AC-1 ENGINE SERVICE MANUAL Table of Contents – Page 1 of 2 ABOUT THIS MANUAL GENERAL INFORMATION ENGINE SPECIFICATIONS FUEL AND LUBRICATION IGNITION TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS (CONT) SAFETY WARNINGS AND NOTES PRODUCT IDENTIFICATION NUMBERS OIL AND FUEL RECOMMENDATIONS STARTING/STOPPING INSTRUCTIONS SERVICE/MAINTENANCE INSTRUCTIONS STORAGE INSTRUCTIONS TROUBLESHOOTING ENGINE FAILS TO START ENGINE STARVES ON ACCELERATION ENGINE IS HARD TO START ENGINE STALLS ENGINE FIRES INTERMITTENTLY ENGINE
AC-1 ENGINE SERVICE MANUAL Table of Contents – Page 2 of 2 INSPECTION AND REPAIR - Continued CRANKCASE INSPECTION & REPAIR MAJOR COMPONENTS INSPECTION & REPAIR REASSEMBLY TYPICAL ASSEMBLY SEQUENCE ENGINE REASSEMBLY INSTALL AIR FILTER BASE, AIR FILTER AND AIR FILTER COVER ASSEMBLE HANDLE ASSEMBLE COVERS
! ABOUT THIS MANUAL This Service Manualwas written expressly for the Toro AC-1 Four Stroke Engine. The Toro Company has made every effort to make the information in this manual complete and correct. We are hopeful you' findthis manual a If you have any questions or comments regarding the information inside, valuable addition to your service shop. please contact us at the following address: The Toro Company Consumer Service Training Department.
Troubleshooting Disassembly ......................... .#. . 2 .............................. Inspection and Repair Reassembly B . . . . . . . . . . . . . . . . . . Information ....... General ...................... ........................... ,. ., . . 4 ..
Table Of Contents Engine Specifications . FuelandLubrication . .............................. .............................. ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Torque Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SafetyWarningsAndNotes ........................... Product IdentificationNumbers . . . . . . . . . . . . . . . . . . . . . . . . . . Oil And Fuel Recommendations . . . . . . . . . . . . . . . . . . . . . . . . .
jB Item ~~ ~ ~~ ~~ Air-cooled, 4-Cycle Engine _ _ _Type Displacement Stroke ~ _ ~ _ _ _ ~ Average Compression Piston Rings Side Clearance ~ ~ - ~ _ _ _ Top Piston Ring Width ~~~ Top Piston Ring End Gap - Middle Piston Ring Width _ _ _ _ _ ~ .
1 Approx Fuel Tank Capacity 18 oz (530ml) TORQUE SPECIFICATIONS tem ~ ~~ ~ Carburetor/Air Filter Base Plate Mounting Screws - ~~~~~ - ~ ~~ Carburetor Mount Insulator Screws ~~ Clutch Housing/Drum Assembly Screws _. ~ ._ ~ ~ ~ _ ~ ~ ~ - _ _ _ --~__ __-~_-- Clutch Rotor Cylinder Head Hex Nuts - ~~ Cylinder Screws ~ Spark Plug ~ -. - . -. .._.._..____ __ . .___ Rear Engine Cover Screw ~~ Front Engine Cover Screws . 1-4 . .
/- SAFETY WARNINGS AND NOTES WARNING: Hot Surfaces! The purpose of safety symbols is to attract your attention to possible dangers. The safety symbols and the explanations with them, deserve your careful attention and understanding. The safety warnings do not by themselves eliminate any danger. The instructions or warnings they give are not substitutes for proper accident prevention measures. Some general warnings follow.
PRODUCT IDENTIFICATION NUMBERS When ordering parts, orin any communication involving an engine or product, always give the: NOTE: READ THESE INSTRUCTIONS CAREFULLY BEFORE A t t e m p t i n g TO START OR OPERATE THIS UNIT. Using old oil or fuel can cause engine damage. This type ofdamage will void the engine warranty Model Number, and Serial Number These numbers are located on a decal (or decals) afRecommended Oil Type fixed to the unit (Figure 1-1). The identification de- .
Checking theOil The importance of checking and maintaining the proper oil levelin the oil pan cannot be overemphasized. Check the oilBEFORE EACH USEas follows: 1 . Make sure the engine is stopped, level and is cool so the oil has had time to. drain into the oil pan (Figure 1-3 for straight shaft units or Figure1-4 for curved shaft units). Figure 1-5. Removing Oil Fill Plug. - Figure 1-3. Level Engine Straight Shaft Unit. 3.6051.020 2.6051.
Changing the Oil For a new engine, change the oil after the first 10 hours of operation. Thereafter, change theoil after every 25 hours or before storing the unit for an extended period of time. Change theoil while the engine is still warm. The oil will flow freely and carry away more impurities. NOTE: To prevent extensive engine wear or damage, always maintain the proper oil levelin the crankcase.
STARTING/STOPPING INSTRUCTIONS ---Run position Partial Choke To Start the Engine choke 1. Set the unit on the ground, check the oil level in the oil pan, and put the ignition switch in the “RUN” (I) position (Figure 1-8). Figure 1-9. Primer Bulb, Choke Lever and Choke Positions. 3.6051.009 , 4. With the unit on the ground, pull the starter rope quickly until the engine sounds like it wants to run (no more than5 pulls) (Fig. 1-10). Figure 1-8. Ignition Switch and Throttle Trigger.3.6051.008 2.
5. Place the choke leverin the “PARTIAL” choke posi- 2. Wash the air filter in detergent and water (Figure 1-11). Rinse the air filter thoroughly in tion (see Figure1-9 on page 1.4). Pull the starter clean water and allowit to dry. rope quickly until the engine starts (no more than 5 pulls). 6. If the engine does not start, repeat steps2 to 8. 7. Run the engine for30 seconds, with the throttle lever fully squeezed (see Figure-6), 1 to warm up. Place the choke lever in the “RUN” position (Figure 1-9).
NOTE: Do not clean the spark plug in a machine which uses abrasive grit. Some grit could remain on the spark plug and enter the engine causing extensive damage. ~ 4. Check the spark plug gap using a wire feeler gauge. Set the gap to0.025 in (0.635 mm)(Figure 1-14). 5. Reinstall the spark plug and torqueto 100-110 in-lb (1 1.3-1 2.3 N-m). L Figure 1-13. Squeezing ExcessOil from Air Filter Element. 3.6051.013 5. Reinstall the air filter in the carburetor/airfilter base.
If the following conditions are experienced, it may be necessary to adjust the carburetor. 407000001-Use the following carburetor adjustment instructions: The engine will not idle 1. Initial Idle Speed Setting:Turn the idle speed screw untilit stops. The engine hesitates or stalls on acceleration.
b b. Squeeze the throttle trigger. If the engine falters or hesitates as it accelerates, turn the idle speed mixture needle out (counterclockwise) 1/16 turn at a time until the engine accelerates rapidly. c. If the idle speed has changed significantly because of steps a. and b. above, readjust the idle speed screw. 7. Final High Speed Mixture Setting: Adjust the high speed mixture needle as follows: a. Squeeze the throttle trigger and run the unit at high speed 3 forto 5 minutes. 3.
8. FinalIdleSpeed Adjustment: Adjusttheidle speed by turning the idle speed screw in (clockwise) or out (counterclockwise)until the cutting head does not rotate.Do not squeeze the throttle trigger when adjusting the idle speed screw. 9. Make sure the air filter coveris reinstalled securely before placing the unit back into service.
b 4. If the clearance is not within specification, adjust as follows: a. Turn the adjusting nut (Figure 1-18), using a 5/16 in (8 mm) wrench or nut driver. To increase the rocker arm to valve clearance, turn the adjusting nut counterclockwise. To decrease the rocker arm to valve clearance, turn the adjusting nutclockwise. b. Recheck the clearance with a flatfeeler gauge and readjust as necessary (see Figure 7). 1-1 Spark Arrester Screen This unitis equipped with a spark arrester screen.
STORAGE INSTRUCTIONS WARNING: Explosive Fuel! Gasoline is extremely flammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well-ventilated, unoccupied buildings, away from sparks or flames. Do not fill the fuel tank while Figure 1-21.Storing a Curved Shaft Unit. 3.6051.021 the engineis hot or running, since spilled fuel could ignite if it comesin contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel.
~ f Special Tools In addition to typical hand tools, the following special tools are required to properly service this engine: Clutch Rotor Tool, P/N 180918 (Figure 1-22). Flywheel HoldingTool, P/N 180919 (Figure 1-23). 0-250 in-lb (0-28.1 N.m) Torque Wrench (Commercially available). Toro(R) Screwdriver or Bit Set (Commercially available). Two-stroke, Magnetic Pick-up Tachometer (Commercially available). Figure 1-23. Flywheel Holding Tool, P/N 18091 9. 3.6051.023 f Figure 1-22.
Troubleshooting Disassembly . . ........................... 2. ...... InspectionandRepair Reassembly 1 .. ........................... GeneralInformation . ........................... 5 ...... ............................
Table Of Contents ............................... ......................... EngineStarvesOnAcceleration Engine Is Hard To Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EngineStalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Engine Fires Intermittently . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EngineDoesNotProduceMaximumPower . . . . . . . . . . . . . . . . . . . Carburetor Floods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
c’ When difficulties occur,be sure to check for simple causeswhich,at first, mayseemtooobviousto be considered. A starting problem, for example, could be caused by an empty fuel tank. The following table lists some common causes of operating troubles and the possible causes and remedies. i I Engine ~Fails To~Start _ ~ - __ ~- ~- ~~ ~ .- ~ ~_ ~~ ____ _ _ . _ ~~ ~~ ~ ~~~ ~ -~ -~- ~ ~~ ~ ~.
1 8 Engine Is Hard To Start . ~~ possible Cause Fouled, improperly gapped or broken spark plug ~ _ _ _ ~ Remedy Clean or replace spark plug; set gap to 0.025 inch (0.635mm). ~ - ~~ ~~ ~ ~~~ Plugged or waterlogged fuel filter ___. ~ _ _ _ _ ~ - ~ ~~ ~ Replace fuel filter - ~ ~~ ~ - ~~~ Improperly adjusted carburetor Adjust carburetor Clogged muffler Clean or replace muffler _- Faulty primer or primer/fuel lines improperly installed -~ ~ - ~ ~- .
Engine Stalls Clean or replace spark plug; set gap to 0.025inch (0.635mm) - -. ~ ~~ Clean fuel tank cap vent Plugged fuel tank cap vent . ~ _ _ _. _ _. _.
Engine Does Not Produce Maximum Power Plugged muffler Plugged spark arrester screen ~ ~ ~~~ ~ Plugged or waterlogged fuel filter -. . . ~ ~~ ~~~~ ~ ~~~ Improperly adjusted carburetor Air leak at carburetor base gasket Intermittent spark ~~~ ~_~ ~. Low compression ~ ~~ ~ ~p ~ ~ ~~ Scored piston and/or cylinder ._. .- ..
Engine Stops After Running Briefly _~__ _. ~ __ _ _ ~ _ _ _ _ _ __ ~~ ~ ~ __ ~ possible Cause i -~ ~~~~ ~ -~ ~~ Partially plugged fuel tank cap vent ~ ~~ ~. _ _ _ ~ ~ ~ _ _ __ ~~ Drain tank and blow out lines Water in fuel ________ Air leak at carburetor base gasket ~ ~~~~ ~~ ~ _ _ ~ Tighten carburetor mounting fasteners or replace carburetor base gaskets - -~ ~~ ~ _ _ ~ _ ~ ~ .
0.025 inch(0.635 mm) ~ ~~ muffler ~ _ _ Plugged ~ _ _ ~ ~ _ _ _ . ~ ~ ~ ~ _ _ - ~ Plugged spark arrester screen .~ ~~ Faulty primer bulb causing flooding . .. .. - ~ ~~~ _ _ ~ ~ . - ~ ~ .-.~ -~ . ~~ ~ ~ ~ ~~~~~ ~ _ _ _ _ . _ _ _ _ _ ~ ~ ~ ~~ .- .
I Replace O-ring and tightenoil fill plug Oil fill plug loose or O-ringis leaking oil -~ ..~~ I Breather housing plugged or damaged, ___- ~~ 1 Gaskets damaged or gasket surfaces nicked - ... ~ Valve guides worn excessively __ .. Replace ..____. breather housing assembly _ ~ smooth gasket surfaces; use new gaskets Replace cylinder head assembly ~~ ~ ~. ~ _ _ _ _ Replaced cylinder Cylinder wall worn or glazed - . ~ ~~ Piston rings and grooves worn excessively Piston , ~ _ _ .
.. ......... 1 .... ......... 2 General Information Troubleshooting Disassembly ..... Inspection and Repair . Reassembly ..... . . . . .......... 3 ......... 4 ..........
Table Of Contents .......................... ........................... RemoveMajorComponents RemoveEngine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Remove The Spark Plug Wire And Spark Plug . . . . . . . . . . . . . . Remove UpperHandle . . . . . . . . . . . . . . . . . . . . . . . . . . RemoveLowerHandle .......................... RemoveAirFilter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TypicalDisassemblySequence 3-3 3-4 3-4 3-4 3-4 3-5 3-6 Remove Air Filter Base.
Typical Disassembly Sequence 7. RemoveEngineCover This section covers the disassembly of major internal 8.RemoveCarburetorMountInsulator engine components.Part 4 lnspection and Repair covers the disassembly, reassembly, inspection and re- 9.RemoveIntakeBaffle pair of the subassemblies of the engine components. 10. Remove Muffler Clean all parts thoroughly as the component parts are 11. Remove Clutch disassembled. Only clean parts can accurately be inspected and gauged for wear or damage.
REMOVE MAJOR COMPONENTS Remove Engine 1. Drain all fuel from the fuel tank. 2. Start the engine and allow itto run until it stalls. Allow the engineto cool. 3 3. Drain the oil from the oil pan. 2.6051.005 Remove The SparkPlug Wire And SparkPlug 1. Disconnect the spark plug wire from the spark plug. Remove the spark plug. Remove Upper Handle NOTE: All screws are T-25Toro(R)screws and can be removed with a T-25 Toro(R) screwdriver. 1. Remove the six (6) screws from the upper handle.
I REMOVE MAJOR COMPONENTS (cont.) I 2. Separate the two halves of the handle by prying the two halves apart with a screwdriver at the . rear of the handle, next to the screw boss NOTE: The anti-vibration isolatoris wedged into the handle, making removalof the halves difficult. E 3 3 2.6047.026 Remove Lower Handle 1. Remove the retainer screw, which holds the switch and throttle trigger assembly in the handle.
REMOVE MAJOR COMPONENTS (cont.) Remove Air Filter 1. Remove the three (3)screws securing the air filter ). cover. Remove the air filter cover NOTE: The choke lever should be in the "PARTIAL" position to remove and install the air filter cover. 3 2. Remove the air filter element from the air filter base . The element is heldin place by eight(8) pins. 2.6047. Remove Air Filter Base, Primer Bulb And Carburetor 1.
REMOVE MAJOR COMPONENTS (cont.) 2. Remove the Z-bend of the throttle cable from the hole in the carburetor throttle lever. NOTE: The Z-bend is located in the third hole from the top of the throttle lever. 3. Remove the carburetor and the two (2) gaskets. Dicard the gaskets. 4. Remove the fuel line from the carburetor fuel inlet fitting. 5. Remove the fuel line from the fuel outlet fitting on carburetor (to primer bulb). 6. Remove the throttle cable from the carburetor mount insulator.
REMOVE MAJOR COMPONENTS (cont.) - Remove Engine Cover Remove the rear engine cover screw 1. 3.6047.035 2. Remove the two (2) screws from the top of the cover and the screw from the front of the cover. Lift the cover up and off of the engine. 3.6047.037 Remove Carburetor Mount Insulator 1. Remove the two (2) screws securing the carburetor mount insulatorto the crankcase.
REMOVE MAJOR COMPONENTS (cont.) 2. Remove the carburetor mount insulator and carburetor mount insulator gasket. 3. Remove the two (2) hex nuts on the back of the carburetor mount insulator. NOTE: For Units Prior to Engine Serial Number 4050000001-The hex nuts were not retained. Be careful not to lose them. 3 Remove Intake Baffle 1. Remove the intake baffle from the cylinder 2.6047.039 Remove 1.
REMOVE MAJOR COMPONENTS (cont.) 2 Remove the muffler and muffler gasket. Discard the old gasket. NOTE: The muffler baffle cannot be removed at this time. NOTE: Do not scrape the gasket surfaces with metal scrapers. Always use wood or plastic scrapers. Remove Clutch 1. Remove the three(3)screws securing the clutch housing/drum assemblyto the fan housing. Remove the clutch housing/drum assembly For units that take attachments, remove the spring. 2.
REMOVE MAJORCOMPONENTS (cont.) I 3. With the starter pawls on the flywheel positioned at the top (12 o'clock) and bottom(6 o'clock), install flywheel holding tool, P/N 18091 9. 4. Lift the starter assembly untilit contacts the clutch rotor. At 9 o'clock on the fan housing, roll the flywheel holding tool into the flywheel until the head of the cap screw on the bottom of the tool fits into the screw hole of the fan housing. 5.
REMOVE MAJOR COMPONENTS (cont.) 6. Using a 3/4 inch socket wrench, turn the clutch rotor tool counterclockwise to remove the clutch rotor. -~ 2.6047.M 7. Remove the clutch rotor and washer. Remove Starter Module Assembly 1. Remove the two (2) screws securing the starter rope eyelet bracket. Remove the starter module assembly.
REMOVE MAJOR COMPONENTS (cont.) Remove Fuel Tank Bracket And Fuel Tank ' 1. Remove thetwo (2) screws from the fuel tank bracket. 2. Remove the fuel tank bracket and fuel tank. 3. Remove the rubber fuel tank pad. 3 Fuel Tank And Lines Disassembly And Reassembly Fuel Line and Filter Removal This unit hastwo fuel linesto the fuel tank. The clear line provides normal fuel flow. The blue line provides a return line for excess fuel flow during the primer operation. 1.
DISASSEMBLE ENGINE Remove Fan Housing 1. Remove the four(4) screws securing the fan housing to the crankcase. Remove the fan housing. 2. Disconnect the switch lead wires. 53 Remove Muffler Baffle 1. Removethemufflerbaffle. Remove Ignition Module 1. Remove the two (2) screws securing the ignition module to the crankcase. Remove the ignition module.
DISASSEMBLE ENGINE(cont.) WARNING: CRACKED OR BROKEN COOLING FINS ARE A HAZARD! Be careful not to crack or off during opbreak any cooling fins. They could fly eration. If cooling fins are cracked or broken, replace the flywheel. 1. Removethespacerfromthecrankshaft. ~ 2. Using a plastic-faced mallet, tap and pull the flywheel until it breaks free from the crankshaft. 3. Remove the flywheel from the crankshaft. ~ I 4. Remove the flywheel key from the crankshaft. Remove Rocker Arm Assembly 1.
DISASSEMBLE ENGINE(cont.) Adjusting Nut 2. Remove the rocker adjusting nuts, rocker arm pivots and rocker arms. Arm NOTE: Always match intake and exhaust parts when disassembling the rocker arm assembly. Rocker Arm 3. Remove the two (2) push rods from the push rod guides. I 4. Remove the four (4) cylinder hex nuts and washers. 2.6060.060 5. Remove the pushrod guides from the cylinder studs. 2.6047.
DISASSEMBLE ENGINE(cont.) Remove Cylinder Head, Valve assembly And Cylinder 1. Lift the cylinder headoff of the cylinder. Remove the cylinder head gasket. 2. Remove the two (2) valves and valve retainers from the cylinder head. NOTE: To make removal of the valves easier, push down on the valve retainers with your fingers and rock themto the side. 3. Remove the two (2) valve springs. NOTE: The valves cannot be ground.Replace necessary.
I DISASSEMBLE ENGINE (cont.) I 4. Remove the two (2) cylinder screws from the cylinder. L 2.6047.065 5. Remove the cylinder and cylinder gasket from the crankcase. NOTE: Do not scrape the gasket from the cylinder. To remove the gasket, soak the cylinder with solvent. 2.6047.066 Remove Piston/connecting rod 1. Remove the piston/connecting rod from the crank- case. Grasp the piston/connecting rod, slide it to the rear and twist slightly. No toolis required.
DISASSEMBLE ENGINE (cont.) Remove Cam Bracket Assembly 1. Remove the two (2) screws from the cam bracket assembly. Remove the cam bracket assembly. Remove Oil Pan 1. Remove the six (6) screws from the oil pan. Re- move theoil pan. Remove Seal NOTE: Remove the seal onlyif oil is leaking from he crankcase. 1. Remove the seal from the flywheel side Of the crankcase, using a seal puller or flathead screwdriver. NOTE: Do not remove the crankshaft from th6 crankcase.
General Information . . . I . . . .. .................. .. .. ... .. .. .. Inspection and Repair Reassembly * ................. Troubleshooting Disassembly .............. ............. ...................
/! !/ l1 Table Of Contents CarburetorDisassemblyAndReassembly Carburetor Disassembly ..... .................... 4-3 4-3 .................... ............................. 4-4 FuelMeteringSide FuelPumpSide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 CarburetorInspectionandCleaning . . . . . . . . . . . . . . . . . . . 4-5 CarburetorReassembly . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 .............................. 4-6 FuelMeteringSide FuelPumpSide . . . . . . . . . . .
I This section covers the disassembly, reassembly, inspection and repair of the subassemblies of the major internal engine components. Clean all parts thoroughly as the component parts are disassembled. Only clean parts can accurately be inspected and gauged for wear or damage. There are many commercially available cleaners that will quickly remove oil and grime from engine parts. When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully.
2. Remove the fuel metering diaphragm and gasket. 2.6047.074 NOTE: These components are under spring tension. Remove them carefully to preventloss. Make sure the spring is not stretched.
CARBURETOR DISASSEMBLY AND REASSEMBLY (cont.) Side Pump Fuel I 1. Remove the idle speed adjusting screw and spring from the fuel pump cover. 2. Remove the fuel pump cover screw and cover . . . , Idle Speed Adjusting Screw 3. Remove 4 the spring, fuel pumpand cover pump diaphragm from the fuel pump cover. NOTE: Furtherdisassembly to removethe throttle plate, throttle lever, choke lever, welch plugs, fuel inlet screen, etc.is not recommended.
CARBURETOR DISASSEMBLY AND REASSEMBLY (cont.) Refer to the appropriate parts manual for service kit part numbers. 1. Inspect the tips of the high speed mixture needle, idle speed mixture needle, and fuel inlet needle for wear or damage. Replace the needles if necessary. Inspect Here 4 2. Gaskets and diaphragms eventually deteriorate and become stiff with age and use. It is good practice to replace gaskets and diaphragms for each repair.
CARBURETOR DISASSEMBLY AND REASSEMBLY(cont.) 2. Place a straight edge across the carburetor body. Use awire feeler gaugeto measure the distance between the straight edge and the top of the fuel metering lever. The fuel metering lever should 0.060-0.070 be in. (1.52-1.78 mm) below the straight edge. 3.6047.079 DEPRESS HERE HIGH If the leveris adjusted too high, the engine will run rich. If the lever is adjusted too low, the engine will run lean. Poor acceleration and erratic operation may also be noted.
CARBURETOR DISASSEMBLY AND REASSEMBLY(cont.) 4. Make sure there are no wrinkles in the metering diaphragm. Install the metering cover and screws. Tighten the screws securely. 2.6047.082 5. Install the high speed mixture (H) and idle mixture (L) adjusting needles and springs. .Turn both needlesin (clockwise) until they are lightly seated. Then turn the needles out (counterclockwise)the following number of turns: 2.6047.
CARBURETOR DISASSEMBLY’ AND REASSEMBLY (cont.) ~ Fuel Pump Side 1. Install the fuel pump diaphragm (next to carburetor body) and gasket. 2. ~ Install the spring, fuel pump cover, and cover screw. Tighten the screw securely. 2.6047.0 3. If necessary, install the idle speed adjusting screw and spring. For Units with Engine Serial Number 407000001 and Greater- Turn the adjusting screw in (clockwise) until itjust touches the throttle lever; then continue turning2 full turns.
STARTER DISASSEMBLY AND REASSEMBLY WARNING: Spring under tension! The rope starter on these engines contains a flat wirespring thatis under tension.Wear eye and hand protection when replacing a worn or broken spring,in case it should uncoil as it is handled. Allow spring tension to be completely relieved and make sure the pulley disengages from spring before removing the pulley retainers, pulley, and starter spring from housing. 2.6060.153 1.
STARTER DISASSEMBLY AND REASSEMBLY (cont.) Starter Disassembly 1. Relieve the spring tension by removing the' pull handle and allowing the pulley to slow/y unwind inside the starter pulley. Make sure the spring tension is fully relieved before proceeding. 2. Remove the two (2) screws and retainers. I 2.8047.088 3. Remove the starter pulley from the starter housing. Pulley Starter Retainer Retainer Screw 4. If necessary, remove the starter spring from the starter housing.
STARTER DISASSEMBLY AND REASSEMBLY (cont.) 5. Remove the starter rope from the pulley. NOTE: Two types of starter pulleys were usedin the production of theAC-1 engine. Your unit is equipped withone of the starter pulleys shown. Starter Inspection and Service E 1. Inspect the starter rope for wear or frays. Replace the ropeif necessary. 2. Inspect the starter pulley for worn pawl engagement teeth.Also check for wear on the surface of pulley thatis in contact with the starter spring. 3.
STARTER DISASSEMBLY AND REASSEMBLY (cont.) ~ Starter Reassembly 1. Install the starter spring into the starter housing as follows: a. Orient the replacement starter spring so the spring windings are clockwise (the open endof spring hookis to the left). b. Grasp the spring near the spring hook with a needle-nose pliers and carefully remove the spring retainer. c. Place the spring into the starter housing. Make sure the spring hook is installed into the grooveof the starter housing. d.
2.6047.089 r 4. Hold the pulley with the pawl engagement teeth towards you. Wrap the rope around the pulley in the clockwise direction. Make sureall of the rope is wound onto the pulley. 2.6060.156 5. Apply a small amountof grease (Mobilgrease(R) HP or equivalent) to the post in the starter housing, spring, and the backside of the pulley. 6. Install the rope guide eyelet onto the starter rope. 7. Place the rope through the eyelet. Install the pull handle on the rope and secure it with a single knot.
STARTER DISASSEMBLYAND, REASSEMBLY (cont.) 8. Install the pulley/rope assembly into the starter housing. Rotate the pulley slightly until the spring hooks onto the pulley and the-pulley drops ‘into place. 9. Holding the pulley down, put1 full turn of Spring tension on the pulley. 10. Install thetwo (2) pulley retainers and screws. Torque the screwsto 20-30 in-lb (2.3-3.4 N-m) I 11. Pull the rope outto its full length and let it return. Check the spring tension and adjust as necessary.
BREATHER DISASSEMBLY AND REASSEMBLY (cont.) Breather Hose Function Test 1. Test the hose by attempting to blow air throughit in both directions. air should flow only in the direction shown (outof the crankcase). 2.6060.159 1. Install the breather housing/plug into the hose. 2. Slide the breather hose assembly, from the inside out, into the rocker arm cover until the breather hose seats into the cover. SPARK ARRESTER SCREEN 1. Remove the spark arrester screw and cover. 2.
PISTON/CONNECTING ROD DISASSEMBLY & ASSEMBLY 1. Remove the three (3)piston rings from the piston/connectingrod. 2. Remove the wrist pin buttons, wrist pin and connecting rod from the piston. Piston Inspection and Repair 1. Inspect the piston and piston rings for wear and damage. Referto the specifications and tolerances in Part 1 - General Information. Replace the piston and piston rings if necessary. 2. Inspect the ring grooves on the piston for carbon deposits.
PISTON/CONNECTING ROD DISASSEMBLY & ASSEMBLY (cont.) 3. Check the side clearance of the piston rings. The maximum side clearanceis .005 inch (0.127 mm). 2.6047.100 Connecting Rod Inspection and Repair 1. Check the bearing area (lower end) for excessive wear, score marks, running and side clearances. Refer to the specifications and tolerances in Part 1- General Information.Replace the connecting rod if necessary. Reassembly 1. Install the piston rings into the ring grooves in the piston.
PISTON/CONNECTING ROD DISASSEMBLY & ASSEMBLY RING GAP ORIENTATION Orient the piston ring gaps as shown Middle Ringling 180 DegreesDegrees To Top RingRing To Top Ring 3.6047.102 Piston Wrist Pin Button 2. Install the connecting rod, wrist pin buttons and wrist pin into the piston. NOTE: Make sure the buttons are installed with the recess of the button facing the piston. CYLINDER HEAD INSPECTION& REPAIR Cylinder Inspection and Repair 1. Check all gasket surfaces to make sure they are free of debris.
CYLINDER HEAD INSPECTION & REPAIR (cont.) Valve Assembly Inspection and Repair I . Inspect the valve springs and related hardware for excessive wear or distortion. 2. Check the valves and valve seat area for evidence of deep pitting, cracks, or distortion. Check the clearance of the valve stems in the guides. NOTE: Difficult starting orloss of power accompanied by high fuel consumption may be symptoms of faulty valves.
CRANKCASE INSPECTION & REPAIR (cont.) Cam Bracket Cam Bracket Disassembly and Inspection 1. Disassemble the cam gear, two(2) followers and bracket . 2. Inspect the cam gear, bracket, and followers for wear or damage. Replace any or all of the parts if necessary. 3. Inspect the teeth on the cam gear.Ifthe teeth are badly worn, chipped or missing, replace the cam gear. ,106 - Cam Bracket Reassembly 1. Make sure you have all of the necessary partsto reassemble the cam bracket assembly. 2.
MAJOR COMPONENTS INSPECTION & REPAIR Fuel Tank and Cap Inspection 1. Inspect the fuel tank for cracks, rubbing, or chaffed spots. Replace the tankif necessary. 2. Inspect the rubber fuel tank mounting pad for condition. Replace the padif necessary. 3. Inspect the fuel tank cap for cracks, damaged vent valve, or other visible signs of damage. Replace the capif necessary. Clutch Inspection 1. Check the clutch rotor for wear or damage. Replace, if necessary. 2.8080.
I MAJOR COMPONENTS INSPECTION & REPAIR (cont.) Flywheel Inspection and Repair Inspect the flywheel for the following conditions: Miissing, broken or cracked fins. Oval shaped pawl pin holes. Broken, damaged or missing springs, pawls or pawl pins. Freedom of movement of pawls. Evidence that the Starter Pawl Repair Kit has been installed (holes in bottom of the flywheel below pawl pins).Engine Other signs of fatigue, wear or damageto the flywheel. 2.6060.
General Information Troubleshooting Disassembly ......................... .......................... Inspection and Repair Reassembly ...................... ..................... ...........................
II Table Of Contents ........................ EngineReassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Install Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Install Cam Bracket Assembly . . . . . . . . . . . . . . . . . . . . 5-4 .................... 5-5 ............................ Install Oil Pan . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cylinder Head Assembly . . . . . . . . . . . . . . . . . . . . . . . 5-6 ....................
The following sequenceis suggested for complete en- 10. gine reassembly. This procedure assumes that all com11. ponents are newor have been reconditioned, and all component subassembly work has been completed. 12. This procedure can be varied to accommodate individual requirements for assembly. 13. NOTE: Make sure the engineis assembled using all 14. specified torque values and clearances. Failure to observe specifications can cause severe engine wear or 15. damage.
ENGINE REASSEMBLY Install Seal 1. I f the seal was removed in Part 3 - Disassembly, press anew seal into the crankcase untilisit flush with the crankcase surface (with the metal surface facing out). NOTE: To make the installation of the seal easier, grease the inner ring of the seal with Mobilgrease (R)HP or an equivalent. 2.6047.109 Install Cam Bracket Assembly 1. 5 Rotate the crankshaft until the crankpinis at top dead center between the timing marks 2.6047.109 2.
ENGINE ASSEMBLY(cont) Make sure the line below the blocked hole, of the cam gearis parallel to the crankcase without turning the engine. 3. Install the cam bracket assembly into the crankcase with thetwo (2) screws. Torque the screwsto 15-20 in-lb (1.7-2.2 N-m). Install Piston/connecting Rod TOP 1. Make sure the piston rings are installed correctly as shown. I 2.6047.
ENGINE ASSEMBLY(cont) r- . RING GAP ORIENTATION Top Ring 45 Deg. CCW To Pin 2. Orient the ring gaps as shown Middle Ring 180 Deg. CCW ToTop Ring Bottom Ring 90 Deg. CCW To Top Ring I I Wrist Pin Axis 3.6047.102 3. Install the piston/connecting rod assembly into the crankcase with the lettering on the bearing of the connecting rod facing the crankshaft counterweight. Slideit down in the crankcase. Angle it slightly and roll it into place. Be sure not to dislodge the wrist pin buttons. 2.6047.
ENGINE ASSEMBLY (cont) 2. Install the the cylinder with thetwo (2) screws into the crankcase. Do not tighten. 2.6047.115 3. Place two (2) new O-rings on the cylinder. Oil them lightly. Install Oil Pan 1. Install the six (6) screws into the oil pan. Torque the screws to35-45 in-lb (3.9-5.0 N-m).
ENGINE ASSEMBLY(cont.) Cylinder Head Assembly 1 . Make sure you haveall of necessary parts to 1 two assemble the cylinder head, which include (2) valves, valve springs and retainers. NOTE: Always match intake and exhaust parts when assembling the cylinder head. I 2.6047.118 2. Install the valves and valve springs. 2.6047.119 3. Install the two (2) valve spring retainers . Make sure the retainers lock onto the valve stems properly.
ENGINE ASSEMBLY(cont.) 4. Install a new cylinder head gasket. The notch on the gasket goesto the spark plug sideof the cylinder and the dome side of the gasket should be up. 5. Place the cylinder head over the four(4) studs. 6. Seal the two (2) cylinder studs in the rocker box with RTV sealing. 7 . Install the push rod guides over the cylinder studs.
ENGINE ASSEMBLY(cont.) 8. Install the cylinder head with the four (4) cylinder hex nuts and washers. NOTE: If the washers need to be replaced, use Genuine Toro hardened washers. These washers have special dimensions that are critical to the engine's tolerances. 9. Install the push rods into the push rod guides. NOTE: Make sure the push rods are seated into the cam followers. Refer to "Cam Bracket Disassembly and Reassembly"in Part 4 inspection and Repair.
ENGINE ASSEMBLY (cont.) Rocker Arm to Valve Clearance Adjustment Every 50 hoursof operation, remove the rocker arm cover and check the rocker arm to valve clearance. 1. Position the crankshaftso that the piston is at the top of the compression stroke (both rocker arms are free and loose). 2. Measure the clearance between the valve stems and rocker arms,using a flat feeler gauge. The recommended rocker arm to valve clearance for both the intake and exhaust .003-.006 is in(.076 mm-.152 mm). 3.
ENGINE ASSEMBLY (cont.) Install Spark Plug 1. Make sure the spark plug gapis set to 0.025 in (.0635 mm). 2. Install the spark plug into the cylinder and torque to 100-110 in-lb (11.2-12.3 N-m). 3.6047.024 Install Muffler 1. Install a new muffler gasket and place the muffler baffle in place. 2.6047.125 2. Install the muffler with the three(3) mounting bolts. Install the lower bolt first to ease the installationof the toptwo (2) bolts.
ENGINE ASSEMBLY (cont.) r Install Intake Baffle 1. Install the intake baffle on the other side of the cylinder. Install Carburetor Mount Insulator 1. Install thetwo (2) hex nuts on the backof the carburetor mount insulator. For Units with Engine Serial Number 405000001 and Greater-The two (2) hex nuts are retained in the carburetor mount insulator. 2. Install a new gasket to the backof the carburetor mount insulator. Install the carburetor mount two (2) insulator to the crankcase with the screws .
ENGINE ASSEMBLY (CONT.) WARNING:CRACKED OR BROKEN COOLING FINS ARE A HAZARD! Be careful not to crack or break any cooling fins. They could off fly during operation. If cooling fins are cracked or broken, replace the flywheel. Install the flywheel key into the keyway on the crankshaft. 2. Position the flywheelso that the key slot in the flywheel aligns with crankshaft key. Place the flywheel onto the crankshaft. 3. Install the flywheel spacer and clutch rotor to hold the flywheelin place. 1.
ENGINE ASSEMBLY (cont.) Install Fan Housing 1. Install the fan housing with the four (4) screws to the crankcase. Torque thefan housing screws to40-45 in-lb (4.5-5.0 N.m). Install Fuel Tank And Fuel Tank Bracket- 1. Install the rubber fuel tank pad to the fuel tank. 2. Install the fuel tank and fuel tank bracket with the two (2) screws. Torque the screws to25-35 in-lb (2.8-3.3 N.m). Install Starter Module Assembly 1. Place the starter module over the crankshaft. 2.
ENGINE ASSEMBLY(cont.) Install Clutch 1. Install the washer and clutch rotor to the crankshaft. Make sure the spacer is installed on the crankshaft. 3. Install the isolator onto the starter housing.
ENGINE ASSEMBLY (cont.) 4. Install the clutch cover with the three(3)screwsEscrews. :he If the unit is equipped with a spring, instal spring. Torque the screws to35-45 in-lb (3.3-5.0 N.m). Install Primer Bulb, Carburetor Andconnecty\cit Fuel Line Use the following procedure to install the primer bulb, carburetor and fuel lines into the air filter base. 1. Install the primer bulb into the air filter base. 2. Install two newcarburetorgasketsandthe carburetor into the air filter base.
ENGINE ASSEMBLY(cont.) 3. Connect the fuel lines to the carburetor and primer bulb. 2.6047.139 Short Fitting (To Carburetor) NOTE: This unit hastwo fuel lines to the fuel tank. The clear line provides normal fuel flow. The blue line provides a return line for excess fuel flow during the primer operation. The short fitting on the bulb comesfrom the carburetorand thelong fitting goes to the fuel tank. Long Fitting (To Tank) 3.6047.140 Install Air Filter Base, Alr Filter and AirFilter Cover 1.
INSTALL AIR FILTER BASE,AIR FILTER ANDAIR FILTER COVER 2. Install the air filter base, primer bulb and' carburetor to the carburetor mount insulator with the three (3) screws. The breather hose must be mounted to the air filter base at the same time. Torque the screws to30-35in-lb (3.3-3.8 N-m). 2.6047.031 3. Install the air filter element onto the air filter base. 3.8047.142 4. Install the air filter cover with the three (3) screws. Torque the screws to25-30 in-lb (2.8-3.3 N.m). 3.6051.
ASSEMBLE HANDLE Install Lower Handle 1. Pull the throttle cable and lead wires through the housing and place them into the grooves in the bottom of the lower handle. Place the switch wire in the bottomof the slot and then the throttle cable. Lead - 20647.143 NOTE: Make sure the wires are placed to the rear of the switch. This will ensure that the switch is in the correct on/off position. 2. Install the spring into the trigger.
ASSEMBLE HANDLE(cont.) 3. Assemble the trigger (with the spring), switch and retainer and place the assembly into the bottom of the lower handle. The throttle cable must go through the retainer. 4. Install the retainer screw, which holds the ;witch and throttle trigger assembly in the lower handle Torque the retainer screw to 15-20 in-lb (1. N.m). Install Upper Handle 1. Install the upper boom into the handle.
ASSEMBLE HANDLE(cont.) 3. Wrap some masking tape around the boom and the lower handle. This will hold the boom onto the anti-rotation cap screw. L 5. Install the upper handle with the six(6) screws. To aid in the installationof the upper handle,lubricate the isolator with soap and water. Torque the screws to20-25 in-lb (2.2-2.8 N-m). it from the lower handle. 6.
ASSEMBLE COVERS Install EngineCover 1. Install the engine cover with the four (4) Screws. Torque the rear engine cover screw 30-35 to in-lb (3.5-4.0 N-m). 3.6047. Torque thetop engine cover screws to 15-20 , in-lb (1.7-2.2 N-m). Torque theside engine cover screw to 20-25 in-lb (2.5-3.0 N-m). 3.6047.036 Before placing the unit back into service, be sure to do the following: 1. Make sure all of the fasteners are tightened securely. 2.
