Toro 20709, 20711 Service 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
Reference Section
TABLE
OF
CONTENTS
Service Section
Safety Information
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
9
Section 1 LMR-16
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
Final Check 30
Choke Adjustment 30
Servicing the Air Filter
Carburetor
30
V-Engine
Troubleshooting 31
3
Table
of
Contents
Service Section (cont'd)
TABLE
OF
CONTENTS
Section
2
Primer Start Carburetor
Identification 32
of
Theory
Governor The0
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
Operation 32
ry
32
Section 3
Section 4
Fuel System
Operation 37
Cap Service 37
Tank Removal 38
Cleaning 38
installation
Tank
Ignition System
Troubleshooting 39
Spark Plug
Operation 39
Service 39
38
V-Engine
Table
of
Contents
Service Section (cont’d)
Section 4 (cont’d)
CD Pack
Flywheel
TABLE
Operation 40
Air Gap Adjustment 41
Removal Installation 41
Operation 41
Removal 41
Installation 42
OF
CONTENTS
Section
Section 6
5
Rewind Starter
Operation 43
Removal and Disassembly 43
Reassembly 44
Engine
Description
Theory
Service Tips
Removal ..............................................................................................................
Disassembly ........................................................................................................
of
Operation ............................................................................................
........................................................................................................
Inspection and Repair
Reed Valve Service
..............................................................................
..................................................................................
.........................................................
Reassembly .........................................................................................................
V-Engine Table
of
Contents
Service Section (cont’d)
TABLE
OF
CONTENTS
Section
Appendix A
7
Pivoting Zone Start Brake
Introduction
Operation
Disassembly 53
Assembly
Exploded View Diagrams A-1
53
53
54
Table
of
Contents
6
V-Engine
SAFETY INFORMATION
This safety symbol means WARNING or PERSONAL SAFETY INSTRUCTION read the instruction
because it has to do with your safety. Failure to comply with the instruction may result in personal injury
or even death.
This manual is intended as a service and repair manual only. The safety instructions provided herein are for troubleshooting, service and repair of the engine only. The individual Operator’s manual will contain safety information
V
on the complete product powered by the
through:
Lawn-Boy Corporation
Publications Department
8111
Lyndale Avenue South
MN
Bloomington,
55430
engine. Operator’s manuals with complete instructions are available
U.S.A.
SAFETY TIPS
Avoid unexpected starting of engine
Always turn
spark plug wire before attempting cleaning, adjustment or repair.
Avoid lacerations and amputations
Stay clear of all moving parts whenever the engine is
running. Treat all normally moving parts as
were moving whenever the engine
the potential to start.
Avoid burns
Do
not touch the engine while it is running or shortly
after it has been running.
Avoid Falls
Do not operate the powered product on slippery surfaces or
Avoid fires
Wipe up any spilled fuel or oil immediately.
off
the powered product and disconnect
if
footing is questionable.
if
they
is
running or has
Avoid asphyxiation
Never operate an engine in 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 type of
fuel.
Avoid accidental misuse of fuel
Always stole fuel in a properly labeled container
designed for gasoline.
Avoid injury due to inferior parts
Use only Lawn-Boy@ original parts to ensure that
important safety criteria are met.
Avoid
Always clear the area of bystanders before starting or
testing powered equipment.
Avoid injury due
Always clear the area of sticks, rocks or any other
debris that could be picked up and thrown by the
powered equipment.
injury to bystanders
to
projectiles
Reference Section
9
Safety Information
Engine Specifications
Bore 2.3810 2.3800 (60.477 85.852 mm)
Stroke 1.7520 1.7497” (44.501 44.442 mm)
Connecting rod length 3.00 (76.2 mm)
Wrist pin diameter
Wrist pin offset
Crankpin diameter
Top and bottom main bearings Dia: Top: .875” (22.23 mm) Bottom:1.125” (28.58 mm)
Displacement
Horsepower
Compression ratio 5.91:l (Range of 5.151 6.668:l)
Carburetor ‘93 models
Carburetor ‘94 models up)
Fuel required
Recommended oil
Fuel tank capacity
Ignition type
CD Pack air gap
Spark timing
.5000”
.070
.742” (18.85 mm)
7.78 cu in (127.51 cc)
4.5
Dual circuit Walbro, float type,’ with fixed main jet
Single-circuit Lawn-Boy with fixed main jet, float type, with primer
32:l premix unleaded regular (87 octane 2-cycle oil
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)
(12.7 mm)
(1.78 mm) toward major thrust side
__-
--_-
Spark plug air gap Champion RJ12C .035 (.889 mm)
Starting system
Governor Air vane
Governed engine speed
Idle speed
Air cleaner
Choke
Fuel filter
Piston Permanent mold, high silicon aluminum
Piston rings Cast iron, semi-keystone top ring
Rope rewind
3050+/- 100 RPM
2200 2800 RPM
Oiled, foam type
Manual, butterfly type (Walbro only)
ln-tank and in-carburetor
10
Reference Section
SPECIFICATIONS
Engine Fastener Torque Requirements
Torque
(cont'd)
45 50
375 425
5
60 70
45
90 110
105 115
300 350
15 25
150 190
140 200
10 13
65 75
58 70
60 70
150 200
65.15
7
in
55 in
ft
Ibs
in
Ibs
(.5 .8 N-m)
in
Ibs
Ibs
in
Ibs
in
in
in
Ibs
in
in
in
Ibs
in
Ibs
in
Ibs
in
Ibs
in
in
Ibs
(60 67 N-m)
lbs
(42 47 N-m)
(6.7 7.8 N-m)
(5.0 6.1 N-m)
(10 12 N-m)
Ibs
(12 13 N-m)
Ibs
(34 39 N-m)
(1.7 2.8 N-m)
Ibs
(17 22 N-m)
Ibs
(16 22 N-m)
(1.1 1.5 N-m)
(7.3 8.4 N-m)
(6.5 7.8 N-m)
_I
(6.7 7.8 N-m)
Ibs
(17 23 N-m)
(7.3 8.4 N-m)
-__I_-----~-
* Use thread-locking compound
Reference Section
11
Specifications
SPECIFICATIONS
Carburetor Specifications (Walbro LMR-16)
Carburetor Specifications (Primer Start)
(cont’d)
12
Reference Section
SPECIAL TOOL REQUIREMENTS
V-Engine
DESCRIPTION
V
Engine Tool Kit 612490
Air Gap Gauge 604659
Piston Stop 61 21 03
Crankshaft Gauge 609968
Piston Ring Compressor 609967
E-12
Where
Note:
If
to
The tools included in this kit are also found in the D and F Engine Tool Kit (part number 683625.)
you already own that kit, you do not need to purchase any additional special tools.
Tool
Torx
Socket Purchase
Purchase:
Requirements
Includes tools shown below necessary to service
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.
Compresses rings into piston grooves during installation of piston.
Use to remove upper and lower crankshaft seals.
Use to properly position upper and lower crankshaft seals.
Use to remove crankcase fasteners.
Locally
Order through Lawn-Boy parts department as you would any other part.
__-
.-
V
Engine.
Reference Section
13
Special Tools
Contents
TROUBLESHOOTING
Engine Will Not Start When “Cold
Engine Will Start When “Cold But Not When “Hot”
Engine Will Not Produce Spark
Engine Flooded With Fuel
Engine Has Low Compression
Engine Lacks Power
Engine Surges
Engine Backfires
Engine Overheats
Engine Vibrates Excessively
Engine Crankshaft Will Not Turn
Engine Produces Mechanical Knocking Sound
Engine Pre-Ignites
Engine Smokes Excessively
Engine Stalls
Spark Plug Fouled
......................................................
14
15
15
15
15
16
16
16
I6
16
17
17
17
17
.I8
18
Engine Will Not Start When “Cold”
Engine flooded with fuel See “Engine Flooded With Fuel” table
Reed valves not closed Replace reed valves
ank with clean, fresh,
re-oil air cleaner element
ve and replace the spark plug
I
Not Produce Spark” table
blade
_I_~
I
Troubleshooting
14
Reference Section
TROUBLESHOOTING
Engine Will Start When “Cold”, But Not When “Hot”
e Flooded With Fuel” table
Engine Will Not Produce Spark
Possible Causes
I
Coil kill wire grounded
Locate and eliminate the unwanted ground
(cont’d)
---~--
Engine Flooded With Fuel
I
Possible Causes Remedies
Overuse of “choke” position
Throttle cable misadjusted Adjust throttle cable
Air cleaner plugged
Fouled spark plug
Carburetor needle stuck open Clean carburetor, replace failed parts
Engine Has
Possible Causes
Worn piston rings
Low
Compression
(‘93
units only)
off
Take throttle
position
Wash and re-oil air cleaner element
Replace spark plug
Remedies
Replace piston rings or short block
Replace piston and rings Piston ring(s) stuck in groove
Remove and replace short block Cylinder worn
“choke”
-_-.-
I
I
Reference Section
15
Troubleshooting
Engine Surges
TROUBLESHOOTING
‘(cont’d)
Possible Causes
Fouled idle circuit
Air leak
Restricted fuel flow
(‘93
models only)
Engine Backfires
Possible Causes Remedies
I
Flywheel key sheared
Muffler filled with carbon
Exhaust ports plugged
Engine Overheats
Possible Causes
Cylinder head cooling fins clogged
Restricted main carburetor jet
Improper gas to oil mixture
Cooling air intake plugged
Remedies
Clean idle circuit
Check sealing surfaces, oil seals, gaskets, and
Check filters and fuel line
Replace key
Clean muffler
Clean ports
Remedies
Clean fins thoroughly
Clean carburetor’ and jet
Ensure mixture is
Remove foreign material and clean
32:l
Engine Vibrates Excessively
Possible Causes
Blade out of balance
Bent blade Replace blade
Loose engine mounting screws
Bent crankshaft
Flywheel out
Troubleshooting
of
balance
Remedies
Balance blade or replace
Tighten engine mounting screws
Replace crankshaft
Replace flywheel
16
-.--_-
if
damaged
Reference Section
TROUBLESHOOTING
(cont’d)
Engine Crankshaft Will
Possible Causes Remedies
Engine brake incorrectly engaged
Blade jammed in housing
Piston seized in its cylinder
Starter jammed
Not
Turn
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
Possible Causes Remedies
Engine Pre-Ignites
Possible Causes Remedies
Wrong spark plug too hot Install the correct type of spark plug
I
I
Replace with fresh unleaded regular fuel
Excessive alcohol in fuel
Sheared flywheel key Inspect and repair
Decarbon engine and muffler
Replace with fresh unleaded fuel having no more than
10%
_I-..
ethanol
Engine Smokes Excessively
Possible Causes Remedies
Slight oil accumulation in crankcase
Fuel/Oil mixture too rich Drain fuel tank and fill with fuel of correct mixture
Carburetor running too rich
None; normal on startup
Clean and re-oil or replace air cleaner element Air cleaner element clogged
Clean and check carburetor
_-
I
I
I
Reference Section
17
Troubleshooting
Engine
Stalls
Spark
Use
Plug
of
leaded fuel resh, unleaded regular
Fouled
Loading...