AND CYLINDER HEAD COVER

Install:

• Cylinder head

3

and cylinder head cover

1

NOTE:

• Temporarily assemble; cylinder head cover

1

, cylinder head cover gasket

2

,

3 gasket

4

in that order, and then install the assembled parts onto the crankcase.

• Apply LOCTITE

®


• Tighten the cylinder head mounting bolts and nut in sequence and in two steps of torque.

.

T

R

.

Cylinder head mounting bolts

1st: 15 N

•

m (1.5 kgf

•

m, 11 ft

•

lb)

2nd:30 N

•

m (3.0 kgf

•

m, 22 ft

•

lb)

5-22

INSTALLING THE THERMOSTAT

Install:

• Thermostat

1

• Plain washer

2

• Gasket

3

• Thermostat cover

4

• Bolt

5

NOTE:

• Always use the new gasket.

• Tighten the bolts in sequence.

.

T

R

.

Thermostat cover bolts

8 N

•

m (0.8 kgf

•

m, 5.9 ft

•

lb)

POWR

EXHAUST COVER

EXHAUST COVER

REMOVING THE EXHAUST COVER

E

Step Job/Part



3 Exhaust outer cover

4 Gasket

5 Exhaust inner cover

6 Gasket

Q’ty

12

3

1

1

Not reusable

1

1

Not reusable

Remarks

5-23

POWR

EXHAUST COVER

E

CHECKING THE EXHAUST COVER

Check:

• Exhaust inner cover

Cracks/damage

→

Replace.

Carbon deposits

→

Clean.

(use a round scraper)

• Exhaust outer cover

Cracks/damage

→

Replace.

CAUTION:

Do not scratch the fitting surfaces of the cylinder and exhaust cover.

INSTALLING THE EXHAUST COVER

Install:

• Exhaust cover

NOTE:

• Apply LOCTITE

®


• Tighten the exhaust cover mounting bolts in sequence and in two steps of torque.

.

T

R

.

Exhaust cover mounting bolts

1st: 4 N

•

m (0.4 kgf

•

m, 3.0 ft

•

lb)

2nd: 8 N

•

m (0.8 kgf

•

m, 5.9 ft

•

lb)

5-24

POWR

CRANKCASE

CRANKCASE

REMOVING THE CRANKCASE

E

Step Job/Part



3 Crankcase


5 Oil seal housing

6 O-ring

7 Oil seal

8 Oil seal

Q’ty

8

2

1

1

1

1

Not reusable

1

Not reusable

2

Not reusable

Remarks

5-25

POWR

CRANKCASE

1

3

2

3

E

ASSEMBLING THE OIL SEAL

HOUSING

Install:

• Oil seal

Needle bearing attachment .........

1

90890-06608

Ball bearing attachment...............

2

90890-06633

Driver rod L3 ..................................

90890-06652

3

NOTE:

Apply Yamaha grease A (water resistant grease) on the oil seals.

5-26

IINSTALLING THE CRANKCASE

1. Apply:

• Gasket Maker®

Applying steps

(1) Clean the matching surfaces of the crankcase and cylinder body.

(2) Apply Gasket Maker® onto the matching surfaces of the cylinder body and the crankcase.

(3) Also apply Gasket Maker® on the oil seal housing.

NOTE:

Do not allow any sealant to overflow from the matching surfaces.

2. Install:

• Oil seal housing

1

NOTE:

Do not give any damage to the lip when installing the oil seal.

POWR

CRANKCASE

E

3. Install:

• Crankcase

NOTE:

• Apply LOCTITE

®


• Tighten the crankcase mounting bolts in sequence and in two steps of torque.

.

T

R

.

Crankcase mounting bolts

1st: 15 N

•

m (1.5 kgf

•

m, 11 ft

•

lb)

2nd: 30 N

•

m (3.0 kgf

•

m, 22 ft

•

lb)

5-27

POWR

CRANKSHAFT AND CYLINDER BODY


REMOVING THE CRANKSHAFT AND CYLINDER BODY

E

1

5

8

3

7

6

5

3

4

Step Job/Part

1 Crankshaft

2 Cylinder body

3 Piston pin clip

4 Piston pin

5 Piston pin washer

6 Small end bearing

7 Piston ring

8 Piston

Q’ty

1

1

4

2

4

68 34 pins/1set

4

2

Remarks

2

5-28

POWR


E

CHECKING THE CYLINDER BODY

1. Check:

• Cylinder inner surface

Score mark

→

Repair/replace.

(use #600 – 800 grit wet sandpaper)

• Water jacket

Mineral deposits/rust/corrosion

→

Clean/replace.

CAUTION:

Do not scratch the contacting surfaces of the crankcase and cylinder head.

2. Check:

• Exhaust passage

Cracks/damage

→

Replace.

Carbon deposits

→

Clean.

(use a round scraper)

CAUTION:

Do not scratch the contacting surfaces of the cylinder and exhaust cover.

D

1

D

2

3. Measure:

• Cylinder bore “D”

(use a cylinder gauge)


→

Rebore/replace.

Cylinder gauge

90890-06759

NOTE:

Measure the cylinder bore diameter at three positions for both D1 and D2. Then, average the measurement.

5-29

POWR


E a n d a W ea r li m

C y li n d e r b a m e r “ D

T a p e r li

“ T ”

7 2 0 0

83 4

7

6

2

–

02

2 mm

83 5 4

1 0

8 386

0 8 mm

0 0 31

O u t o oun d li m t “ R ”

0 5 mm

0 0 20

D = M a x m u m D 1 , D 2 , D 3 , D 4 , D 5 o r D 6

T = M ax m u m D 1 o r D 2 ) m u m D 5 o r D 6))))

= M a x m u m D 1 – D 2 ) o r D 3 – D 4 ) o r D 5 – D

A: 15 mm (0.59 in) below the cylinder top

B: 25 mm (0.98 in) above the exhaust port

C: 100 mm (3.94 in) below the scavenging port

CHECKING THE PISTON

1. Check:

• Piston wall

Wear/scratch/damage

→

Replace.

2. Check:

• Piston head

• Piston ring groove

Carbon deposits

→

Clean.

CAUTION:

Take care not to scratch or cut the aluminum surface.

5-30

POWR


3. Measure:

• Piston diameter

(use an outside micrometer)


→

Replace.

Outside micrometer

90890-03008

E

Measuring point “H”

a nd a

O ve r s e p

1 : 2 5

2 : 5 0

10.0 mm

(0.3937 in)

a m

84 4 5

85 4 3

Piston diameter

71.94 – 71.96 mm

(2.8323 – 2.8331 in)

NOTE:

When measuring the piston diameter, position the micrometer in relation to the piston pin hole as shown.

b c a

5-31

CALCULATING THE

PISTON-TO-CYLINDER CLEARANCE

Calculate:

• Piston-to-cylinder clearance.


→

Replace the piston and piston rings, the cylinder or both.

Piston-tocylinder clearance

=

Cylinder bore diameter

–

Piston diameter

Piston-to-cylinder clearance

0.060 – 0.065 mm

(0.0024 – 0.0026 in)

POWR


CHECKING THE PISTON PINS AND

SMALL-END BEARINGS

1. Check:

• Piston pin

• Small-end bearing

Heat discoloration

→

Replace.

Damage/scratches

→

Replace.

E

2. Measure:

• Piston pin outside diameter

(use an outside micrometer)


→

Replace.

Outside micrometer

90890-03006

Piston pin outside diameter

19.895 – 19.900 mm

(0.7833 – 0.7835 in)

3. Measure:

• Piston pin boss inside diameter

(use an inside micrometer)


→

Replace.

Inside micrometer

90890-03010

Piston pin boss inside diameter

19.904 - 19.915 mm

(0.7836 - 0.7841 in)

5-32

POWR


E

4. Check:

• Free play (when piston pin is in place of the piston).

There should be no noticeable play.

Free play exists

→

Replace the pin and/or piston.

CHECKING THE PISOTN RINGS

NOTE:

• Before checking the piston rings, be sure to check the cylinder body.

• Piston rings should be replaced as a set

(per piston).

1. Check:

• Piston ring

Broken/damage

→

Replace.

2. Measure:

• Piston ring end gap a

(use a thickness gauge)


→

Replace.

Piston ring end gap

0.20 - 0.35 mm (0.0079 - 0.0137 in)

Piston ring end gap limit

0.35 mm (0.014 in)

Measuring point “H”

15 mm (0.591 in)

5-33

POWR


E

NOTE:

Push the piston ring into the cylinder with the piston crown.

3. Measure:

• Piston ring side clearance b

(use a thickness gauge)


→

Replace.

Piston ring side clearance

Top: 0.03 - 0.05 mm

(0.0012 - 0.0020 in)

2nd: 0.03 - 0.07 mm

(0.0012 - 0.0028 in)

NOTE:

When measuring the piston ring side clearance, the outside of the piston ring should be flush with the piston wall.

5-34

CHECKING THE CRANKSHAFT

1. Measure:

• Crank width

(use the digital caliper)


→

Repair/replace.

Crank width

a

56.90 - 56.95 mm

(2.2401 - 2.2421 in)

Crank width

b

153.7 - 154.0 mm

(6.0512 - 6.0630 in)

Crank width

c

39.9 - 40.1 mm

(1.5709 - 1.5787 in)

POWR


E

2. Measure:

• Runout

(Use a crank stand alignment and dial gauge.)


→

Repair/replace.

Crank stand alignment

90890-03107

Dial gauge set

90890-01252

Runout limit

d

0.03 mm (0.0012 in)

3. Measure:

• Connecting rod side clearance

(Use a thickness gauge.)


→

Repair/replace.

Connecting rod side clearance

e

0.2 - 0.7 mm (0.0079 - 0.0276 in)

4. Measure:

• Axial play


→

Repair/replace.

Maximum axial play

2.0 mm (0.079 in)

f

5-35

POWR


E

5. Check:

• Crankshaft bearings

Abnormal noise/damage / roughness

→

Replace.

CAUTION:

Do not use compressed air to spin the bearings dry. This causes damage to the bearing surfaces.

NOTE:

Do not reuse the bearing, always replace it with a new one.

5-36

POWR


E

INSTALLING THE PISTON AND

PISTON RINGS

Install:

• 2nd piston ring

• Top piston ring

CAUTION:

• Install the piston ring with the T mark facing up.

• Align each piston ring end gap with its respective locating pin.

• After installing the piston rings, check that they move smoothly.

NOTE:

Apply Yamaha 2-stroke motor oil on the piston ring and piston ring groove.

INSTALLING THE CRANKSHAFT AND

PISTON

1. Install:

• Small-end bearing

Needles per piston

34 pieces

5-37

Small-end bearing installer

90890-06527

2. Install:

• Piston

Installing steps

(1) Assemble the washer a

and the piston to the crankshaft.

(2) Push out the small-end bearing installer with piston pin.

(3) Install circlip.

CAUTION:

Install the piston with “UP” mark on the piston crown facing towards the flywheel side.

NOTE:

Apply Yamaha 2-stroke motor oil on the small-end bearing and piston pin.

POWR

3

1


2

3. Install:

• Cylinder body

1

• Crankshaft and piston

2

• Dowel pin

3

3

E

NOTE:

• Apply Yamaha 2-stroke motor oil to each cylinder wall and piston and their ring grooves.

• Coat all the crankshaft bearings with the engine oil.

• The crankshaft bearing locating pin should fit into the slit in the cylinder.

• The UP mark on the piston crown should be on the flywheel side.

1

1

CHECKING THE ANODE

Check:

• Anode

1

Wear

→

Replace.

Corrosion

→

Sand.

NOTE:

When it is reduced to the size of one-third

(1/3), replace it.

5-38

POWR

CRANK SHAFT

CRANK SHAFT

DISASSEMBLING THE CRANKSHAFT

E

Step

1 O-ring

2 Oil seal

3 Bearing

4 Collar

5 Crank 1

6 Crank pin

7 Washer

8 Connecting rod

9 Bearing

10 Crank 2

11 Bearing

12 Labyrinth seal

13 Clip

Job/Part

5-39

Q’ty

2

1

1

1

1

2

4

2

1

1

1

Not reusable

1

Not reusable

1

Remarks


POWR

CRANK SHAFT

E

Step

14 Crank 3

15 Crank 4

16 Bearing

17 Washer

Job/Part Q’ty

1

1

1

1

Remarks

5-40

POWR

OK

CRANK SHAFT

E

REMOVING THE CRANKSHAFT

BEARING

Upper bearing

1. Remove:

• Upper bearing

1

Remove the upper bearing with hands.

2. Remove:

• Collar

Pressure pin B ...............................

90890-02390

Bearing separator .........................

90890-06534

a

2

NOTE:

• By forcing the pressure pin B a

with a hydraulic press, remove the bearing.

• When forcing out the crank pin, use care so that the crankshaft does not fall off.

• The upper bearing and the collar should always be replaced as a set.

• Once removed, do not reuse the collar.

Always replace it with a new one.

1

2 a

5-41

Lower bearing

Remove:

• Lower bearing

1

Pressure pin B ...............................

90890-02390

Bearing separator .........................

90890-06534

a

2

NOTE:

• By forcing the pressure pin B a

with a hydraulic press, remove the bearing.

• When forcing out the crank pin, use care so that the crankshaft does not fall off.

CAUTION:

• Apply pressure to the pressure pin B slowly.

a

• Hold the pressure pin in line with the press screw spindle.

POWR

CRANK SHAFT

1 a

E

Crank 1 and crank 4 removal

Remove:

• Crank 1

• Crank 4

Plate A............................................

90890-02386

Pressure pin B ...............................

90890-02390

1 a

Removing steps

(1) By forcing the pressure pin B a

with a hydraulic press, remove the crank pin.

(2) When forcing out the crank pin, use care so that the crankshaft does not fall off.

(3) To remove crank 4, follow the same procedure.

CAUTION:

• Apply pressure to the pressure pin B slowly.

a

• Hold the pressure pin B

a

in line with the press screw spindle.

1 b

5-42

Crank 2 and crank 3 removal

1. Remove:

• Crank 2

• Crank 3

Support..........................................

90890-02394

Pressure pin B ...............................

90890-02390

1 a

NOTE:

• Place the pressure pin B a

on the crank

2 center shaft b

, and force it out using a press.

• When forcing out the crank pin, use care so that the crank does not fall off.

POWR

CRANK SHAFT

E

CAUTION:

• Apply pressure to the pressure pin B

a

slowly.

• Hold the pressure pin B

a

in line with the press screw spindle.

OK

2. Remove:

• Labyrinth seal

1

• Clip

2

1

2

3. Remove:

• Bearing

Removing steps

(1) Remove roller bearing (outer race)

(2) Remove roller bearing (inner race) using hydraulic press.

Bearing separator

90890-06534

5-43

POWR

CRANK SHAFT

E

Crank pin removal

Remove:

• Crank pin

Plate A............................................

90890-02386

Pressure pin B ...............................

90890-02390

1 a

Removing steps

(1) By forcing the pressure pin B a

with a hydraulic press, remove the crank pin.

(2) Remove the crank pins from Crank 2 and Crank 3.

(3) Pressure pin should be pressed down straight.

4

5

ASSEMBLING THE CRANKSHAFT

CAUTION:

• When reassembling the crankshaft, wash all component parts in suitable cleaning solvent.

• Always use new bearings and crank pins.

5-44

Fitting the crank pin

(to the crank 2 and crank 4)

1. Install:

• Spacer B

1

(to crank pin hole)

• Crank 2

3

Spacer B ........................................

90890-02396

Support..........................................

90890-02394

1

2

2. Install:

• Crank pin

4

(new)

NOTE:

• Insert the crank pin into the pin hole by tapping it with a copper hammer

5

.

• Apply Yamaha 2-stroke motor oil on the crank pin.

POWR

CRANK SHAFT

E

3. Press-fit:

• Crank pin

4

NOTE:

• Don’t apply force in excess of 5 tons.

• The crank pin should be press-fitted into both crank 2 and crank 4.

CAUTION:

Take care so that the crank pin

4

is set squarely to the crank web

6

.

5-45

Assembling cranks 1 and 2,3 and 4

1. Install (special service tools):

• Flange

1

• Body

2

• Bolt

• Washer

• Bushing-5 (D25)

3

• Height ring-13 (H57)

4

NOTE:

Align the cut in the height ring a

with cut in the body b

.

Flange ............................................

90890-02351

Body ...............................................

90890-02352

Bolt

90890-02353

Washer

90890-02354

Bushing-5 (D25) ...........................

90890-02359

Height ring-13 (H57) ....................

90890-02379

3

4

1

2

POWR

9

2

8

CRANK SHAFT

3 c

E

2. Install:

• Crank 2

5

or crank 4

• Washer

6

• Bearing

7

NOTE:

Apply Yamaha 2-stroke motor oil on the washer and big end bearing.

3. Install:

• Connecting rod

8

• Washer

9

CAUTION:

• The model No.

c

facing upward (crank

1 or crank 3 side).

• Apply Yamaha 2-stroke motor oil on the connecting rod and washer.

4. Install (special service tools):

• Pressure plate

1

• Bushing-14 (for crank 1)or Bushing-

12 (for crank 3)

2

5. Install:

• Crank 1

3

or crank 3 (on the bushing)

Bushing-14 (for crank 1) ...............

90890-02419

Bushing-12 (D35) (for crank 3) ....

90890-02366

Pressure plate................................

90890-02384

2

2

1

1

5-46

6. Install:

• Crank 1

1

or crank 3

(use pressure plate)

NOTE:

• Align the crank pin hole

2

with the crank pin

3

fitted to crank 2 or crank 4.

• Apply Yamaha 2-stroke motor oil on the crank 1 or crank 3.

POWR

CRANK SHAFT

E

7. Press-fit:

• Crank 1 or crank 3

Press body ....................................

90890-02385

4

CAUTION:

• Be sure to press-fit the crank 1 or crank

3 squarely onto the crank pin.

• Apply Yamaha 2-stroke motor oil on the crank pin.

a

8. Measure:

• Crank width a

Use the digital caliper.


→

Reassemble/ repress.

Digital caliper

90890-06704

Measurements should be made at

1

to

5

.

Crank width

a

56.90 - 56.95 mm

(2.2401 - 2.2421 in)

NOTE:

If either distance is out of specification, reassemble or repress the crankshaft.

5-47

POWR

CRANK SHAFT

E

9. Measure:

• Connecting rod side clearance e

(Use the thickness gauge.)


→

Reassemble.

Thickness gauge (mm)

90890-06054

Connecting rod side clearance

e

0.2 - 0.7 mm (0.0079 - 0.0276 in)

NOTE:

If side clearance exceeds tolerance, disassemble the crankshaft and replace any worn parts.

3 a

10. Install:

• Roller bearing (on the crank 2)

1

11. Press-fit:

• Roller bearing (inner race)

2

NOTE:

• Position the roller bearing with the stamped mark a facing upward and press-fit it until it contacts the crank 2.

• Apply Yamaha 2-stroke motor oil on the roller bearing.

Plate A............................................

90890-02386

Bearing pressure B........................

90890-02392

b c

CAUTION:

B e sure to p re ss -f it the rol le r b ea rin g squarely onto crank 2.

12. Install:

• Roller bearing (outer race)

3

5-48

POWR

CRANK SHAFT

E

Connecting the No. 1 cylinder crankshaft to the No. 2 cylinder crankshaft

1. Install:

• Labyrinth seal

1

(to crank 3

2

)

• Clip

3

Plate A

90890-02386

NOTE:

Apply Yamaha 2-stroke motor oil on the labyrinth seal.

2. Install:

• Plate B

1

(between crank 1 and crank 2)

• Crank 1 and crank 2

2

(on the crank

Plate B............................................

90890-02387

1

CAUTION:

• Align the match marks and 2.

a

on crank 3

• Apply Yamaha 2-stroke motor oil on the crank 3 and 2.

5-49

3. Press-fit:

• Crank 2 and crank 3

(apply a force of 7 ton)

Height ring-13 (H57) .....................

90890-02379

Press body .....................................

90890-02385

1

2

POWR

CRANK SHAFT

E

CAUTION:

Be sure to press-fit the No. 1 crank squarely onto No. 2 crank.

2

1 a

INSTALLING CRANKSHAFT BEARING

Lower bearing (for crank 4)

1. Install:

• Bearing

1

(to crank 4

2

)

Bearing pressure B

90890-02392

CAUTION:

• Install the bearing with its stamped

a

• Apply Yamaha 2-stroke motor oil on the bearing.

• Be sure to press-fit the ball bearing squarely onto crank 4.

5-50

Upper bearing (for crank 1)

1. Install:

• Collar

3

Bushing-5 (D25) ............................

90890-02359

Bearing pressure C........................

90890-02393

a b

2. Install:

• Upper bearing

4

(to crank 1)

Install the upper bearing with hands.

NOTE:

Apply Yamaha grease A (water resistant grease) on the collar and upper bearing.

POWR

CRANK SHAFT

E

Run-out check

1. Measure:

• Runout

Use the crank stand alignment

1 and digital gauge

2

.


→

Adjust.

Crank stand alignment

90890-03107

Digital gauge set

90890-01252

Runout limit

0.03 mm (0.0012 in)

NOTE:

If the dial gauge reading is 0.03 mm (0.0012

in) or more, adjust the crankshaft so that the reading is less than 0.03 mm (0.0012 in).

Use a copper hammer, as shown.

2. Measure:

• Axial play


→

Repair/replace.

Maximum axial play “

f

”

2.0 mm (0.079 in)

CHECKING THE CRANKSHAFT

Refer to "CHECKING THE CRANKSHAFT" on page 5-34.

5-51

LOWR

CHAPTER 6

LOWER UNIT

LOWER UNIT .................................................................................................. 6-1

REMOVING THE LOWER UNIT ............................................................... 6-1

REMOVING THE PROPELLER ................................................................. 6-3

CHECKING THE PROPELLER .................................................................. 6-3

INSTALLING THE PROPELLER ............................................................... 6-3

INSTALLING THE TRIM TAB ................................................................... 6-3

WATER PUMP ................................................................................................ 6-4

REMOVING THE WATER PUMP ............................................................. 6-4

CHECKING THE WATER PUMP HOUSING ............................................ 6-5

CHECKING THE IMPELLER AND INSERT CARTRIDGE ........................ 6-5

CHECKING THE WOODRUFF KEY ......................................................... 6-5

INSTALLING THE IMPELLER AND WATER PUMP HOUSING .............. 6-5

SHIFT ROD ..................................................................................................... 6-6

REMOVING THE SHIFT ROD .................................................................. 6-6

PROPELLER SHAFT HOUSING ..................................................................... 6-7

REMOVING THE PROPELLER SHAFT HOUSING .................................. 6-7

DISASSEMBLING THE PROPELLER SHAFT HOUSING ....................... 6-8

DISASSEMBLING THE PROPELLER SHAFT .......................................... 6-9

REMOVING THE PROPELLER SHAFT HOUSING ................................ 6-10

DISASSEMBLING THE PROPELLER SHAFT HOUSING ..................... 6-10

CHECKING THE REVERSE GEAR ......................................................... 6-11

CHECKING THE BEARING .................................................................... 6-11

CHECKING THE PROPELLER SHAFT HOUSING ................................. 6-11

ASSEMBLING THE PROPELLER SHAFT HOUSING ........................... 6-12

CHECKING THE DOG CLUTCH ............................................................ 6-13

CHECKING THE PROPELLER SHAFT ................................................... 6-13

CHECKING THE SHIFT PLUNGER ........................................................ 6-13

CHECKING THE SHIFT SPRING ........................................................... 6-13

DRIVE SHAFT ............................................................................................... 6-14

REMOVING THE DRIVE SHAFT ............................................................ 6-14

REMOVING THE DRIVE SHAFT ............................................................ 6-15

REMOVING THE DRIVE SHAFT BEARING .......................................... 6-15

DISASSEMBLING THE FORWARD GEAR ............................................ 6-15

CHECKING THE PINION AND FORWARD GEAR ................................ 6-16

CHECKING THE DRIVE SHAFT ............................................................. 6-16

CHECKING THE BEARINGS ................................................................. 6-16

ASSEMBLING THE FORWARD GEAR .................................................. 6-16

INSTALLING THE DRIVE SHAFT BEARING ......................................... 6-16

INSTALLING THE DRIVE SHAFT .......................................................... 6-17

LOWER CASE ............................................................................................... 6-18

DISASSEMBLING THE LOWER CASE .................................................. 6-18

E

LOWR

CHECKING THE DRIVE SHAFT SLEEVE .............................................. 6-19

CHECKING THE NEEDLE BEARING ..................................................... 6-20

ASSEMBLING THE LOWER CASE ........................................................ 6-20

SHIMMING ................................................................................................... 6-21

SELECTING THE PINION SHIMS ......................................................... 6-22

SELECTING THE FORWARD GEAR SHIMS ......................................... 6-24

SELECTING THE REVERSE GEAR SHIMS ........................................... 6-26

BACKLASH ................................................................................................... 6-28

MEASURING THE FORWARD GEAR BACKLASH ............................... 6-28

MEASURING THE REVERSE GEAR BACKLASH ................................. 6-29

E

3

4

5

1

2

8

9

6

7

LOWR

LOWER UNIT

6

LOWER UNIT

REMOVING THE LOWER UNIT

E

Step Job/Part

1 Cotter pin

2 Castle nut

3 Washer

4 Spacer

5 Propeller

6 Spacer

7 Nut

8 Shift connector


10 Trim tab

11 Bolt

12 Anode

13 Screw

6-1

Q’ty

1

1

1

1

2

1

1

1

1

1

1

Not reusable

1

1

Remarks


LOWR

LOWER UNIT

E

Step Job/Part

14 Nut

15 Water inlet cover 1

16 Water inlet cover 2

17 Gear oil level check screw

18 Gasket

19 Gear oil drain screw

20 Gasket

21 Bolt

22 Nut

23 Lower unit

24 Pin

25 Extension

26 Pin

6-2

Q’ty

1

1

2

1

1

1

1

4 Transom S, L

4 Transom Y

1

2

1 Transom Y

2 Transom Y

Remarks

LOWR

LOWER UNIT

6-3

E

REMOVING THE PROPELLER

Remove:

• Propeller

WARNING

Do not hold the propeller with your hands when removing or installing it. Be sure to remove the battery leads from the batteries and the lanyard engine stop switch. Put a block of wood between the cavitation plate and propeller to keep the propeller from turning.

CHECKING THE PROPELLER

Check:

• Blades

• Splines

Bent/cracks/damage/wear

→

Replace.

• Bushing

Slippage

→

Replace.

INSTALLING THE PROPELLER

Install:

• Propeller

WARNING

Do not hold the propeller with your hands when removing or installing it. Be sure to remove the battery leads from the batteries and the lanyard engine stop switch. Put a block of wood between the cavitation plate and propeller to keep the propeller from turning.

NOTE:

If the groove in the propeller nut is not aligned with the cotter pin hole, tighten the nut further until they are aligned.

INSTALLING THE TRIM TAB

Install:

• Trim tab

NOTE:

• To ease installation, mark the original position of the trim tab.

• Steering load varies depending on the trim tab position as installed.

LOWR

WATER PUMP

WATER PUMP

REMOVING THE WATER PUMP

E

Step Job/Part

1 Bolt

2 Plate

3 Water tube

4 O-ring

5 O-ring

6 Water seal rubber

7 Water pump housing

8 Insert cartridge

9 O-ring

10 Impeller

11 Impeller plate

12 Dowel pin

13 Woodruff key

6-4

Q’ty

4

1 Transom S, L

1

1

1

1

Not reusable

1

Not reusable

1

1

1

1

Not reusable

1

1

Remarks

LOWR

WATER PUMP

CHECKING THE WATER PUMP

HOUSING

Check:

• Water pump housing

Cracks/damage

→

Replace.

CHECKING THE IMPELLER AND

INSERT CARTRIDGE

Check:

• Impeller

• Insert cartridge

Cracks/damage/wear

→

Replace.

CHECKING THE WOODRUFF KEY

Check:

• Woodruff key

Damage/wear

→

Replace.

E

INSTALLING THE IMPELLER AND

WATER PUMP HOUSING

Install:

• Impeller

1

• Insert cartridge

2

• Water pump housing

3

NOTE:

• When installing the insert cartridge

2

, align its projection with the hole in the water pump housing

3

.

• When installing the water pump housing, turn the drive shaft clockwise.

• Apply Yamaha grease A (water resistant grease) on the impeller

1

, the insert cartridge

2

, and the water pump

6-5

LOWR

SHIFT ROD

SHIFT ROD

REMOVING THE SHIFT ROD

E

Step Job/Part

Impeller plate

1 Bolt

2 Bracket

3 Plate

4 O-ring

5 Oil seal housing

6 Lower casing packing

7 Dowel pin

8 Shift rod

9 Rubber seal

10 Oil seal

6-6

Q’ty Remarks

1

1

2

Refer to "WATER PUMP" on page 6-4.

2

1

1

1

Not reusable

1

1

Not reusable

1

LOWR

PROPELLER SHAFT HOUSING


REMOVING THE PROPELLER SHAFT HOUSING

E

Step

Gear oil

Job/Part

Shift rod assembly

1 Bolt

2 Propeller shaft housing

3 Washer

4 Propeller shaft

2

1

1

1

Q’ty Remarks

Refer to "CHANGING AND CHECKING

THE GEAR OIL" on page 3-19.

Refer to "SHIFT ROD" on page 6-6.

6-7

LOWR


DISASSEMBLING THE PROPELLER SHAFT HOUSING

E

Step Job/Part

1 O-ring

2 O-ring

3 Reverse gear

4 Reverse gear shim

5 Ball bearing

6 Oil seal

7 Needle bearing

8 Propeller shaft housing

9 Washer

* As required

6-8

Q’ty

*

1

2

1

1

1

1

Not reusable

2

Not reusable

1

Remarks

LOWR


DISASSEMBLING THE PROPELLER SHAFT

E

Step

1 Shift plunger

2 Cross pin ring

3 Cross pin

4 Spring

5 Dog clutch

6 Propeller shaft

Job/Part Q’ty

1

1

1

1

1

1

Remarks

6-9

LOWR


1

2

3

E

REMOVING THE PROPELLER SHAFT

HOUSING

Remove:

• Propeller shaft housing

Bearing housing puller claw ........

90890-06546

Stopper guide plate ......................

90890-06501

Center bolt.....................................

90890-06504

1

2

3

1

3

2

4

DISASSEMBLING THE PROPELLER

SHAFT HOUSING

1. Remove:

• Reverse gear

Bearing separator .........................

90890-06534


90890-06501

Stopper guide stand.....................

90890-06538

Bearing puller ass’y ......................

90890-06535

1

2

3

4

6-10

LOWR


2. Remove:

• Ball bearing

1

2

3

E


90890-06501


90890-06538


90890-06535

1

2

3

NOTE:

Do not reuse the bearing. Always replace it with a new one.

1

2

3. Remove:

• Oil seal

• Needle bearing

Driver rod L3 ..................................

90890-06652

Needle bearing attachment .........

90890-06615

1

2

CHECKING THE REVERSE GEAR

Check:

• Teeth

• Dogs

Damage/wear

→

Replace.

6-11

CHECKING THE BEARING

Check:

• Bearing

Pitting/rumbling

→

Replace.

CHECKING THE PROPELLER SHAFT

HOUSING

Check:


Cracks/damage

→

Replace.

LOWR

1

3 a


b

ASSEMBLING THE PROPELLER

SHAFT HOUSING

1. Install:

• Needle bearing

E

Needle bearing position ...............

31.0 - 31.5 mm (1.24 in)

a

2

Driver rod-SS .................................

90890-06604


90890-06615

Bearing depth plate ......................

90890-06603

1

2

3

A

1

2 a

NOTE:

Install the needle bearing with its manufacturer’s marks motor oil.

b facing up. Apply Yamaha

2. Install:

• Oil seals

Oil seal position ...........................

6.0 - 6.5 mm (0.26 in)

a

Driver rod L3 ..................................

90890-06652


90890-06611

1

2

CAUTION:

It is essential that the oil seals are installed correctly (as shown in the illustration). If they are installed the wrong way round, oil or water will leak out.

6-12

LOWR

a


3

1

2

E

3. Install:

• Reverse gear

1

• Reverse gear shim(s)

2

• Ball bearing

3


4

NOTE:

• Before press-fitting the ball bearing, install the reverse gear shim(s).

• Install the ball bearing with its manufacturer’s marks gear.

a facing the reverse

1

4

CAUTION:

Place a suitable base under the gear to protect it from damages.

CHECKING THE DOG CLUTCH

Check:

• Dog clutch

Damage/wear

→

Replace.

6-13

CHECKING THE PROPELLER SHAFT

Check:

• Propeller shaft

Damage/wear

→

Replace.

Maximum runout

0.1 mm (0.004 in)

CHECKING THE SHIFT PLUNGER

Check:

• Shift plunger

Wear

→

Replace.

CHECKING THE SHIFT SPRING

Check:

• Spring

Wear

→

Replace.

LOWR

DRIVE SHAFT

DRIVE SHAFT

REMOVING THE DRIVE SHAFT

E

Step Job/Part

Propeller shaft housing

1 Pinion gear nut

2 Pinion gear

3 Drive shaft

4 Forward gear

5 Drive shaft bearing

Q’ty Remarks

Refer to "PROPELLER SHAFT HOUS-

ING" on page 6-7.

1

1

1

1

1

6-14

LOWR

DRIVE SHAFT

1

E


Remove:

• Pinion gear nut

• Drive shaft

Drive shaft holder 3 ......................

90890-06517

1

Removing Steps

(1) Apply 12mm wrench on the pinion gear nut.

(2) Support the lower case with rags to hold the wrench in position.

(3) Turn the drive shaft holder

1

.

1

1

2


BEARING

Remove:

• Taper roller bearing

Bearing inner race attachment ....

90890-06643

1

DISASSEMBLING THE FORWARD

GEAR

Remove:


1

• Forward gear

2

Bearing separator

90890-06534

CAUTION:

Place a suitable base on the gear axle to prevent damage to the top of the axle.

6-15

LOWR

DRIVE SHAFT

CHECKING THE PINION AND

FORWARD GEAR

Check:

• Teeth

• Dogs

Damage/wear

→

Replace.

E

CHECKING THE DRIVE SHAFT

Check:

• Drive shaft

Damage/wear

→

Replace.

Maximum runout

0.5 mm (0.020 in)

CHECKING THE BEARINGS

Check:

• Bearings

Pitting/rumbling

→

Replace.

1

1

6-16

ASSEMBLING THE FORWARD GEAR

Install:

• Forward gear



90890-06644

1

INSTALLING THE DRIVE SHAFT

BEARING

Install:

• Drive shaft bearing


90890-06645

1

LOWR

DRIVE SHAFT

1

INSTALLING THE DRIVE SHAFT

1. Install:

• Forward gear

(with the tapered roller bearing)

• Drive shaft

(with the tapered roller bearing)

• Pinion gear

E


90890-06517

1

2. Tighten:

• Pinion gear nut

.

T

R

.

Pinion gear nut

50 Nm (5.0 kgf

•

m, 37 ft

•

lb)

Tightening steps

(1) Apply 12mm wrench on the pinion gear nut.

(2) Support the lower case with rags to hold the wrench in position.

(3) Turn the drive shaft holder

1

.

NOTE:

Tighten the pinion gear nut with the same tools that were used for removal.

6-17

LOWR

LOWER CASE

LOWER CASE

DISASSEMBLING THE LOWER CASE

E

Step Job/Part

1 Drive shaft bearing outer race

2 Pinion gear shim

3 Drive shaft sleeve

4 Needle bearing

5 Tapered roller bearing outer race

6 Forward gear shim

Q’ty

1

*

1

1

1

*

Remarks

* As required

6-18

LOWR

2

LOWER CASE

1

3

2

1

E

1. Remove:

• Drive shaft bearing outer race

• Pinion gear shim(s)


90890-06501


90890-06535


90890-06538

1

2

3

2. Remove:

• Drive shaft needle bearing and sleeve

Driver rod L3 ..................................

90890-06652


90890-06615

1

2

3. Remove:

• Forward gear bearing outer race and shim (s)


90890-06501


90890-06535

1

2

CHECKING THE DRIVE SHAFT

SLEEVE

Check:

• Drive shaft sleeve

Damage/wear

→

Replace.

6-19

LOWR

LOWER CASE

CHECKING THE NEEDLE BEARING

Check:

• Needle bearing

Pitting/rumbling

→

Replace.

E b a

2

3

1

1 2

1

2 a

6-20

ASSEMBLING THE LOWER CASE

1. Install:

• Forward gear shim(s)

1

• Tapered roller bearing outer race

2

Bearing outer race attachment

90890-06622

Driver rod LL

90890-06605

2. Install:

• Drive shaft needle bearing

Depth

a

185.0 - 186.0 mm (7.32 in)


90890-06615

Driver rod SL .................................

90890-06602

Bearing depth plate ......................

90890-06603

1

2

3

NOTE:

Install the drive shaft needle bearing with the manufactuer’s marks facing up.

3. Install:

• Pinion gear shim(s) a

• Drive shaft bearing outer race b

Driver rod LS .................................

90890-06606

Bearing outer race attachment ....

90890-06628

1

2

LOWR

SHIMMING

SHIMMING

E

NOTE:

• There is no need to select shims when reassembling with the original case and inner parts.

• Shim calculations are required when reassembling with the original inner parts and a new case (the difference between the original inner parts and the new case).

• Measurements and adjustments are required when replacing the inner part(s).

6-21

LOWR

1

2

SHIMMING

M

6-22

E

SELECTING THE PINION SHIMS

NOTE:

Select the shim thickness (T3) by using the specified measurement(s) and the calculation formula.

Select:

• Shim thickness (T3)

Selecting steps

(1) Install the pinion height gauge, drive shaft and bearing (with bearing race).

Pinion height gauge .....................

90890-06702


90890-06517

1

2

NOTE:

• Attach the pinion height gauge to the drive shaft so that the shaft is at the center of the hole.

• After the wing nuts contact the fixing plate, tighten them another 1/4 of a turn.

(2) Install the pinion gear and pinion gear nut.

.

T

R

.

Pinion gear nut

50 N

•

m (5.0 kgf

•

m, 37 ft

•

lb)

(3) Measure (M).

Digital caliper

90890-06704

NOTE:

• Measure the clearance between the pinion height gauge and the pinion, as shown.

• Perform the same measurement at three points on the pinion.

• Find the average of the measurements

(M).

• When using the digital caliper, be sure to place it at right angles to the pinion.

Otherwise, measurement will be incorrect.

LOWR

SHIMMING

6-23

E

(4) Calculate the pinion gear shim thickness (T3).

Pinion gear shim thickness (T3) =

M - 27 mm - P/100 mm

NOTE:

• "P" is the deviation of the lower case dimension from standard. It is stamped on the trim tab mounting surface of the lower case in 0.01 mm units. If the "P" mark is missing or unreadable, assume a "P" value of "0", and check the backlash when the unit is assembled.

• If the "P" mark is negative (-), then add the "P" value to the measurement.

Example:

If M is "28.30 mm" and "P" is "+5", then:

T3 = 28.30 mm - 27 mm - (+5)/100 mm

= 1.3 mm - 0.05 mm

= 1.25 mm (0.049 in)

If M is "28.24 mm" and "P" is "-3", then:

T3 = 28.24 mm - 27 mm - (-3)/100 mm

= 1.24 mm + 0.03 mm

= 1.27 mm (0.05 in)

(5) Select the pinion gear shim(s) (T3).

Calculated numeral at 1/100th place more than or less

1.10

1.20

1.20

1.30

1.40

1.50

1.60

1.70

1.30

1.40

1.50

1.60

1.70

1.83

Using shim

1.2

1.3

1.4

1.5

1.6

0.7, 1.0

0.7, 1.1

Available shim thickness

0.7, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 and

1.6 mm

LOWR

1

2

SHIMMING

6-24

E

SELECTING THE FORWARD GEAR

SHIMS

NOTE:

Select the shim thickness (T1) by using the specified measurement(s) and the calculation formula.

Select:


Selecting steps

(1) Measure (M).

Shimming plate ............................

90890-06701

Digital caliper ................................

90890-06704

1

2

NOTE:

• Turn the tapered roller bearing outer race two or three times so that the rollers seat.

Then, measure the height of the bearing, as shown.

• Perform the same measurement at three points on the tapered roller bearing outer race.


(M).

• When using the digital caliper, be sure to place it at right angles to the shimming plate.


(2) Calculate the forward gear shim thickness (T1).

Forward gear shim thickness (T1) =

17.5 mm + F/100 mm - M

NOTE:

• "F" is the deviation of the lower case dimension from standard. It is stamped on the trim tab mounting surface of the lower case in 0.01 mm units. If the "F" mark is missing or unreadable, assume an "F" value of "0", and check the backlash when the unit is assembled.

• If the "F" mark is negative (-), then subtract the "F" value from the measurement.

LOWR

SHIMMING

Example:

If M is "16.25 mm" and "F" is "+4", then:

T1 = 17.5 mm + (+4)/100 - 16.25 mm

= 17.5 mm + 0.04 - 16.25 mm

= 1.29 mm (0.051 in)

If M is "16.26 mm" and "F" is "-3", then:

T1 = 17.5 mm + (-3)/100 - 16.26 mm

= 17.5 mm - 0.03 - 16.26 mm

= 1.21 mm (0.048 in)

E

(3) Select the forward gear shim(s) (T1).


1.00

1.10

1.20

1.30

1.40

1.10

1.20

1.30

1.40

1.50

Using shim

1.0

1.1

1.2

1.3

1.4


1.0, 1.1, 1.2, 1.3 and 1.4 mm

6-25

LOWR

SHIMMING

6-26

E

SELECTING THE REVERSE GEAR

SHIMS

NOTE:

Select the shim thickness (T2) the specified measurement(s) and the calculation formula.

Select:


Selecting steps

(1) Measure (M2).

Shimming plate ............................

90890-06701

Digital caliper ................................

90890-06704

1

2

NOTE:

• Measure the height of the gear as shown.

• Perform the same measurement at three points on the gear.


(M2).

• When using the digital caliper, be sure to place it at right angles to the shimming plate.


(2) Calculate the reverse gear shim thickness (T2).

Reverse gear shim thickness (T2) =

80 mm + R/100 - M2

NOTE:

• "R" is the deviation of the lower case dimension from standard. It is stamped on the anode mounting surface of the lower case in 0.01 mm units. If the "R" mark is missing or unreadable, assum a

"R" value of "0", and check the backlash when the unit is assembled.

• If the "R" mark is negative (-), then subtract the "R" value from the measurement.

LOWR

SHIMMING

E

Example:

If M2 is "78.79 mm" and "R" is "+5", then:

T2 = 80 mm + (+5)/100 - 78.79 mm

= 80 mm + 0.05 mm - 78.79 mm

= 1.26 mm (0.050 in)

If M2 is "78.75 mm" and "R" is "-3", then:

T2 = 80 mm + (-3)/100 - 78.75 mm

= 80 mm - 0.03 mm - 78.75 mm

= 1.22 mm (0.048 in)

(3) Select the reverse gear shim(s) (T2).


1.00

1.10

1.20

1.30

1.10

1.20

1.30

1.32

Using shim


1.0, 1.1, 1.2 and 1.3 mm

1.0

1.1

1.2

1.3

6-27

LOWR

BACKLASH

E

BACKLASH

NOTE:

• Do not install the water pump components when measuring the backlash.

• Measure both the forward and reverse gear backlashes.

• If both the forward and reverse gear backlashes are larger than specification, the pinion gear may be too high.

• If both the forward and reverse gear backlashes are smaller than specification, the pinion gear may be too low.

6-28

MEASURING THE FORWARD GEAR

BACKLASH

1. Measure:

• Forward gear backlash


→

Adjust.

Forward gear backlash

0.31 - 0.72 mm (0.012 - 0.028 in)

Measuring steps

(1) Set the shift rod into the neutral position.

(2) Install the propeller shaft housing puller so it pushes against the propeller shaft.

.

T

R

.

Bearing housing puller claw ........

90890-06564


90890-06501

Center bolt.....................................

90890-06504

1

2

3

Center bolt

5 N

•

m (0.5 kgf

•

m, 3.7 ft

•

lb)

LOWR

BACKLASH

E

(3) Install the backlash indicator onto the drive shaft (16mm (0.63 in) diameter).

Backlash indicator ........................

90890-06706

4

(4) Install the dial gauge onto the lower unit and have the dial gauge plunger contact the mark on the backlash indicator.

Magnet base plate ........................

90890-07003

Dial gauge set ...............................

90890-01252

Magnet base .................................

90890-06705

5

6

7

(5) Slowly turn the drive shaft clockwise and counterclockwise. When the drive shaft stops in each direction, measure the backlash.

2. Adjust:

• Forward gear backlash

Remove or add shim(s).

Forward gear backlash

Shim thickness

Less than

0.31 mm (0.012 in)

More than

0.72 mm (0.028 in)

To be decreased by

(0.52 - M)

××××

0.49

To be increased by

(M - 0.52)

××××

0.49

Available shim thickness:

1.0, 1.1, 1.2, 1.3 and 1.4 mm

M : Measurement

6-29

MEASURING THE REVERSE GEAR

BACKLASH

1. Measure:

• Reverse gear backlash


→

Adjust.

Reverse gear backlash

0.93 - 1.65 mm (0.037 - 0.065 in)

LOWR

BACKLASH

1

E

Measuring steps

(1) Set the shift rod into the neutral position.

(2) Load the reverse gear by installing the propeller without the collar

1

, and then tighten the propeller nut.

.

T

R

.

Propeller nut

5 N

•

m (0.5 kgf

•

m, 3.7 ft

•

lb)

(3) Install the backlash indicator onto the drive shaft (16 mm (0.63 in) diameter).

Backlash indicator ........................

90890-06706

2

(4) Install the dial gauge onto the lower unit and have the dial gauge plunger contact the mark on the backlash indicator.

Magnet base plate ........................

90890-07003

Dial gauge set ...............................

90890-01252

Magnet base .................................

90890-06705

3

4

5

(5) Slowly turn the drive shaft clockwise and counterclockwise. When the drive shaft stops in each direction, measure the backlash.

2. Adjust:

• Reverse gear backlash

Remove or add shim(s).

Reverse gear backlash

Shim thickness

Less than

0.93 mm (0.037 in)

To be decreased by

(1.29 - M)

××××

0.49

More than

1.65 mm (0.065 in)

To be increased by

(M - 1.29)

××××

0.49


1.0, 1.1, 1.2 and 1.3 mm

M : Measurement

6-30

BRKT

CHAPTER 7

BRACKET UNIT

STEERING HANDLE ...................................................................................... 7-1

DISASSEMBLING THE STEERING HANDLE ......................................... 7-1

CHECKING THE STEERING HANDLE .................................................... 7-3

ASSEMBLING THE STEERING HANDLE ............................................... 7-3

BOTTOM COWLING ...................................................................................... 7-5

REMOVING THE BOTTOM COWLING ................................................... 7-5

CHECKING THE BOTTOM COWLING .................................................... 7-7

INSTALLING THE BOTTOM COWLING .................................................. 7-7

SHIFT ACTUATOR .......................................................................................... 7-8

DISASSEMBLING THE SHIFT ACTUATOR ............................................ 7-8

REMOVING THE BRACKET ...................................................................7-11

CHECKING THE SHIFT ACTUATOR ......................................................7-11

ASSEMBLING THE SHIFT ACTUATOR ................................................ 7-12

UPPER CASE ................................................................................................ 7-14

REMOVING THE UPPER CASE ............................................................. 7-14

CHECKING THE UPPER CASE .............................................................. 7-16

INSTALLING THE UPPER CASE ........................................................... 7-16

DISASSEMBLING THE UPPER CASE .................................................. 7-17

CHECKING THE EXHAUST MANIFOLD ............................................... 7-18

ASSEMBLING THE UPPER CASE ........................................................ 7-18

STEERING ARM ........................................................................................... 7-19

REMOVING THE STEERING ARM ........................................................ 7-19

CHECKING THE STEERING ARM ......................................................... 7-20

INSTALLING THE STEERING ARM ...................................................... 7-20

CLAMP BRACKETS ...................................................................................... 7-21

REMOVING THE CLAMP BRACKETS .................................................. 7-21

CHECKING THE CLAMP BRACKETS .................................................... 7-24

INSTALLING THE CLAMP BRACKETS ................................................. 7-25

E

3

4

5

1

2

8

9

6

7

BRKT

STEERING HANDLE

7

STEERING HANDLE

DISASSEMBLING THE STEERING HANDLE

E

Step Job/Part

1 Throttle cable

2 Throttle cable

3 Grommet



6 Steering handle cover

7 Collar

8 Collar

9 Plain washer

10 Wave washer

11 Screw

12 Handle

13 Washer

7-1

Q’ty

1

1

1

1

1

1

1

1

2

1

1

1

1

Remarks


BRKT

STEERING HANDLE

E

Step Job/Part

14 Compression spring

15 Bushing

16 Bolt

17 Self-locking nut

18 Steering friction

19 Throttle lever

20 Steering handle 1

Q’ty

1

1

1

1

1

1

1

Remarks

7-2

BRKT

STEERING HANDLE

E

CHECKING THE STEERING HANDLE

Check:

• Steering friction

1

• Throttle lever

2

Crack/damage

→

Replace.

• Throttle cable

3

Bent/broken

→

Replace.

7-3

ASSEMBLING THE STEERING

HANDLE

1. Install:

• Steering handle 1

1

• Throttle lever

2

• Throttle friction

3

2. Connect:

• Throttle cable

1

(loose cable side)

• Throttle cable

2

(tight cable side)

NOTE:

• Connect the inner cable end in the groove, and fit the outer cable end into the hole.

• Apply Yamaha grease A (water resistant grease) to the throttle lever and throttle cable.

BRKT

4

3

2

1

STEERING HANDLE

E

3. Install:

• Bushing

1

• Compression spring

2

• Washer

3

• Handle

4

NOTE:

• Align the throttle lever shaft end with the hole in the handle.

• After installing steering handle, make sure the movement of throttle cables by moving it.

1

2

4. Install:

• Plain washer

1

• Wave washer

2

• Collar

3

• Steering handle

4

• Collar

5

• Steering handle cover

6

• Bolt

7

NOTE:

Apply Yamaha grease A (water resistant grease) to the throttle cables, washers and the steering handle crown.

7-4

5. Install:

• Throttle cables

1

(through bottom cowling)

• Grommet

2

NOTE:

Pass the throttle cables through the steering handle on the steering bracket. Be sure the throttle cable is routed correctly.

BRKT

BOTTOM COWLING

BOTTOM COWLING

REMOVING THE BOTTOM COWLING

E

Step Job/Part

1 Nut

2 Collar

3 Grommet

4 Washer

5 Bottom cowling

6 Grommet

7 Engine stop switch

8 Choke knob

9 Grommet

10 Grommet

11 Grommet

12 Spring pin

13 Throttle lever

7-5

Q’ty

1

1

1

1

4

4

4

4

1

1

1

1

1

Remarks


BRKT

BOTTOM COWLING

E

Step Job/Part

14 Bushing

15 Throttle control shaft

16 Friction spacer


18 Clamp lever 2

19 Bushing

20 Wave washer

21 Clamp lever 1

Q’ty

1

1

2

1

1

2

1

1

Remarks

7-6

BRKT

BOTTOM COWLING

E

CHECKING THE BOTTOM COWLING

1. Check:

• Bottom cowling

Crack/damage

→

Replace.

2

1

1

2

1

4

3

2. Check:

• Clamp lever

Wear/damage

→

Replace.

NOTE:

Apply Yamaha grease A (water resistant grease) or replace parts as required.

INSTALLING THE BOTTOM COWLING

1. Install:

• Bushing

1

• Throttle control shaft

2

• Throttle lever

3

• Spring pin

4

NOTE:

Always use the new spring pin.

2. Install:

• Bottom cowling

1

• Nuts

2

NOTE:

Apply Yamaha grease A (water resistant grease) to the clamp lever shaft.

7-7

BRKT

SHIFT ACTUATOR

SHIFT ACTUATOR

DISASSEMBLING THE SHIFT ACTUATOR

E

Step Job/Part

1 Rubber seal

2 Rubber seal 2


4 Nut

5 Washer

6 Bracket

7 Gasket

8 Nut

9 Washer

10 Bolt


12 Bracket

13 Dowel pin

7-8

Q’ty

1

2

1

1

1

1

4

1

2

2

1

1

1

Remarks


BRKT

SHIFT ACTUATOR

E

Step Job/Part

14 Bushing 2



17 Shift cam plunger

18 Cotter pin

19 Washer

20 Cotter pin

21 Washer

22 Joint

23 Bolt

24 Shift lever

25 Grommet

26 Cam plate

7-9

Q’ty

1

1

1

1

1

1

1

1

1

1

1

Not reusable

2

1

Not reusable

Remarks


BRKT

SHIFT ACTUATOR

E

Step

27 Bushing

28 Grease nipple

29 Cotter pin

30 Washer

31 Plate washer

32 Shift rod 1

33 Spring pin

34 Shift rod lever

35 Plate washer

36 Collar

37 Shift rod

38 Torsion spring

Job/Part

7-10

Q’ty

1

2

1

1

1

2

1

1

Not reusable

1

2

1

1

Not reusable

Remarks

BRKT

SHIFT ACTUATOR

E

REMOVING THE BRACKET

Remove

• Bolts

1

(upper side)

• Bolt

2

(under side)

NOTE:

The bolt

2

(under side) must be removed from the bottom side of the upper case.

7-11

CHECKING THE SHIFT ACTUATOR

1. Check:

• Shift lever

1

• Shift cam plunger

2

• Cam plate

3

• Joint

4

• Shift rod lever

5

• Shift rod

6

• Shift rod 1

7

Wear/damage

→

Replace.

NOTE:

Apply Yamaha grease A (water resistant grease) or replace parts as required.

2. Check:

• Bracket

1

• Bracket

2

(remote control attachment)

Crack/damage Replace.

BRKT

SHIFT ACTUATOR

3. Check:

• Rubber seal

1

• Rubber seal

2

Crack/damage

→

Replace.

E

ASSEMBLING THE SHIFT ACTUATOR

1. Install:

• Bracket

1

• Collar

2

• Shift rod lever

3

• Shift rod

4

• Spring pin

5

• Joint

6

• Cotter pin

7

• Grease nipple

8

NOTE:

• Always use the new spring pin and the cotter pin.

• Apply Yamaha grease A (water resistant grease) to the collar inner surface, grease nipple and shift rod 1.

2. Hook:

• Torsion spring

1

NOTE:

Hook it onto the shift rod lever and the bracket.

1

3. Install:

• Cam plate

1

NOTE:

Apply Yamaha grease A (water resistant grease) to the cam plate shaft.

7-12

BRKT

1

SHIFT ACTUATOR

2

E

4. Install:

• Shift cam plunger

1

• Compression spring

• Bushing

2

NOTE:

Apply Yamaha grease A (water resistant grease) to the shift cam plunger.

5. Install:

• Shift lever

1

• Bolt

2

• Arm

3

.

T

R

.

Bolt

2

11 N

•

m (1.1 kgf

•

m, 8.1 ft

•

lb)

3

1

2

4

2

6. Install:

• Bracket

1

(to upper casing)

• Bolts

2

• Nut

3

(mount rubber front upper)

• Rubber seal

4

(over the bracket)

.

T

R

.

Bolt

2

11 N

•

m (1.1 kgf

•

m, 8.1 ft

•

lb)

Nut

3

17 N

•

m (1.7 kgf

•

m, 13 ft

•

lb)

7-13

BRKT

UPPER CASE

UPPER CASE

REMOVING THE UPPER CASE

E

Step Job/Part


2 Nut


4 Nut


6 Lower mount rubber housing

7 Mount rubber (side lower)

8 Lower mount cover

9 Mount rubber (front lower)

10 Nut

11 Washer

12 Upper case

13 Nut

7-14

Q’ty

2

1

2

2

2

2

2

2

1

2

2

1

2

Remarks


BRKT

UPPER CASE

E

Step Job/Part

14 Bolt

15 Washer

16 Nut

17 Mount rubber (side upper)

18 Gasket


20 Mount rubber (front upper)

Q’ty

2

2

2

2

4

2

1

Remarks

7-15

BRKT

UPPER CASE

CHECKING THE UPPER CASE

Check:

• Upper case

1

Crack/damage

→

Replace.

• Mount rubber

2

Wear/crack/damage

→

Replace.

E

7-16

INSTALLING THE UPPER CASE

Install:

• Mount rubber

1

(front upper)

• Mount rubber

2

(side upper) – with gaskets

• Nut

3

• Upper case

4

(to swivel bracket)

• Nut

5

(side upper)

• Mount rubber

6

(side lower)

• Mount rubber

7

(front lower)

• Lower mount cover

8

• Lower mount rubber housing

9

.

T

R

.

Nut

5

17 N

•

m (1.7 kgf

•

m, 13 ft

•

lb)

Bolt

(lower mount rubber housing

9

)

17 N

•

m (1.7 kgf

•

m, 13 ft

•

lb)

NOTE:

Make sure the lower mount rubber housing is installed with the “UP” mark pointing upward.

BRKT

UPPER CASE

DISASSEMBLING THE UPPER CASE

E

Step Job/Part

1 Bolt

2 Exhaust guide

3 Bolt

4 Exhaust manifold

5 Exhaust seal 2

6 Exhaust seal 1

7 Cotter pin

8 Gasket

9 Gasket

10 Water tube

11 Water seal rubber

7-17

Q’ty

1

1

4

1

1

Not reusable

1

Not reusable

1

Not reusable

1

1

Not reusable

1

1

Remarks

BRKT

UPPER CASE

E

CHECKING THE EXHAUST MANIFOLD

Check:

• Exhaust manifold

1

• Exhaust guide

2

Carbon deposits

→

Clean.

Crack/corrosion

→

Replace.

ASSEMBLING THE UPPER CASE

1. Install:

• Exhaust manifold

1

• Exhaust guide

2

• Exhaust seals

3

• Gasket

4

NOTE:

Always use new gaskets and exhaust seals.

If old ones are used, gas leakage may result due to invisible scratches or stretches.

2. Install:

• Water seal rubber

• Water tube

NOTE:

Install the water seal rubber so that it aligns with the locating hole a

in the upper case.

7-18

BRKT

STEERING ARM

STEERING ARM

REMOVING THE STEERING ARM

E

Step Job/Part

1 Bolt

2 Seal rubber

3 Bolt

4 Bracket

5 Dowel pin

6 Steering pivot shaft

7 Washer

8 Bushing

9 Friction piece

10 Bushing

11 O-ring

12 Bushing

7-19

Q’ty

1

1

2

1

1

1

4

1

1

1

1

Not reusable

1

Remarks

BRKT

STEERING ARM

CHECKING THE STEERING ARM

1. Check:

• Bracket

1

• Steering pivot shaft

2

Crack/damage

→

Replace.

2. Check:

• Bushing

3

• Bushing

4

• Friction piece

5

Wear/damage

→

Replace.

E

11

9

10

INSTALLING THE STEERING ARM

Install:

• Bracket

1

• Steering pivot shaft

2

• Bushing

3

• Bushing

4

• Friction piece

5

• O-ring

6

• Washer

7

• Washer

8

• Dowel pin

9

(to pivot shaft)

• Bolt

10

• Bolt

11

(steering friction)

NOTE:

• Always use the new O-ring.

• Apply Yamaha grease A (water resistant grease) to the busing, O-ring and the grease nipples.

• After installing the steering bracket, make sure the movement of steering pivot shaft by moving it.

7-20

BRKT

CLAMP BRACKETS

CLAMP BRACKETS

REMOVING THE CLAMP BRACKETS

E

Step Job/Part

1 Tension spring

2 Tilt rod

3 Conical spring

4 Nut

5 Washer

6 Bolt

7 Collar

8 Clamp bracket cap

9 Nut

10 Clamp bracket plate

11 Clamp bracket 1

12 Clamp bracket 2

13 Clamp bracket bolt

7-21

Q’ty

1

2

1

1

1

1

1

1

2

1

1

1

1

Remarks


BRKT

CLAMP BRACKETS

E

Step Job/Part

14 Washer

15 Bushing

16 Tilt lever cover

17 Tilt lever

18 Torsion spring

19 Circlip

20 Pin

21 Spring return lever

22 Tilt lock rod

23 Tilt lock rod

24 Cotter pin

25 Pin

26 Tilt lock plate (outer)

7-22

Q’ty

1

1

1

1

1

1

1

1

2

1

1

2

2

Remarks


BRKT

CLAMP BRACKETS

E

Step Job/Part

27 Pin

28 Tension spring

29 Bolt

30 Shallow water lever

31 Cover

32 Tilt lock plate (inner)

33 Grease nipple

34 Swivel bracket

35 Spring pin

36 Stopper knob

37 Stopper shaft

7-23

Q’ty

2

1

2

2

1

1

4

1

1

1

1

Remarks

BRKT

CLAMP BRACKETS

CHECKING THE CLAMP BRACKETS

1. Check:

• Clamp bracket

1

(port side)

• Clamp bracket

2

(starboard side)

• Swivel bracket

3

Crack/damage

→

Replace.

E

2. Check:

• Tilt lock plate

1

(outer)

• Tilt lock plate

2

(inner)

• Shallow water lever

3

• Tension spring

4

• Tension springs

5

Bent/crack/damage

→

Replace.

3. Check:

• Tilt rod

1

Bent/damage

→

Replace.

• Conical spring

2

Crack/damage

→

Replace.

4. Check:

• Tilt lever 1

1

• Tilt lever 2

2

• Tilt lock rod

3

• Torsion spring

4

Crack/damage

→

Replace.

5. Check:

• Bushing

1

Wear/damage

→

Replace.

7-24

BRKT

CLAMP BRACKETS

E

INSTALLING THE CLAMP BRACKETS

1. Install:

• Swivel bracket

1

(with bushings)

• Shallow water lever

2

• Tension springs

3

• Tilt lock lever

4

(inner) – front side

• Tilt lock lever

5

(outer) – rear side

• Pin

6

• Cotter pin

7

NOTE:

• Always use the new cotter pin.

• Apply grease to parts when specified.

1

6

4

3

8

7

5

2

2. Install:

• Swivel bracket

1

• Pin

2

• Tilt lever

3

• Circlip

4

• Tilt lock rod

5

(hook to inner tilt lock plate)

• Tilt lock rod

6

(hook to tilt lever 1

7

)

• Torsion spring

8

NOTE:

• Always use the new circlip.

• Apply water resistant grease to the pin and tilt levers.

7-25

BRKT

CLAMP BRACKETS

3. Install:

• Clamp bracket

1

(port side)

• Clamp bracket

2

(starboard side)

• Transom clamp handle

3

• Stopper shaft

4

• Stopper knob

5

• Spring pin

6

E

NOTE:

• Always use the new pin and a spring pin.

• Apply Yamaha grease A (water resistant grease) to the transom clamp screw, stopper shaft and the grease nipple.

6

1

5

6

8

7-26

4. Install:

• Clamp bracket bolt

1

• Clamp bracket

2

(starboard side)

• Washer

3

• Swivel bracket

4

• Torsion spring

5

• Tilt lever

6

• Washer

7

• Clamp bracket

8

(port side)

• Nut

9

(clamp bracket bolt)

• Bolt

10

• Collar

11

• Nut

12

• Tilt rod

13

(with conical spring

14

)

• Tension spring

15

NOTE:

Place the tilt lever

6

inside the clamp bracket

8

(port side) as shown.

.

T

R

.

Nut

9

45 N

•

m(4.5 kgf

•

m, 33 ft

•

lb)

ELEC

– +

CHAPTER 8

ELECTRICAL SYSTEM

ELECTRICAL COMPONENT .......................................................................... 8-1

ELECTRICAL COMPONENTS ANALYSIS ..................................................... 8-2

DIGITAL CIRCUIT TESTER ...................................................................... 8-2

MEASURING THE PEAK VOLTAGE ........................................................ 8-2

PEAK VOLTAGE ADAPTER ...................................................................... 8-2

MEASURING A LOW RESISTANCE .............................................................. 8-3

IGNITION SYSTEM ........................................................................................ 8-4

WIRING DIAGRAM .................................................................................. 8-4

CHECKING THE SPARK PLUGS ............................................................. 8-5

CHECKING THE IGNITION SPARK GAP ................................................ 8-5

CHECKING THE SPARK PLUG CAPS ..................................................... 8-6

REMOVING THE SPARK PLUG CAPS (STANDARD TYPE) ................... 8-6

INSTALLING THE SPARK PLUG CAPS (STANDARD TYPE) ................. 8-6

CHECKING THE IGNITION COILS .......................................................... 8-7

CHECKING THE CHARGE COIL .............................................................. 8-8

CHECKING THE PULSER COIL ............................................................... 8-9

CDI UNIT ................................................................................................ 8-10

CHECKING THE CDI UNIT .................................................................... 8-11

IGNITION CONTROL SYSTEM .................................................................... 8-13

WIRING DIAGRAM ................................................................................ 8-13

CHECKING THE ENGINE STOP SWITCH ............................................. 8-14

CHARGING SYSTEM ................................................................................... 8-15

WIRING DIAGRAM ................................................................................ 8-15

CHECKING THE LIGHTING COIL .......................................................... 8-16

E

3

4

5

1

2

8

9

6

7

ELEC

– +

ELECTRICAL COMPONENT

8

ELECTRICAL COMPONENT

E

1

4

5

2

3

6

Ignition coil

Charge coil

Pulser coil

CDI unit

Engine stop switch

Lighting coil

8-1

B : Black

Br : Brown

G : Green

L : Blue

W : White

B/O : Black/Orange

B/W : Black/White

W/B : White/Black

W/R : White/Red

ELEC

– +

ELECTRICAL COMPONENTS ANALYSIS

ELECTRICAL COMPONENTS

ANALYSIS

DIGITAL CIRCUIT TESTER

E

Digital circuit tester

90890-03174

NOTE:

“ ” indicates a continuity of electricity which means a closed circuit at the respective switch position.

MEASURING THE PEAK VOLTAGE

WARNING

When checking the peak voltage, do not touch any of the connections of the digital tester lead wires.

NOTE:

• When checking the condition of the ignition system, it is useful to know the peak voltage.

• Cranking speed is dependant on many factors (e.g., fouled or weak spark plugs, a weak battery). If one of three is defective, the peak voltage will be lower than specification.

• If the peak voltage measurement is not within specification, the engine will not operate properly.

8-2

PEAK VOLTAGE ADAPTER

NOTE:

The peak voltage adapter should be used with the digital circuit tester.

Peak voltage adapter

90890-03172

ELEC

– +

MEASURING A LOW RESISTANCE

E

NOTE:

• When measuring the peak voltage, set the selector to the DC voltage mode.

• Make sure the peak voltage adapter lead are properly installed in the digital tester.

• Make sure the positive pin (the “+” mark facing up as shown) on the peak voltage adapter is installed into the positive terminal of the digital tester.

• The test harness is needed for the following tests.

8-3

Measuring steps

(1) Connect the peak voltage adapter probes to the connectors.

(2) Start or crank the engine and observe the measurement.

MEASURING A LOW RESISTANCE

When measuring a resistance of 10

Ω

or less with the digital tester, the correct measurement cannot be obtained because of the tester’s internal resistance.

To obtain the correct value, subtract the internal resistance from the displayed measurement.

Correct value

Displayed measurement - internal resistance

NOTE:

The internal resistance of the digital tester can be obtained by connecting both of its probes.

ELEC

– +

IGNITION SYSTEM

IGNITION SYSTEM

WIRING DIAGRAM

E

1

4

5

2

3

Spark plug

Ignition coil

Charge coil

Pulser coil

CDI unit

8-4

B : Black

Br : Brown

L : Blue

B/O : Black/Orange

B/W : Black/White

W/B : White/Black

W/R : White/Red

ELEC

– +

IGNITION SYSTEM

E

CHECKING THE SPARK PLUGS

Refer to "CHECKING THE SPARK

PLUGS" on page 3-22.

Standard spark plug

NGK B7HS-10

CHECKING THE IGNITION SPARK GAP

WARNING

• Do not touch any of the connections of the spark gap tester lead wires.

• Do not let sparks leak out of the removed spark plug cap.

• Keep flammable gas or liquids away, since this test can produce sparks.

Check:

• Ignition spark gap

Below specification

→

Check the ignition system.

Minimum ignition spark gap

8.0 mm (0.31 in)

Checking steps

(1) Remove the spark plugs from the engine.

(2) Connect a spark plug cap to the ignition tester.

Ignition tester

90890-06754

(3) Adjust the ignition spark gap to 11 mm

(0.43 in) by turning the adjust knob.

NOTE:

Be careful so that the spark gap does not come excessively off the measuring position [11 mm (0.43 in)].

8-5

ELEC

– +

IGNITION SYSTEM

E

(4) Crank the engine and observe the spark through the discharge window of the ignition tester.

NOTE:

• If there is no spark or the spark is weak, check spark plug cap, ignition coil, pulser coil, charge coil and CDI unit.

• If a good spark is obtained, the problem is not with the ignition system, but possibly with the spark plug(s) or another component.

CHECKING THE SPARK PLUG CAPS

Check

• Spark plug cap

1

Crack/damage

→

Replace.

REMOVING THE SPARK PLUG CAPS

(STANDARD TYPE)

Removing steps

(1) Remove the spark-plug cap

1

by pulling the cap, and remove the plug-cup spring

2 from the high-tension cable

3

.

8-6

INSTALLING THE SPARK PLUG CAPS

(STANDARD TYPE)

Installing steps

(1) Cut about length a

off the end of the high-tension cable

3

.

Length

a

5mm (0.20 in)

ELEC

– +

IGNITION SYSTEM

E

(2) Press in the plug cap spring

4

until it touches the high tension cable at b

, then bend c

as shown.

CHECKING THE IGNITION COILS

1. Check:

• Ignition coil

1

Crack/damage

→

Replace.

2. Measure:

• Ignition coil resistance


→

Check the peak voltage (charge coil, pulser coil, CDI unit)/Replace.

Ignition coil resistance

Primary

B/W - B

0.18 - 0.24

Ω

Secondary

B - output

2.70 - 3.70 k

Ω

NOTE:

When making secondary leads resistance test, disconnect spark plug cap.

8-7

ELEC

– +

IGNITION SYSTEM

E

CHECKING THE CHARGE COIL

1. Measure:

• Charge coil resistance


→

Check the peak voltage.

Charge coil resistance

Br - L

342 - 418

Ω

Measuring steps

(1) Disconnect the Brown (Br) and Blue (L) leads from the wire harness.

(2) Connect the tester to the charge coil as shown.

2. Measure:

• Charge coil output peak voltage

Below specification

→

Replace.

Charge coil output peak voltage

Br – L

a n n g

O p e n e

1 4 1 46

5 0 0 3 5 0 0 o s e d

1 50 1 50

NOTE:

For the peak voltage measurement, connect the adaptor as the illustration

A

for the open circuit, and as the illustration

B

for the closed circuit.

8-8

ELEC

– +

IGNITION SYSTEM

E

CHECKING THE PULSER COIL

1. Measure:

• Pulser coil resistance


→


Pulser coil resistance

W/R - B (#1), W/B - B (#2)

311 - 381

Ω

Measuring steps

(1) Disconnect the White/Red (W/R), White/

Black (W/B) and Black (B) leads from the wire harness.

(2) Connect the tester to the pulser coil as shown.

2. Measure:

• Pulser coil output peak voltage

Below specification

→

Replace.

P u s e r c o il o pu t p e a k v a g

R – , W B –

O p e n a e n n g 5 0 0 3 5 0 0 o s e d

1 6 2 6

NOTE:


A


B


8-9

ELEC

– +

IGNITION SYSTEM

CDI UNIT

E

1 CDI unit

8-10

B : Black

Br : Brown

L : Blue

W : White

B/O : Black/Orange

B/W : Black/White

W/B : White/Black

W/R : White/Red

ELEC

– +

IGNITION SYSTEM

E

CHECKING THE CDI UNIT

1. Measure:

• CDI unit

1

resistance


→


Pocket tester

90890-03112

NOTE:

• Digital circuit tester cannot be used for this check. Use analogue tester.

• CDI resistance values will vary from meter to meter, especially with electronic digital meters. For some testers, polarity of leads is reversed.

Measuring steps

(1) Disconnect the CDI unit

1

leads from the wire harness.

(2) Connect the pocket tester (

Ω

× 1K) to the CDI unit as shown list.

Refer to "CDI UNIT" on page 8-10.

NOTE:

There is a point at which the pointer swings greatly and swings back. Read the point where the point has returned to stop.

8-11

ELEC

– +

IGNITION SYSTEM

E

2. Measure:

• CDI unit output peak voltage

Below specification

→

Replace.

CDI unit output peak voltage

B/O - B, B/W - B

a n n g

O p e n e

5 0 0 3 5 0 0 o s e d

5.5

130.0 135.0 135.0

NOTE:

Before measuring CDI unit output peak voltage, mak e sure that no abnormality is observed on the charge coil and the pulser coil.

NOTE:


A


B


8-12

ELEC

– +

IGNITION CONTROL SYSTEM


WIRING DIAGRAM

E

1

2

CDI unit

Engine stop switch

B : Black

W : White

8-13

A

B

C

ELEC

– +


CHECKING THE ENGINE STOP

SWITCH

Check:

• Continuity


→

Replace.

Lead color

White Black

Remove the lock-plate

A

Install the lock-plate

B

Push the button

C

E

8-14

ELEC

– +

CHARGING SYSTEM

CHARGING SYSTEM

WIRING DIAGRAM

E

1 Lighting coil

G : Green

8-15

ELEC

– +

CHARGING SYSTEM

E

CHECKING THE LIGHTING COIL

1. Measure:

• Lighting coil resistance


→

Checking the peak voltage.

Lighting coil resistance:

G – G

0.31 - 0.37

Ω

Measuring steps

(1) Connect the tester to the lighting coil as shown.

NOTE:

When measuring the resistance of 10

Ω

or less using the digital tester, the correct measurement cannot be obtained.

Re f e r t o " M E AS U R I N G A LOW R E S I S -

TANCE" on page 8-3.

2. Measure:

• Lighting coil output peak voltage

Below specification

→

Replace.

Lighting coil output peak voltage

G – G

a n k

O p e n e d o s e d

5 0 3 5 0 1 5 0 3 5 0 o s e

1 4

O p e n e d

3 0

8-16

TRBL

ANLS

CHAPTER 9


TROUBLE ANALYSIS ..................................................................................... 9-1

TROUBLE ANALYSIS CHART ................................................................. 9-1

TROUBLE SHOOTING FOR PEAK VOLTAGE ............................................... 9-4

E

3

4

5

1

2

8

9

6

7

TRBL

ANLS


9


E

NOTE:

The following items should be checked before the "TROUBLE ANALYSIS CHART" is consulted.

1. The battery is charged and its specific gravity is within specification.

2. There are no incorrect wiring connections.

3. Wiring connections are properly secured and are not rusty.

4. The lanyard is installed onto the engine stop switch.

5. The shift position is in neutral.

6. Fuel is reaching the carburetor/vapor separator.

7. The rigging and engine setting are correct.

8. The engine is free from any "Hull problem".

TROUBLE ANALYSIS CHART

Trouble mode Check elements

Relative part

Reference

Chapter

:

:

: : :

:

: : : : :

: : : :

: :

: :

:

:

:

:

: : :

: : :

: : :

:

:

:

:

:

:

:

:

:

:

: :

9-1

FUEL SYSTEM

Fuel line

Fuel joint

Fuel filter

Fuel pump

Carburetor

• Idle speed adjustment

• Pilot screw adjustment

Link adjustment

POWER UNIT

Compression

Reed valves

Cylinder head gasket

4

4

4

4

4

3

3

3

3

5

5

TRBL

ANLS



E

:

:

:

:

:

:

Relative part

Reference

Chapter

6

6

6

6

6

6

6

6

6

6

7

7

7

5

5

5

5

5

5

5

5

5

8

TRBL

ANLS



E

Relative part

Reference

Chapter

: :

:

: : :

:

:

:

:

: :

:

: :

:

: : :

: :

• Ignition coils

• Charge coil

• Pulser coil

• CDI unit

Ignition control system

• Engine stop switch

Charging system

:

• Lighting coil

8

8

8

8

8

8

9-3

TRBL

ANLS

TROUBLE SHOOTING FOR PEAK VOLTAGE

TROUBLE SHOOTING FOR PEAK VOLTAGE

E

1.

2.

Items

Poor starting

Unstable idle speed

Symptoms

• No firing. The starter motor cranks the engine, but no firing takes place in the cylinder.

• Firing takes place in the cylinder, but the engine stops soon.

• Start-up time is too long. The engine will not start up easily.

• The engine speed is not stable at idle.

• The engine stalls when the throttle lever is opened.

• The engine stalls after it is warmed up.

3.

Unstable engine speed

• The engine does not run smoothly.

• The engine speed drops during acceleration.

Check the ignition system.

1) Check the lead to ignition coil, CDI unit, pulser coil and charge coil.

NG

Contamination, Loose connection

Corrosion

OK

2) Check the spark gap.

NG

Above specification

OK

3) Check the plug cap (resistance).

NG


OK

4) Check the ignition coils (resistance).

NG


OK

5) Check the CDI unit resistance and output peak voltage.

OK

Above specification

NG

6) Check the charge coil resistance and output peak voltage.

NG

Below specification

OK

7) Check the pulser coil resistance and output peak voltage.

NG

Below specification

OK

Replace the CDI unit.

Clean

Correct

Replace the spark plug.

Replace.

Replace.

Replace the ignition coil.

Replace the charge coil.

Replace the pulser coil.

9-4

YAMAHA MOTOR CO., LTD.

Printed in Japan

Oct. 2000-0.3

×

1

(EK25BMH)

Printed on recycled paper

WIRING DIAGRAM

EK25BMH

B

B/W

1 Ignition coil

#1

B

B

3 Charge coil

G

G

Br

L

W/R W/B B

4

Pulser coil

B B

B/W

B

2 Ignition coil

#2

B

B B/W B/W Br L W/R W/B B

5 CDI unit

B/W

B/O

Br

L W/R

W/B

B

W

B W/B

W/R

L Br B/O B/W B

G

G

6 Engine stop switch

W

B

B

W W

B

Br

G

L

R

W

B/O

B/W

G/W

W/B

W/R

Black

Brown

Green

Blue

Red

White

Black/orange

Black/white

Green/white

White/black

White/red

Yamaha EK25BMH Service manual

CONTENTS

GENERAL INFORMATION

SPECIFICATIONS

PERIODIC CHECK AND

ADJUSTMENT

FUEL SYSTEM

RECOIL STARTER

LOWER UNIT

BRACKET UNIT

ELECTRICAL SYSTEM

TROUBLE ANALYSIS

WIRING DIAGRAM

Related manuals

Table of contents

Yamaha EK25BMH Service manual

CONTENTS

GENERAL INFORMATION

SPECIFICATIONS

PERIODIC CHECK AND

ADJUSTMENT

FUEL SYSTEM

RECOIL STARTER

LOWER UNIT

BRACKET UNIT

ELECTRICAL SYSTEM

TROUBLE ANALYSIS

WIRING DIAGRAM

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Table of contents