TECUMSEH T E C H N I C I A N ' S H A N D B O O K This manual covers engine models: OHH50 - 65, OHHSK50 - 130, OHV11 - OHV17, OVM120, OVRM40-675, OVRM120, OVXL/C120, OVXL120, OVXL125. Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine and Transmission manuals; booklets; and wall charts are available through Tecumseh. For complete listing write or call CONTAINS SEARS CRAFTSMAN CROSS REFERENCE 4-CYCLE OVERHEAD VALVE ENGINES CONTENTS Page Page CHAPTER 1 GENERAL INFORMATION ....................... 1 INLET NEEDLE AND SEAT ............................................ 20 ENGINE IDENTIFICATION ............................................. 1 FLOAT INSTALLATION ................................................... 20 INTERPRETATION OF MODEL NUMBER ..................... 1 FUEL BOWL AND BOWL NUT ....................................... 21 SHORT BLOCKS ............................................................. 2 IMPULSE FUEL PUMP ................................................... 21 FUELS ............................................................................. 2 PRIMER BULB ................................................................ 21 ENGINE OIL .................................................................... 2 FINAL CHECKS ............................................................... 21 CAPACITIES.................................................................... 2 OIL CHANGE INTERVALS .............................................. 3 CHAPTER 4 GOVERNORS AND LINKAGE ................. 22 OIL CHECK ...................................................................... 3 GENERAL INFORMATION ............................................. 22 OIL CHANGE PROCEDURE .......................................... 3 OPERATION .................................................................... 22 TUNE-UP PROCEDURE ................................................. 3 TROUBLESHOOTING .................................................... 22 STORAGE ....................................................................... 4 ENGINE OVERSPEEDING ............................................. 22 DRAINING THE FUEL SYSTEM ..................................... 4 ENGINE SURGING ......................................................... 22 OIL CYLINDER BORE .................................................... 4 SERVICE ......................................................................... 23 GOVERNOR ADJUSTMENT .......................................... 23 CHAPTER 2 AIR CLEANERS ....................................... 5 GOVERNOR GEAR AND SHAFT SERVICE .................. 23 GENERAL INFORMATION ............................................. 5 GOVERNOR GEAR OR SHAFT REPLACEMENT, OPERATION .................................................................... 5 UPSET STYLE GOVERNOR SHAFT .......................... 23 COMPONENTS ............................................................... 5 GOVERNOR SHAFT REPLACEMENT, RETAINING TROUBLESHOOTING OR TESTING ............................. 6 RING STYLE ................................................................ 24 SERVICE ......................................................................... 6 SPEED CONTROLS AND LINKAGE .............................. 25 DISASSEMBLY PROCEDURE ....................................... 6 CONVERSION TO REMOTE CONTROL ....................... 27 POLYURETHANE-TYPE FILTER ELEMENT OVM, OVXL, OHV VERTICAL SPEED CONTROL ........ 28 OR PRE-CLEANER..................................................... 7 OHV 11-17 HORIZONTAL SPEED CONTROL............... 28 PAPER -TYPE FILTER ELEMENT ................................. 7 FLOCKED SCREEN ........................................................ 7 CHAPTER 5 RECOIL STARTERS ................................. 29 GENERAL INFORMATION ............................................. 29 CHAPTER 3 CARBURETORS AND FUEL SYSTEMS . 8 OPERATION .................................................................... 29 GENERAL INFORMATION ............................................. 8 COMPONENTS ............................................................... 29 OPERATION .................................................................... 8 SERVICE ......................................................................... 29 FUEL PRIMERS .............................................................. 9 ROPE SERVICE .............................................................. 29 IMPULSE FUEL PUMPS ................................................. 9 ROPE RETAINER REPLACEMENT ............................... 30 FLOAT STYLE CARBURETORS .................................... 9 STYLIZED REWIND STARTER (OHH, OVRM, OHM, CARBURETOR VISUAL IDENTIFICATION .................... 10 OHSK, OVM, OVXL, OHV 11-13), AND STAMPED SERIES I CARBURETORS ............................................. 10 STEEL STARTER ......................................................... 30 SERIES III & SERIES IV CARBURETORS .................... 10 DISASSEMBLY PROCEDURE ....................................... 30 SERIES VI CARBURETORS .......................................... 10 ASSEMBLY PROCEDURE ............................................. 31 SERIES VII ...................................................................... 10 STYLIZED REWIND STARTER WITH PLASTIC SERIES VIII ..................................................................... 11 RETAINER .................................................................... 31 SERIES IX ....................................................................... 11 DISASSEMBLY PROCEDURE ....................................... 31 WALBRO MODEL LMK ................................................... 11 ASSEMBLY ...................................................................... 32 TESTING ......................................................................... 12 KEEPER SPRING STYLE STARTERS .......................... 32 SERVICE ......................................................................... 12 DISASSEMBLY PROCEDURE ....................................... 32 CARBURETOR PRE-SETS AND ADJUSTMENTS........ 12 ASSEMBLY PROCEDURE ............................................. 33 PRE-SETS AND ADJUSTMENTS STYLIZED STARTER (OHV 13.5 -17) ............................ 34 (TECUMSEH AND WALBRO CARBURETORS) ......... 13 ASSEMBLY ...................................................................... 34 FINAL ADJUSTMENTS ................................................... 13 TECUMSEH CARBURETORS ........................................ 13 CHAPTER 6 ELECTRICAL SYSTEMS .......................... 35 WALBRO CARBURETOR ............................................... 13 GENERAL INFORMATION ............................................. 35 CARBURETOR DISASSEMBLY PROCEDURE ............. 14 OPERATION .................................................................... 35 IMPULSE FUEL PUMP ................................................... 15 STARTING CIRCUIT AND ELECTRIC STARTERS ....... 35 FLOAT ADJUSTING PROCEDURE ................................ 16 CHARGING CIRCUIT ...................................................... 35 INSPECTION ................................................................... 16 CONVERTING ALTERNATING CURRENT TO THROTTLE AND CHOKE ............................................... 16 DIRECT CURRENT ...................................................... 36 IDLE AND HIGH SPEED MIXTURE ADJUSTING HALF WAVE RECTIFIER SINGLE DIODE ..................... 36 SCREW ........................................................................ 16 FULL WAVE RECTIFIER BRIDGE RECTIFIER ............. 36 FUEL BOWL RETAINING NUT ....................................... 16 COMPONENTS ............................................................... 36 FUEL BOWL, FLOAT, NEEDLE AND SEAT ................... 17 BATTERY......................................................................... 36 ASSEMBLY PROCEDURE ............................................. 18 WIRING ............................................................................ 36 WELCH PLUGS ............................................................... 18 ELECTRICAL TERMS ..................................................... 37 THROTTLE SHAFT AND PLATE .................................... 18 BASIC CHECKS .............................................................. 37 CHOKE SHAFT AND PLATE .......................................... 19 TROUBLESHOOTING ELECTRICAL STARTER FUEL INLET FITTING ..................................................... 19 CIRCUIT FLOW CHART .............................................. 38 HIGH AND LOW SPEED ADJUSTING SCREW, TROUBLESHOOTING ELECTRICAL CHARGING MAIN NOZZLE ............................................................. 19 CIRCUIT FLOW CHART .............................................. 39 C Tecumseh Products Company 1998 i Page Page TESTING PROCEDURE ................................................. 40 CHAPTER 9 INTERNAL ENGINE AND CYLINDER ..... 58 STARTING CIRCUIT ....................................................... 40 GENERAL INFORMATION ............................................. 58 CHARGING CIRCUIT ...................................................... 40 OPERATION .................................................................... 58 350 MILLIAMP CHARGING SYSTEM ............................ 40 4-CYCLE ENGINE THEORY .......................................... 58 18 WATT A.C. LIGHTING ALTERNATOR....................... 41 LUBRICATION SYSTEMS .............................................. 59 35 WATT A.C. .................................................................