Table of Contents
Preface x
1 Basics 1
Four-cycle engines 1
Valve configuration 3
Lubrication 5
Two-cycle engines 6
Piston-ported or third-port induction 6
Reed valve induction 8
Scavenging 8
Displacement 10
Compression ratio 11
Horsepower, torque, and rpm 12
Emissions 15
Regulations 16
Stratified charging 17
Hybrids 17
Fuel injection 23
Catalytic converters 24
Fuel 26
Gas cans 27
Durability 28
2 Troubleshooting 35
Basics 36
No start 37
Compression 37
Fuel 37
Spark 38
Crankshaft binds or freezes during cranking 38
Kickback during cranking 40
Loss of power and/or bogging under acceleration 41
Refusal to idle 42
Engine runs a few minutes and quits 43
Exhaust smoke 43
Excessive vibration 44
3 Ignition and related systems 45
Troubleshooting 45
Spark plugs 45
Heat range 46
Reading spark plugs 46
Repairing spark-plug threads 51
Flywheel 51
Flywheel keys and keyways 54
Flywheel installation 57
Breaker-point magnetos 57
Servicing contact-point magnetos 60
Magnetron solid-state magnetos 65
Operation 65
Aftermarket upgrades 67
CDI systems 67
Precautions to take with CDI systems 68
Tecumseh CDI 69
Smart Spark 70
Troubleshooting the Smart Spark 71
Setting the E-gap 71
Battery and coil ignitions 72
Operation 73
Troubleshooting 73
4 Fuel systems 75
Tools and supplies 75
Fuel tank 76
Fuel filters 76
Fuel and pulse lines 77
Air filters 77
Diaphragm fuel pumps 78
Carburetors 79
Cleaning 79
Detaching the carburetor from the engine 82
Carburetor basics 83
Float carburetor operation 84
High-speed circuit 84
Low-speed circuit 84
Anti-afterfire solenoid 87
Cold-start enrichment 87
Float carburetor service 87
Fuel entry 89
Diaphragm carburetors 98
Fuel entry 100
Fuel delivery 100
Nozzle check valve and capillary screen 100
Purge pump 102
Throttle valve carburetors 102
Diaphragm carburetor service 105
Troubleshooting diaphragm carburetors 106
Diaphragm carburetor malfunctions 109
Suction-lift carburetors 110
Suction-lift carburetor service 111
Carburetor adjustments 115
Governors 118
Electronic fuel injection 119
Documentation and tools 120
Precautions 121
Troubleshooting 122
EFI operation 123
5 Rewind starters 129
Side pull 129
Troubleshooting 130
Overview of service procedures 130
Briggs & Stratton 135
Disassembly 135
Assembly 136
Eaton 137
Disassembly 142
Assembly 144
Fairbanks-Morse 145
Disassembly 146
Assembly 146
Vertical pull 149
Briggs & Stratton 150
Disassembly 150
Assembly 152
Tecumseh 155
Disassembly 156
Assembly 156
Vertical pull, vertical engagement 158
Rope replacement 158
Disassembly 159
Assembly 160
6 Electrical system 163
Starting circuits 163
Lead acid 163
NiCad 166
Starter motors 169
Charging circuits 175
7 Engine mechanical 183
Cylinder head 183
Valves 186
Valve guides 194
Valve seats 196
Valve lash adjustment 196
Push rods 199
Breathers 200
Reed valves 200
Pistons and rings 202
Inspection 202
Piston pins 207
Piston rings 208
Installation 208
Cylinder bores 213
Connecting rods 213
Rod orientation 215
Rod inspection 216
Rod assembly 218
Crankshafts and cam timing 220
Camshafts 223
Main bearings 225
Antifriction bearings 225
Plain bearings 226
Thrust bearings 227
Seals 227
Governor 229
Lubrication systems 229
Appendix Internet resources 233
Two- and four-stroke engines 233
Fuel systems 236
Ignition systems 237
Forums 237
Index 239
