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