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Briggs & Stratton Twin Cylinder L-Head Repair Manual

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For Briggs & Stratton Discount Parts Call 606-678-9623 or 606-561-4983


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  • Page 1 For Briggs & Stratton Discount Parts Call 606-678-9623 or 606-561-4983
  • Page 2: Table Of Contents

    TABLE OF CONTENTS (For Section Reference, See Pages VI through VIII.) GENERAL INFORMATION ........Section 1 IGNITION .
  • Page 3 COMMON SPECIFICATIONS FOR OPPOSED TWIN CYLINDER ENGINES Sleeve Bore Models: 400400, 400700, 402400, 402700, 404400, 404700, 422400, 422700, 462700 Aluminum Bore Models: 401400, 401700, 421400, 421700 Common Specifications – All Model Series Armature Air Gap  Ignition Magnetron .008” – .012” (0.20 – 0.30 mm) Breaker Point Ignition .010”...
  • Page 4 STANDARD AND REJECT DIMENSIONS – ALL MODEL SERIES DESCRIPTION STANDARD DIMENSION REJECT DIMENSION Cylinder Bore (All) 3.4365” – 3.4375” (87.28 – 87.31 mm) 3.4405” (87.38 mm) Out of round: Aluminum Bore .0025” (.06 mm) Sleeve Bore .0015” (.04 mm) Main Bearing (Magneto) 1.379”...
  • Page 5 English to Metric Conversion Table Fraction Decimal Fraction Decimal 1/64 0.0156 0.3969 33/64 0.5156 13.0969 1/32 0.0312 0.7938 17/32 0.5312 13.4938 3/64 0.0469 1.1906 35/64 05469 13.8906 1/16 0.0625 1.5875 9/16 0.5625 14.2875 5/64 0.0781 1.9844 37/64 0.5781 14.6844 3/32 0.0938 2.3812 19/32...
  • Page 6 Drill Size – Decimal Equivalent In Inches .040 .0995 .161 .228 .332 .041 .1015 .166 .234 .339 .042 .104 .1695 15/64 .2344 11/32 .3438 .043 .1065 11/64 .1719 .238 .348 .0465 7/64 .1094 .173 .242 .358 .052 .110 .177 .246 23/64 .3594 .055 .111...
  • Page 7 SECTION REFERENCE SECTION (By Subject) Air Cleaner ..................Maintenance Air Guides .
  • Page 8 SECTION REFERENCE (Continued) SECTION Connecting Rod Checking ..................Installation .
  • Page 9 SECTION REFERENCE (Continued) SECTION Oil Slinger ..................Oil Trough .
  • Page 10: General Information

    Section 1 GENERAL INFORMATION Section Contents Page MAINTENANCE ............... . . Fuel And Oil Recommendations .
  • Page 11: In The Interest Of Safety

    In the Interest of Safety This safety alert symbol indicates that this You are not ready to operate this engine if message involves personal safety. Words you have not read and understood the danger, warning and caution indicate degree following safety items. Read this entire of hazard.
  • Page 12 BRIGGS & STRATTON NUMERICAL IDENTIFICATION SYSTEM All Briggs & Stratton engines have a unique numerical identification system. Each engine is identified by a Model, Type and Code number. Example: Model Type Code 422777 1125 01 99052115 This chart explains the numerical model designation system. It is possible to determine most of the important mechanical features of the engine by merely knowing the model number.
  • Page 13 MAINTENANCE 5 Hours 25 Hours or 50 Hours or 100 Hours or 100-300 Maintenance Schedule or Daily Every Season Every Season Every Season Hours Check oil level♦ D Note 1 Change oil (splash lube) D Note 1 Change oil (pressure lube) D Note 1 Change oil filter D Note 2...
  • Page 14 Change Oil – Splash Lube Engines Change Oil – Pressure Lube Engines The crankcase capacity of twin cylinder engines The crankcase capacity of pressure lube twin cylinder without oil filters is approximately three pints. engines is approximately: 3-1/2 Pints (1.65 liters) with filter NOTE: Early production engines had approxi- 3 Pints (1.42 liters) without filter mately 3-1/2 pint (1.65 liter) oil capacity.
  • Page 15 Clean Cooling System Air Cleaner Maintenance Grass particles, chaff or dirt can clog the air cooling WARNING: NEVER OPERATE engine with system, especially after prolonged service in cutting air cleaner cover or air cleaner element dry grass or very dirty air. Continued operation with a removed! Fire may result.
  • Page 16 DO NOT use petroleum solvents, such as kerosene, to Remove Combustion Chamber Deposits clean paper cartridge. They may cause cartridge to Combustion chamber deposits should be removed deteriorate. DO NOT oil paper cartridge. DO NOT use every 100 – 300 hours or whenever cylinder heads are pressurized air to clean or dry paper cartridge.
  • Page 17 Check Ignition (With Electric Starter) IGNITION TESTER NOTE: Magnetron ignition system requires a #19368 minimum of 350 RPM to produce spark. With spark plugs installed, attach a #19368 ignition tester to each spark plug lead and ground the other end of the tester as shown in Fig.
  • Page 18 If plugs are dry, look for – Tools Required 1. Tachometer, Tool #19200 1. Leaking carburetor mounting gaskets 2. Two #19368 Ignition Testers 2. Gummy or dirty carburetor 3. Screwdriver with insulated handle 3. Float needle valve stuck shut Attach ignition tester, Tool #19368, between the spark 4.
  • Page 19 If the RPM loss is greater than 75 RPM, this indicates ment problems, and what to look for as the most that the cylinder with the least RPM loss is the weakest common cause. of the two cylinders. Look to that cylinder for a problem. See Example.
  • Page 20 Section 2 IGNITION Section Contents Page GENERAL INFORMATION ..............ARMATURES .
  • Page 21: General Information

    SPECIFICATIONS FOR ALL OPPOSED TWIN CYLINDER ENGINE MODELS Flywheel Nut Torque Basic Armature Flywheel Puller Model Series Air Gap Part No. Ft. Lbs. With Magnetron .008” to .012” (.20 to .30 mm) 400000, 460000 19203 203.0 With Breaker Points .010” to .014” (.25 to .36 mm) BREAKER POINT IGNITION CONTACT POINT GAP: .020”...
  • Page 22: Remove Armature

    Remove Armature All Models – The flywheel does not need to be EQUIPMENT removed to service ignition except to check the STOP SWITCH flywheel key. WIRE Remove Armature – Breaker Point Ignition On engines with breaker points, it may be necessary to remove carburetor or carburetor and intake manifold.
  • Page 23: Install Magnetron  Module

    3. Remove sealant and or tape holding wires to BACK SIDE OF ARMATURE SHOWN armature. 4. Unsolder and separate module wire and armature SEALANT primary wire, Fig. 7. 5. Separate armature ground wire and module UNSOLDER WIRE ground wire. NOTE: Avoid damaging armature and module when unsoldering or soldering.
  • Page 24: Install Armature - All Models

    4. Twist armature ground wire and module ground GROUND WIRE wire together and route wires as shown. MODULE SCREW GROUND 5. Attach ground wires to armature lamination with WIRE ARMATURE ground screw, Fig. 11. GROUND WIRE 6. Seal wires to back of armature with Permatex No.
  • Page 25: Adjust Armature Air Gap - All Models

    Adjust Armature Air Gap – All Models 1. Rotate flywheel until magnet is under armature laminations. 2. Place thickness gauge between magnet and arma- ture laminations, Fig. 14. Magnetron Ignition: .008”-.012” (.20 mm-.30 mm) Breaker Point Ignition: .010”-.014” (.25 mm-.36 mm) 3.
  • Page 26: Install Plunger And Seal

    Install Plunger And Seal 1. Assemble seal to plunger. FIBER TIP UP 2. Install plunger with fiber tip up, Fig. 18. GROOVE 3. Slide seal over plunger boss until it contacts cylinder. SEAL LIP SHOULD PLUNGER CONTACT BOSS CYLINDER Fig. 18 – Install Plunger and Seal Install Breaker Points GASKET Place breaker point cover gasket on engine with tab to...
  • Page 27: Adjust Breaker Points

    Adjust Breaker Points 1. Rotate crankshaft until points are at widest opening. 2. Turn breaker point adjusting screw clockwise to increase or counterclockwise to decrease point gap. 3. Set point gap at .020” (.51 mm). 4. Tighten locknut and recheck gap, Fig. 21. .020”...
  • Page 28: Flywheel

    FLYWHEEL Remove Flywheel DO NOT strike flywheel with a hard object or a metal tool as this may cause flywheel to shatter #19244 in operation. Always use approved flywheel CLUTCH WRENCH removal tools. Remove Flywheel Nut – Pre Twin II (Type Nos.
  • Page 29: Inspect Flywheel Key, Keyways, Flywheel And Crankshaft

    Inspect Flywheel Key, Keyways, CHECK Flywheel and Crankshaft Check flywheel key for damage. Check flywheel for cracks, broken fins or keyway damage. Also check crankshaft keyways and taper for damage, Fig. 27. Replace crankshaft, if damaged. Fig. 27 – Check Flywheel and Crankshaft Install Flywheel –...
  • Page 30: Flywheel Fan And Retainer (Type Nos. 1100 & Above)

    Flywheel Fan And Retainer TORQUE SCREWS (Type Nos. 1100 & Above) The fan and retainer do not need to be removed unless fan or retainer is damaged or warped. RETAINER To remove fan, remove two fan retainer screws, fan retainer and fan. To install fan, place fan on to flywheel, aligning recess in flywheel with boss on back of fan.
  • Page 31: Equipment To Test Stop Switches

    Equipment To Test Stop Switches The Digital Multimeter, Tool Tool #19357 or #19390 is available from your Briggs & Stratton source of supply. The meter may be used to measure Volts, Ohms, or Amperes, Fig. 32. Testing With Digital Multimeter 1.
  • Page 32: Check Single Terminal Rotary Key Switch

    Check Single Terminal Rotary Key Switch 1. Disconnect stop switch wire from spade terminal. 2. Connect one meter lead to spade terminal and other lead to switch mounting surface or a good ground. 3. With key in “OFF” position. There should be conti- nuity.
  • Page 33: Check Stationary Stop Switch

    Check Stationary Stop Switch Stationary stop switch is located on governor control bracket. 1. Push down on wire retainer and remove stop switch wire. 2. Connect one meter lead to engine ground and other lead to stop switch wire retainer, Fig. 38. 3.
  • Page 34: Carburetion

    Section 3 CARBURETION Section Contents Page CARBURETOR STYLES ................Current Style –...
  • Page 36: Carburetor Styles

  • Page 37: Current Style - Type Nos. 1100 And Above

    Current Style – Type Nos. 1100 And Above DUAL BOWL VENTS Engines Built After 98101500 4 SCREW PUMP COVER The current style carburetor has no external adjust- ments other than idle speed. Components are NOT CAST-IN LOGO interchangeable with previous carburetors. The air cleaner base has two holes to accommodate the dual bowl vents and the throttle link is 1/16”...
  • Page 38: Remote Fuel Pump Carburetor

    Remote Fuel Pump Carburetor Carburetors used for remote fuel pump applications are manufactured without integral pumps, Fig.6. The remote fuel pump is supplied by the equipment manufacturer. Fuel pump pressure must not exceed 1.5 psi (0.10 Bar). NOTE: Excessive fuel pump pressure may result in an over rich carburetor mixture and, ultimately cylinder scoring and, or other engine damage resulting from crankcase...
  • Page 39: Horizontal Crankshaft Models - Pre-Twin Ii (Type Nos. Under 1100)

    4. Remove carburetor from intake manifold, Fig. 10. a. Discard gaskets. Fig. 10 – Remove Carburetor Horizontal Crankshaft Models – Pre-Twin II (Type Nos. Under 1100) Carburetor and intake manifold must be removed as an assembly, Fig. 11. 1. Remove air cleaner assembly. 2.
  • Page 40: Disassemble Carburetor - All Styles

    DISASSEMBLE CARBURETOR – ALL STYLES The disassembly procedure for all style carburetors is similar enough that it can be considered the same. Refer to figures 1 and 2 for reference and the names of components. Separate upper and lower carburetor body. Remove float and inlet needle. Remove idle jet, pilot jet or idle mixture valve, if equipped.
  • Page 41: Replace Nylon Throttle Shaft Bushings

    Two style throttle shaft bushings are used on opposed twin cylinder carburetors, Fig. 16. 1. A replaceable split nylon bushing. 2. A replaceable steel bushing. The bushings are not interchangeable. NYLON BUSHING STEEL BUSHING Fig. 16 – Throttle Shaft Bushings Replace Nylon Throttle Shaft Bushings 1.
  • Page 42: Replace Fuel Inlet Seat

    3. Assemble 1/4” x 20 nut, 1/4” flat washer and fuel 1/4” x 20 NUT 1/4” FLAT tank spacer #94047 or #94038 to self threading WASHER screw. 4. Thread assembly into bushing. 5. Tighten nut until bushing is removed, Fig. 20. FUEL TANK SPACER...
  • Page 43: Install Inlet Seat - Engines Built Before 98101500

    2. Assemble 1/4” x 20 nut, 1/4” flat washer and fuel #92278 NUT tank spacer #94047 or #94038 to self threading 1/4” FLAT WASHER screw. 3. Thread assembly into seat. 4. Tighten nut until seat is removed, Fig. 24. FUEL TANK SPACER Fig.
  • Page 44 4. Assemble fuel inlet valve to float and install float, Fig. 28. NOTE: Float height is not adjustable. FLOAT FUEL INLET VALVE Fig. 28 – Install Float 5. Assemble new seal and spacer to throttle shaft and insert into carburetor body, Fig. 29. SEAL a.
  • Page 45: Assemble Fuel Pump

    Assemble Fuel Pump NOTE: Check valves are not replaceable, Fig. 32. CHECK VALVES ARE NOT REPLACEABLE Fig. 32 – Assemble Check Valves GASKET 10. Assemble Remaining components as shown, DIAPHRAGM Fig. 33. DIAPHRAGM a. Torque pump cover to 20 in. lbs. (2.0 Nm). DIAPHRAGM SPRING COVER...
  • Page 46 4. Assemble spring to fuel inlet valve, Fig. 36. 5. Install float assembly in upper body. FLOAT SPRING Fig. 36 – Install Float 6. Invert upper body and check float height, Fig. 37. 7. Float should be parallel to gasket surface. SAME FLOAT Fig.
  • Page 47 10. Install idle mixture valve or pilot jet, If equipped. 11. Install fixed main jet and plug or solenoid, or high speed mixture valve, if equipped, Fig. 40. a. Torque plug or solenoid to 100 in. lbs. (11.0 Nm). TORQUE 100 in.
  • Page 48: Install Carburetor

    INSTALL CARBURETOR To install carburetor and manifold or carburetor, see “Remove Carburetor,” this section and assemble in reverse order of removal. Torque carburetor mounting screws to 100 in. lbs. (11.0 Nm). Torque intake manifold screws to 90 in. lbs. (10.0 Nm). Install fuel line and fuel pump pulse line. Make sure all connections are tight. INSTALL AIR CLEANER ASSEMBLY IMPORTANT: ALL MODELS, breather tubes must be 1 breather tube hole...
  • Page 49: Static Governor Adjustment (Before Running Engine)

    ALL MODELS STATIC GOVERNOR ADJUSTMENT (Before Running Engine) 1. Loosen governor lever nut. Push on governor PARTS REMOVED FOR CLARITY lever until throttle is wide open. Do not bend governor link or distort governor lever. 2. Rotate governor shaft counter-clockwise as far it TORQUE TO 100 in.
  • Page 50: Governed Idle Adjustment - Type Nos. 1100 And Above

    Governed Idle Adjustment – Type Nos. 1100 IDLE SPEED ADJUSTING And Above SCREW 1. Move control lever on equipment to SLOW position. NOTE: Engines equipped with current style carburetor or carburetors with screw in pilot jet, proceed to step 6. 2.
  • Page 51: Dynamic Governor Adjustment – Type Nos. Below

    Dynamic Governor Adjustment – Type Nos. Below 1100 ALL ADJUSTMENTS MUST BE MADE WITH THE AIR CLEANER INSTALLED. The following tools are required when making gover- 19200 19389 nor adjustments. 1. An accurate tachometer, such as Tool #19200 or #19389. 19352 2.
  • Page 52: Fixed High Speed Jet Carburetors

    Fixed High Speed Jet Carburetors If throttle response is poor or a hesitation occurs when the engine is accelerated, or when engaging an electric clutch, the following procedure can be used to determined if a lean mixture is the cause. 4 DOTS Partially close the choke.
  • Page 53: Testing Solenoid

    Testing Solenoid If solenoid does not click, the problem may be in equipment wiring or solenoid. To determine whether problem is with wiring or solenoid, perform the following tests in the order shown. Test Equipment The digital multimeter, Tool #19390, is required to test the solenoid equipment wiring.
  • Page 54: Check Anti-Afterfire Operation (Engine Running)

    When the switch is in the start or run position, the vacuum valve assembly is energized. This opens the valve in the vacuum valve assembly and allows the carburetor float bowl to vent through the air cleaner. The carburetor float bowl vents through the vacuum block assembly and vacuum valve assembly, Fig.
  • Page 56 Section 4 GOV. CONTROLS & GOVERNOR Section Contents Page MECHANICAL GOVERNOR ............. . General Information .
  • Page 57: Mechanical Governor

    MECHANICAL GOVERNOR General Information The purpose of the governor is to maintain, within certain limits, a desired engine speed, even though loads may vary. The governor spring tends to pull the throttle open. The force of the counterweights, which are operated by centrifugal force, tends to close the throttle.
  • Page 58: Governed Idle

    Governed Idle All Twin II twin cylinder engines equipped for remote control are equipped with governed idle. A detent in the equipment control provides governed idle when the equipment control is moved to the full slow position. Pre-Twin II, twin cylinder engines equipped for remote control have provision for governed idle. Equipment manufac- turer’s control may or may not provide a detent for governed idle.
  • Page 59: Horizontal Crankshaft

    Remote Control Adjustment – Pre-Twin II (Type Nos. Below 1100) Horizontal Crankshaft CASING 1. Move speed control lever to full ‘‘SLOW” position. CLAMP SCREW 2. Loosen control casing clamp at governor control bracket or intake manifold. 3. Move control casing and wire in direction shown by arrow, Fig.
  • Page 60: Mechanical Governor

    MECHANICAL GOVERNOR Remove Governor Gear The governor gear is located in the crankcase cover on horizontal crankshaft engines or in the sump on vertical crankshaft engines. Drain oil and remove engine from equipment. Remove spark plugs. 1. To relieve cam gear bearing pressure on the cover or sump, rotate crankshaft until #1 cylinder intake valve is open.
  • Page 61: Remove Governor Shaft - Twin Ll (Type Nos. 1100 & Above)

    Opposed twin cylinder engines have three (3) styles of OIL SEAL bushings on the governor shaft, Fig. 14, Fig. 15 and Fig. 16. They are not interchangeable. BUSHING Remove Governor Shaft – Twin ll (Type Nos. 1100 & Above) 1. Remove “E” ring from governor shaft, Fig. 14. GOVERNOR 2.
  • Page 62: Install Governor Shaft - Twin Ll (Type Nos. 1100 & Above)

    7. Temporarily, install governor shaft. Do not install TOOL “E” ring. #19129 DRIVER 8. Using governor shaft as a pilot, install new bushing using Tool #19129. BUSHING 9. Press bushing in until it bottoms, Fig. 18. Fig. 18 – Install Bushing Install Governor Shaft –...
  • Page 63: Install Governor Shaft (Early Style)

    Install Governor Shaft “E” RING (Early Style) THICK WASHER Early style twin cylinder governor shaft bearings are an integral part of the cylinder and are not replaceable. If CYLINDER bearings are worn, replace cylinder. BEARING 1. Assemble thrust washer to governor shaft and CYLINDER insert governor shaft through lower support and LOWER...
  • Page 64: Dynamic Governor Adjustment

    Dual speed controls or 1800 RPM Generators, have a throttle restrictor to limit throttle travel, Fig. 26. Move restrictor out to allow throttle to move to wide open THROTTLE throttle position for governor adjustment. After gover- RESTRICTOR nor lever is torqued, move governor lever to close throttle so restrictor will snap back to its normal position.
  • Page 65 3. Refer to Service Engine Sales Manual Microfiche, MAXIMUM RPM MS-6225 or the Service Sales Manual, MS-4052 Model Type Trim for Top-No-Load RPM by engine model and type 422437 0015 3400 number. See Example, Fig. 29. 422437 0015 3400 422437 0016 3400 422437...
  • Page 66 6. Re-attach regulator knob to bracket. Adjust speed DECREASE regulator knob, NO TAG, to obtain Regulated RPM for the generator type shown in Table 1. NOTE: Final adjustment should be made with INCREASE generator loaded to rated capacity or manufacturers specifications. Fig.
  • Page 67 Constant Speed – Pre-Twin II (Type Nos. Below 1100) TANG TANG BENDER 1. Loosen constant speed locking screw and washer and move control lever until a 1/8” (3 mm) rod can be inserted through two (2) holes in governor control plate, Fig. 37. INCREASE 2.
  • Page 68: Dual Speed Control - Pre-Twin Ll (Type Nos. Below 1100)

    6. Turn speed regulator nut clockwise until Top-No- Load RPM is obtained. 7. Bend tang until it touches speed control lever. INCREASE SPEED REGULATOR Fig. 41 – Adjust Top-No-Load Dual Speed Control – Pre-Twin ll (Type Nos. Below 1100) 1. Refer to Equipment Manufacturers Service Manu- al and Operating Instructions for operating proce- dures and adjustment of parts supplied by Manufacturers of control system.
  • Page 69: 1800 Rpm Generator - Pre-Twin Ll (Type Nos. Below 1100)

    1800 RPM Generator – Pre-Twin ll (Type Nos. Below 1100) 1. Disconnect governed idle spring and start engine. Turn speed regulating nut to obtain 1850 RPM, Top-No-Load RPM, Fig. 45. 2. Stop engine. SPEED REGULATOR Fig. 45 – Adjust Low Speed INCREASE 3.
  • Page 70: Compression

    Section 5 COMPRESSION Section Contents Page GENERAL INFORMATION ..............CYLINDER HEAD REMOVAL .
  • Page 71: General Information

    GENERAL INFORMATION CYLINDER IDENTIFICATION Compression testing information and procedures are NUMBER described in “Troubleshooting” in Section 1. Cylinders and cylinder heads are numbered as shown in Fig. 1. 42–2 42–1 Fig. 1 – Cylinder Number Location CYLINDER HEAD REMOVAL CYLINDER 1.
  • Page 72: Removing Valves

    3. Remove nine (9) head bolts from each cylinder LONGER LONGER BOLTS BOLTS head, Fig. 4. (EXHAUST) (EXHAUST) 4. Remove cylinder heads and gaskets. Discard old gaskets. NOTE: Some models use three (3) longer head bolts located around the exhaust valve area.
  • Page 73: Valve Spring Retainers

    Valve Spring Retainers ROTATOR Fig. 7 shows the two styles of valve spring retainers used. NOTE: When removing valves and valve springs, STEM identify parts to prevent interchanging. RETAINER WARNING: VALVE SPRINGS are under high pressure! Hold shop rag around spring and loosen spring compressor slowly to release COLLARS pressure from spring.
  • Page 74: Valve Guides

    VALVE GUIDES REJECT Check Valve Guides GAUGE 19151 Check valve guide bushings for wear using reject gauge Tool #19151, Fig. 10. If gauge enters guide 5/16” (8 mm) or more, guide must be repaired or replaced. Valve Guide Repair Kit #19232 Valve guides may be reconditioned using Valve Guide Repair Kit, #19232.
  • Page 75: Finish Reaming

    Finish Reaming 1. Finish ream guide with reamer #19233, and pilot guide #19234, Fig. 14. FINISH REAM a. Lubricate reamer with Stanisol or kerosene. THROUGH TO VALVE 2. Ream clockwise through entire guide into valve TAPPET CHAMBER tappet chamber, 3. Keep turning reamer clockwise when removing reamer from guide.
  • Page 76: Valve Guide Bushing Identification

    Valve Guide Bushing Identification (.366” (.367” (.379” (.440” (.441” See Fig. 18 to identify bushing that has been removed. (9.3 mm) O.D.) (9.32 mm) O.D.) (9.63 mm) O.D.) (11.18 mm) O.D.) (11.2 mm) O.D.) BRASS BRASS BRASS GRAY COPPER Then select correct replacement bushing shown. Special Instructions Two grooves on replacement bushing, #231218, go down.
  • Page 77: Inspect Valve Seats

    Intake valve seats may be reconditioned using valve É É É É É É É seat cutter tool #19237. Use 30° cutter for intake. 3/64” – 1/16” (1.2 mm – 1.6 mm) 30° É É É If valve seat is wider than dimension shown in Fig. 22, 45°...
  • Page 78: Remove Valve Seat

    Remove Valve Seat BODY IN PLACE 1. Use valve seat puller, Tool #19138, Fig. 25, to remove valve seat insert. a. Puller body must not rest on valve seat insert. 2. Tighten bolt until insert is free of cylinder. VALVE SEAT PULLER NUT EXHAUST VALVE...
  • Page 79: Installing Part #21612 Exhaust Valve Seat Insert

    Installing Part #21612 Exhaust Valve Seat Insert 1. Modify Tool #19131 counterbore cutter as shown, INCREASE Fig. 27. CUTTER STOP 2. With old valve seat insert removed, install pilot DEPTH .030 Tool #19127 into exhaust valve guide. CAREFULLY DRIVE WITH BRASS Fig.
  • Page 80: Check And Adjust Valve Clearance

    CHECK AND ADJUST VALVE CLEARANCE Turn crankshaft until piston is 1/4” (6.35 mm) past Top Dead Center, compression stroke, for cylinder being checked. See specifications below. 1. If clearance is less than specified, grind end of valve stem to obtain proper clearance. 2.
  • Page 81: Install Exhaust Valve

    Install Exhaust Valve Coat valve stem with valve guide lubricant, Tool #93963. 1. Place exhaust valve spring and rotator or retainer into valve spring compressor, Tool #19063, and compress spring completely. 2. Insert compressed spring into valve tappet cham- ber and slide coated exhaust valve stem in through exhaust valve guide, through spring and rotator or retainer until valve seats.
  • Page 82 Section 6A REWIND STARTERS Section Contents Page REMOVE REWIND STARTER ............. DISASSEMBLY .
  • Page 83: Remove Spring

    5. Grasp outer end of spring with pliers and pull out of housing as far as possible, Fig. 3. 6. Turn spring 1/4 turn and remove from pulley or bend one of the tangs with Tool #19229 and lift out starter pulley to disconnect spring.
  • Page 84: Install Rope

    Fig. 8 – Inserting Rope Install Rope 1. Inspect rope. Replace if frayed. 2. Insert rope through handle and tie a figure eight knot, Fig. 8, Fig. 9. 3. Insert pin through knot and pull tightly into handle, Fig. 10. ALWAYS SEAL BOTH ENDS OF KNOT. A rope inserter tool may be made by using a piece of music wire or spring wire, and forming it as shown in Fig.
  • Page 85: Starter Clutch

    Starter Clutch If necessary, the sealed clutch can be disassembled by using a screwdriver or wedge to pry the retainer cover from the housing, as shown in Fig. 12. Fig. 13 shows disassembled starter clutch. Fig. 12 – Disassembling Sealed Clutch 1.
  • Page 86 Section 6B ELECTRIC STARTERS Section Contents Page GENERAL INFORMATION ..............Starter Location .
  • Page 87: General Information

    GENERAL INFORMATION This starter motor uses a gear type engagement method, similar to an automobile starter. When the starter motor is activated, the pinion gear engages a ring gear attached to the engine flywheel and cranks the engine. Starter Location Fig.
  • Page 88: Troubleshooting

    TROUBLESHOOTING NOTE: If a starting problem is encountered, the h. Battery leads too long or wire too small. engine itself should be thoroughly checked Battery too small. to eliminate it as the cause of starting 2. Engine Will Not Crank – difficulty.
  • Page 89: Tachometer

    Tachometer A tachometer is available from your Briggs & Stratton source of supply. Order as Tool #19200. The tachome- ter measures from 800 to 50,000 revolutions per minute (RPM), Fig. 8. Fig. 8 – Tachometer Starter Motor Test Bracket EXTRA HOLE FOR TWO 9.5 MM (3/8”) HOLES FOR MOUNTING STARTER MOUNTING STARTER...
  • Page 90: Conditions Affecting Starter Motor Performance

    Conditions Affecting Starter Motor c. Grounded armature (wire insulation worn and wire touching armature lamination or shaft). Performance Will be indicated by excessive current draw or 1. Binding or seized starter motor bearings. no RPM. 2. A shorted, open or grounded armature. 3.
  • Page 91: Disassemble Starter Motor Drive - Roll Pin Style

    4. Remove retainer, return spring, spring washer, pinion gear, and starter clutch, Fig. 16. RETAINER STARTER CLUTCH RETURN SPRING SPRING WASHER PINION GEAR Fig. 16 – Removing Starter Drive Disassemble Starter Motor Drive – Roll Pin Style If starter is equipped with a plastic cap, it must be removed before removing roll pin.
  • Page 92: Assemble Starter Drive - C-Ring Style

    Assemble Starter Drive – C-ring Style 1. Assemble starter clutch to starter shaft and rotate STARTER RETAINER clutch until it drops into place, Fig. 19. CLUTCH 2. Install pinion gear with beveled side of teeth up. Then install return spring making sure spring is in RETURN recess of starter gear.
  • Page 93: Assemble Starter Drive - Roll Pin Style With Plastic Cap

    Assemble Starter Drive – Roll Pin Style With Plastic Cap COVER 1. Assemble starter clutch on armature shaft and ROLL PIN rotate clutch until it drops into place. SLOT CLUTCH 2. Install pinion gear with chamfered edge of pinion RETAINER gear teeth away from motor, Fig.
  • Page 94: Starter Motor

    STARTER MOTOR Disassemble Starter Motor C-RING IMPORTANT: DO NOT clamp motor housing in a vise RETAINER or strike with a steel hammer. Starter motors contain SPRING two ceramic magnets which can be broken or cracked WASHER if the motor housing is hit, deformed or dented. SPRING NOTE: For ease of re-assembly, mark starter PINION...
  • Page 95: Replace Brushes

    Inspect Armature Commutator PIECE OF BROKEN HACKSAW BLADE The armature commutator may be cleaned with fine sandpaper. DO NOT use emery cloth. Commutator may be machined to no less than 1.230” (31.24 mm), Fig. 26. Slots between commutator bars should be cleaned with a hack saw blade after cleaning or machining, Fig.
  • Page 96: Assemble Starter Motor

    ASSEMBLE STARTER MOTOR When all parts have been inspected, lightly lubricate bearings in both end caps with #20 oil. NOTE: On brush end cap with flat coil brush spring, install armature on to brush end cap before installing brushes. 1. Place brush in holder. 2.
  • Page 97: Install Drive End Cap

    NOTE: Some starter housings have a large notch INSULATED TERMINAL which indexes over the insulated terminal, Fig. 35. NOTCH Fig. 35 – Assemble Starter 6. While pushing down on armature and brush end cap, slide starter housing down until large notch HOLD ARMATURE indexes with insulated terminal boss, Fig.
  • Page 98: Replace Ring Gear

    REPLACE RING GEAR FLAT RING GEAR HEAD To replace a worn or damaged flywheel ring gear, SCREWS proceed as follows. 1. Mark the center of the rivets holding the ring gear to flywheel, with a center punch. 2. Drill out the rivets using a 3/16” drill. 3.
  • Page 99: Checking Battery

    Checking Battery Testing Battery 1. Physical check – clean if necessary. Use Digital Multimeter, Tool #19357 or #19390. a. Corrosion Set meter to read DC Volts. b. Dirt Attach RED meter test clip to positive (+) battery c. Terminal and clamps secure and in good terminal.
  • Page 100: Alternators

  • Page 101: Alternator Identification

    ALTERNATOR IDENTIFICATION The alternator systems installed on Briggs & Stratton Twin Cylinder Engines can easily be identified by the color of the stator output wires and connector. Table No. 1 provides a means of identifying the various alternator systems. Refer to test page for output specifications and test procedure.
  • Page 103: Flywheel Identification

    STATOR ASSEMBLY WHITE LEAD (LIGHTS) WHITE CONNECTOR 1-1/16 X 11/16 (27 mm X 18 mm) BLACK MAGNETS LEAD (LIGHTS) Fig. 9 – Medium Magnet LEAD (BATTERY) BLACK LEADS YELLOW YELLOW CONNECTOR LEADS REGULATOR RECTIFIER • 16 amps AC from stator to regulator-rectifier. Two black leads from stator.
  • Page 104: Test Equipment

    TROUBLESHOOTING The following list is provided to aid you in diagnosing problems with alternator systems. COMPLAINT POSSIBLE CAUSES • Engine RPM too low. “Battery not charging” • Defective battery. • Loose or corroded battery ground leads. • Loose or corroded battery charge leads. •...
  • Page 105: Alternator Output Testing

    ALTERNATOR OUTPUT TESTING AC Output Test When checking alternators make the tests in the 1. Insert RED test lead into receptacle in following sequence. meter. 1. Test alternator output. 2. Insert BLACK test lead into COM receptacle in 2. Test diode(s) or regulator-rectifier (if equipped). meter.
  • Page 106: Diode Test

    NOTE: Service replacement diode harnesses RED TEST CLIP TO are available. Use Rosin Core solder when OUTPUT PIN TERMINAL installing new harness. Use shrink tubing or tape all connections. DO NOT USE CRIMP CONNECTORS. DUAL CIRCUIT ALTERNATOR Dual circuit alternators use a single polarized plug with two pins.
  • Page 107: Diode Test

    6. With engine running at 3600 RPM output should AC Output Test be between 2 – 4 amps DC. 1. Insert RED test lead into receptacle in a. Output will vary with battery voltage. If battery meter. voltage is at its maximum, output will be 2.
  • Page 108: Alternator Output Test

    WHEN CHECKING ALTERNATOR COM- 6. Reverse test leads. PONENTS, MAKE THE TESTS IN THE FOLLOWING a. If meter “Beeps” once, diode is installed back- SEQUENCE: wards. Alternator Output Test b. If meter still displays “OL,” diode is defective (open). 1. Insert RED test lead into receptacle in meter.
  • Page 109: 5 & 9 Amp Regulated Alternator

    NOTE: Service replacement diode harnesses When testing regulator-rectifier for amperage output, a 12 volt battery with a minimum charge of 5 volts is are available. required. There will be no charging output if battery voltage is below 5 volts. 5 & 9 AMP REGULATED ALTERNATOR The 5 &...
  • Page 110 Alternator output (10, 13 or 16 Amp) is determined by regulated system, use DC Shunt, Tool flywheel alternator magnet size. Therefore, stator and #19359, to avoid blowing fuse in meter. regulator-rectifier are the same for the 10 and 16 amp See special instructions for installation system.
  • Page 111: Regulator-Rectifier With Charge Indicator

    are clean and secure. If there is still no or low 6. If no or low output is found, be sure that regulator- output, replace the regulator-rectifier. rectifier is grounded properly and all connections are clean and secure. If there is still no or low output, replace the regulator-rectifier.
  • Page 112 Typical 16 Amp Regulated Alternator Wiring Diagram – 6 Pole Switch With Charge Indicator Light Alternator Anti-Afterfire Stop Solenoid Switch Key Switch Charge Indicator Light AC Output Wires Blue Wire Regulator Rectifier Raised Rib Solenoid Tab Red Wire Terminal DC Output Battery Starter Terminal...
  • Page 113: Testing Charge Indicator

    Testing Charge Indicator QUAD CIRCUIT ALTERNATOR It is important that the test procedure be done in a The quad circuit alternator system provides AC current systematic manner to identify whether the problem is through two output leads to the regulator-rectifier. The related to the regulator-rectifier or the charging indica- regulator-rectifier converts AC current to DC and tor wiring system.
  • Page 114: Test Lighting Circuit (-Dc)

    When testing regulator-rectifier for amperage output a 1 OHM 20 WATT RESISTOR 12 volt battery with a minimum charge of 5 volts is required. There will be no charging output if battery voltage is below 5 volts. (AVAILABLE FROM ELECTRIC TEST PLUG SUPPLY HOUSE) NOTE: Connect test leads before starting engine.
  • Page 115: Installation

    Checking Battery 1. Physical check – clean if necessary. a. Corrosion b. Dirt c. Terminal and clamps (secure – good conditions) 2. Bring battery to full charge. DO NOT EXCEED CHARGE RATE OF 1/10 AMPERE for every ampere of battery rating! CONSULT Fig.
  • Page 116: Lubrication

    Section 8 LUBRICATION Section Contents Page DESCRIPTION ................Change Oil –...
  • Page 117: Description

    OIL RECOMMENDATIONS ° F -20 ° C -30 TEMPERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE Use a high quality detergent oil classified ‘‘For Service SE” or higher. Use no special additives with recommended oils. DESCRIPTION Two types of lubrication systems are available on Briggs & Stratton “L” head twin cylinder engines: 1.
  • Page 118: Change Oil - Pressure Lube Engines

    Change Oil – Pressure Lube Engines The crankcase capacity of pressure lube twin cylinder engines is approximately: GASKET 3-1/2 Pints (1.65 liters) with filter 3 Pints (1.42 liters) without filter IMPORTANT: DO NOT OVERFILL. Check and main- 1/2 – 3/4 TURN tain oil level regularly.
  • Page 119: Remove Breather

    Horizontal crankshaft twin cylinder engines manufac- 2 BREATHER tured before 91080000 have a breather valve in each TUBES 2 BREATHERS cover assembly and two (2) breather tubes, Fig. 6. Fig. 6 – Horizontal Crankshaft Models Before Date Code 91080000 Vertical crankshaft twin cylinder engines have only one breather valve and breather tube: for #1 cylinder, BREATHER TUBE...
  • Page 120: Install Breather - All Vertical Crankshaft Models & Horizontal Crankshaft Models After Code 91080000

    Route the spark plug leads and ground and primary IGNITION CABLE ROUTING NOTCH IN (breaker point engines) wire through the notch in air SPARK PLUG LEADS AIR GUIDE AND GROUND WIRE guide, # 1 cylinder side, Fig. 10. GROUND WIRE SPARK PLUG LEADS Fig.
  • Page 121: Inspect Breather Tube(S)

    Inspect Breather Tube(s) Breather tube(s) should be checked for cracks, holes or hardening. Replace, if damaged. Breather tube(s) on current (Twin II) horizontal crankshaft models can be identified by a molded flat area for remote control wire clearance, Fig. 13. CONTROL WIRE CLEARANCE Fig.
  • Page 122: Splash Lube

    Install breather tubes on filtered side of air cleaner element, Fig. 17. If breather tubes are incorrectly installed, premature engine wear will result. 1 breather tube hole 2 breather tube holes Vertical Crankshaft Horizontal Crankshaft Horizontal Crankshaft After Code 91080000 Before Code 91080000 Fig.
  • Page 123: Oil Trough - Model Series 421400, 422400

    Oil Trough – Model Series 421400, 422400 Model Series 422400 manufactured before 89030000, and Model Series 421400 were equipped with an oil trough, with the dipper on #1 connecting rod, Fig. 20. When replacing oil dipper with dipper #222480, the oil trough must be removed.
  • Page 124: Testing Oil Gard

    The sensor acts as a current limiting device in series WARNING KEY SWITCH with the 12 volt battery and warning device and/or stop DEVICE OFF switch. The sensor screws into a boss in the sump base and has a protective cap with metering holes that regulate the amount of crankcase oil that contacts the 12 VOLT sensor.
  • Page 125: Pressure Lube

    PRESSURE LUBE Engine Models 400440, 400770, 402440, 402770, 404440, 404770, 422440, 422770 and 462770, are equipped with a full pressure lubrication system with an oil filter. A direct drive oil pump supplies lubrication to all bearing journals at 10-50 psi (.0.7-3.4 Bar), Fig. 27, Fig. 29. The oil pump draws oil through a screened pick up in the engine base and pumps the oil through the oil filter.
  • Page 126: Inspect Oil Pump

    A pressure relief valve located in the oil filter adapter, Fig. 31, or optional remote oil filter adapter, Fig. 32, limits the maximum oil pressure in the system. Examine pressure relief valve seat for proper seating. Seat must have no nicks or burrs. Pressure relief valve spring length is 1.125”...
  • Page 127: Oil Pressure Switch (Optional)

    Oil Pressure Switch (Optional) A 1/8” NPTF plug in the oil filter adapter can be removed to install an optional oil pressure switch. When the oil pressure drops below approximately 5 PSI (.35 Bar), the switch may be used to activate a warning device and/or stop the engine, Fig.
  • Page 128: Oil Cooler (Optional)

    Oil Cooler (Optional) Some models are equipped with an optional oil cooler, Fig. 38. The oil cooler is mounted on the cylinder cover plate. Filtered oil is routed through the oil cooler through two oil lines from a special oil filter adapter. Forced air from the flywheel fan flows through the oil cooler fins dissipating heat from the engine oil.
  • Page 130: Engine Disassembly

    Section 9 ENGINE DISASSEMBLY ENGINE COMPONENTS 1. Cylinder Shield 12. Valve Seal 22. Connecting Rod Bolt 2. Air Cleaner Assembly 13. Intake Valve Spring 23. Washer 3. Carburetor 14. Intake Valve Retainer 24. Crankshaft 4. Intake Manifold 15. Valve Tappet 25.
  • Page 131 ENGINE DISASSEMBLY Drain oil and remove engine from equipment. Remove exhaust system, air cleaner assembly, intake manifold and carburetor assembly. See Section 3. Remove blower housing, air guides, cylinder shields, cylinder heads and valves. See Section 5. Remove flywheel and armature. See Section 2. 1.
  • Page 132: Cylinders & Bearings

    Section 10 CYLINDERS & BEARINGS Section Contents Page CHECK CYLINDER ..............Resizing Cylinders .
  • Page 133: Check Cylinder

    CHECK CYLINDER CENTER Check cylinder for cracks, stripped threads or broken BOTTOM fins. Check cylinder bores for damage or scoring. Use telescoping gauge, Tool #19404, and dial caliper, MEASURE AT Tool #19199, or inside micrometer to determine the SIX POINTS size of the cylinder bore.
  • Page 134: Cylinder Finish (Cross Hatch)

    Honing is done with a variable speed 1/2”, portable drill It is recommended that the cylinder bores be recondi- and a honing fixture. See page 8 for dimensions to tioned to restore the cross hatch when new piston rings make your own honing fixture. are to be installed in a cylinder that is within specifica- tion.
  • Page 135: Check Plain Bearings

    Check Plain Bearings Plain main bearings should be repaired if scored or if plug gauge, Tool #19219, will enter bearing. Try gauge at several locations in bearing, Fig. 5. If gauge is not available, refer to reject specifications shown below. MAIN BEARING REJECT SIZE Á...
  • Page 136: Check Du Bearings

    Check DU Bearings DU main bearings should be replaced if damaged or if plug gauge, Tool #19219, will enter bearing. Try gauge #19226 at several locations in bearing, Fig. 5. If gauge is not available, refer to Table No. 2 for reject dimensions. Remove DU Bearings –...
  • Page 137: Install Oil Seal - Pto - Horizontal Crankshaft Models

    Install DU PTO Bearing – Horizontal Crankshaft Models NOTE: Engine models 400440, 402440 404440 and 422440 have a full pressure lubrica- tion system. Engines manufactured before date code 89730000 were equipped with DU bearings with a machined oil reservoir, Fig. 11. Refer to illustrated parts list for correct bearing number by model and date code.
  • Page 138: Install Oil Seal - Pto - Vertical Crankshaft Models

    Install DU PTO Bearing – Vertical THIS END TOWARD Crankshaft Models THRUST FACE NOTE: DU bearing, Part #231180, for vertical 3/4” (19.0 mm) crankshaft engines must be installed with HOLE 3/4” (19.0 mm) offset toward thrust face, Fig. 14. 1. Place sump on cylinder support, Tool #19227, with 7/8”...
  • Page 139: Honing Fixture

    Honing Fixture 6-5/16” (160.3 mm) Material: Wood 2” x 8” 2-13/32” 12” long (61.1 mm) 7-1/2” Material: (190.5 mm) Wood 50.8 mm x 5” 4-13/16” 203.2 mm (127 mm) (122.2 mm) 304.8 mm long 13/32” Thru Hole (4) Cylinder Mounting (10.3 mm) Hardware 3-1/2”...
  • Page 140: Crankshafts & Camshafts

    Section 11 CRANKSHAFTS & CAMSHAFTS Section Contents Page CHECK CRANKSHAFT – ALL MODELS ........... Check Ball Bearings .
  • Page 141 Crankshaft crankpin may be re-ground for .020” connecting rods. See specifications below for crank- (.51 mm) undersize connecting rods. See Illustrated shaft grinding dimensions. Complete instructions are Parts List for correct part number for undersize included with the undersize connecting rods. CRANKSHAFT GRINDING DIMENSIONS Á...
  • Page 142 After the bearing has been removed, rough spots on POLISH LINES the journal should be polished with emery cloth (500 grit). Break down new emery cloth by rubbing several times over the edge of a piece of steel before using for polishing.
  • Page 143 CHECKING CAMSHAFT Inspect gear teeth for wear and nicks, Fig. 7. Camshaft, camshaft journals and lobe rejection sizes *IGNITION JOURNAL CAM LOBES FLATS (2) are shown below. Check oil gallery for blockage or ON CAM obstructions on pressure lube camshaft. NOTE ALL MODELS: Camshaft bearing reject dimension is .6275”...
  • Page 144: Pistons - Rings - Rods

    Section 12 PISTONS – RINGS – RODS Section Contents Page GENERAL INFORMATION ............. . . REMOVE PISTON AND CONNECTING ROD .
  • Page 145: Remove Connecting Rod

    Model Series 400400, 400700, 402400, 402700, EARLY PISTONS SLIGHT DISCOLORATION 404400, 404700, 422400, 422700 and 462770 have cast iron sleeve cylinders. For correct part numbers for ring sets and piston assemblies, refer to Illustrated Parts List. Select correct ring sets or piston assemblies by Model Series. Pistons designed for cast iron sleeve cylinders have a shiny finish.
  • Page 146: Check Rings

    Check Rings To check rings, first clean all carbon from the end of the rings. Insert old rings one at a time, approximately one FEELER inch down into the cylinder bore. GAUGE Check ring end gap with feeler gauge, Fig. 5. If ring end RING gap is greater than shown in Table No.
  • Page 147: Check Connecting Rod

    Check Connecting Rod CRANKPIN Check connecting rod bearings, Fig. 8. See reject BEARING sizes below. If crankpin bearing is scored or worn the connecting rod must be replaced. Connecting Rod Reject Size Á Á Á Á Á Á Á Á Á Á Á Á Á Á...
  • Page 148: Assemble Rings To Piston

    The piston pin is a slip fit in both piston and connecting All Models 400000-420000 & Pressure Lube – 460770 rod. Oil piston pin. Place a piston pin lock in groove on one side of piston. Insert piston pin from opposite side of piston until pin stops against piston pin lock, Fig.
  • Page 149 NOTE: Briggs & Stratton opposed twin cylinder engines use pistons with offset piston pins. The notch on the piston must face the flywheel side of engine, Fig. 14. NOTCH FLYWHEEL SIDE Fig. 14 Thoroughly clean and then oil cylinder bore. Rotate crankshaft until crankpin journal is at bottom of stroke.
  • Page 150: Torque Connecting Rods

    NOTE: ENGINE MODELS 462770: With piston and connecting rod assemblies installed, make sure the machined relief areas on the connecting rod and cap are together and facing cam gear, Fig. 17. RELIEF AREA MUST FACE CAM GEAR Special Notes For Horizontal Crankshaft Splash Lube Engines: Engines with a Top-No-Load Speed Above 2400 RPM:...
  • Page 152: Engine Assembly

    Section 13 Engine Assembly Section Contents Page INSTALL CRANKSHAFT ..............Install Crankshaft And Camshaft –...
  • Page 153: Install Crankshaft

    INSTALL CRANKSHAFT Install Crankshaft And Camshaft – Plain Bearing Models CAM- SHAFT Lubricate crankshaft, tappets, camshaft journals and TIMING MARK lobes with engine oil. Assemble timing gear to (DOT) crankshaft. 1. Install tappets. 2. Install crankshaft into cylinder. 3. Align timing marks and install camshaft, Fig. 1. CRANKSHAFT TIMING MARK...
  • Page 154 2. Lubricate cylinder bores and crankpin and rotate crankshaft until it as at bottom of stroke. 3. Install #1 piston with notch on piston toward flywheel side, Fig. 4. NOTCH a. Push piston down by hand until connecting rod is seated on crankpin. FLYWHEEL SIDE 4.
  • Page 155: Special Notes For Horizontal Crankshaft Splash Lube Engines

    Special Notes For Horizontal Crankshaft DIPPER NO. 222480 NO. 1 ROD Splash Lube Engines: Engines with a Top-No-Load Speed Above 2400 RPM: Install only one oil dipper on #1 connecting rod, Fig. 7. Use ONLY dipper part #222480. Engine models 421000 and 422400 manufactured before date code 92072000 were not originally equipped with this dipper.
  • Page 156: Install Crankcase Cover Or Sump

    INSTALL CRANKCASE COVER OR SUMP 1. Install crankcase cover or sump with new gasket. 2. To engage governor gear (horizontal or vertical crankshaft models) and oil slinger (vertical crankshaft models) rock crankshaft back and forth. 3. Torque screws to 225 in. lbs. (25.0 Nm), Fig. 10. TORQUE SCREWS TO 225 in.
  • Page 157: Install Flywheel - All Models

    INSTALL FLYWHEEL – ALL MODELS TORQUE WRENCH CLEAN FLYWHEEL and crankshaft taper removing all oil, dirt or grease. 1. Assemble flywheel to crankshaft and align keyways. 2. Insert flywheel key into crankshaft. Torque Flywheel Nut – Pre Twin II Models (Type Nos.
  • Page 158: Adjust Armature Air Gap - All Models

    Install breaker point ignition armature as shown in Fig. 16. The right hand mounting screw holds the ground lead(s) on breaker point ignition systems. Push armature away from flywheel and tighten one screw to hold armature away from flywheel. NOTE POSITION OF SPARK PLUG WIRES Fig.
  • Page 159: Install Valves

    INSTALL VALVES Install Intake Valve and Seal 1. Coat valve stem with Valve Guide Lubricant #93963 and install in intake valve guide until stem just starts to enter valve tappet chamber, Fig. 18. INTAKE VALVE STEM NOTE: Be sure valve guide lubricant, Part #93963, is not on valve face, seat or retainer grooves.
  • Page 160: Install Cylinder Heads

    INSTALL CYLINDER HEADS Some models use three (3) longer head bolts located around the exhaust valve area. If a short bolt is used in the wrong position, it may not engage enough threads. A long bolt in the wrong position may bottom on fins, either breaking the fins or leaving the cylinder head HEAD HEAD...
  • Page 161: Install Breathers - Horizontal Crankshaft Models Before Code 91080000

    Install Breathers – Horizontal Crankshaft Models Before Code 91080000 CYLINDER NO. 2 GASKET GASKETS (2) Install new dipstick tube seal in cylinder before installing air guide. GUIDE 1. Install gasket between valve chamber and breath- er, #1 side. 2. Install one gasket between the valve chamber and CYLINDER air guide, #2 side.
  • Page 162: Static Governor Adjustment

    WARNING: BEFORE STARTING or running engine, static adjustment of the governor must be completed! Failure to make the static adjustments first could result in engine overspeeding which may result in engine damage, property damage or personal injury. TORQUE TO 100 in. lbs. STATIC GOVERNOR ADJUSTMENT (11.0 Nm) 1.
  • Page 164: Mufflers

    Section 14 MUFFLERS Section Contents Page GENERAL INFORMATION ..............REMOVE MUFFLER .
  • Page 165: Remove Muffler

    REMOVE MUFFLER Horizontal Crankshaft Ducted Engines 1. Remove cylinder air guide assemblies, Fig. 2. 2. Remove four (4) hex head cap screws, Fig. 3. 3. Lift off muffler assembly, Fig. 4. CYLINDER NOTE: Use penetrating oil to loosen seized GUIDE exhaust pipes and exhaust nipples.
  • Page 166: Remove Exhaust Nipples (If Equipped)

    Remove Exhaust Nipples (If Equipped) Remove exhaust nipples by loosening lock nuts first and then turn out nipples. Penetrating oil may be EXHAUST NIPPLE required to loosen and prevent galling exhaust port threads, Fig. 5. LOCKNUT Fig. 5 – Exhaust Nipple Remove Port Liners (If Equipped) Remove two (2) cap screws, port liners and gasket, Fig.
  • Page 167 2. Remove two (2) screws at top edge of cylinder air guides and one screw from bottom of each air guides, Fig. 9. 2 SCREWS 1 SCREW Fig. 9 – Remove Air Guides 3. Air guides and top plate can now be removed. 4 SCREWS Fig.
  • Page 168: Remove Exhaust Nipples (If Equipped)

    Remove Exhaust Nipples (If Equipped) Remove exhaust nipples by loosening lock nuts first EXHAUST and then turn out nipples. Penetrating oil may be NIPPLE required to prevent galling exhaust port threads, Fig. 12. LOCKNUT Fig. 12 – Exhaust Nipple Remove Port Liners (If Equipped) Remove two (2) cap screws, port liners and gasket, Fig.
  • Page 169: Install Muffler And Mounting Bracket

    Install Muffler and Mounting Bracket REAR INSERT 1. Assemble muffler to mounting bracket loosely with four (4) cap screws. HEAT 2. Install muffler assembly on engine sliding muffler GUIDE SHIELD FRAME pipes onto exhaust nipples or port liners. 3. Install four (4) screws through muffler mounting bracket into crankcase cover or sump, torquing screws to 225 in.
  • Page 170: Install Muffler Adapters

    3. Tighten all screws securely. Repeat for other cylin- der, Fig. 19. CYLINDER CYLINDER AIR GUIDE SHIELD Fig. 19 – Install Cylinder Shield and Air Guides Install Muffler Adapters LOCKNUT 1. Install lock nut on muffler adapter, Fig. 20. 2. Thread adapter into exhaust port finger tight. Do not tighten lock nut at this time.
  • Page 171: Install Small Lo-Tone Mufflers

    3. Install muffler brace straps and spacers, Fig. 23. BRACE SPACER Fig. 23 – Install Brace 4. Tighten muffler adapter lock nuts, Fig. 24. LOCKNUT Fig. 24 – Lock Nuts Install Small Lo-Tone Mufflers BOLTS 1. Install muffler with new gasket, two shoulder bolts GASKET and lock, Fig.