1988-1989 YAMAHA 20 25HP 2-STROKE OUTBOARD Repair Manual

1988 - 1989 OUTBOARD / MOTEUR HORS-BORD SERVICE MANUAL / MANUEL D’ATELIER Model : 20ESF, 20ESG, 20LF, 20LG, 20SF, 20SG, 25ELF, 25ELG, 25ESF, 25ESG, 25LF, 25LG, 25SF, 25SG 6L2281977500 *6L2281977500*

AIO000-O' 20G/25G SERVICE MANUAL © 1988 Yamaha Motor Co., Ltd. 1st Edition, May 1988 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means including photocopying and recording without the written permission of the copyright holder. Such ,written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. Printed in Japan P/N 6L2-28197-70

A20000-0 NOTICE This manual has been prepared by the Yamaha Motor Company primarily for use by Yamaha deal- ers and their' trained mechanics when performing maintenance procedures and repairs to Yamaha equil)merit. Il: has been written to suit the needs of persons who have a basic under- standin9 of the mechanical and electrical concepts and procedures inherent in the work, for without such knowledge attemgted repairsor se_¥iceto the equipment could renderit unsafe or unfit for use. Because the 'Yamaha Motor Company Ltd 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.Authorised Yamahadealers are notified periodically of modifi- cations and significant changes in specifications and procedures, and these are incorporated in successive editions of this manual.

A30000-0 INDEX GEN EI:_AL INFORMATION GEN INFO SPE'Cl F ICATION _EC I GENERALSERVICE GEN SRVC ¢, · _i_1 FU['L ,.,YSTEM FUEL POWER UNIT 6i1: POWR _m__r L OWEFI UNIT LOWR BI:b_,C K El' UNIT --' BRKT ELE'CI'RICALSYSTEM _; ELEC TROU13LE-SHOOTING TRBL SHI'G

CHAPTER 1. GENERAL INFORMATION HOW TO LISE THIS MANUAl ............................................................ 1-1 MANUAL FORMAT ..................................................................... 1-1 THE ILLUSTRATIONS .................................................................. 1-1 REFERENC_-S.............................................................................. 1-1 SPECIFICATIO;NS ....................................................................... '1 -1 WARNINGS, CAUTIONS and NOTES ............................................ 1-2 SYMBOLS ................................................................................. 1-3 IDENTIFICATION .............................................................................. 1-4 SERIAL NUMBER ........................................................................ 1-4 ENGINF SERIAL NUMBER ............................................................. 1-4 STARTING SERIAL NUMBERS ....................................................... 1-4 SAFETY WHILE WORKING ............................................................... 1-5 SPECIAL TOOLS .............................................................................. 1-7 SPECIAL TOOLS FOR TUNE-UP ..................................................... 1-7 SPECIAL TOOLS FOR ENGINE SERVICE ......................................... 1-7 SPECIAL TOOLS FOR LOWER UNIT SERVICE ................................. 1-8 SEALING AGENTS AND LUBRICANTS .......................................... 1-8 CHAPTER 2 SPECIFICATIONS GENERAL :SPECIFICATIONS ................................................................ 2-1 MAIINTENANCE SPECIFICATIONS ..................................................... 2-3 TIGHTENII_IG TORQUE ................................................................... 2-1 3 GENERAL TORQUE SPECIFICATIONS ................................................ 2-1 3

D,ooc,2.o. CHAPTER 3 GENERAL SERVICE' PREDELIVERYSERVICE ................................................................................ 3-'1 PACKING LISTS ....................................................................................... 3-'1 STEERING HANDLE INSTALLATION ..................................................... 3-2 ELECTRIC WIRING ................................................................................... 3-3 FUEl' LINE ................................................................................................... 3-(3 GEAR OIL LEVEL ...................................................................................... 3-7 OPERATION OF CONTROLS AND MOVING PA!_{TS .......................... 3-7 AIR BLEEDING OF THE OIL INJECTION PUMP ..................................3-8 FUEL LEAKAGE ......................................................................................... 3-9 WATER LEAKAGE ..................................................................................... 3-9 EXHAUST LEAKAGE ................................................................................ 3-9 ENGINE AND LOWER UNIT NOISE .......................................................3-9 IDLE-SPEED.............................................................................................. 3-9 IGNITION TIMING ...................................................................................... 3-9 MOTOR EXTERIOR .................................................................................... 3-9 INSTRUCTING THE NEW OWNER ........................................................ 3-9 PERIODIC SERVICE .................................................................................... 3-10 MAINTENANCE SCHEDULE ................................................................... 3-10 ANODE ......................................................................................................... 3-10 F3ATTERY ................................................................................................... 3-11 CARBURETTOR ...................................................................................... 3-12 CARBURETTOR LINK ADJUSTMENT .................................................. 3-12 CYLINDER HEAD BOLTS, ENGINE MOUNTING BOLTS, AND FLYWHEEL NUT ..................................................................................... 3-12 FUEL FILTER ........................................................................................... 3-12 FUEL TANK AND FUEL LINE .............................................................. 3-13 GEAR OIL .................................................................................................. 3-13 IDLE-SPEED ............................................................................................. 3-14 IGNITION TIMING ADJUSTMENT ........................................................ 3-15 NEUTRAL OPENING LIMIT ADJUSTMENT ........................................ 3-'16 OIL INJECTION PUMP .......................................................................... 3-'16 CHECKING THE OIL LEVEL WARNING SYSTEM ............................. 3-17 OIL PUMP LINK ADJUSTMENT ........................................................... 3-18 PRC)PELLER ............................................................................................... 3-'18 SPARK PLUG.......................................................................................... 3-'1 c_ START-IN-GEAR PROTECTION ADJUSTMENT .................................. 3-'19 THROTTLE LINK ADJUSTMENT ........................................................... 3-2(;)

.ooooo. CHAPTER 4 FUEL SYSTEM EXPLOID['D DIAGRAM ........................................................................ 4-1 (;LEANING AND INSPECTION ........................................................... 4-2 INSTALLATION ............................................................................... 4-4 CARBURET'rOR .............................................................................. 4-5 REM()VAL AND DISASSEMBLY ................................................... 4-6 INSP[-CTION .............................................................................. 4-7 ASSE!MBLY ............................................................................... 4-8 INSTAL,LATION ............................................................................ 4-9 OIL IN.IECTiON SYSTEM ................................................................ 4-10 CLEANING AND INSPECTION ..................................................... 4-11 INS'FALLATION ........................................................................ 4-1 1 _oo,:,oo- CHAPTER 5 POWER UNIT I-XPLODIEDDIAGRAM ..................................................................... 5-1 PREPARATION FOR OVERHAUL ........................................................ 5-2 REMOVAL ...................................................................................... 5-2 IZ)ISASSEMBLY ............................................................................... 5-3 IINSPECTION ................................................................................... 5-4 CLL:ANING THE CYLINDER HEAD ................................................. 5-4 CYLINE)ER BLOCK ....................................................................... 5-5 PISTON ....................................................................................... 5-6 PISTON RING ............................................................................. 5-7 PISTON PIN AND SMALL, END BEARING ........................................ 5-8 CRANKSHAFT ........................................................................... 5-8 REED VALVE ............................................................................. 5-9 THEFIMOSTAT .......................................................................... 5-1 0 BALL BEARING ........................................................................ 5-10 DRIVE GEAR (OIL INJECTION PUMP DRIVE) ................................ 5-11

ASSEMBLY AND ADJUSTMENT ...................................................... 5-12 BEARING, OILSEAL AND O-RING ............................................... 5-12 PISTON .................................................................................... 5-12 SMALL END BEARINGS AND PISTON ASSEMBLY ........................ 5-13 CRANK CYLINDER ASSEMBLY ................................................... 5-13 CYLINDER HEAD AND EXHAUST COVER .................................... 5-14 INTAKE MANIFOLD .................................................................. 5-15 FUEL SYSTEM AND ELECTRICAL SYSTEM .................................. 5-15 IINS'rALLATION ............................................................................. 5-15 IRE!COILSTARTER ......................................................................... 5-16 REMOVAL AN[;) DISASSEMBLY ................................................. 5-17 INSPECTION ............................................................................ 5-18 INSTALLATION ........................................................................ 5-21 CHAPTER 46 LOWER UNIT IEXPLODEDDIAGRAM ...................................................................... 6-1 PREPARATION FOR REMOVAL ......................................................... 6-2 RFIVIOVAL ....................................................................................... 6-2 DISASSEMBLY ............................................................................... 6-2 INSPECTION ................................................................................... 6-5 GEAR CASE .............................................................................. 6--5 BEARING HOUSING .................................................................... 6-5 WATER PUMP HOUSING ............................................................ 6--5 IMPELLER .................................................................................. 66 OIL-SEAL HOUSING ..................................................................... 6-6 GEARS ...................................................................................... 66 BEARINGS ................................................................................ 6-6 CLUTCH DOG AND COMPONENTS .............................................. 6-6 DRIVE SHAFT AND PROPELLER SHAFT ........................................ 6-7 DRIVE SHAFT SLEEVE ................................................................. 6-7 SHIFT-PLUNGER, SHIFT-SHAFT, AND BOOT ................................. 6-7' PRC)PELLER/TFIlM TAB/ANODE ..................................................... 6-7'

ASSEMilBILYAND ADJUSTMENT. ...................................................... 6-8 SHIM SELECTION ....................................................................... 6-8 AS...;EMBLY ............................................................................. 6-1 1 BACKLASH ............................................................................. 6-1 3 WATER PUMP INSTALLATION .................................................... 6-14 LOWF'R UNIT LEAKAGE CHECK ................................................. 6-1 5 INSTALLATION ............................................................................. 6-16 K,o_:,2_o. CHAPTER7 BRACKET UNIT I-XPLODI-D DIAGRAM ...................................................................... 7-1 I:_EMOVAL ....................................................................................... 7-2 INSPECTION .................................................................................... 7-3 MOUNTING-BOLT ....................................................................... 7-3 RUBBER MOUNTS ....................................................................... 7-3 COLLAR ..................................................................................... 7-3 TILT LOCK PLATES ..................................................................... 7-3 LEVERS .................................................................................... 7-3 ASSEMBLY .................................................................................... 7-4 M,o_o2.o. CHAPTER 8 ELECTRICAL SYSTEM I-LECTRICALCOMPONENTS ............................................................. 8-1 WIRINGDIAGRAM .......................................................................... 8-3 I:IEMOVAL ...................................................................................... 8-6 C, LEANING, INSPECTION AND REPAIR ............................................... 8-8 PULSER COIL ............................................................................ 8-8 CHARGE COIL ........................................................................... 8-8 LIGHTING COIL ........................................................................... 8-8 IGNITION COIL ............................................................................ 8-9 REPLACEMENT OF SPARK-PLUG CAP .......................................... 8-9

C.D.I. UNIT ............................................................................. 8-10 CHOKE SOLENOID [E MODEL] .................................................... 8-1 "1 STARTER RELAY [E MODEL] ..................................................... 8-1 '1 RECTIFIER [E MODEL] ............................................................... 8-11 FUSE [E MODEl_] ...................................................................... 8-1;2 THERMO-SWlTCH [EO, MO MODEL] ........................................... 8-1:2 OIL LEVEL WARNING LAMP [OIL IN.JE-CTION MODEL] .................. 8-1;3 (])IL LEVEL SENSOR ]OIL INJECTION MODI-L] .............................. 8-13 WIRING HARNESS ................................................................... 8-14- TERMINAL ASC;EMBLY ............................................................. 8-15 BATTERY [E MODEL] ................................................................ 8-1 5 STOP SWITCH ........................................................................... 8-15 INSTALLATION .............................................................................. 8-16 FLYWHEEL MAGNETO .......................................... .................... 8-16 STARTER MOTOR [E MODEL] ......................................................... 8-17 REMOVAL ................................................................................ 8_17 DISASSEMBLY ......................................................................... 8-1 7 INSPECTION ............................................................................. 8-18 ASSEMBLY .............................................................................. 8-20 INSTALLATION ........................................................................ 8-21 CHAPTER 9 TROUBLE-SHOOTING 'I'ROUBLE-SHOOTING DIAGRAM ....................................................... 9-1 HOW TO TROUBLE-SHOOT .......................................................... 9-1 ENGINE IS HARD TO START OR WILL NOT START (Manual starter model) ....................................................................... 9-2 ENGINE WILL NOT START (Electric starter model) ................................ 9-7 ROUGH IDLING ............................................................................... 9--8 !-NGINE STALLS ............................................................................. 9.-9 ENGINE WILL NOT STOP ............................................................... 9-10 GEAR SHIFTING IS IMPOSSIBLE OR IHARD ....................................... 9-11 OIL INJECTION SYSTEM ................................................................ 9-!14.

1988-1989 YAMAHA 20 25HP 2-STROKE OUTBOARD Repair Manual

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