4-CYCLE OVERHEAD VALVE ENGINES - Small Engine Discount

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TESTING PROCEDURE ................................................. 40
STARTING CIRCUIT ....................................................... 40
CHARGING CIRCUIT ...................................................... 40
350 MILLIAMP CHARGING SYSTEM ............................ 40
18 WATT A.C. LIGHTING ALTERNATOR....................... 41
35 WATT A.C. .................................................................. 41
2.5 AMP D.C., 35 WATT LIGHTING ............................... 41
3 AMP DC ALTERNATOR SYSTEM - DIODE IN
HARNESS SLEEVE ..................................................... 42
5 AMP D.C. ALTERNATOR SYSTEM
REGULATOR-RECTIFIER UNDER BLOWER
HOUSING ..................................................................... 43
3 AMP D.C. 5 AMP A.C. ALTERNATOR ......................... 43
MODELS OVM/OVXL/OHV12.5 ..................................... 44
MODELS OHV 13.5 - 17 (3/5 AMP SPLIT) ..................... 44
MODELS OVM/OVXL/OHV12.5
(RED BETWEEN ENGINE AND DIODE) .................... 44
MODELS OHV 13.5 - 17
(RED BETWEEN ENGINE AND DIODE) .................... 45
7 AMP D.C. ALTERNATOR SYSTEM
REGULATOR-RECTIFIER UNDER ENGINE
HOUSING ..................................................................... 45
10 AMP A.C. ALTERNATOR ........................................... 46
16 AMP ALTERNATOR SYSTEM WITH EXTERNAL
REGULATOR ................................................................ 46
VOLTAGE REGULATORS .............................................. 46
FUEL SHUT-DOWN SOLENOIDS .................................. 46
LOW OIL SHUTDOWN SWITCHES ............................... 47
LOW OIL PRESSURE SENSOR .................................... 47
LOW OIL SENSOR .......................................................... 47
ELECTRIC STARTER SERVICE .................................... 48
12 VOLT OR 120 VOLT ELECTRIC STARTERS ........... 48
INSPECTION AND REPAIR ............................................ 49
BRUSH CARD REPLACEMENT..................................... 49
CHAPTER 7 FLYWHEEL BRAKE SYSTEMS ............... 50
GENERAL INFORMATION ............................................. 50
OPERATION .................................................................... 50
COMPONENTS ............................................................... 51
SERVICE ......................................................................... 51
BRAKE BRACKET ASSEMBLY ...................................... 52
IGNITION GROUNDOUT TERMINAL ............................. 52
STARTER INTERLOCK SWITCH ................................... 52
CONTROL CABLE .......................................................... 52
BRAKE BRACKET REPLACEMENT .............................. 52
CHAPTER 8 IGNITION ................................................... 53
GENERAL INFORMATION ............................................. 53
OPERATION .................................................................... 53
SOLID STATE IGNITION SYSTEM (CDI) ....................... 53
COMPONENTS ............................................................... 53
TESTING PROCEDURE ................................................. 54
FOUR CYCLE IGNITION TROUBLESHOOTING ........... 55
SERVICE ......................................................................... 56
SPARK PLUG SERVICE ................................................. 56
CONDITIONS CAUSING FREQUENT SPARK
PLUG FOULING ........................................................... 56
IGNITION TIMING CHECK ............................................. 57
SERVICE TIPS ................................................................ 57
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CHAPTER 9 INTERNAL ENGINE AND CYLINDER ..... 58
GENERAL INFORMATION ............................................. 58
OPERATION .................................................................... 58
4-CYCLE ENGINE THEORY .......................................... 58
LUBRICATION SYSTEMS .............................................. 59
COUNTERBALANCE SYSTEMS ................................... 59
COMPONENTS ............................................................... 60
ENGINE OPERATION PROBLEMS ............................... 61
ENGINE OPERATION PROBLEMS ............................... 62
TESTING ......................................................................... 63
ENGINE KNOCKS ........................................................... 63
ENGINE OVERHEATS .................................................... 63
SURGES OR RUNS UNEVENLY ................................... 63
ENGINE MISFIRES ......................................................... 63
ENGINE VIBRATES EXCESSIVELY .............................. 64
BREATHER PASSING OIL ............................................. 64
EXCESSIVE OIL CONSUMPTION ................................. 64
LACKS POWER .............................................................. 65
SERVICE ......................................................................... 65
DISASSEMBLY PROCEDURE ....................................... 65
CYLINDERS .................................................................... 68
CYLINDER HEAD AND VALVE TRAIN SERVICE ......... 69
VALVES, SPRINGS, AND PUSH RODS ........................ 69
PISTONS, RINGS, AND CONNECTING RODS ............. 70
PISTON ........................................................................... 70
PISTON RINGS ............................................................... 70
PISTON RING ORIENTATION ....................................... 70
CONNECTING RODS ..................................................... 71
CRANKSHAFTS AND CAMSHAFTS .............................. 71
CAMSHAFTS ................................................................... 71
VALVE SEATS ................................................................. 72
VALVE LIFTERS .............................................................. 73
VALVE GUIDES ............................................................... 73
VALVE GUIDE REMOVAL (OVM, OHM, OHSK110
& 120, OVXL ONLY) .................................................... 73
VALVE GUIDE INSTALLATION (OVM, OHM,
OHSK110 & 120, OVXL ONLY) ................................... 73
CRANKCASE BREATHERS ........................................... 74
TOP MOUNTED BREATHER ......................................... 74
SIDE MOUNTED BREATHER ........................................ 74
CYLINDER COVER, OIL SEAL, AND BEARING
SERVICE ...................................................................... 75
CYLINDER COVER ........................................................ 75
OIL SEAL SERVICE ........................................................ 75
CRANKSHAFT BEARING SERVICE .............................. 75
BALL BEARING SERVICE .............................................. 75
SERVICE BUSHING ....................................................... 76
BUSHING SIZE CHART.................................................. 76
ENGINE ASSEMBLY ...................................................... 76
CHAPTER 10 .................................................................. 83
ENGINE SPECIFICATIONS AND SEARS
CRAFTSMAN CROSS-REFERENCE ......................... 83
OVERHEAD VALVE SEARS CRAFTSMAN
CROSS REFERENCE ................................................. 83
ENGINE SPECIFICATIONS............................................ 85
OVERHEAD VALVE TORQUE SPECIFICATIONS ........ 86
OVERHEAD VALVE TORQUE SPECIFICATIONS ........ 87
CHAPTER 11 EDUCATIONAL MATERIALS
AND TOOLS ............................................................... 88
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