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LAWN-BOY V-ENGINE SERVICE MANUAL

Table of Contents – Page 2 of 2

SECTION 3 FUEL SYSTEM

FUEL SYSTEM - OPERATION

FUEL SYSTEM - CAP SERVICE

FUEL SYSTEM - TANK REMOVAL

FUEL SYSTEM - CLEANING

FUEL SYSTEM - TANK INSTALLATION

SECTION 4 IGNITION SYSTEM

IGNITION SYSTEM - TROUBLESHOOTING

IGNITION SYSTEM - SPARK PLUG OPERATION

IGNITION SYSTEM - SPARK PLUG SERVICE

IGNITION SYSTEM - CD PACK OPERATION

IGNITION SYSTEM - CD PACK AIR GAP ADJUSTMENT

IGNITION SYSTEM - CD PACK REMOVAL/INSTALLATION

IGNITION SYSTEM - FLYWHEEL OPERATION

IGNITION SYSTEM FLYWHEEL REMOVAL

IGNITION SYSTEM - FLYWHEEL INSTALLATION

SECTION 5 REWIND STARTER

REWIND STARTER - OPERATION

REWIND STARTER - REMOVAL AND DISASSEMBLY

REWIND STARTER - REASSEMBLY

SECTION 6 ENGINE

ENGINE - DESCRIPTION

ENGINE - THEORY OF OPERATION

ENGINE - SERVICE TIPS

ENGINE - REMOVAL

ENGINE - DISASSEMBLY

ENGINE - INSPECTION AND REPAIR

ENGINE - REED VALVE SERVICE

ENGINE - REASSEMBLY

SECTION 7 PIVOTING ZONE START BRAKE

INTRODUCTION

PIVOTING ZONE START BRAKE - OPERATION

PIVOTING ZONE START BRAKE - DISASSEMBLY

PIVOTING ZONE START BRAKE - ASSEMBLY

APPENDIX A

Summary of Contents for V-Engine

Page 1: ...TOR ASSEMBLING AIR BOX TO CARBURETOR LMR 16 CARBURETOR INSTALLATION LMR 16 CARBURETOR FINAL CHECK LMR 16 CARBURETOR CHOKE ADJUSTMENT LMR 16 CARBURETOR SERVICING THE AIR FILTER LMR 16 CARBURETOR TROUBL...

Page 2: ...ION SYSTEM CD PACK REMOVAL INSTALLATION IGNITION SYSTEM FLYWHEEL OPERATION IGNITION SYSTEM FLYWHEEL REMOVAL IGNITION SYSTEM FLYWHEEL INSTALLATION SECTION 5 REWIND STARTER REWIND STARTER OPERATION REWI...

Page 3: ...V Engine...

Page 4: ...nce Schedule 19 Air Filter 19 Spark Plug 20 Cleaning the Exhaust System 21 Service Section Section 1 LMR 16 Carburetor Identification 25 Theory of Operation 25 Governor Theory 25 Removal 26 Disassembl...

Page 5: ...ly 34 Cleaning and Inspection 34 Assembly 34 Installation 35 Presetting the Governor 35 Final Check 35 Servicing the Air Filter 36 Troubleshooting 36 Section 3 Section 4 Fuel System Operation 37 Cap S...

Page 6: ...oval Installation 41 Flywheel Operation 41 Removal 41 Installation 42 Section 5 Section 6 Rewind Starter Operation 43 Removal and Disassembly 43 Reassembly 44 Engine Description Theory of Operation Se...

Page 7: ...TABLE OF CONTENTS Service Section cont d Section 7 PivotingZone Start Brake Introduction 53 Operation 53 Disassembly 53 Assembly 54 Appendix A Exploded View Diagrams A 1 Table of Contents 6 V Engine...

Page 8: ...gineis running Treat all normally moving parts as if they were moving whenever the engineis running or has Avoid burns Do not touch the engine whileit is running or shortly after it has been running A...

Page 9: ...capacity Ignition type CD Pack air gap Spark timing Dual circuit Walbro float type with fixed main jet Single circuit Lawn Boy with fixed main jet float type with primer 32 l premixunleadedregular 87...

Page 10: ...60 70 in Ibs 6 7 7 8 N m 45 55 in Ibs 5 0 6 1 N m 90 110 in Ibs 10 12 N m 105 115 in Ibs 12 13 N m 300 350 in Ibs 34 39 N m 15 25in Ibs 1 7 2 8 N m 150 190 in Ibs 17 22 N m 140 200 in Ibs 16 22 N m 10...

Page 11: ...SPECIFICATIONS Carburetor Specifications Walbro LMR 16 cont d Carburetor Specifications Primer Start 12 Reference Section...

Page 12: ...ing flywheel or installing piston Sets correct gap on crankshaft support __ Compressesringsintopistongroovesduringinstallationofpiston Use to remove upper and lower crankshaft seals Use to properly po...

Page 13: ...e Vibrates Excessively 16 Engine Crankshaft Will Not Turn 17 Engine Produces Mechanical Knocking Sound 17 Engine Pre Ignites 17 Engine Smokes Excessively 17 Engine Stalls I8 Spark Plug Fouled 18 Engin...

Page 14: ...units only Take throttleoff choke position Throttle cable sadjusted st I Air cleaner plugged Replace spark plug Fouled spark plug Wash and re oil air cleaner element Carburetor needle stuck open Clean...

Page 15: ...n ports Engine Overheats Possible Causes Remedies Cylinder head cooling fins clogged Remove foreign material and clean Cooling air intake plugged Ensure mixtureis 32 l Improper gasto oil mixture Clean...

Page 16: ...rong spark plug too hot Install the correct type of spark plug Excessive alcohol in fuel Replace with fresh unleaded regular fuel Decarbon engine and muffler Replace with fresh unleaded fuel having no...

Page 17: ...Engine Stalls Spark Plug Fouled Use of leaded fuel...

Page 18: ...y season or every25 hours clean the air filter housing and element Do so more frequently under dusty conditions Notes Do not operate the engine without theair filter in place Doing so may damage the e...

Page 19: ...ed allowing direct passage of air and dir to carburetor Spark Plug A spark plug thatis dirty pitted carbon covered or has worn electrodes may cause hard starting and poor operation Clean or replace sp...

Page 20: ...over they must be open 4 Removethethreebolts to removethemuffler cover Drop the cover down to inspect the condition of the exhaust ports etc Figure 8 5 Pullthestarterropeuntilthepistoncoversthe exhaus...

Page 21: ...owered Figure 10 By inserting a tube from the carburetor float bowl into the venturi Figure 11 lower air pressure at the venturi draws fuel through the tube The fuel oil mix is then picked up by and m...

Page 22: ...l line Pull the carburetor assembly down and away from the engine such that the air vane clears the hole in the shroud base Figure 13 7 Removethethrottlecablescrewandnutand disconnect the cable from t...

Page 23: ...Remove the float shaft float and inlet needle Remove the fuel inlet Viton seat using a short piece of wire or a shot of compressed air Using an awl pierce the Welch plug then carefully remove itso tha...

Page 24: ...necessary to check float height However always make sure that no liquid is inside the float before reinstalling Figure 19 4 Positionthebowlgasketonthetopedgeofthe carburetor body Carburetor 5 Placebow...

Page 25: ...torwiththemountingflange facing you and the throttle wide open 2 Presetthegovernorbyturningthecollar so that the window on the collar is 3 4 clicks to the right of the pulse hole LMR 16 Carburetor Ass...

Page 26: ...orrect components Fuel tank and in line filters must not be plugged Fuel cap vent hole must not be plugged Air filter must be clean and oiled Crankcase seal Crankcase seals must be installed properly...

Page 27: ...tor adjustment Adjust to 5 8 to 3 4 turnopen Dirt in idle mixture pocket Remove Welch plug and clean I Restricted filter s Seal all Welch plugs Welch plug leaking Clean filter s Engine Surges carburet...

Page 28: ...ushes through this tube air pressure at the center of the passage is lowered Figure 29 Byinsertingatubefromthecarburetorfloatbowlinto the venturi Figure 30 lower air pressure at the venturi draws fuel...

Page 29: ...r 5 Disconnectthefuellineandtheprimertubefrom the carburetor fittings Figure 32 Figure 32 6 Pullthecarburetorassemblydownandaway from the engine such that the air vane governor clears the holein the s...

Page 30: ...hspeedjetfrom the nozzle Primer Start Carburetor Cleaning and 1 Withthecarburetorcompletelydisassembled thoroughly clean all partsin a parts cleaning solution and inspect for wear or deterioration Blo...

Page 31: ...open position Install the fuel line and primer tube on the appropriate carburetor fittings Check that the choke air vane assembly moves freely Install the air filter element and cover plugs Primer Sta...

Page 32: ...cedure in Maintenance pages19 and 20 CAUTION Do not operate the engine without a filter element or with a dry element engine life will be shortened Figure38 PRIMER START CARBURETOR TROUBLESHOOTING Eng...

Page 33: ...lacementof the cap also prevents interference with the starting rope in Zone Start applications The fuel capis a four piece design Figure 40 with an inner sealing disc that is vented to a baffle assem...

Page 34: ...ke while working around gasoline Release the clamping pliers and drain the fuel into a container designed to receive gasoline 2 If youremovedthefuellinefromthetankoutlet catch the fuel asit drains out...

Page 35: ...ged or sheared Flywheel magnets demagnetized or weak Ignition System Spark Plug Operation The spark plug ignites the oil fuel mixture by producing a spark just before the piston reaches top dead cente...

Page 36: ...rk advance assembly etc Figure 44 shows the location of the CD Pack used in the V Engine Figure 44 As the flywheel magnet passes the CD Pack an AC voltage is induced into the charge coil This AC volta...

Page 37: ...ighten screws to a torque of 100 in Ibs 11 N m Figure 50 Figure51 Figure 50 Ignition System Flywheel Operation The flywheelis connected directlyto the Crankshaft secured by a flywheel key and nut and...

Page 38: ...Removekeyandcheck its condition 6 Replacecrankshaftand orflywheel if keyway is 7 Checkflywheelforwearandflywheelmagnets Ignition System Flywheel Installation 1 Makesureflywheelkeyway is absolutelycle...

Page 39: ...is a 3 8 hex while the other three are 5 16 hex Figure 55 Figure 56 5 Removethe two starterengagementdogsand springs Take noteof the positioning of the springs for correctinstallationlater Figure 56 6...

Page 40: ...ipsshoulder screw Tighten the screwto a torqueof 33 in Ibs 3 7 N m Figure 59 Figure 59 CAUTION Wear gloves for protection while performing proceduresof the next step plate counterclockwise5 turns Inse...

Page 41: ...6 6 7 9 N m Figure 61 8 Turnthefueltankoverandnoticethe two extruded tabs These tabs match the holes in the rear portionof the shroud and will automatically align the mounting holes of the fuel tank a...

Page 42: ...aust port When both ports are sealed the remaining travel compresses theair fuel mixture to prepare it for ignition The travel of pistontowards the spark plug is calledthe compression stroke Figure 62...

Page 43: ...t from the in Ibs 12 13 N m mower as follows 2 Oil Seals 3 page A 2 Visually inspect for 1 Disconnect the spark plug wire 2 Disassemblethe T starterhandle to untiethe 3 Core Plugs 1 page A 2 Visually...

Page 44: ...igures 67 68 Remove the drivebelt from the pulley belt will stay with the engine as cover is removed Figure 66 7 RemovetheCDPack page41 Note Step 8 covers 93carburetors 94 carburetors have an addition...

Page 45: ...ngement p n 677389 in the spark plug hole 12 Under the mower deck remove the three 1 2 Engine Disassembly Note In addition to the figures supplementing the engine disassembly in the following paragrap...

Page 46: ...n 609904 for installation CAUTION Do not attempt to clean any hole with a drill bit An enlarged hole will reduce compression and engine efficiency and 016with 030as the wear limit Engine Reed Valve S...

Page 47: ...rod 4 Lubricateandassemblebearings letteredside out to Crankshaft and install crankshaft 5 Installrodcap ensurethatmatingmarksare aligned Clean old screws thoroughly and apply Loctite 271 Figure 76 To...

Page 48: ...install 14 Installcarburetor andgovernorassembly see 15 Install starter and shroud assembly and starter 16 Reconnectfuellinesandelectricalsystemleads 17 Testrunengine flywheel see page 42 page 30 for...

Page 49: ...ontrolled by a switch The switch is closed when the blade control bail is in the at rest vertical position Figure 81 Lowering the bail to the main mower handle opens the switch Switch leads are connec...

Page 50: ...uires replacement remove the second screw 9 to remove the brake mounting plate from the engine Pivoting Zone Start Brake Assembly 1 If thebrakemountingplatewasnotremoved from the engine simply reconne...

Page 51: ...sted below as they appear on the following pages of this section Power Head Exploded View A 2 Ignition and Exhaust Exploded View A 3 Starter and Walbro LMR 16 Carburetor Exploded View A 4 Walbro LMR 1...

Page 52: ...tor reed 8 Washer head hex screw 4 9 HSH cap screw 2 10 Split liner 2 11 Needle Bearings 12 Upper main bearing 13 Crankshaft Appendix 14 Bearing 15 Connecting rod assembly 16 Retaining ring 17 Wrist p...

Page 53: ...lf tapping screw 6 Brake switch leadwire 7 Ground strap 8 Insulationstrap 9 Self expanding plastic rivet 2 10 Shoulder screw 11 Brake plate assembly 12 Screw 13 Brake mountingplate 14 Hex washer head...

Page 54: ...e 5 not used 6 Screw 2 7 Air filter 8 Air filter cover 9 Retainer 10 Lever 11 Screw 12 Washer 13 Throttle spring Appendix 14 Air vane collar 15 Air vane 16 Screw 3 17 Shroud assembly 18 Hex flange nut...

Page 55: ...Bowl gasket Fuel bowl Bowl retainer gasket Bowl screw Quantity 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 I 12 13 14 15 16 17 Ref No Part No 684286 684285 683783 682782 683778 683777 683781 Description Quanti...

Page 56: ...Air vane collar 16 Float 5 Throttle spring 17 Float pin 6 Throttle plate 18 Carburetor bowl 7 Cable bracket 19 Screw 4 8 Screw 2 20 Washer 9 Air filter base 21 Main jet 10 Inlet seat 22 Air filter 11...

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