TABLE OF CONTENTS

1- DESCRIPTION & OPERATION

FOUR-STROKE ENGINE OPERATION 1-1

COOLING 1-4

ENGINE "BUILD-UP" COMPONENTS 1-4

MODEL NUMBER GUIDE 1-5

ENGINE IDENTIFICATION 1-6

2- TROUBLESHOOTING

PROCEDURES 2-1

ENGINE CHECKOUT 2-2

FLOW CHART INDEX 2-4

Chart #1 Eng. fails to start 2-5

Chart #2 Crankshaft fails to rotate hand starter 2-8

Chart #3 Crankshaft fails to rotate elec. cranking mtr. 2-9

Chart #4 Engine lacks pwr. 2-10

Chart #5 Engine skips or misses 2-13

Chart #6 Engine vibrates 2-15

Chart #7 Engine knocks or is noisy 2-18

Chart #8 Engine overheats 2-23

Chart #9 Engine idles poorly 2-26

Chart #10 -- Engine stalls on acceleration 2-27

Chart #11 Engine surges 2-31

Chart #12 Carburetor requires adjustment 2-35

Chart #13 -- Ignition system inoperative 2-38

3- TUNING

INTRODUCTION 3-1

TUNE-UP SEQUENCE 3-1

SPARK PLUG EVALUATION 3-2

SERVICE AIR CLEANER 3-3

THROTTLE, CHOKE, GOVERNOR LINKAGE 3-4

SERVICE BATTERY 3-6

CLEAN COOLING FINS 3-7

COMPRESSION TEST 3-8

CHECK IGNITION SYSTEM 3-8

SERVICE FUEL SYSTEM 3-9

CARBURETOR FINAL

ADJUSTMENTS 3-10

CHANGE CRANKCASE OIL 3-11

CHECK DRIVEN COMPONENT 3-12

4- FUEL

INTRODUCTION AND CHAPTER COVERAGE 4-1

GENERAL CARBURETOR INFORMATION 4-1

Carburetors with Float 4-1

GASOLINE, "SOUR" FUEL, AND GASOHOL 4-3

FUEL PROBLEMS 4-4

AIR CLEANERS 4-5

SERVICE FLAT CARTRIDGE AIR CLEANER 4-6

Removal 4-6

Installation 4-6

SERVICE OVAL DUAL ELEMENT AIR CLEANER 4-7

Removal 4-7

Cleaning & Inspecting 4-8

Installation 4-8

SERVICE RECTANGULAR DUAL ELEMENT AIR CLEANER 4-10

Removal 4-10

Installation 4-10

CARBURETOR SERVICE INFORMATION 4-10

SERVICE FLO-JET -- ONE-PIECE SIDE DRAFT CARB.URETOR

Removal & Disassembling 4-11

Cleaning & Inspecting 4-15

Assembling & Installation 4-16

CARBURETOR ADJUSTMENT OHV ENGINES 4-22

THROTTLE CONTROLS, CHOKE AND GOVERNOR LINKAGE 4-23

MECHANICAL GOVERNOR 4-26

Static Adjustment 4-27

5- IGNITION

INTRODUCTION AND CHAPTER COVERAGE 5-1

SPARK PLUG EVALUATION 5-1

SERVICE MAGNETRONS 5-4

Removal 5-5

Disassembling 5-6

Cleaning & Inspecting 5-6

Assembling 5-6

Installation 5-6

Air Gap Table 5-7

6- ENGINE BLOCK

INTRODUCTION AND CHAPTER COVERAGE 6-1

DISASSEMBLING 6-2

Preparation 6-2

Valves, Valve Retainers, Rocker Arm & Push Rods 6-3

Cylinder Head 6-4

Flywheel 6-5

Oil Pump 6-7

Crankcase Cover 6-8

Camshaft 6-11

Connecting Rod & Piston 6-11

Piston Disassembly 6-12

Crankshaft & Cam Gear 6-13

CLEANING & INSPECTING Breather Valve 6-15

Valves, Springs, & Seats 6-16

Oil Pumps, Stingers & Dippers 6-19

Piston, Rings, & Rod 6-21

Crankshaft Service 6-24

Cylinder Service 6-26

Magneto & PTO Bearings 6-28

Flywheel Service 6-29

ASSEMBLING Crankshaft 6-30

Piston & Connecting Rod 6-30

Camshaft & Gear 6-34

Oil Pump 6-38

Breather 6-39

Flywheel 6-41

Valves 6-42

Cylinder Head 6-43

Muffler & Exhaust Pipe 6-45

Rocker Arm & Push Rod 6-45

Valve Cover 6-46

7- ELECTRICAL

INTRODUCTION 7-1

BATTERIES 7-1

Nickel Cadmium 7-1

Dry Storage-Type 7-2

Lead Acid-Wet Cell 7-2

Gel Cell 7-5

JUMPER CABLES 7-5

ALTERNATORS 7-6

Simple Testing 7-6

Detailed Testing 7-7

CRANKING MOTOR CIRCUIT 7-12

CRANKING MOTOR TROUBLESHOOTING 7-13

CRANKING MOTOR SERVICE 7-13

Removal & Disassembly 7-14

Cleaning & Inspecting 7-15

Testing Components 7-16

Assembling 7-17

8- HAND REWIND STARTER

INTRODUCTION AND CHAPTER COVERAGE 8-1

SERVICE TYPE "A" – TOP MOUNT -- HORIZONTAL PULL 8-2

Removal & Disassembling 8-2

Cleaning & Inspecting 8-4

Assembling & Installation 8-5

SERVICE TYPE "B" -- TOP OR SIDE MOUNT 8-7

Removal & Disassembling 8-7

Cleaning & Inspecting 8-7

Assembling & Installation 8-7

ROPE REPLACEMENT 8-9

FLYWHEEL BRAKE 8-12

Removal 8-12

Inspection 8-13

Assembling & Installation 8-14

Brake Shoe Test 8-16

9- MAINTENANCE

INTRODUCTION 9-1

PERIODIC MAINTENANCE 9-1

MAINTENANCE SCHEDULE 9-2

CRANKCASE LUBRICATION 9-3

AIR CLEANER 9-6

BREATHERS 9-7

IGNITION SYSTEM 9-8

VALVE CLEARANCE CHECK AND ADJUSTMENT 9-10

PREPARATION FOR STORAGE 9-11

10- COUNTERBALANCE

DESCRIPTION 10-1

SERVICE OSCILLATING COUNTERBALANCE 10-1

Preparation 10-2

Removal l0-2

Disassembling 10-2

Inspection 10-3

Assembling & Installation 10-3

SERVICE ROTATING COUNTERBALANCE 10-4

Preparation 10-4

Removal 10-4

Inspection 10-4

Installation 10-4

APPENDIX

METRIC CONVERSION CHART A-1

DRILL SIZE CONVERSION CHART A-2

BRIGGS & STRATTON MODEL NUMBER GUIDE A-3

CONVERSION CHART – MODEL NUMBER/HORSEPOWER A-4

ALTERNATORS A-5

VALVE TAPPET CLEARANCE A-5

CAMSHAFT REJECT SIZES A-5

IDLE SPEED TABLE A-6

ENGINE OIL CAPACITY A-6

ARMATURE AIR GAP A-6

CYLINDER BORE STD. DIA. A-6

CRANKCASE BEARING REJECT A-6

PISTON PIN REJECT A-7

CRANKSHAFT REJECT A-7

RING END GAP REJECT A-7

CONNECTING ROD REJECT A-7

FLYWHEEL NUT TORQUE VALUE A-8

CRANKCASE COVER BOLT TORQUE VALUE A-8

CONNECTING ROD BOLT TORQUE VALUE A-8

CYLINDER HEAD BOLT TORQUE VALUE A-8