Lawn-Boy V-Engine User manual

LAWN-BOY V-ENGINE SERVICE MANUAL
Table of Contents – Page 1 of 2
REFERENCE SECTION
SAFETY
SPECIFICATIONS - ENGINE SPECIFICATIONS
SPECIFICATIONS - ENGINE FASTENER TORQUE REQUIREMENTS
SPECIFICATIONS - CARBURETOR SPECIFICATIONS (WALBRO LMR-16)
SPECIAL TOOL REQUIREMENTS
TROUBLESHOOTING
MAINTENANCE
SECTION 1 WALBRO LMR-16 CARBURETOR
LMR-16 CARBURETOR - IDENTIFICATION
LMR-16 CARBURETOR - THEORY OF OPERATION
LMR-16 CARBURETOR - GOVERNOR THEORY
LMR-16 CARBURETOR - REMOVAL
LMR-16 CARBURETOR - DISASSEMBLY
LMR-16 CARBURETOR - CLEANING AND INSPECTION
LMR-16 CARBURETOR - ASSEMBLY
LMR-16 CARBURETOR - PRESETTING THE GOVERNOR
LMR-16 CARBURETOR - 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-TROUBLESHOOTING
SECTION 2 PRIMER START CARBURETOR
PRIMER START CARBURETOR - IDENTIFICATION
PRIMER START CARBURETOR - THEORY OF OPERATION
PRIMER START CARBURETOR - GOVERNOR THEORY
PRIMER START CARBURETOR - REMOVAL
PRIMER START CARBURETOR - DISASSEMBLY
PRIMER START CARBURETOR - CLEANING AND INSPECTION
PRIMER START CARBURETOR - ASSEMBLY
PRIMER START CARBURETOR - INSTALLATION
PRIMER START CARBURETOR - PRESETTING THE GOVERNOR
PRIMER START CARBURETOR - FINAL CHECK
PRIMER START CARBURETOR - SERVICING THE AIR FILTER
PRIMER START CARBURETOR TROUBLESHOOTING
ENGINE STARTS HARD
ENGINE RUNS RICH
ENGINE RUNS LEAN
FUEL LEAKS FROM CARBURETOR

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

V-Engine

TABLE OF CONTENTS
Reference Section
Safety Information 9
Engine Specifications 10
Engine Fastener Torque Requirements 11
Carburetor Specifications 12
Special Tool Requirements 13
Troubleshooting 14
Maintenance 19
Recommended Maintenance Schedule 19
Air Filter 19
Spark Plug 20
Cleaning the Exhaust System 21
Service Section
Section1 LMR-16 Carburetor
Identification 25
Theory of Operation 25
Governor Theory 25
Removal 26
Disassembly 27
Cleaning and Inspection 27
Assembly 28
Presetting the Governor 29
Assembling Air Box to Carburetor 29
Installation 30
FinalCheck 30
Choke Adjustment 30
Servicing the Air Filter
30
Troubleshooting 31
V-Engine 3 Table of Contents

TABLE OF CONTENTS
Service Section (cont'd)
Section 2 PrimerStartCarburetor
Identification 32
Theory
of Operation 32
Governor The0
ry 32
Removal 33
Disassembly 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 Service 37
Tank Removal 38
Cleaning 38
Tank
installation 38
Ignition System
Troubleshooting 39
Spark Plug
Operation 39
Service 39
V-Engine Table
of Contents

TABLE OF CONTENTS
ServiceSection(cont’d)
Section 4 (cont’d)
CD Pack
Operation 40
Air Gap Adjustment 41
Removal 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 ............................................................................................
Service Tips ........................................................................................................
Removal..............................................................................................................
Disassembly........................................................................................................
Inspection and Repair ..............................................................................
Reed Valve Service ..................................................................................
Reassembly.........................................................................................................
V-EngineTable of Contents

TABLE OF CONTENTS
Service Section (cont’d)
Section 7 PivotingZoneStartBrake
Introduction 53
Operation 53
Disassembly 53
Assembly 54
Appendix A
Exploded View Diagrams A-1
Table of Contents
6
V-Engine

SAFETY INFORMATION
ThissafetysymbolmeansWARNINGorPERSONALSAFETYINSTRUCTIONreadtheinstruction
because it has to do with your safety. Failure to comply with the instruction may result in personal injury
This manualis intended as a service and repair manual only. The safety instructions provided herein are for trou-
bleshooting, service and repair of the engine only. The individual Operator’s manual will contain safety information
on the complete product powered by the
V engine. Operator’s manuals with complete instructions are available
through:
or even death.
Lawn-Boy Corporation
Publications Department
8111 Lyndale Avenue South
Bloomington,
MN 55430 U.S.A.
SAFETY TIPS
Avoid unexpected startingof engine
Always turn off the powered product and disconnect
spark plug wire before attempting cleaning, adjust-
ment or repair.
Avoid lacerations and amputations
Stay clear of all moving parts whenever the engineis
running. Treat all normally moving parts as
if they
were moving whenever the engine
is runningor has
Avoid burns
Do not touch the engine whileit is running or shortly
after it has been running.
Avoid Falls
thepotential to start.
Avoid asphyxiation
Never operate an enginein a confined area without
proper ventilation.
Avoid fires and explosions
Use a container designed for gasoline. Avoid spilling
fuel and never smoke while working with any typeof
fuel.
Avoid accidental misuseof fuel
Always stolefuel in a properly labeled container
designed for gasoline.
Avoid injury dueto inferior parts
Use only Lawn-Boy@ original partsto ensure that
important safety criteria are met.
Do not operate the powered product on slippery sur-
faces or
if footing isquestionable.
Avoid injuryto bystanders
Always clear the area of bystanders before starting or
Avoid fires
Wipe up any spilled fuel oroil immediately. testing powered equipment.
Avoid injury due to projectiles
Always clear the areaof sticks, rocks or any other
debris that could be picked up and thrown by the
powered equipment.
ReferenceSection 9 SafetyInformation

Engine Specifications
Bore2.3810 2.3800 (60.47785.852mm)
Stroke1.75201.7497”(44.50144.442mm)
Connectingrodlength 3.00 (76.2mm)
Wrist pin diameter
.5000” (12.7 mm)
Wrist pin offset
.070 (1.78 mm) toward major thrust side
Crankpin diameter .742”(18.85 mm)
Top and bottom main bearings Dia:Top:.875”(22.23mm)Bottom:1.125”(28.58mm)
Displacement 7.78 cu in (127.51 cc)
Horsepower 4.5
Compressionratio 5.91:l (Rangeof5.151 6.668:l)
Carburetor ‘93 models
Carburetor ‘94 models up)
Fuel required
Recommendedoil
Fuel tank 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(87octane2-cycleoil
Lawn-Boy Ashless 2-cycle oil
1.5 quarts
Solid state CD Pack, magneto type
.010(.25 mm)
2’8’ BTDC (Cranking);22’ 28’ (Running)
__-
--_-
SparkplugairgapChampionRJ12C .035 (.889mm)
Starting system
GovernorAirvane Rope rewind
Governedenginespeed
Idlespeed 3050+/- 100 RPM
2200 2800 RPM
Aircleaner
Choke
Fuel filter
Oiled, foam type
Manual, butterfly type (Walbro only)
ln-tank and in-carburetor
PistonPermanentmold,highsiliconaluminum
PistonringsCastiron,semi-keystonetopring
10
Reference Section

SPECIFICATIONS (cont'd)
Engine Fastener Torque Requirements
* Use thread-locking compound
Reference Section
Torque
45 50 ft Ibs (60 67 N-m)
375 425
in lbs (42 47 N-m)
5
7 in Ibs (.5 .8 N-m)
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 25
in Ibs (1.7 2.8 N-m)
150 190
in Ibs (17 22 N-m)
140 200
in Ibs (16 22 N-m)
10 13
in Ibs (1.1 1.5 N-m)
65 75
in Ibs (7.3 8.4 N-m)
58 70
in Ibs (6.5 7.8 N-m)
60 70
in Ibs (6.7 7.8 N-m)
150 200
in Ibs (17 23 N-m)
65.15
in Ibs (7.3 8.4 N-m)
-__I_-----~-
_I
11
Specifications

SPECIFICATIONS
Carburetor Specifications (Walbro LMR-16)
(cont’d)
Carburetor Specifications (Primer Start)
12
Reference Section

SPECIAL TOOL REQUIREMENTS
V-Engine Tool Requirements
DESCRIPTION
V EngineToolKit612490
AirGapGauge604659 PistonStop612103
CrankshaftGauge609968
PistonRingCompressor609967
E-12
Torx SocketPurchase Locally
Includes tools shown below necessaryto service
V Engine.
Sets .010”gap between flywheel and coil.
Prevents piston from traveling over TDC. Use when servicing flywheel
or installing piston.
Sets correct gap on crankshaft support.
__-
Compressesringsintopistongroovesduringinstallationofpiston.
Use to remove upper and lower crankshaft seals.
Use to properly position upper and lower crankshaft seals.
Use to remove crankcase fasteners.
.-
Where to Purchase: Order through Lawn-Boy parts department as you would any other part.
Note: The tools includedinthis kit are also foundinthe D and F Engine Tool Kit (part number 683625.)
If you already own that kit, you do not needto purchase any additional special tools.
ReferenceSection 13 SpecialTools

TROUBLESHOOTING
Contents
Engine Will Not Start When“Cold 14
Engine Will Start When“Cold But Not When “Hot”
...................................................... 15
Engine Will Not Produce Spark
15
Engine Flooded With Fuel
15
Engine Has Low Compression
15
Engine Lacks Power 16
Engine Surges
16
Engine Backfires 16
Engine Overheats
I6
Engine 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
Engine Will Not Start When “Cold”
ank with clean, fresh,
re-oilair cleaner element
ve and replace the spark plug
I Not Produce Spark” table
blade
_I_~
EnginefloodedwithfuelSee“EngineFloodedWithFuel”table I
ReedvalvesnotclosedReplacereedvalves
Reference Section
14
Troubleshooting

TROUBLESHOOTING (cont’d)
EngineWillStartWhen“Cold”,ButNotWhen“Hot”
e Flooded With Fuel” table
Engine Will Not Produce Spark
PossibleCauses
I Coil killwiregrounded Locateandeliminatetheunwantedground
---~--
Engine Flooded With Fuel
I PossibleCausesRemedies
Overuse of “choke” position (‘93 units only) Take throttle
off “choke”
position
ThrottlecablemisadjustedAdjustthrottlecable
I
Air cleaner plugged
Replace spark plug
Fouled spark plug
Wash and re-oil air cleaner element
CarburetorneedlestuckopenCleancarburetor,replacefailedparts
I
Engine Has Low Compression
Possible Causes
Worn piston rings
Remedies
Remove and replace short block Cylinder worn
Replace piston and rings Piston ring(s) stuckingroove Replace piston rings or short block
-_-.-
Reference Section
15 Troubleshooting

TROUBLESHOOTING ‘(cont’d)
Engine Surges
PossibleCauses Remedies
Fouled idle circuit (‘93 models only)
Air leak Clean idle circuit
Check filters and fuel line
Restricted fuel flow Check sealing surfaces,oil seals, gaskets, and
Engine Backfires
I
PossibleCausesRemedies
Flywheel key sheared
Exhaust ports plugged Clean muffler
Muffler filled with carbon Replace key
Clean ports
Engine Overheats
PossibleCauses Remedies
Cylinder head cooling fins clogged
Removeforeignmaterialandclean
Cooling air intake plugged Ensure mixtureis
32:l
Improper gasto oil mixture Clean carburetor’and jet
Restricted main carburetor jet Clean fins thoroughly
Engine Vibrates Excessively
Possible Causes
Balance blade or replace if damaged
Blade outof balance
Remedies
-.--_-
BentbladeReplaceblade Loose engine mounting screws
Bent crankshaft Tighten engine mounting screws
Replace flywheel
Flywheel out
of balance
Replace crankshaft
Troubleshooting 16 ReferenceSection

TROUBLESHOOTING (cont’d)
EngineCrankshaftWill Not Turn
PossibleCausesRemedies I
Engine brake incorrectly engaged
Blade jammedinhousing
Pistonseized in itscylinder
Starterjammed
Disengage brake and inspect
and repair as necessary
Inspect and repair or replace
Inspect and repair or replace
Repair starter
Engine Produces Mechanical Knocking Sound
PossibleCausesRemedies I
Engine Pre-Ignites
PossibleCausesRemedies
WrongsparkplugtoohotInstallthecorrecttypeofsparkplug
Excessive alcohol in fuel
Replace with fresh unleaded regular fuel
Decarbon engine and muffler
Replace with fresh unleaded fuel having no more than
10% ethanol
_-
_I-..
ShearedflywheelkeyInspectandrepair I
Engine Smokes Excessively
PossibleCausesRemedies I
Slight oil accumulationincrankcase
Clean and re-oil or replace air cleaner element Air cleaner element clogged
None; normal on startup
Fuel/OilmixturetoorichDrainfueltankand fill withfuelofcorrectmixture
I
Carburetor running too rich Clean and check carburetor
ReferenceSection 17 Troubleshooting

Engine Stalls
Spark Plug Fouled
Use of leadedfuelresh,unleadedregular

Recommeded Maintenance Schedule
25 HoursAirFilter
50 Hours
100 Hours
Blade Brake
I
Exhaust Ports
I
I
Cooling System
Check blade and engine mounting
f
boltsand screwstight to ensure safe operation.
replace.
Check for leakage and/ordeterioration
Air Filter
Once every season, or every 25 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 engine or cause
excessive engine wear.
Figure 1 shows the ‘93 carburetor; ‘94 models have
an additional wire clampto release.
1. Toremove air filter,snapcover latchopen,
swing to side and unhook. Remove the cover
and air filter
(Figure 1).
Filter
Cover
Figure 1
ReferenceSection 19 Maintenance

MAINTENANCE (cont’d)
Air Filter (cont’d)
2. Washairfilter in laundrydetergent.
Squeeze filter to remove excess liquid and blot
dry with a paper towel or rag
(Figure 2).
Figure 2
3. ApplyonetablespoonofSAE 30 oil totheair
filter
(Figure 3). Lightly squeeze filter until oilis
distributed evenly throughout filter. Blot lightly
with paper towelto remove excess oil.
Replace filter with cleanest side facing
carburetor.
Note: Be sure filteris properly seated in air box and
is not puckered (allowing direct passageof air anddir
to carburetor).
Spark Plug
A spark plug thatis dirty, pitted, carbon coveredor
has worn electrodes may cause hard starting and
poor operation.
Clean or replace spark plug once a season or every
25 hours, whichever occurs first. Use Champion
RJ12C,
or equivalent.
Remove spark plug and clean with a wire brush,
removing carbon buildup. DO NOT SANDBLAST.
Check condition of plug for cracks, damaged or worn
electrodes.Replace
if necessary.
1. Setsparkpluggapat 0.035 inch(.85mm).
See
Figure 4.
,035 in.
(.85 mm)
Figure 4
2.Installsparkplugfingertight,thentorque to
180 in Ibs (15
ft Ibs) (20 N-m_ Figure 5.
Figure 5
Figure 3
Maintenance 20 ReferenceSection

MAINTENANCE (cont'd)
CleaningTheExhaustSystem
Warning: Disconnect the spark plug wireto prevent
accidentally starting the engine.
1. Usinga 1/2drivewitha 15/16socket,remove
the blade nut that secures both the mulch fan
and bladeto the engine. Use heavy duty gloves
to hold the blade while removing the nut
(Figure 6).
I
Figure 6
2. Usingasofthammer,gentlytapthebladedrive
to remove
it from the shaftof the engine
(Figure 7).
Figure 7
3. If necessary,cleanthesmalllouvers in the
muffler cover; they must be open.
4. Removethethreebolts to removethemuffler
cover. Drop the cover down to inspect the
conditionof the exhaust ports, etc.
(Figure 8).
5. Pullthestarterropeuntilthepistoncoversthe
exhaust ports
(Figure 9). Clean them with
a 3/8” (9 mm) wooden dowel.
Ports
Figure9
Reassembling Exhaust System
1. Insertthreeboltsintothemufflercoverand
tighten to a torqueof 150-1
90 in Ibs
(1
7-22 N-m)
the engine to matchits shaft angle.
15/16" nut. Be sure the small circular bosses on
the blade drive collar match the holesinthe
blade. Tighten the nut to 50 ft Ibs (68 N-m)
(Figure 6).
2. Re-installthebladedrive,bevelededgetowards
3. Re-installthebladeandmulchfanwiththe
ReferenceSection 21 Maintenance