Engine - Wacker Neuson

www.wackergroup.com

0160157en 0207

Engine

WM 90

REPAIR MANUAL

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WM 90 Repair

Foreword Operating / Parts Information You must be familiar with the operation of this machine before you attempt to troubleshoot or repair it. Basic operating and maintenance procedures are described in the Operator’s Manual supplied with the machine. Keep a copy of the Operator’s Manual with the machine at all times. Use the separate Parts Book supplied with the machine to order replacement parts. If you are missing either of the documents, please contact Wacker Corporation to order a replacement. Damage caused by misuse or neglect of the unit should be brought to the attention of the operator to prevent similar occurrences from happening in the future.

This manual provides information and procedures to safely repair and maintain the above Wacker model(s). For your own safety and protection from injury, carefully read, understand, and observe all instructions described in this manual. THE INFORMATION CONTAINED IN THIS MANUAL IS BASED ON MACHINES MANUFACTURED UP TO THE TIME OF PUBLICATION. WACKER CORPORATION RESERVES THE RIGHT TO CHANGE ANY PORTION OF THIS INFORMATION WITHOUT NOTICE.

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Foreword

WARNING

WM 90 Repair

CALIFORNIA Proposition 65 Warning: Engine exhaust, some of its constituents, and certain vehicle components, contain or emit chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

Laws Pertaining to Spark Arresters Notice: State Health Safety Codes and Public Resources Codes specify that in certain locations spark arresters be used on internal combustion engines that use hydrocarbon fuels. A spark arrester is a device designed to prevent accidental discharge of sparks or flames from the engine exhaust. Spark arresters are qualified and rated by the United States Forest Service for this purpose. In order to comply with local laws regarding spark arresters, consult the engine distributor or the local Health and Safety Administrator.

All rights, especially copying and distribution rights, are reserved. Copyright 2007 by Wacker Corporation No part of this publication may be reproduced in any form or by any means, electronic or mechanical, including photocopying, without express written permission from Wacker Corporation. Any type of reproduction or distribution not authorized by Wacker Corporation represents an infringement of valid copyrights, and violators will be prosecuted. We expressly reserve the right to make technical modifications, even without due notice, which aim at improving our machines or their safety standards.

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WM 90 Repair

Table of Contents

1.

Emission Control System Information

2.

Safety Information 2.1 2.2 2.3 2.4 2.5 2.6

3.

4.

Operating Safety ................................................................................ 14 Operator Safety while using Internal Combustion Engines ................ 15 Service Safety .................................................................................... 16 Label Locations .................................................................................. 17 Safety Labels ...................................................................................... 18 Operating Labels ................................................................................ 21

23

Specifications ..................................................................................... 23 Performance ....................................................................................... 24

Theory of Operation 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

5.

13

Technical Data 3.1 3.2

25

Application .......................................................................................... 25 Recommended Fuel ........................................................................... 25 Before Starting ................................................................................... 25 To Start ............................................................................................... 26 To Stop ............................................................................................... 27 Component Descriptions .................................................................. 27 Cross Section Across Shaft ................................................................ 32 Cross Section Across Shaft Components .......................................... 33 Cross Section Along Shaft ................................................................. 34 Cross Section Along Shaft Components ............................................ 35

Maintenance 5.1 5.2 5.3 5.4

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36

Periodic Maintenance Schedule ......................................................... 36 Servicing Air Cleaner .......................................................................... 37 Servicing Fuel Filter and Fuel Tank .................................................... 38 Long-Term Storage ............................................................................ 39

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Table of Contents 6.

Dissassembly/Reassembly General Information 6.1 6.2 6.3 6.4

7.

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Removing Engine from Rammer .........................................................41 Draining Oil ..........................................................................................43 Removing Recoil Starter and Blower Housing ....................................44 Removing Muffler ................................................................................45 Removing Governor Lever, Carburetor, Speed Control Lever ............46 Removing Ignition Coil, Flywheel, and Spark Plug ..............................47 Removing Rocker Cover and Cylinder Head ......................................48 Removing Bearing Cover ....................................................................49 Removing Camshaft and Tappets .......................................................50 Removing Connecting Rod and Piston ...............................................51 Removing Crankshaft ..........................................................................52 Removing Intake and Exhaust Valves .................................................53

Reassembly Procedures 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15

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Tools ....................................................................................................40 Ordering Parts .....................................................................................40 Reference Numbers ( ) ........................................................................40 Weight Block .......................................................................................40

Disassembly Procedures 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12

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WM 90 Repair

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Notes on Reassembly .........................................................................54 Crankshaft ...........................................................................................54 Reassembling Piston ...........................................................................55 Reassembling Piston and Connecting Rod .........................................56 Installing Piston ...................................................................................57 Installing Tappets and Camshaft .........................................................58 Adjusting Crankshaft End Play ............................................................59 Installing Main Bearing Cover .............................................................60 Cylinder Head ......................................................................................61 Reassembling Rocker Arms and Push Rods ......................................62 Adjusting Valve Clearances ................................................................63 Installing Rocker Cover and Spark Plug ..............................................64 Installing Flywheel Magneto ................................................................65 Installing Ignition Coil ..........................................................................65 Installing Governor, Speed Control System, and Carburetor ..............66


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WM 90 Repair 8.16 8.17 8.18 8.19 8.20

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Table of Contents

Adjusting Governor System ................................................................ 67 Installing Muffler ................................................................................. 67 Installing Blower Housing and Recoil Starter ..................................... 68 Re-installing Engine ........................................................................... 69 Break-in Operation ............................................................................. 71

Sub Systems 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9

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Magneto ............................................................................................. 72 Engine Basic Electric Theory ............................................................. 72 Electrical Components ....................................................................... 73 Automatic Decompression System .................................................... 74 Diaphragm-Type Carburetor .............................................................. 75 Carburetor Disassembly Procedure ................................................... 78 Carburetor Inspection ......................................................................... 79 Carburetor Reassembly ..................................................................... 79 Carburetor Adjustments ..................................................................... 80

10. Recoil Starter 10.1 10.2 10.3 10.4 10.5 10.6 10.7

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Recoil Starter Disassembly ................................................................ 81 Checking the Recoil Starter After Reassembly .................................. 85 Starter Assembly Exploded View ....................................................... 86 Disassembling the Starter .................................................................. 87 Inspecting the Starter ......................................................................... 87 Assembling the Starter ....................................................................... 88 Replacing the Starter Rope ................................................................ 89

11. Clearance Data and Limits Table 11.1

Term Descriptions .............................................................................. 91

12. Troubleshooting 12.1 12.2

91

99

Troubleshooting Introduction .............................................................. 99 Troubleshooting Procedures .............................................................. 99


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Emission Control System Information 1.

Emission Control System Information Source of Emissions The combustion process produces carbon monoxide, oxides of nitrogen, and hydrocarbons. Control of hydrocarbons and oxides of nitrogen is very important because, under certain conditions, they react to form photochemical smog when subjected to sunlight. Carbon monoxide does not react in the same way, but it is toxic. Wacker utilizes lean carburetor settings and other systems to reduce the emissions of carbon monoxide, oxides of nitrogen, and hydrocarbons. The U.S. and California Clean Air Acts EPA and California regulations require all manufacturers to furnish written instructions describing the operation and maintenance of emission control systems. The following instructions and procedures must be followed in order to keep the emissions from your Wacker engine within the emissions standards. Tampering and Altering Tampering with or altering the emission control system may increase emissions beyond the legal limit. Among those acts that constitute tampering are: •Removal or alteration of any part of the intake, fuel, or exhaust systems. •Altering or defeating the speed-adjusting mechanism to cause the engine to operate outside its design parameters. Problems That May Affect Emissions If you are aware of any of the following symptoms, have your engine inspected and repaired by your servicing dealer. •Hard starting or stalling after starting. •Rough idle. •Misfiring or backfiring under load. •Afterburning (backfiring). •Black exhaust smoke or high fuel consumption.

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Emission Control System Information Replacement Parts The emission control systems on your Wacker engine were designed, built, and certified to conform with EPA and California emissions regulations. We recommend the use of genuine Wacker parts whenever you have maintenance done. These original-design replacement parts are manufactured to the same standards as the original parts, so you can be confident of their performance. The use of replacement parts that are not of the original design and quality may impair the effectiveness of your emission control system. A manufacturer of an aftermarket part assumes the responsibility that the part will not adversely affect emission performance. The manufacturer or rebuilder of the part must certify that use of the part will not result in a failure of the engine to comply with emission regulations. Maintenance Follow the maintenance schedule. Remember that this schedule is based on the assumption that your machine will be used for its designed purpose. Sustained high-load or high-temperature operation, or use in unusually wet or dusty conditions, will require more frequent service. OXYGENATED FUELS Some conventional gasolines are being blended with alcohol or an ether compound. These gasolines are collectively referred to as oxygenated fuels. To meet clean air standards, some areas of the United States and Canada use oxygenated fuels to help reduce emissions. If you use an oxygenated fuel, be sure it is unleaded and meets the minimum octane rating requirement. Before using an oxygenated fuel, try to confirm the fuel’s contents. Some States / Provinces require this information to be posted on the pump. The following are EPA-approved percentages of oxygenates: ETHANOL - (ethyl or grain alcohol) 10% by volume. You may use gasoline containing up to 10% ethanol by volume. Gasoline containing ethanol may be marketed under the name “Gasohol”. MTBE - (methyl tertiary butyl ether) 15% by volume. You may use gasoline containing up to 15% MTBE by volume.

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Emission Control System Information METHANOL - (methyl or wood alcohol) 5% by volume. You may use gasoline containing up to 5% methanol by volume, as long as it contains cosolvents and corrosion inhibitors to protect the fuel system. Gasoline containing more than 5% methanol by volume may cause starting and/or performance problems. It may also damage metal, rubber, and plastic parts of your fuel system. If you notice any undesirable operating symptoms, try another service station, or switch to another brand of gasoline. Fuel system damage or performance problems resulting from the use of an oxygenated fuel containing more than the percentages of oxygenates mentioned above are not covered under warranty. EMISSIONS COMPONENT DEFECT WARRANTY COVERAGE This emission warranty is applicable in all States. Wacker Corporation, N92 W15000 Anthony Avenue, Menomonee Falls, WI 53051-1504, (herein "Wacker") warrant(“s”) to the initial retail purchaser and each subsequent owner, that this non-road engine (herein "engine") has been designed, built, and equipped to conform at the time of initial sale to all applicable regulations of the U.S. Environmental Protection Agency (EPA), and that the engine is free of defects in materials and workmanship which would cause this engine to fail to conform with EPA regulations during its warranty period. For the components listed under PARTS COVERED, the service dealer authorized by Wacker will, at no cost to you, make the necessary diagnosis, repair, or replacement necessary to ensure that the engine complies with applicable U.S. EPA regulations. EMISSISON COMPONENT DEFECT WARRANTY PERIOD The warranty period for this engine begins on the date of sale to the initial purchaser and continues for a period of 2 years. PARTS COVERED Listed below are the parts covered by the Emission Components Defect Warranty. Some of the parts listed below may require scheduled maintenance and are warranted up to the first scheduled replacement point for that part. (1) Fuel Metering System (i) Carburetor and internal parts (and/or pressure regulator or fuel injection system). (ii) Air/fuel ratio feedback and control system, if applicable. (iii) Cold start enrichment system, if applicable. (iv) Regulator assembly (gaseous fuel, if applicable) . (2) Air Induction System

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Emission Control System Information (i) Intake manifold, if applicable. (ii) Air filter. (3) Ignition System (i) Spark plugs. (ii) Magneto or electronic ignition system. (iii) Spark advance/retard system, if applicable. (4) Exhaust manifold, if applicable (5) Miscellaneous Items Used in Above Systems (i) Electronic controls, if applicable. (ii) Hoses, belts, connectors, and assemblies. (iii) Filter lock assembly (gaseous fuel, if applicable). OBTAINING WARRANTY SERVICE To obtain warranty service, take your engine to the nearest authorized Wacker service dealer. Bring your sales receipts indicating date of purchase for this engine. The service dealer authorized by Wacker will perform the necessary repairs or adjustments within a reasonable amount of time and furnish you with a copy of the repair order. All parts and accessories replaced under this warranty become the property of Wacker. WHAT IS NOT COVERED Conditions resulting from tampering, misuse, improper adjustment (unless they were made by the service dealer authorized by Wacker during a warranty repair), alteration, accident, failure to use the recommended fuel and oil, or not performing required maintenance services. The replacement parts used for required maintenance services. Consequential damages such as loss of time, inconvenience, loss of use of the engine or equipment, etc. Diagnosis and inspection charges that do not result in warranty-eligible service being performed. Any non-authorized replacement part, or malfunction of authorized parts due to use of non-authorized parts. OWNER'S WARRANTY RESPONSIBILITIES As the engine owner, you are responsible for the performance of the required maintenance listed in your owner's manual. Wacker recommends that you retain all receipts covering maintenance on your engine, but Wacker cannot deny warranty solely for the lack of receipts or for your failure to ensure the performance of all scheduled maintenance. As the engine owner, you should however be aware that Wacker may deny warranty coverage if your engine or a part has failed due to abuse, neglect, improper maintenance or unapproved modifications.

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Emission Control System Information You are responsible for presenting your engine to the nearest service dealer authorized by Wacker when a problem exists. If you have any questions regarding your warranty rights and responsibilities, you should contact the WACKER CORPORATION Product Support Department (U.S.A. 1-800-770-0957, Canada 1-877977-0775) for the information. THINGS YOU SHOULD KNOW ABOUT THE EMISSION CONTROL SYSTEM WARRANTY: MAINTENANCE AND REPAIRS You are responsible for the proper maintenance of the engine. You should keep all receipts and maintenance records covering the performance of regular maintenance in the event questions arise. These receipts and maintenance records should be transferred to each subsequent owner of the engine. Wacker reserves the right to deny warranty coverage if the engine has not been properly maintained. Warranty claims will not be denied, however, solely because of the lack of required maintenance or failure to keep maintenance records. MAINTENANCE, REPLACEMENT OR REPAIR OF EMISSION CONTROL DEVICES AND SYSTEMS MAY BE PERFORMED BY ANY REPAIR ESTABLISHMENT OR INDIVIDUAL; HOWEVER, WARRANTY REPAIRS MUST BE PERFORMED BY A SERVICE DEALER AUTHORIZED BY WACKER. THE USE OF PARTS THAT ARE NOT EQUIVALENT IN PERFORMANCE AND DURABILITY TO AUTHORIZED PARTS MAY IMPAIR THE EFFECTIVENESS OF THE EMISSION CONTROL SYSTEM AND MAY HAVE A BEARING ON THE OUTCOME OF A WARRANTY CLAIM. If other than the parts authorized by Wacker are used for maintenance replacements or for the repair of components affecting emission control, you should assure yourself that such parts are warranted by their manufacturer to be equivalent to the parts authorized by Wacker in their performance and durability. HOW TO MAKE A CLAIM All repair qualifying under this limited warranty must be performed by a service dealer authorized by Wacker. In the event that any emissionrelated part is found to be defective during the warranty period, you shall notify WACKER CORPORATION Product Support Department (U.S.A. 1-800-770-0957, Canada 1-877-977-0775) and you will be advised of the appropriate warranty service dealer or service providers where the warranty repair can be performed.

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WM 90 Repair 2.

Safety Information

Safety Information This manual contains DANGER, WARNING, CAUTION, NOTICE and NOTE callouts which must be followed to reduce the possibility of personal injury, damage to the equipment, or improper service. This is the safety alert symbol. It is used to alert you to potential personal injury hazards. Obey all safety messages that follow this symbol to avoid possible injury or death.

DANGER indicates a hazardous situation which, if not avoided, will result in death or serious injury. DANGER

WARNING indicates a hazardous situation which, if not avoided, could result in death or serious injury. WARNING

CAUTION indicates a hazardous situation which, if not avoided, could result in minor or moderate injury. CAUTION

NOTICE: Used without the safety alert symbol, NOTICE indicates a hazardous situation which, if not avoided, could result in property damage. Note: Contains additional information important to a procedure.

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Safety Information 2.1

WM 90 Repair

Operating Safety

WARNING

Familiarity and proper training are required for the safe operation of machine. Machines operated improperly or by untrained personnel can be dangerous. Read the operating instructions contained in both this manual and the engine manual and familiarize yourself with the location and proper use of all controls. Inexperienced operators should receive instruction from someone familiar with the machine before being allowed to operate it.

2.1.1

NEVER operate this machine in applications for which it is not intended.

2.1.2

NEVER allow anyone to operate this equipment without proper training. People operating this equipment must be familiar with the risks and hazards associated with it.

2.1.3

NEVER touch the engine or muffler while the engine is on or immediately after it has been turned off. These areas get hot and may cause burns.

2.1.4

NEVER use accessories or attachments that are not recommended by Wacker. Damage to equipment and injury to the user may result.

2.1.5

NEVER leave machine running unattended.

2.1.6

NEVER tamper with or disable the function of operating controls.

2.1.7

NEVER use choke to stop engine.

2.1.8

NEVER operate the machine in areas where explosions may occur.

2.1.9

ALWAYS read, understand, and follow procedures in the Operator’s Manual before attempting to operate the equipment.

2.1.10 ALWAYS be sure that all other persons are at a safe distance from the machine. Stop the machine if people step into the working area of the machine. 2.1.11 ALWAYS be sure operator is familiar with proper safety precautions and operation techniques before using machine. 2.1.12 ALWAYS wear protective clothing appropriate to the job site when operating equipment. 2.1.13 ALWAYS wear hearing protection when operating equipment. 2.1.14 ALWAYS keep hands, feet, and loose clothing away from moving parts of the machine. 2.1.15 ALWAYS use common sense and caution when operating the machine. 2.1.16 ALWAYS be sure the rammer will not tip over, roll, slide, or fall when not being operated. 2.1.17 ALWAYS turn the engine OFF when the rammer is not being operated.

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WM 90 Repair

Safety Information

2.1.18

ALWAYS guide the rammer in such a way that the operator is not squeezed between the rammer and solid objects. Special care is required when working on uneven ground or when compacting coarse material. Make sure to stand firmly when operating the machine under such conditions.

2.1.19

ALWAYS operate the rammer in such a way that there is no danger of it turning over or falling in, when working near the edges of breaks, pits, slopes, trenches and platforms.

2.1.20

ALWAYS store the equipment properly when it is not being used. Equipment should be stored in a clean, dry location out of the reach of children.

2.1.21

ALWAYS close fuel valve on engines equipped with one when machine is not being operated.

2.1.22

ALWAYS operate machine with all safety devices and guards in place and in working order. DO NOT modify or defeat safety devices. DO NOT operate machine if any safety devices or guards are missing or inoperative.

2.2

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Operator Safety while using Internal Combustion Engines

DANGER

Internal combustion engines present special hazards during operation and fueling. Read and follow the warning instructions in the engine owner’s manual and the safety guidelines below. Failure to follow the warnings and safety guidelines could result in severe injury or death.

2.2.1

DO NOT smoke while operating the machine.

2.2.2

DO NOT smoke when refueling the engine.

2.2.3

DO NOT refuel a hot or running engine.

2.2.4

DO NOT refuel the engine near an open flame.

2.2.5

DO NOT spill fuel when refueling the engine.

2.2.6

DO NOT run the engine near open flames.

2.2.7

DO NOT run the machine indoors or in an enclosed area such as a deep trench unless adequate ventilation, through such items as exhaust fans or hoses, is provided. Exhaust gas from the engine contains poisonous carbon monoxide gas; exposure to carbon monoxide can cause loss of consciousness and may lead to death.

2.2.8

ALWAYS refill the fuel tank in a well-ventilated area.

2.2.9

ALWAYS replace the fuel tank cap after refueling.

2.2.10

ALWAYS check the fuel lines and the fuel tank for leaks and cracks before starting the engine. Do not run the machine if fuel leaks are present or the fuel lines are loose.

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WM 90 Repair

Service Safety

WARNING

Poorly maintained machines can become a safety hazard! In order for the machine to operate safely and properly over a long period of time, periodic maintenance and occasional repairs are necessary.

2.3.1

DO NOT attempt to clean or service the machine while it is running. Rotating parts can cause severe injury.

2.3.2

DO NOT operate the machine without an air cleaner.

2.3.3

DO NOT remove air cleaner cover, paper element, or precleaner while engine is running.

2.3.4

DO NOT alter engine speeds. Run the engine only at speeds specified in the Technical Data Section.

2.3.5

DO NOT crank a flooded engine with the spark plug removed on gasoline-powered engines. Fuel trapped in the cylinder will squirt out the spark plug opening.

2.3.6

DO NOT test for spark on gasoline-powered engines if the engine is flooded or the smell of gasoline is present. A stray spark could ignite the fumes.

2.3.7

DO NOT use gasoline or other types of fuels or flammable solvents to clean parts, especially in enclosed areas. Fumes from fuels and solvents can become explosive.

2.3.8

ALWAYS replace the safety devices and guards after repairs and maintenance.

2.3.9

ALWAYS keep the area around the muffler free of debris such as leaves, paper, cartons, etc. A hot muffler could ignite the debris and start a fire.

2.3.10 ALWAYS do Periodic Maintenance as recommended in the Operator’s Manual. 2.3.11 ALWAYS clean debris from engine cooling fins. 2.3.12 ALWAYS replace worn or damaged components with spare parts designed and recommended by Wacker Corporation. 2.3.13 ALWAYS disconnect the spark plug on machines equipped with gasoline engines, before servicing, to avoid accidental start-up. 2.3.14 ALWAYS keep the machine clean and labels legible. Replace all missing and hard-to-read labels. Labels provide important operating instructions and warn of dangers and hazards.

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WM 90 Repair 2.4

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Safety Information

Label Locations

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WM 90 Repair

Safety Labels Wacker machines use international pictorial labels where needed. These labels are described below:

Label

Meaning This molded-in label contains important safety and operating information. If it becomes illegible, the cover must be replaced. Refer to the Parts Book for ordering information.

DANGER! Engines emit carbon monoxide; operate only in well-ventilated area.

Read the operator's manual for machine information.

DANGER! No sparks, flames or burning objects near machine.

Shut off the engine before refueling.

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WM 90 Repair Label

Safety Information Meaning CAUTION! Use only clean, filtered gasoline fuel.

WARNING! Hot surface!

WARNING! Serious injury if struck by compressed spring or cover. If the spring system cover is removed improperly, the springs can eject.

Guaranteed sound power level in dB(A).

CAUTION! Use only clean, filtered gasoline fuel.

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Safety Information Label

WM 90 Repair Meaning A nameplate listing the model number, item number, revision number, and serial number is attached to each unit. Please record the information found on this plate so it will be available should the nameplate become lost or damaged. When ordering parts or requesting service information, you will always be asked to specify the model number, item number, revision number, and serial number of the unit.

This machine may be covered by one or more patents.

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WM 90 Repair 2.6

Safety Information

Operating Labels Wacker machines use international pictorial labels where needed. These labels are described below:

Label

Meaning Turn the engine switch to the ON position.

Close the choke.

Pull the rewind starter.

Open the choke.

Turn the engine switch to "OFF".

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Safety Information Label

WM 90 Repair Meaning Throttle control lever: Turtle = Idle or Slow Rabbit = Full or Fast

Fuel valve: Closed Open

Engine stop button: Press to stop engine. Choke: 0 = Open l = Closed

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WM 90 3.

Technical Data

Technical Data 3.1

Specifications

Engine Model

WM 90 Engine

Engine Speed - full

rpm

4200 ± 100

Engine Speed - idle

rpm

2000 ± 100

Clutch Engagement

rpm

2500 ± 100

Spark Plug

type

NGK BM4A or BMR4A

mm (in)

0.6–0.7 (0.023–0.028)

(kg/cm2) psi

8.0–9.7 (120–140)

Electrode Gap Cylinder Head Compression (cold) Air Cleaner

type

Three-stage with cyclonic precleaner

Engine Lubrication

oil grade

SAE 10W30 SE, SF or higher

Engine Oil Capacity

ml (oz.)

300 (10)

Cooling System

type

Forced air

Ignition system

type

Solid-state, flywheel magneto

Starting system

type

Recoil starter

Governor system

type

Centrifugal flyweight

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Technical Data 3.2

Ref

WM 90

Performance

Description

Ref

Description

a

Maximum torque

d

Recommended horsepower range

b

Continuous rated horsepower

e

Output

c

Maximum horsepower

f

Torque

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WM 90 4.

Theory of Operation

Theory of Operation 4.1

Application Rammers are designed to compact loose soils and gravel to prevent settling and to provide a firm, solid base for the placement of footings, concrete slabs, foundations, and other structures.

4.2

Recommended Fuel This engine is certified to operate on automotive unleaded gasoline. Use only fresh, clean gasoline. Gasoline containing water or dirt will damage fuel system.

4.3

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Before Starting 4.3.1

Read safety instructions at the beginning of this manual.

4.3.2

Make sure that the gas tank is full.

4.3.3

Check engine oil level.

4.3.4

Place rammer on loose soil or gravel. DO NOT start rammer on hard surfaces such as asphalt or concrete.

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WM 90

To Start See Graphic: wc_gr001454 Note: After transporting the rammer horizontally, upright the rammer and allow the oil to drain back through the engine. It may take up to 2 minutes for the oil level to recover. 4.4.1

Open fuel valve (e).

4.4.2

Turn engine switch to "ON" (d).

4.4.3

If the engine is cold, close choke (b1) on the carburetor. Note: Occasionally, warm engines will need to be choked.

4.4.4

With throttle in idle position (c2), pull the starter rope (a) until the engine starts.

4.4.5

On engines equipped with the low oil shutoff switch, see section Low Oil Shutoff Switch for additional information. Note: First time use, engines recently serviced, run out of fuel or not used for long periods of time may need the rope to be pulled more times to move fuel to the carburetor.

4.4.6

Open choke (b2) on the carburetor as the engine warms up. Note: A cold engine should be allowed to warm up at the idle position (c2) for approximately one (1) minute. Failure to open the choke after the engine attempts to start may cause flooding. NOTICE: Always open choke (b2) with throttle in idle position (c2). Opening choke with throttle not in idle position (c2) may result in rammer motion. d

c1

a

c2 c3 c4

e

b2

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b1

WM 90

Theory of Operation

4.5

To Stop See Graphic: wc_gr001454

4.6

4.5.1

Place throttle in the idle position (c2).

4.5.2

Turn engine switch to "OFF" (d).

4.5.3

Close fuel valve (e).

Component Descriptions

Component Illustration

Component Description The cylinder/crankcase is a single piece aluminum die-casting. The cylinder liner, made of special cast iron, is molded into the aluminum casting. The crankcase has a mounting surface on the output shaft side, where the main bearing cover is attached.

wc_gr001870

The main bearing cover is an aluminum diecasting with thick reinforcing walls and ribs, which is mounted on the output shaft side of the crankcase. Remove the main bearing cover to inspect the inside of the engine. Pilots and bosses are machined on the cover for direct mounting of the engine onto rammers. Oil gauge (a).

a

wc_gr001871

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Theory of Operation Component Illustration

WM 90 Component Description The crankshaft is forged carbon steel, and the crank pin is induction-hardened. The output end of the shaft has a crankshaft gear that is pressed into position.

wc_gr001872

The connecting rod is an aluminum alloy diecasting and its large and small ends function as bearings. The piston is an aluminum alloy casting, and carries two compression rings and one oil ring.

wc_gr001873

a

The piston rings are made of special cast iron. The profile of the top ring and the second ring are shown in the illustration. The oil ring is a three-part ring designed for better sealing and less oil consumption.

b

c wc_gr001874

The camshaft is made of special cast iron, and camshaft and gear are cast together in one piece. Both sides of the shaft fit into the plain bearings on the crankcase and main bearing cover.

wc_gr001875

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WM 90

Theory of Operation


IN

a

Component Description The intake valve is located on the flywheel side of the cylinder head. Hard alloy valve seats are molded in the cylinder head and satellite is fused to the exhaust valve face. The cylinder baffle leads cooling air to the exhaust valve area for optimum cooling. Reference: intake (a); exhaust (b).

EX

b

wc_gr001876

The cylinder head is an aluminum die-casting which utilizes wedge-type combustion chamber for high combustion efficiency.

wc_gr001877

The governor is a centrifugal flyweight type which ensures constant operation at the selected speed during load variations. The governor gear (a) with governor weights is installed on the main bearing cover.

a

wc_gr001878

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Theory of Operation Component Illustration

WM 90 Component Description The large fins (a) on the flywheel provide sufficient cooling air capacity for the inlet and exhaust area and cylinder. The cylinder baffle directs the cooling air flow efficiently.

a

wc_gr001949

All the rotating and sliding parts are splashlubricated by the oil splasher (a) on the connecting rod.

a

wc_gr001879

The ignition system is a transistor-controlled magneto system which consists of a flywheel (a) and an ignition coil (b) with a built-in transistor mounted on the crankcase. This system has an automatic ignition timing advance system for easy starting.

b

a

wc_gr001880

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30

WM 90

Theory of Operation


Component Description WM 90 engines use a diaphragm-type carburetor.

wc_gr001881

The air cleaner is a heavy-duty three-stage type with cyclonic precleaner.

wc_gr002032

An automatic decompression mechanism (a), that opens the exhaust valve before the piston reaches maximum compression, is assembled on the camshaft for easy starting. During engine operation the decompression system is overpowered by centrifugal force and compression is fully utilized to produce power.

a wc_gr001883

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31


WM 90

Cross Section Across Shaft

1 1 13 2

12

3

11

10 9

8

7

wc_tx000388gb.fm

wc_gr001884

32

WM 90 4.8

Theory of Operation Cross Section Across Shaft Components See Graphic: wc_gr001884

.

Ref

Description

Ref

Description

1

Cylinder head

9

Main bearing cover

2

Piston pin

10

PTO shaft

3

Ignition coil

11

Piston ring

4

Blower housing

12

Piston

5

Recoil starter

13

Muffler

6

Flywheel

14

Exhaust valve

7

Crankcase

15

Intake valve

8

Flange adapter

wc_tx000388gb.fm

33


WM 90

Cross Section Along Shaft

1 14

4

10 g

wc_tx000388gb.fm

34

WM 90

Theory of Operation

4.10 Cross Section Along Shaft Components See Graphic: wc_gr001885 .

Ref

Description

Ref

Description

1

Push rod

9

Stiffener

2

Carburetor

10

Plug

3

Air cleaner

11

Oil gauge

4

Tappet

12

Connecting rod

5

Camshaft

13

Spark plug

6

Governor lever

14

Rocker arm

7

Speed control lever

15

Rocker cover

8

Crankshaft

wc_tx000388gb.fm

35

Maintenance 5.

WM 90 Repair

Maintenance 5.1

Periodic Maintenance Schedule

Before each use

Every 50 hours

Check for fluid leaks. Check engine oil. Check fuel level. Check for loose hardware. Clean debris from engine. Change engine oil*. Clean air cleaner. Check and clean spark plug. Check and adjust valve clearances. Remove carbon deposits from cylinder head. Disassemble and clean carburetor. Clean fuel filter and fuel tank. Replace fuel lines. Overhaul engine. * Change oil after initial 20 hours of operation on new or rebuilt engines.

wc_tx000392gb.fm

36

Every 100 hours

Every 300 hours

Every 500 hours or yearly

WM 90 Repair 5.2

Maintenance

Servicing Air Cleaner See Graphic: wc_gr001306 NEVER use gasoline or other types of low flash point solvents for cleaning the air filter. A fire or explosion could result. WARNING

NOTICE: NEVER run the engine without the main paper air filter (b). Severe engine damage will occur. Clean elements using the following procedure: 5.2.1

Remove the air cleaner cover (a). Remove the main paper filter element (b) and secondary prefilter (c) and inspect them for holes or tears. Replace the elements if they are damaged.

5.2.2

Main paper filter element (b): Replace the main paper filter element if it appears heavily soiled.

5.2.3

Prefilter (c): Clean the prefilter with low-pressure compressed air. When very soiled, wash the prefilter in a solution of mild detergent and warm water. Rinse it thoroughly in clean water. Allow the prefilter to dry thoroughly before reinstalling. Note: Do not oil the prefilter.

5.2.4

Wipe out the filter housing (d) with a clean cloth. Do not use compressed air. NOTICE: Do not allow dirt to get into the engine intake port (k) while cleaning. Damage to engine will result.

5.2.5

Check that the precleaner debris ejector slot (i) is clear.

a

b

c

i d

k wc_tx000392gb.fm

37

wc_gr001306

Maintenance 5.3

WM 90 Repair

Servicing Fuel Filter and Fuel Tank See Graphic: wc_gr002017 5.3.1

Drain fuel tank completely.

5.3.2

Remove fuel line from fuel flow valve (a).

5.3.3

Unscrew fuel filter assembly (b) from tank.

5.3.4

Clean filter with parts cleaning solvent.

5.3.5

Inspect gasket (c) and filter for damage and replace them if necessary.

5.3.6

Clean sediment from inside of fuel tank.

5.3.7

Re-install gasket, fuel filter, valve, and fuel lines.

c b a wc_gr002017

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38

WM 90 Repair 5.4

wc_tx000392gb.fm

Maintenance

Long-Term Storage 5.4.1

Drain the fuel from the tank.

5.4.2

Start the engine and run it until remaining fuel is used.

5.4.3

Remove the spark plug. Pour approximately 30 ml (1 oz.) of clean SAE 10W30 engine oil into the cylinder through the spark plug opening.

5.4.4

Pull the starter rope slowly to distribute oil in the engine.

5.4.5

Re-install the spark plug.

39

Dissassembly/Reassembly General Information 6.

WM 90 Repair

Dissassembly/Reassembly General Information 6.1

Tools Because all possible problems encountered while repairing the machine cannot be anticipated, it is up to the mechanic to use common sense and good judgement in tool selection. The use of any special tools is recommended only for those operations where the use of conventional tools proves inadequate. Before substituting another tool or procedure, you should be satisfied that neither personal injury nor damage to the component will result.

6.2

Ordering Parts The repair procedures contained in this manual do not include part numbers. For parts replacement information, refer to the Parts Book originally supplied with the machine. If the original Parts Book has been lost, a replacement may be ordered from Wacker Corporation. When ordering a replacement Parts Book, please list the model number, item number, revision level, and serial number of the machine. Parts Books are also available on the Wacker Corporation Web site. See www.wackergroup.com. Enter the site as a visitor.

6.3

Reference Numbers ( ) Repair procedures contain reference numbers enclosed in parentheses ( ). These numbers refer to the item numbers shown on the assembly drawings and other detailed drawings. They are included to aid the mechanic in identifying parts and assembling components.

6.4

Weight Block See Graphic: wc_gr000843 The weight block symbol gives an approximate weight measurement to aid the mechanic when lifting/hoisting larger components.

250 kg (550 lbs.) wc_gr000843

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40

WM 90 Repair 7.

Disassembly Procedures

Disassembly Procedures 7.1

Removing Engine from Rammer See Graphic: wc_gr001954, wc_gr003661, wc_gr001956, and wc_gr001957

wc_tx000389gb.fm

7.1.1

Disconnect the spark plug cap (a) from the spark plug.

7.1.2

Disconnect the fuel line (b) from the carburetor and plug the line.

7.1.3

Disconnect the stop switch wire (c).

7.1.4

Disconnect the wiring (k) from the low-oil unit (l) (if equipped).

7.1.5

Remove the M8 x 16 bolt and washer (d) securing the guard to the engine.

7.1.6

Remove the M8 bolt and washer (e) securing the guard to the rammer crankcase.

7.1.7

Remove the six M8 bolts (f) securing the lower guard to the engine and remove the guard.

7.1.8

Remove the wire running from the engine to the low-oil unit (if equipped).

7.1.9

Loosen the retainer (g) from the throttle cable. Pry open the clamp (h) and remove the throttle cable.

7.1.10

Loosen the clamp (i) securing the air intake hose to the carburetor and remove the hose.

7.1.11

Remove the four nuts (j) securing the engine to the adapter and remove the heat shield and the engine.

41


WM 90 Repair

d

c

a

k

b f j e

l

wc_gr003661

wc_gr001954

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42

WM 90 Repair 7.2


Draining Oil See Graphic: wc_gr001886 Note: In the interests of environmental protection, place plastic sheeting and a container under the machine to collect the liquid which drains off. Dispose of this liquid properly. 7.2.1

Remove the drain plug (a) and gasket (b).

7.2.2

Remove oil gauge (c) and gasket (d).

7.2.3

Drain oil from crankcase. Replace plug, oil gauge, and gaskets when complete.

c d

a b

wc_gr001886

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43


WM 90 Repair

Removing Recoil Starter and Blower Housing See Graphic: wc_gr003650 7.3.1

Remove the bolts (a) and remove the recoil starter (b) from the housing.

7.3.2

Remove the flange bolts (f), cap screw (g), and remove the blower housing (h).

g

a

b

f h wc_gr003650

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44

WM 90 Repair 7.4


Removing Muffler See Graphic: wc_gr001888

wc_tx000389gb.fm

7.4.1

Remove the flange nuts (a).

7.4.2

Remove the flange bolts (b).

7.4.3

Remove the bolts and washers (c) and remove the muffler (d) and the gasket (e).

45


WM 90 Repair

Removing Governor Lever, Carburetor, Speed Control Lever See Graphic: wc_gr001890

wc_tx000389gb.fm

7.5.1

Mark the hole in which the governor spring (a) is attached and remove the spring.

7.5.2

Loosen the M6 bolt (b) and remove the governor lever (c).

7.5.3

Remove the governor rod (d) and the rod spring (e), and if necessary, bushing (f).

7.5.4

Remove the carburetor flange (g), the gaskets (h), the carburetor (i).

7.5.5

Remove the bolts (j) securing the insulator (k) and remove the insulator and gasket (m).

7.5.6

Remove the M6 pivot bolt (n) and washer (o) and remove the speed control lever (p).

7.5.7

Also remove return spring (q) and spacer (r).

7.5.8

Remove the two M6 x 8 flange bolts (s) and remove the base plate (t).

46

WM 90 Repair 7.6


Removing Ignition Coil, Flywheel, and Spark Plug See Graphic: wc_gr001891 7.6.1

Remove the spark plug (a).

7.6.2

Remove the two M6 x 25 bolts (b) and remove the ignition coil (c).

7.6.3

Remove the M12 nut and washer (d), four M6 bolts (e), and remove the starter pulley (f) and flywheel (g). If necessary, break the nut loose by tapping the handle of the wrench with a hammer. To remove the flywheel, hold an aluminum bar (h) against the flywheel side of the crankshaft and tap the bar with a hammer.

7.6.4

Remove the Woodruff key (i) from the crankshaft.

h

c a

e f b

g

d

i wc_gr001891

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47


WM 90 Repair

Removing Rocker Cover and Cylinder Head See Graphic: wc_gr001892

wc_tx000389gb.fm

7.7.1

Remove the four M6 x 60 bolts (a) and remove the rocker cover (b) and gasket (c).

7.7.2

Remove the breather (d), gaskets (e), and spacer (f).

7.7.3

Remove the two M8 x 55 bolts (g) and the two M8 bolts (h), remove the cylinder head (k) and gasket (l)

7.7.4

Remove the pipes (m) and push rods (n).

7.7.5

If necessary, remove the seal (i) and the guide (j).

48

WM 90 Repair 7.8


Removing Bearing Cover See Graphic: wc_gr001893 7.8.1

Remove the nine M6 x 30 bolts and washers (a) and remove the main bearing cover (b). Note: If necessary, use a rubber mallet (c) and tap the cover to loosen it from the crankcase.

c

b a

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wc_gr001893

49


WM 90 Repair

Removing Camshaft and Tappets See Graphic: wc_gr001894 7.9.1

Lay crankcase on the flywheel side and push the tappets (a) into the crankcase and remove the camshaft (b).

a

b b

wc_gr001894 wc_tx000389gb.fm

50

WM 90 Repair


7.10 Removing Connecting Rod and Piston See Graphic: wc_gr001895 7.10.1

Remove connecting rod bolts (a) and connecting rod cap (b).

7.10.2

Turn crankshaft until piston (c) comes to top dead center, push out connecting rod (d) and piston assembly through top of cylinder. Note: Scrape off all carbon deposits that might interfere with removal of piston from upper end of cylinder.

7.10.3

Remove the clips (e) and the piston pin (f) to remove connecting rod from piston.

7.10.4

Being careful not to damage the rings or piston, remove the rings (g) from the piston by spreading them at the gap and pulling them from the piston.

e

g c f

e d

b a wc_gr001895

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WM 90 Repair

7.11 Removing Crankshaft See Graphic: wc_gr001896 7.11.1 To remove the crankshaft (a), tap lightly on flywheel end of the crankshaft with a rubber mallet (b).

a

b wc_gr001896

wc_tx000389gb.fm

52

WM 90 Repair


7.12 Removing Intake and Exhaust Valves See Graphic: wc_gr001897 Note: The procedure is the same for removing each valve. 7.12.1

Remove pivot bolt (a), rocker arm (b), and nut (c).

7.12.1

Press down the spring retainer (d), take out the collet (e), and then remove spring retainer and valve spring (f).

7.12.2

Remove intake (g) and exhaust (h) valves from cylinder head. Reference: guide plate (i).

a b d e

c

f i

g h wc_gr001897

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53

Reassembly Procedures 8.

WM 90 Repair

Reassembly Procedures 8.1

Notes on Reassembly Observe the following prior to/during reassembly of the engine:

8.2

•

Clean each part carefully, taking special care with the piston, cylinder, crankshaft, connecting rod, and bearings.

•

Scrape off any carbon deposits on the cylinder head and the piston head. Be particularly careful when removing carbon from the piston ring grooves.

•

Inspect oil seals for any damage to the lip. Replace them if damaged. Apply oil to lip before re-assembling.

•

Replace all gaskets with new ones.

•

Replace keys, pins, bolts and nuts with new ones if necessary.

•

Tighten nuts and bolts to the specified torque settings.

•

During re-assembly, apply oil to all moving parts.

•

Check clearances and end plays. Adjust the clearances as necessary.

•

When mounting any major moving part, rotate it with your hand to check for any jamming or abnormal noise.

Crankshaft See Graphic: wc_gr001898 8.2.1

Wrap the keyway portion of the crankshaft (a) with polyvinyl tape (b) and insert the crankshaft into the crankcase, taking care not to damage the oil seal lip.

a

b wc_gr001898

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54

WM 90 Repair 8.3

Reassembly Procedures

Reassembling Piston See Graphic: wc_gr001874, wc_gr001899 and wc_gr001900 Install each piston ring in the correct groove of the piston by widening it enough to slide it over the piston. Note: When installing the piston rings, make sure not to twist the rings too much as they may become damaged. 8.3.1

Install the three-piece oil ring (c) first. When installing the oil ring, install the middle section first, then the outer two outer sections.

8.3.2

Install the second ring (b). When installing the second ring, make sure that the “RN” mark is face up.

8.3.3

Install the top ring (a).

a

b

c wc_gr001874 wc_gr001900

wc_gr001899

wc_tx000389gb.fm

55


WM 90 Repair

Reassembling Piston and Connecting Rod See Graphic: wc_gr001901 8.4.1

Install the piston (a) onto the connecting rod (b) using the piston pin (c) and two clips (d).

d a c

d b

wc_gr001901

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56

WM 90 Repair 8.5


Installing Piston See Graphic: wc_001902, wc_gr001903, and wc_gr001904 8.5.1

Position the piston rings so that the gaps in the rings are at 90° intervals from each other (a = top ring, b = second ring, c = oil ring).

8.5.2

Apply oil to the piston rings, the cylinder bore, and the large end of the connecting rod.

8.5.3

Position the “MA” mark on the crankshaft so that it faces the flywheel side of the engine when assembled. Then, using a ring guide (d), hold the piston rings in and lower the piston into the cylinder. Note: If you do not have a ring guide, hold the piston rings in with your fingers while tapping lightly on the piston head with a block of wood or rubber mallet.

8.5.4

Rotate the crankshaft down to the bottom dead center and lightly tap the piston head until the large end of the connecting rod touches the crank pin.

8.5.5

To mount the connecting rod, line up the matching marks (e) and fit the connecting rod cap to the connecting rod. Secure the two halves together using two M5 bolts. Torque bolts to: 5.9–7.8 Nm (4.3–5.7 ft.lbs).

8.5.6

Check for free movement of the connecting rod by turning the crankshaft slowly.

d

"MA"

wc_gr001902

e wc_gr001904 wc_tx000389gb.fm

57


WM 90 Repair

Installing Tappets and Camshaft See Graphic: wc_gr001905 8.6.1

Oil the tappets (a) and install them. Push them in fully to avoid damage during camshaft (b) installation.

8.6.2

Remove spacer (c) to allow viewing of timing mark.

8.6.3

Lubricate the bearing surfaces of camshaft. Align the timing marks (d) on the camshaft with the timing marks on the crankshaft and install the camshaft into the crankcase. NOTICE: Incorrect valve timing will cause malfunction of the engine.

a

c

d b

wc_gr001905

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58

WM 90 Repair 8.7


Adjusting Crankshaft End Play See Graphic: wc_gr001906 Adjust the end play to 0.2 mm (0.008 in.) using the proper spacer. Determine the proper spacer in the following manner: 8.7.1

Measure the height “A”. Distance from main bearing cover mating surface (a) to the inner race of the ball bearing (b).

8.7.2

Measure the depth “B”. Distance from the crankcase mating surface (c) to the crankshaft gear (d). B-A = side clearance Side clearance - 0.2 mm (0.008 in.) = thickness of crankshaft shim. Spacer shims are available in the following thicknesses: 0.6 mm (0.024 in.) 0.8 mm (0.031 in.) 1.0 mm (0.039 in.)

8.7.3

Reference: crankcase (e); crankshaft (f); depth gauge (g).

g b f d

d

a c

e wc_gr001906

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59


WM 90 Repair

Installing Main Bearing Cover See Graphic: wc_gr001907 8.8.1

Lubricate the oil seal and bearing surfaces with engine oil.

8.8.2

Coat the mating surfaces of the main bearing cover (a) and crankcase (b) with Loctite® 515 Gasket Eliminator or equivalent.

8.8.3

Using nine M6 x 30 bolts and washers (c) secure the main bearing cover to the crankcase. Tighten bolts in pattern shown on illustration. Torque the bolts to: 9.8–11.8 Nm (7.2–8.7 ft.lbs.).

4 3

5 6

2

7

1

b

9 8

a

c

wc_gr001907

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60

WM 90 Repair 8.9


Cylinder Head 8.9.1

Clean carbon and gum deposits from the valves, seats, ports, and guides. Inspect them once clean. Replace valves that are badly burned, pitted, or warped.

8.9.2

When installing valves in cylinder head, oil the valve stems and insert them into valve guide. Then place cylinder head on a flat table, install spring and spring retainer.

8.9.3

Valve guides should be replaced when valve stem clearance exceeds specifications. See Clearance Data and Limits Table.

8.9.4

Draw valve guides out and press new guides in. See Clearance Data and Limits Table.

8.9.5

After replacing valves and guides, lap valves in place until a uniform ring shows around the face of the valve. Clean valves and wash cylinder head thoroughly.

8.9.6

Install cylinder head onto cylinder with new head gasket. Tighten the four M8 x 55 flange bolts in a crisscross pattern, in three incremental steps using the following torque values: Step 1: 5.0 Nm (3.6 ft.lbs.) Step 2: 9.8 Nm (7.2 ft.lbs.) Step 3: 18.6–20.6 Nm (13.7–15.2 ft.lbs.)

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WM 90 Repair

8.10 Reassembling Rocker Arms and Push Rods See Graphic: wc_gr001908 8.10.1 Insert push rods (a) into crankcase. Place push rod tip into the hollow of the tappet top. NOTICE: An oil return slot is located next to the tappet boss. If you do not put the push rod in the tappet properly, the push rods will fall into the crankcase. If this happens, removal of the main bearing cover will be necessary to remove them. 8.10.2 Place the gasket (b) on the crankcase. Position the intake valve (c) and the exhaust valve (d) into the cylinder head (e). Using four M8 x 55 flange bolts (f), secure the cylinder head to the crankcase . 8.10.3 Position the guide plate (g). Insert the valve spring (h), the spring retainer (i), and secure them to the valve using the collet (j). Complete for both intake and exhaust. 8.10.4 Using the pivot bolt (l) and the M6 nut (m), install the rocker arm (k). Complete for both intake and exhaust. l k j m

i h

g

f e

d

c

b a

wc_gr001908 wc_tx000389gb.fm

62

WM 90 Repair


8.11 Adjusting Valve Clearances See Graphic: wc_gr001909 and wc_gr001910 Note: Check and adjust valve clearances when engine is cold. 8.11.1

Temporarily fit the flywheel in position.

8.11.2

Position the piston at the top dead center of the compression stroke by matching the alignment mark on the flywheel (a) with the alignment mark on the crankcase (b).

8.11.3

Loosen the nut (c) under the rocker arm. Position a feeler gauge (e) as shown and turn the pivot bolt (d) until the clearance measures 0.07– 0.13 mm (0.0028–0.0051 in.). Tighten pivot bolt. Complete for both intake and exhaust valves.

8.11.4

Check operation of the valves by turning the crankshaft. Recheck the valve clearances.

b a

wc_gr001909

e d

c wc_gr001910

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WM 90 Repair

8.12 Installing Rocker Cover and Spark Plug See Graphic: wc_gr001911 Note: Replace the gasket with a new one each time the rocker cover is removed. 8.12.1 Using four M6 bolts (a), secure the rocker cover (b) and gasket (c) to the cylinder head. 8.12.2 Remove any carbon deposits from the spark plug and inspect the electrode for damage. Replace the spark plug if necessary. Use NGK BM6A or BMR6A Electrode gap: 0.6–0.7 mm (0.23–0.27 in.). Spark Plug Torque: New plug: 11.8–14.7 Nm (8.7–10.9 ft.lbs.) Reused plug: 22.6–24.5 Nm (16.6–18.1 ft.lbs.)

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64

WM 90 Repair


8.13 Installing Flywheel Magneto 8.13.1

Place the Woodruff key in the keyway of the crankshaft. Thoroughly wipe off oil and grease from the tapered portion of the crankshaft and also from the flywheel center hole.

8.13.2

Install the flywheel, M12 nut and washer to the crankshaft. Hold the flywheel using a strap wrench and torque the nut to 44.2–49.1 Nm (32.5–36.2 ft.lbs.).

8.14 Installing Ignition Coil See Graphic: wc_gr001913 8.14.1

Using two M6 x 25 bolts and washers, mount the ignition coil (a) to the engine. Before tightening the bolts, adjust the air gap using a thickness gauge (b). Adjust the air gap to 0.3–0.5 mm (0.012–0.020 in.).

a b wc_gr001913

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WM 90 Repair

8.15 Installing Governor, Speed Control System, and Carburetor See Graphic: wc_gr001890 8.15.1 Install governor lever (a) to governor shaft, then tighten the locking bolt (b) temporarily. 8.15.2 Install baseplate (t) to crankcase using two M6 x 8 flange bolts (s). 8.15.3 Install the speed control lever (p), friction washer (o), pivot bolt (n), spacer (r) and return spring (q). 8.15.4 Attach the governor spring (c) to proper holes (as marked during disassembly) of governor lever and speed control lever. 8.15.5 Using bolts (j), install insulator (k) and gasket (m). 8.15.6 Install carburetor (i) and gaskets (h) to cylinder head. Also install appropriate carburetor flange (g). 8.15.7 Install bushing (f). Install governor rod (d) to governor lever and throttle lever of carburetor. Attach spring (e) over governor rod. 8.15.8 See section Adjusting Governor System.

s r p o n

q t m

i

e k

f d a

c

j h g

wc_gr001890

b

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WM 90 Repair


8.16 Adjusting Governor System See Graphic: wc_gr001914 8.16.1

Turn the speed control lever (a) all the way toward the high speed position and secure it by tightening the self-locking screw.

8.16.2

Check that the governor lever (b) is pulled by the governor spring (c) and carburetor throttle valve is fully open.

8.16.3

Turn the governor shaft (d) clockwise all the way using a screw driver, and tighten the lock bolt to secure the lever on the shaft.

8.16.4

Loosen the lock nut to allow the speed control lever to move freely. Reference: governor rod spring (e); normal hooking position of governor spring (f).

e

c f b

a

d

wc_gr001914

8.17 Installing Muffler See Graphic: wc_gr001888 8.17.1

wc_tx000389gb.fm

Using two flange nuts (a), two flange bolts (b), and bolts and washers (c), install muffler (d) and gasket (e).

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WM 90 Repair

8.18 Installing Blower Housing and Recoil Starter See Graphic: wc_gr003650 8.18.1 Install the blower housing (h) using the flange bolts (f) and cap screw (g). 8.18.2 Install the recoil starter (b) to the housing using the bolts (a).

g

a

b

f h wc_gr003650

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WM 90 Repair


8.19 Re-installing Engine See Graphic: wc_gr001954, wc_gr003661, wc_gr001956, and wc_gr001957

wc_tx000389gb.fm

8.19.1

Position the engine so that mounting studs protrude from the adapter plate mounted to the rammer crankcase. Position heatshield and secure engine and heatshield to rammer with four nuts (j).

8.19.2

Connect the wire from the low-oil unit (l) (if equipped) to the engine.

8.19.3

Using six M8 bolts (f) mount the guards to the engine. Secure upper guard to engine using M8 x 16 bolt (d) and to rammer crankcase using M8 bolt (e).

8.19.4

Secure the throttle cable to the engine by crimping clamp (h). Feed cable through retainer (g) and tighten screw.

8.19.5

Secure air intake hose to engine by crimping clamp (i).

8.19.6

Reconnect stop switch wire (c).

8.19.7

Connect the wiring (k) from the low-oil unit (l) (if equipped).

8.19.8

Reconnect fuel line (b) to the carburetor.

8.19.9

Reconnect spark plug (a).

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WM 90 Repair

d

c

a

k

b f j e

l

wc_gr003661

wc_gr001954

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WM 90 Repair


8.20 Break-in Operation A new engine or one that has been completely overhauled by being fitted with a new piston, rings, valves, and connecting rod should be thoroughly run-in before being put into service. Good bearing surfaces and running clearances between the various parts can only be established by operating the engine under reduced speed and loads for a short period of time. Run-in the engine according to the schedule below. During the run-in period, check for oil leaks, make final carburetor adjustments, and regulate the engine operating speed. Step

Engine Load

Speed (rpm)

Duration (min.)

1

No load

2500

10

2

No load

3000

10

3

No load

3600

10

4

0.7 kW (1.0 hp)

3000

30

5

1.0 kW (1.9 hp)

3600

60

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Sub Systems 9.

WM 90 Repair

Sub Systems 9.1

Magneto The ignition system of the WM 90 is a breakerless flywheel magneto with an automatic advancing system. This system has no breaker points and thus is free from the starting and running problems associated with dirty, burnt, or corroded breaker points. The electronic automatic advancing ensures easy starts and high performance at operating speed by advancing the ignition timing to the most suitable point.

9.2

Engine Basic Electric Theory See Graphic: wc_gr001916 9.2.1

Revolution of the flywheel generates electricity in the primary side of the ignition coil, and the base current I1 flows to the power transistor. Current I1 turns the power transmitter “ON” and the electric current I2 flows.

9.2.2

At lower engine revolution, when the flywheel reaches the ignition point, the low speed ignition timing control circuit operates to run the base current I3 to turn the signal transistor A “ON” allowing the current I1 to bypass as current I4. At this moment, the power transistor turns “OFF” and the current I2 is abruptly shut off resulting in the high voltage generated in the secondary coil which produces sparks at the spark plug.

9.2.3

At higher engine revolution, the advancing control circuit operates at the ignition timing to run the base current I5 to turn the signal transistor B “ON” allowing the current I1 to bypass as current I6. At this moment the power transistor turns “OFF” and the current I2 is abruptly shut off resulting in the high voltage generated in the secondary coil which produces sparks at the spark plug. The operating timing of the advancing control circuit advances in accordance with the increase of engine speed resulting in the advancing of the ignition timing shown in the chart.

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9.3

Sub Systems

Electrical Components See Graphic: wc_gr001916

Ref

Description

Ref

Description

1

Low-speed ignition timing circuit

9

Spark plug

2

Signal transistor A

10

Ignition timing (BTDC)

3

Automatic advancing control circuit

11

Engine revolution (rpm)

4

Signal transistor B

12

Step advancing

5

Resistor

13

Stop switch

6

Power transistor

14

Connector

7

Primary coil

15

Ignition coil

8

Secondary coil

16

Flywheel

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Sub Systems 9.4

WM 90 Repair

Automatic Decompression System See Graphic: wc_gr001917 WM 90 engines employ an automatic decompression system as a standard feature. This system enables easy starting of the engine, with lighter recoil pull. The automatic decompression system releases the compression of the engine by lifting up the exhaust valve at cranking speeds. At the end of the compression process, the release lever (a) lifts up the tappet (b) which in turn opens the exhaust valve slightly to release compression. The release lever has a flyweight (c) on one end and a crescent cam (d) on the other. When the engine is cranked, the crescent cam projects above the cam profile and lifts up the tappet because the gravity force on the weight is larger than the centrifugal force on the weight. Reference: exhaust cam (e); camshaft (f); rotation direction (g).

b a

c

d

e

e

g

f wc_gr001917

See Graphic: wc_gr001918 When the cranking speed reaches a specified rpm, the crescent cam (d) is retracted under the cam profile because the centrifugal force applied to the flyweight (c) becomes larger than the force of the gravity on the weight and thus it is shifted to the position shown. c b

a

d

e

e g

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f

74

wc_gr001918

WM 90 Repair 9.5

Sub Systems

Diaphragm-Type Carburetor See Graphic: wc_gr001919

Ref

Description

Comment

1

Engine impulse

The alternating action of the positive pressure and negative pressure inside the engine crankcase operates the fuel pump diaphragm.

2

Fuel pump diaphragm The fuel pump diaphragm undulates in response to the engine impulse and as a result, it feeds the fuel through the fuel pump.

3

Fuel inlet

The fuel inlet is the opening through which fuel is drawn from the fuel tank.

4

Inlet valve

The inlet valve opens when the diaphragm is submitted to the action of a negative pressure in response to the movement of the pump diaphragm and the inlet valve shuts when it is submitted to a positive pressure.

5

Outlet valve

The outlet valve shuts when it is submitted to the action of a negative pressure and opens when submitted to a positive pressure.

6

Inlet screen

The inlet screen filters the fuel that is drawn from the fuel tank to the carburetor.

7

Inlet needle valve

The inlet needle valve controls the fuel that is fed from the fuel pump to the metering chamber.

8

Throttle valve

The throttle valve controls the volume of air drawn into the engine, thereby changing the engine speed.

9

Air vent hole

The air vent hole is open to the atmosphere, with the purpose of allowing smooth operation of the metering diaphragm.

10

Metering diaphragm

The metering diaphragm has the function of operating the metering lever, which is pulled up by the variations in the negative pressure of the engine.

11

Metering lever

The metering lever has the function of opening/closing the inlet valve by transmitting the movements of the metering diaphragm to that valve.

12

Metering lever spring

The metering lever spring has the function of pushing up the metering lever, thereby shutting the needle valve when the engine is stopped and when the metering chamber is full of fuel.

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Sub Systems

WM 90 Repair

Ref

Description

Comment

13

Metering chamber

The metering chamber is the fuel storage compartment that has the function of supplying fuel to the nozzle holes and other parts.

14

First idle hole

The first idle hole is the only fuel supply hole that is available when the engine is idling.

15

Second and third idle holes

The second and third idle holes have the function of supplying fuel when the throttle is at an intermediate opening state between the idling state and the fully open state.

16

Idle needle

The idle needle has the function of controlling the fuel when the engine is at idling speeds and when the throttle is at low speed position.

17

High-speed needle

The high speed needle has the function of controlling the fuel when the engine is operating at high speed and when the throttle is at a high speed position.

18

Main nozzle

The main nozzle is the hole through which fuel is ejected when the engine is operating at high speed and when the throttle is at a high speed position.

19

Venturi

The venturi has the function of increasing the air flow ar the nozzle section, thereby improving the atomization of the fuel.

20

Choke valve

The choke valve has the function of shutting the suction of air when the engine is started at a cold state, thereby securing the temporary supply of rich fuel/air mixture.

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Sub Systems

2

4

5 6

3 1 8

19

15

18

14

17

20

16 7 11

13 10

9 wc_gr001919

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12

Sub Systems 9.6

WM 90 Repair

Carburetor Disassembly Procedure See Graphic: wc_gr001920 Prior to disassembling the carburetor, wash it with an appropriate cleaning solvent. 9.6.1

Loosen the pump cover screw (14) and remove the screw and the pump cover (13).

9.6.2

Remove the pump gasket (12) and the diaphragm (11).

9.6.3

Place the carburetor with the metering side up and remove the metering cover screws (8).

9.6.4

Remove the metering cover (7), the diaphragm assembly (6), and the gasket (5).

9.6.5

Loosen the metering lever pin screw (17) and remove the lever (4), pin (18), spring (3), and needle valve (2).

14 13

12 15

20

11 1

10 9

19 16

2 18 17

3 4 5 6 7

8

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wc_gr001920

78

WM 90 Repair 9.7

Sub Systems

Carburetor Inspection See Graphic: wc_gr001920

9.8

9.7.1

Clean the carburetor and components with an appropriate solvent.

9.7.2

Check the gaskets for any deformation and/or damage. Replace any deformed or damaged gaskets.

9.7.3

Make sure that the pump diaphragm (11) is not damaged. Also make sure that the inlet valve and outlet valve are flat and not bent.

9.7.4

Make sure that the metering diaphragm (6) is not damaged and that the plate is not bent.

9.7.5

Check the throttle shaft (19) and the choke shaft (20) for smooth operation.

9.7.6

Check the inlet screen (1) for dirt. If the screen is dirty, wash it and blow it out with compressed air.

9.7.7

Check the inlet valve for abnormal wearing. If the inlet valve is worn, replace it.

Carburetor Reassembly See Graphic: wc_gr001920

wc_tx000390gb.fm

9.8.1

Mount the inlet screen (1) to the carburetor body.

9.8.2

Mount the inlet needle (2), metering lever spring (3), metering lever (4), and other related components.

9.8.3

Mount, in this order, the metering gasket (5), metering diaphragm, (6), and cover (7). Tighten the four cover screws.

9.8.4

Next, mount in this order, the pump diaphragm (11), pump gasket (12), and pump cover (13). Tighten the pump cover screw.

79

Sub Systems 9.9

WM 90 Repair

Carburetor Adjustments See Graphic: wc_gr001920 Idling Adjustment: 9.9.1

Start the engine and adjust the idle adjust screw (15) so that the engine is running at a speed slightly lower than the speed at which the clutch engages. High-Speed Adjustment:

9.9.2

Set the throttle valve (16) to the fully open position and check whether the engine rotates at the maximum engine speed as listed in the Technical Data section.

14 13

12 15

20

11 1

10 9

19 16

3 4

2 18 17

5 6 7

8

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wc_gr001920

80

WM 90 Repair

Recoil Starter

10. Recoil Starter 10.1 Recoil Starter Disassembly For machines with item numbers 0009386 rev. 111 and lower; 0009340 rev. 111 and lower; 0620051 rev. 107 and lower See Graphic: wc_gr001830 Wear eye protection when working on the recoil starter. CAUTION

To release the reel spring power: 10.1.1

Hold the starter knob and pull out the starter rope.

10.1.2

Pull out the rope fully and align the rope knot in the reel with the rope guide.

10.1.3

Hold the reel down firmly with both thumbs, taking care to not allow it to spring back. Note: The following procedure requires the help of an assistant.

10.1.4

Remove the knot from the reel, untie the knot and pull the rope out toward the starter knob.

10.1.5

While controlling the reel with your thumbs, slowly wind it back as far as it will go. Note: When the rope is pulled out to its full length, the force stored in the spring reaches its maximum. Take care when handling the reel.

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Recoil Starter

WM 90 Repair

See Graphic: wc_gr001831 To remove the components: 10.1.6 Grip the case (a) and loosen the set screw (b). 10.1.7 Remove, in this order: the set screw, the ratchet guide (c), the friction spring (d), and the ratchet (e).

See Graphic: wc_gr001831 Remove the reel: 10.1.8 Hold down the reel (f) gently, to keep it from escaping from its case, and rotate it slowly back and forth by quarter turns until it moves smoothly. 10.1.9 Lift the reel up slightly and remove it from the case. 10.1.10 If the spring is about to pop out of the reel, repeat the previous two steps. Note: Since the spring is stored in the reel, make sure not to drop or shake the reel after removing it. Place it on a flat secure surface such as a table.

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Recoil Starter

Reassembly See Graphic: wc_gr001832 Re-installing the reel: 10.1.11 Apply grease (Exxon Unirex or equivalent) (a) to the surface of the case. 10.1.12 Adjust the position of the inner end of the spring reel. Reference (b): position where the inner end of the spring touches the rib of the bearing. 10.1.13 Hold the reel in such a way that the inner end of the spring hooks onto the shaft hook (c) and then place the reel carefully back into the case.

See Graphic wc_gr001833 and wc_gr001834 Reinstalling the components: 10.1.14 Mount the ratchet into the reel. The ratchet should be in the closed position (a). 10.1.15 Mount the ratchet guide assembly (b), taking care to not move the ratchet or lose the friction spring (d). 10.1.16 Tighten the set screw (c). Torque to 5.5 Nm (4.0 ft.lbs.).

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Recoil Starter

WM 90 Repair

See Graphic: wc_gr001835 Tensioning the reel spring: 10.1.17 Grip the case and turn the reel 6 times counterclockwise. 10.1.18 Rotate the reel so that the rope hole (a) is aligned with the rope guide (b).

See Graphic: wc_gr001836 and wc_gr001837 Installing the rope: Note: This procedure requires help from an assistant. 10.1.19 Pass the rope through the rope guide and the rope hole of the reel and pull through approximately 20 cm (7-3/4 in.) out of the reel. 10.1.20 Tie a knot in the end of the rope. 10.1.21 Put the rope into the reel, taking care that the rope end does not stick up. 10.1.22 Grasp the rope firmly with one hand approximately 50 cm (19-5/8 in.) from the rope guide and keep the rope tense, taking care that the rope is not pulled into the reel. 10.1.23 Release the reel carefully and allow the rope to be wound back slowly by the force of the spring until the knob reaches the rope guide.

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WM 90 Repair

Recoil Starter

10.2 Checking the Recoil Starter After Reassembly For machines with item numbers 0009386 rev. 111 and lower; 0009340 rev. 111 and lower; 0620051 rev. 107 and lower Note: Carry out the following procedures to ensure proper operation of the starter assembly. 10.2.1 •

If the starter knob is too heavy to pull, check that each part has been assembled as specified.

•

If the ratchet does not work, check for missing parts such as the friction spring.

10.2.2

wc_tx000627gb.fm

Pull the starter rope 2–3 times.

Pull out the starter knob as far as it will go.

•

If the starter rope remains in the rope slot in the reel, the spring may be over-stressed. To fix this, pull out the starter rope approximately 30 cm (11-3/4"), and controlling the rotation of the reel with your thumb, allow the starter rope to rewind about one or two turns.

•

If the starter rope rewinds slowly or only partially, apply grease or oil to the rotary parts or the friction surfaces. If this does not help, try winding up the spring one or two turns, taking care to not over-stress the spring.

•

If there is a sound indicating that the spring is off the hook and the starter rope cannot be wound back, reassemble the recoil starter from the beginning.

85

Recoil Starter

WM 90 Repair

10.3 Starter Assembly Exploded View For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher

1

4 5

6 13

9 7

10 8

3

11

2

12

wc_gr002880

See Graphic: wc_gr002880 Ref

Description

Ref

Description

1

Starter assembly

8

Spring

2

Rope

9

Ratchet wheel

3

Handle

10

Cover

4

Wear plate

11

Lock washer

5

Return spring

12

Locknut

6

Starter pulley

13

Starter housing

7

Washer

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-

86

--

WM 90 Repair

Recoil Starter

10.4 Disassembling the Starter

For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher See Graphic: wc_gr002880 10.4.1

Remove the starter assembly from the fan cover and release the spring tension as described in section Replacing the Starter Rope.

10.4.2

Untie the rope (2) and remove the handle (3).

10.4.3

Remove the locknut (12), lock washer (11), and cover (10).

10.4.4

Remove the ratchet (9), spring (8), and washer (7). Note the position of the ratchet and the spring to ensure proper reassembly.

10.4.5

Slowly lift the rope reel pulley (6) from the starter housing (13). Also remove the wear plate (4). If necessary, carefully remove the spring (5) from the rope reel pulley.

10.5 Inspecting the Starter For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher See Graphic: wc_gr002881 Starter Return Spring Replace the starter return spring if it is broken, or appears distorted or twisted. Check that the starter return spring ends are bent 180° (a). The starter return spring may be difficult to seat in the slots on the starter housing and the rope reel pulley, if the return spring ends are stretched out (b) or damaged. Rope Reel Pulley Inspect the rope reel pulley for wear in the area where the starter return spring makes contact. Remove any dirt and grease from between the spring windings. Slip the rope reel pulley over the center post in the housing and check its movement. The rope reel pulley should rotate freely on the post with a minimum amount of side play. Ratchet Check the ratchet tooth for wear. The tip (c) should be pointed, not rounded. A worn ratchet may slip when engaging the flywheel. Replace the ratchet when it is worn. wc_tx000627gb.fm

87

Recoil Starter

WM 90 Repair Rope Check the rope length. It is 150 cm (60 in.) when new. If the rope is too short, it may bottom out when pulled and damage the starter.

b

a

d

e

c

f wc_gr002881

10.6 Assembling the Starter For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher See Graphic: wc_gr002880 and wc_gr002881 10.6.1 Clean all the components of the starter before reassembling the starter. 10.6.2 Note: To reduce dirt and dust from collecting between the spring windings, avoid using grease to lubricate the tarter return spring or the inside of the reel where the spring seats. Use a light lubricating oil such as WD40 instead. 10.6.3 Install the spring (e)(5) by placing the outside end of the spring in the slot (d) on the rope reel pulley (f) (6). Wrap the spring in a counterclockwise direction inside the pulley until it is completely wound. Oil the spring lightly once it is wound.

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WM 90 Repair

Recoil Starter

10.6.4

Lightly grease the center post of the housing and install the wear plate (4) and the rope reel pulley. Rotate the rope reel pulley until the spring seats in the slot at the center of the housing (13). Install the washer (7) over the center post and seat it into the rope reel pulley. NOTICE: Failure to replace the washer will cause the ratchet to bind and prevent the rope reel pulley from rotating freely.

10.6.5

Add the spring (8) and the ratchet (9) to the assembly. Do not grease the ratchet.

10.6.6

Install the cover (10) and secure it in place using the lock washer (11) and locknut (12). Torque the locknut to 8 Nm (6 ft.lbs.). Install the rope as described in section Starter Rope Replacement.

10.7 Replacing the Starter Rope For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher See Graphic: wc_gr002882 The starter rope can be replaced without removing the rope reel pulley from the starter assembly. Removal: 10.7.1

Remove the starter assembly from the flywheel housing.

10.7.2

Lift the rope through the notch (a) in the drum. Pull out as much of the rope as possible. Hold the rope and let the spring pull the drum around clockwise until all spring tension is released.

10.7.3

Untie the knot and remove the rope. Installation:

wc_tx000627gb.fm

10.7.4

Thread the new rope through the rope reel pulley and then through the housing. Install the handle and knot (b) each end of the rope as shown. Be sure the end of the rope does not protrude from the rope reel (c) or it may interfere with the movement of the starter.

10.7.5

Lift the rope up through the notch in the edge of the drum and rotate the drum counterclockwise to wind the spring. Guide (d) the rope around as the drum is rotated. After two complete revolutions, remove the rope from the notch and allow it to be pulled around the drum by the spring tension (e). Repeat this procedure until all the rope is on the drum and the handle rests against the housing.

10.7.6

Reattach the starter assembly to the flywheel housing.

89

Recoil Starter

WM 90 Repair

a b

c

d

e wc_gr002882

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90

WM 90 Repair

Clearance Data and Limits Table

11. Clearance Data and Limits Table 11.1 Term Descriptions The following table lists critical dimensions of specific parts. The “Standard” column lists the dimension of the part as new from the factory. The “Limit” column lists the maximum allowance. If the measurement exceeds the “Limit” dimension listed, replace or repair the part. Item

Standard mm (in.)

Limit mm (in.)

0.05 or less (0.002)

0.1 (0.004)

0.8–1.1 (0.0315–0.0433)

2.0 (0.079)

5.500–5.518 (0.2165–0.2172)

---

Cylinder head Flatness

wc_gr001921

Intake/exhaust valve contact width

wc_gr001922

Intake exhaust

wc_gr001923

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Clearance Data and Limits Table Item Piston

STD

Outer diameter at skirt in thrust direction

WM 90 Repair Standard mm (in.)

Limit mm (in.)

50.97–50.99

50.88 (2.0031)

(2.0067–2.0075)

Oversize (+0.25)

(2.0165–2.0173)

Oversize (+0.50)

(2.0264–2.0272)

51.38 (2.0228

0.035–0.080 (0.0014–0.0031)

0.15 (0.006)

2nd

0.035–0.080 (0.0014–0.0031)

0.15 (0.006)

Oil Ring

0.010–0.065 (0.0004–0.0026)

0.15 (0.006)

10.991–11.009 (0.4327–0.4334)

11.035 (0.4344)

10.992–11.000 (0.4328–0.4331)

6.05 (0.238)

51.22–51.24

51.47–51.49

51.13 (2.0123)

wc_gr001925

Ring groove-side clearance

Top

wc_gr001926

Piston pin hole

wc_gr001927

Piston pin outside diameter

wc_gr001928

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WM 90 Repair

Clearance Data and Limits Table Item

Standard mm (in.)

Limit mm (in.)

0.010–0.049 (0.0004–0.0019)

0.25 (0.010)

Top ring

0.15–0.35 (0.006–0.014

1.5 (0.0591)

2nd ring

0.35–0.55 (0.014–0.022

1.5 (0.0591)

Oil ring

0.05–0.25 (0.002–0.010

1.5 (0.0591)

Clearance between piston and cylinder at skirt

wc_gr001929

Piston ring end gap

wc_gr001930

Cylinder Inner diameter Standard

51.000–51.019

STD

wc_gr001924

(2.008–2.009)

First reboring

51.250–51.269 (2.0177–2.0185)

Same as above

Second reboring

51.500–51.519 (2.0276–2.0283)

Same as above

Roundness after reboring

Less than 0.01 (0.0004)

Cylindricity after reboring

Less than 0.01 (0.0004)

wc_tx000391gb.fm

To be rebored when the difference between max. and min. diameter reaches 0.1 (0.004).

93



Limit mm (in.)

20.000–20.013

20.1 (0.7913)

Connectng rod Large-end inner diameter

(0.7874–0.7879)

120˚

Clearance between large end and crank pin

0.037–0.063 (0.0015–0.0025)

0.2 (0.008)

wc_gr001933

Small end inner diameter

11.010–11.021 (0.4335–0.4339)

11.08 (0.4362)

wc_gr001934

Clearance bewteen small end and piston pin

0.010–0.029 (0.0004–0.0011)

wc_gr001935

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94

0.12 (0.0047)

WM 90 Repair


Standard mm (in.)

Limit mm (in.)

0.1–0.7

1.0 (0.04)

Large end side clearance

(0.004–0.028) wc_gr001936

Crankshaft Crank pin outer diameter

19.950–19.963 (0.7854–0.7859)

19.85 (0.7815)

wc_gr001937

Journal outer diameter

D1

D2

D1 and D2

19.988–19.997 (0.7869–0.7873)

---

wc_gr001938

Camshaft Cam peak height (intake and exhaust)

18.3–18.5 (0.720–0.728)

wc_gr001939

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95

18.15 (0.715)

Clearance Data and Limits Table Item Journal outside diameter

D1


Limit mm (in.)

9.972–9.987

9.95 (0.3917)

D1

(0.3926–0.3932)

D2

(0.3926–0.3932)

D2

9.972–9.987

9.95 (0.3917)

wc_gr001940

Intake/exhaust valves

5.440–5.455

Intake

(0.2142–0.2148)

5.35 (0.2106)

Valve stem outer diameter

Exhaust

5.426–5.444 (0.2136–0.2143)

5.35 (0.2106)

wc_gr001941

Clearance between valve stem and valve guide

0.045–0.078

Intake

(0.0018–0.0031)

Exhaust

0.056–0.092 (0.0022–0.0036)

0.3 (0.0118)

0.3 (0.012)

wc_gr001942

Valve clearance in cold state

Intake/ Exhaust

wc_gr001943

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96

0.07–0.13 (0.0028 - 0.0051)

---

WM 90 Repair


Standard mm (in.)

Limit mm (in.)

7.960–7.975 (0.3134–0.3140)

---

8.00–8.015 (0.3150–0.3140)

---

0.025–0.055 (0.0010–0.0022)

---

Tappet Stem outside diameter

wc_gr001944

Guide inside diameter

wc_gr001945

Tappet guide clearance

wc_gr001946

Valve seat angle (intake and exhaust) Valve cutter angle (a) Valve contact width (b)

a: 90° b: 0.8 – 1.1 (0.031–0.043)

b b a wc_gr001948

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97

2.0 (0.079)



Limit mm (in.)

26.7 (1.05)

---

Valve spring free length

wc_gr001947

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98

WM 90 Repair

Troubleshooting

12. Troubleshooting 12.1 Troubleshooting Introduction If the engine shows any sign of malfunction, the cause should be determined immediately and the appropriate countermeasures should be taken to prevent the problem from worsening. This troubleshooting section describes certain known problems, their possible causes, and appropriate action to take. Note, however, that the list of problems listed here is not all-encompassing. Generally speaking, since there is the possibility of multiple causes for a single problem, please use your experience and common sense when deciding on what action to take. The following three conditions must be met for the engine to start: 1. The cylinder must be filled with the proper fuel-air mixture. 2. There must be good compression in the cylinder. 3. There must be good spark, properly timed to ignite the mixture. The engine cannot be started unless the these three conditions are met. There are other factors as well that will make engine starting difficult, such as a heavy load on the engine when attempting to start, or heavy back pressure due to a long exhaust pipe.

12.2 Troubleshooting Procedures 12.2.1

Fuel System Problems:

12.2.1.1 No gasoline in tank, or the fuel cock is closed. 12.2.1.2 The carburetor is not choked sufficiently especially when engine is cold. 12.2.1.3 Water, dust or gum in the gasoline interfering with fuel flow to carburetor. 12.2.1.4 Inferior grade gasoline or poor quality gasoline not vaporized enough to produce the correct fuel-air mixture. 12.2.1.5 The carburetor needle valve is held open by dirt or gum. This trouble can be detected as the fuel flows out of the carburetor when the engine is idling. 12.2.1.6 If the carburetor overflows, excessive fuel runs into the cylinder when starting the engine, making the fuel-air mixture too rich to burn. If this happens, remove the spark plug and turn the starting pulley a few turns to let the rich fuel-air mixture out of the spark plug hole and into the atmosphere. Keep the choke valve open during this operation. Dry the spark plug well, screw it into place, and try to start the engine again. wc_tx000393gb.fm

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12.2.2 Ignition System Problems: Check the following when experiencing a lack of spark. 12.2.2.1 Wires of the ignition coil, spark plug, or contact breaker disconnected. 12.2.2.2 Ignition coil damaged or shorted. 12.2.2.3 Spark plug wire wet or soaked with oil. 12.2.2.4 Spark plug dirty or wet. 12.2.2.5 Spark plug gap incorrect. 12.2.2.6 Spark plug electrode connected or bridged. 12.2.2.7 Incorrect spark timing. 12.2.2.8 Proper connection of all wires. 12.2.3 Compression System: If starting difficulties and loss of power are not due to the fuel system or ignition system, the fault may be due to lack of compression. Make the following checks to the compression system. 12.2.3.1 Internal engine is completely dry because of a long period of storage. 12.2.3.2 Loose or broken spark plug. This causes a hissing noise made by the fuel-air mixture running out of the cylinder in compression stroke during cranking. 12.2.3.3 Damaged head gasket or loose cylinder head. This will also make a hissing noise. 12.2.3.4 If the correct compression is not obtained even after remedying the above, problems may be due to incorrect valve clearance. Disassemble the engine and proceed further as follows: •

Valve stuck open due to carbon or gum on the valve stem.

•

If the piston rings are stuck on the piston, remove the piston and connecting rod from the engine. Clean and replace the parts if necessary.

12.2.4 Engine Misfires: 12.2.4.1 Incorrect spark plug electrode gap. Adjust gap. 12.2.4.2 Ignition cable worn. 12.2.4.3 Weak spark. 12.2.4.4 Ignition wire connections loose. 12.2.4.5 Water in gasoline. 12.2.4.6 Insufficient compression.

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WM 90 Repair 12.2.5

Troubleshooting Engine Stops:

12.2.5.1 Fuel tank empty. Water, dirt, gum, etc. in gasoline. 12.2.5.2 Vapor lock. Gasoline evaporating in the fuel lines due to overheating of the engine. 12.2.5.3 Vapor lock in the fuel lines or carburetor due to using too volatile gas blend (winter formula) in the hot season. 12.2.5.4 Air vent hole in the fuel tank cap plugged. 12.2.5.5 Bearing parts seized due to lack of lubrication. 12.2.5.6 Magneto or ignition coil faulty. 12.2.6

Engine Overheats:

12.2.6.1 Crankcase oil level low. Add oil immediately. 12.2.6.2 Spark timing incorrect. 12.2.6.3 Low-grade gasoline being used or engine is overloaded. 12.2.6.4 Cooling air circulation restricted. 12.2.6.5 Cooling air path misdirected causing loss of cooling efficiency. 12.2.6.6 Cylinder head cooling fins clogged with dirt. 12.2.6.7 Engine being operated in an enclosed space without sufficient cooling air. 12.2.6.8 Exhaust gas discharge restricted, or carbon deposits in the combustion chamber. 12.2.6.9 Engine running on low-octane gasoline detonates due to heavy load at low speed. 12.2.7

Engine Knocks:

12.2.7.1 Poor quality gasoline. 12.2.7.2 Engine operating under heavy load at low speed. 12.2.7.3 Carbon or lead deposits in the cylinder head. 12.2.7.4 Spark timing incorrect. 12.2.7.5 Loose connecting rod bearing due to wear. 12.2.7.6 Loose piston pin due to wear. 12.2.8

Engine Backfires Through Carburetor:

12.2.8.1 Water or dirt in gasoline, or low grade gasoline. 12.2.8.2 Intake valve stuck. 12.2.8.3 Valves overheated or hot carbon particles in the combustion chamber. 12.2.8.4 Engine cold. wc_tx000393gb.fm

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Notes

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Threadlockers and Sealants Threadlockers and Sealants Threadlocking adhesives and sealants are specified throughout this manual by a notation of “S” plus a number (S#) and should be used where indicated. Threadlocking compounds normally break down at temperatures above 175°C (350°F). If a screw or bolt is hard to remove, heat it using a small propane torch to break down the sealant. When applying sealants, follow instructions on container. The sealants listed are recommended for use on Wacker equipment. TYPE ( ) = Europe Loctite 222 Hernon 420 Omnifit 1150 (50M)

COLOR USAGE Purple Low strength, for locking threads smaller than 6 mm (1/4”). Hand tool removable. Temp. range: -54 to 149°C (-65 to 300°F) Blue Medium strength, for locking threads Loctite 243 Hernon 423 larger than 6 mm (1/4”). Omnifit 1350 (100M) Hand tool removable. Temp. range: -54 to 149°C (-65 to 300°F) Loctite 271/277 Red High strength, for all threads up to 25 mm Hernon 427 (1”). Omnifit 1550 (220M) Heat parts before disassembly. Temp. range: -54 to 149°C (-65 to 300°F) Loctite 290 Green Medium to high strength, for locking Hernon 431 preassembled threads and for sealing Omnifit 1710 (230LL) weld porosity (wicking). Gaps up to 0.13 mm (0.005”) Temp. range: -54 to 149°C (-65 to 300°F) Loctite 609 Green Medium strength retaining compound for Hernon 822 slip or press fit of shafts, bearings, gears, Omnifit 1730 (230L) pulleys, etc. Gaps up to 0.13 mm (0.005”) Temp. range: -54 to 149°C (-65 to 300°F) Loctite 545 Brown Hydraulic sealant Hernon 947 Temp. range: -54 to 149°C (-65 to 300°F) Omnifit 1150 (50M) Loctite 592 White Pipe sealant with Teflon for moderate Hernon 920 pressures. Omnifit 790 Temp. range: -54 to 149°C (-65 to 300°F) Loctite 515 Purple Form-in-place gasket for flexible joints. Hernon 910 Fills gaps up to 1.3 mm (0.05”) Omnifit 10 Temp. range: -54 to 149°C (-65 to 300°F)

PART NO. – SIZE 73287 - 10 ml

29311 - .5 ml 17380 - 50 ml

29312 - .5 ml 26685 - 10 ml 73285 - 50 ml 28824 - .5 ml 25316 - 10 ml

29314 - .5 ml

79356 - 50 ml

26695 - 6 ml 73289 - 50 ml 70735 - 50 ml

Threadlockers and Sealants Threadlockers and Sealants (continued) Threadlocking adhesives and sealants are specified throughout this manual by a notation of “S” plus a number (S#) and should be used where indicated. Threadlocking compounds normally break down at temperatures above 175°C (350°F). If a screw or bolt is hard to remove, heat it using a small propane torch to break down the sealant. When applying sealants, follow instructions on container. The sealants listed are recommended for use on Wacker equipment. TYPE ( ) = Europe COLOR USAGE Loctite 496 Clear Instant adhesive for bonding rubber, metal Hernon 110 and plastics; general purpose. Omnifit Sicomet 7000 For gaps up to 0.15 mm (0.006”) Read caution instructions before using. Temp. range: -54 to 82°C (-65 to 180°F) Loctite Primer T Aerosol Fast curing primer for threadlocking, Hernon Primer 10 Spray retaining and sealing compounds. Must Omnifit VC Activator be used with stainless steel hardware. Recommended for use with gasket sealants.

PART NO. – SIZE 52676 - 1oz.

2006124-6 oz.

Torque Values Torque Values Metric Fasteners (DIN)

TORQUE VALUES (Based on Bolt Size and Hardness)

8.8

10.9

WRENCH SIZE

12.9

Size

Nm

ft.lb.

Nm

ft.lb.

Nm

ft.lb.

Metric

Inch

Metric

Inch

M3

1.2

*11

1.6

*14

2.1

*19

5.5

7/32

2.5

–

M4

2.9

*26

4.1

*36

4.9

*43

7

9/32

3

–

M5

6.0

*53

8.5

6

10

7

8

5/16

4

–

M6

10

7

14

10

17

13

10

–

5

–

M8

25

18

35

26

41

30

13

1/2

6

–

M10

49

36

69

51

83

61

17

11/16

8

–

M12

86

63

120

88

145

107

19

3/4

10

–

M14

135

99

190

140

230

169

22

7/8

12

–

M16

210

155

295

217

355

262

24

15/16

14

–

M18

290

214

405

298

485

357

27

1-1/16

14

–

M20

410

302

580

427

690

508

30

1-1/4

17

–

1 ft.lb. = 1.357 Nm

* = in.lb.

1 inch = 25.4 mm

Torque Values Torque Values (continued) Inch Fasteners (SAE)

Size

Nm

ft.lb.

Nm

ft.lb.

Nm

ft.lb.

Metric

Inch

Metric

Inch

No.4

0.7

*6

1.0

*14

1.4

*12

5.5

1/4

–

3/32

No.6

1.4

*12

1.9

*17

2.4

*21

8

5/16

–

7/64

No.8

2.5

*22

3.5

*31

4.7

*42

9

11/32

–

9/64

No.10

3.6

*32

5.1

*45

6.8

*60

–

3/8

–

5/32

1/4

8.1

6

12

9

16

12

–

7/16

–

3/32

5/16

18

13

26

19

33

24

13

1/2

–

1/4

3/8

31

23

45

33

58

43

–

9/16

–

5/16

7/16

50

37

71

52

94

69

16

5/8

–

3/8

1/2

77

57

109

80

142

105

19

3/4

–

3/8

9/16

111

82

156

115

214

158

–

13/16

–

–

5/8

152

112

216

159

265

195

24

15/16

–

1/2

3/4

271

200

383

282

479

353

–

1-1/8

–

5/8

1 ft.lb. = 1.357 Nm

* = in.lb.

1 inch = 25.4 mm

Wacker Construction Equipment AG · Preußenstraße 41 · D-80809 München · Tel.: +49-(0)89-3 54 02 - 0 · Fax: +49 - (0)89-3 54 02-3 90 Wacker Corporation · P.O. Box 9007 · Menomonee Falls, WI 53052-9007 · Tel. : (262) 255-0500 · Fax: (262) 255-0550 · Tel. : (800) 770-0957 Wacker Asia Pacific Operations · Skyline Tower, Suite 2303, 23/F · 39 Wang Kwong Road, Kowloon Bay, Hong Kong · Tel. +852 2406 60 32 · Fax: +852 2406 60 21