R-TEK/DURAFORCE (E) ENGINE SERVICE MANUAL
Contents
1. 9 Engine Produces Mechanical Knocking Sound 1 9 Engine Pre lgnites eru ete iet gA 10 Engine Smokes Excessively Smoke is light colored engine runs well 10 Engine Smokes Excessively Smoke is dark engine runs poorly 10 Engine Stalls I ett a e a es e ler atri P eels 11 Spark Plug Fouled iine trae ee bx EAR dix dates bg ddp 11 MAINTENANGE fi 33 ege thee eM do bo ea el Sette et gees 13 Recommended Maintenance Schedule 0 13 Air Filter Mower Only edad ns 14 Spak PUG tnos deae Ces euis Late ue tr OR E 4 14 Cleaning the Exhaust System Lawn Mower 15 Cleaning the Exhaust System Snowthrower 2 16 Reassembling Exhaust System Mower 16 TABLE OF CONTENTS 52 X H 17 IdentifiCatior s rediens Pit2. 57 Gup Assembly Test sinri diketa oa mi a e eile bats aw ier d tL Ld idee e 57 SAFETY INFORMATION General injury or even death SAFETY This safety symbol means WARNING or PERSONAL SAFETY INSTRUCTION read the instruction because it has to do with your safety Failure to comply with the instruction may result in personal This manual is intended as a service and repair manual only The safety instructions provided herein are for troubleshooting service and repair of the engine only The individual Operator s manual will contain safety information on the complete product powered by the E series engine Operator s manuals with complete instructions are available through Lawn Boy Corporation The Toro Company Parts Department 8111 Lyndale Avenue South Bloomington MN 55420 U S A Safety Tips Avoid unexpected starting of engine Always turn off the powered product and disconnect the spark plug wire before attempting cleaning adjustment or repair Avoid lacerations and amputations Stay clear of all moving parts whenever the engine is running Treat all normally moving parts as if they were moving whenever the engine is running or has the potential to start Avoid burns Do not touch the engine while it is running or shortly after it has been running Avoid Falls Do not operate the powered product on slippery surfaces or if footing is questionable Avo
3. 2 Engine Fastener Torque Requirements 3 Standard TOrdques i eet ax robe ag dub UE quss ug massi aad es ur A tn 4 Carburetor Specifications 4 4 SPECIAL TOOL REQUIREMENTS 5 TROUBLESHOOTING e nep Serene PIE GU a wur tie ms itn ei oq ed 6 Engine Will Not Start When 0 6 Engine Will Start When Cold But Not When Hot 6 Engine Will Not Produce Spark 7 Engine Flooded With Fuel 7 Engine Has Low 7 Engine Eacks POWer airna deerat bx ee EURO X PUE E IS DAR RIS ORDER 8 Engine Surges ss Dose Gabeira fen ca denen ET needs sn 8 Engine Backfires si pex WEITE VIDGRICERETPEMERUOIVPCPLEDLALMEBUSCPLIWS 8 Engine OverheatS 9 Engine Vibrates Excessively 2 9 Engine Crankshaft Will Not Turn
4. Replace fuel cap Ignition inadvertently grounded Inspect and repair to remove unwanted ground Carburetor vent plugged Clear vent of obstruction Engine overheated Clear debris from fins or cause of overheating Improper lubrication Tear down and inspect for damage Spark Plug Fouled Possible Causes Remedies Incorrect spark plug Use correct spark plug Carburetor running too rich Clean rebuild carburetor Clogged air cleaner element Clean and re oil element or replace mower only Overuse of choke position Weak ignition system Move control off choke position and check throttle cable adjustment Replace CD ignition pack Worn rings and or cylinder Rebuild engine or short block Use of poor fuel Drain fuel tank and replace with fresh unleaded regular fuel having the correct oil mixture Fuel oil mixture too rich Drain fuel tank and fill with fuel of correct mixture Wrong Cil Use Toro 2 cycle oil Lawn Boy DuraForce oil or NMMA TCW3S approved oil 11 THIS PAGE INTENTIONALLY LEFT BLANK Recommended Maintenance Schedule MAINTENANCE Frequency 5 Hours Item Fasteners Comments Check blade and engine mounting fasteners frequently Keep all nuts bolts and screws tight to ensure safe operation 25 Hours Housing Mower only Remove the buildup of grass clippings and di
5. 67 Nm NA Nut Flywheel 375 425 in Ibs 42 47 Nm 375 425 in lbs 42 47 Nm Seat Float Valve 16 28 in Ibs 1 7 4 0 Nm 22 32 in lbs 2 4 3 5 Nm Screw Brake Plate Assembly 60 70 in Ibs 6 7 7 8 Nm NA Screw Carburetor Mounting 20 30 in Ibs 2 2 3 4 Nm Screw CD Ignition Pack Screw Cylinder to Crankcase 20 30 in Ibs 2 2 3 4 Nm 90 110 in Ibs 10 12 Nm 55 90 in Ibs 6 2 10 0 Nm 90 110 in Ibs 10 12 Nm 55 90 in Ibs 6 2 10 0 Nm Screws Engine Mounting 170 220 in Ibs 19 25 Nm 170 220 in Ibs 19 25 Nm Screw Float Bowl 10 13 in Ibs 1 1 1 5 Nm 10 13 in Ibs 1 1 1 5 Nm Screw Muffler 611228 55 90 in Ibs 6 2 10 0 Nm 55 90 in lbs 6 2 10 0 Nm Screw Muffler Cover Screw Muffler Plate 55 90 in lbs 6 2 10 0 Nm 140 200 in Ibs 16 22 Nm NA NA Screw Reed 10 13 in Ibs 1 1 1 5 Nm NA Screw Rod Cap to Rod 65 75 in lbs 7 3 8 4 Nm 65 75 in 1 5 7 3 8 4 Nm Screw Shroud 58 70 in Ibs 6 5 7 8 Nm Screw Shroud Base 58 70 in Ibs 6 5 7 8 Nm 58 70 in Ibs 6 5 7 8 Nm 58 70 in Ibs 6 5 7 8 Nm Spark Plug 150 200 in Ibs 17 23 Nm 150 200 in Ibs 17 23 Nm Rewind Starter to blower housing NA 20 30 in Ibs
6. The filter is welded in the bottom of the tank over a sediment reservoir The tank is mounted above the level of the carburetor and uses gravity to supply fuel through a 25 D 6 35 mm rubber hose to the carburetor The fuel hose is friction fitted to the tank outlet at one end and to the carburetor at the other end The fuel tank is vented through an opening in the fuel cap The fuel opening on the tank is opposite the fuel outlet helping to prevent damage to the filter screen by funnels and gasoline filler spouts that may be inserted into the fuel tank during refueling The placement of the cap also prevents interference with the starting rope in Zone Start mower applications The fuel cap is a four piece design see Figure 44 with an inner sealing disc that is vented to a baffle assembly in the body of the cap The baffle assembly allows expansion in the tank or splash against the bottom of the cap without the loss of fuel Atmospheric pressure is allowed into the tank from an opening in the cap to allow gravity to feed fuel to the carburetor If an individual part of the cap fails the entire assembly must be replaced 0720 022 Figure 44 FUEL SYSTEM Fuel Cap Service 1 The fuel cap may not be disassembled however the vent opening on the cap and inner sealing disc should be kept free of debris 2 The venting ability of the cap may be tested by filling the cap with water and observing the flow of water out of
7. 2 2 3 4 Nm Screw Manifold NA 55 70 in Ibs 6 2 7 8 Nm Screw Muffler NA 100 130 in Ibs Overtorquing will crack the carb body and cause the engine to run rich 3 page rev 8 06 SPECIFICATIONS Item DuraForce R tek Nut Shroud 100 130 in Ibs 10 14 Nm 140 170 in Ibs 16 19 Nm Screw Starter Bracket to Recoil NA 30 35 in 3 4 3 8 Nm Screw Gov Pivot Block to Cyl NA 30 35 in lbs 3 4 3 8 Nm Screw Elect Start to Crankcase 140 200 in Ibs 16 22 Nm 75 100 in lbs 8 2 11 Nm Standard Torques Size US Metric 10 24 20 30 in Ibs 5 1 6 21 Nm 1 4 20 55 90 in lbs 6 2 10 0 Nm 5 16 18 140 200 in Ibs 16 22 Nm Carburetor Specifications Item DuraForce R tek Type Lawn Boy float type dual circuit with primer and choke Body Material Minlon Seat material Brass with Viton tipped needle Both are replaceable Inlet Needle Pop Off Pressure 5 psi 7 kg cm2 Wet Main Jet 77 5 73 8 Main Nozzle Brass Pilot Jet 37 5 42 5 High Altitude NA Float Adjustment Float height 500 030 bowl flange no gasket to top of float SPECIAL TOOL REQUIREMENTS SPECIAL TOOLS Listing Description Order From Part Number Comments Use Air Gap Gauge Toro 604659 Sets 010 2
8. adea ais 17 Theory of Operation 17 Troubleshooting ec arene be eenepberbieiseestrtirfeisteea 18 Preliminary Check esa rete iad oyu ead ei hys ERE MARS 19 Removal of DuraForce 1 20 Removal of R tek Carburetor 4 20 Disassembly sc ies Mauer onlay E US Suh dE ste he Bad CIR ea ERAS Me ante Reine ated 21 Cleaning and Inspection 23 AASSOMDIY ita sea tat ae dai dads ad eee 23 Installationi fen vo sii A Pad oe a hed 25 Governor PEON tive dees AP a Sei See eat 26 Reed Valve Engine DuraForce Engines Only 26 Piston Ported Engine R tek Engines Only 26 Presetting the Governor DuraForce Engines 26 Servicing the Air Filter DuraForce Engines Only 27 FUEL SYSTEM erc ae et ee ee Beale 29 Operation ids ses tek es peta Ger ae eee he we OS ae Das Mea eas Peat 29 FueliGap SENICE uei re goles
9. brake mounting plate was not removed from process is completed See Figure 91 the engine simply reconnect the grounding lead to the push on terminal directly above the ground strap stop 4 and continue with the reassembly process Note If the brake mounting plate was removed tighten screw 9 to 60 70 in Ibs 6 78 7 91 Nm Secure the replacement brake plate to the engine with shoulder screw 7 Tighten it to 90 in Ibs 9 2 Nm Ensure that the brake plate pivots freely Slide the cable into the narrow slot on the brake mounting plate and then push the cable into the hole making sure the tabs lock into the bracket Figure 91 0891 1 One end of the compression spring has a hook shape to it that end hooks over an indentation in the brake plate Squeeze the compression spring A and slip it over the cable between the brake mounting plate and brake plate See Figure 90 5 Figure 90 0893 051a Insert the leaded ball end of the cable into the vertical slot B of the brake plate See Figure 90 49 THIS PAGE INTENTIONALLY LEFT BLANK 50 ELECTRIC START SYSTEM 120 VOLT Troubleshooting Starter Motor Fails to Turn Possible Cause Correction Power not reaching product Plug another appliance into extension cord to ensure cord is OK Starter switch malfunction Check switch using a volt ohmmeter set for resistance Ensure that there is continuity when the switch is d
10. eg 8 80 a ee eee 29 Cleaning ci Set bets dias uad edd tente 29 IGNITION SYSTEM sl eis ch 5 5 Tira unsere Ru me d ek SS 31 rede ee edocet eet vods eeepc etuer ett 31 T Stihig Gites denarii edd Dale pdt ue 31 Spark Plug 1 31 Spark Plug 2 2 4 32 CD Pack Operation o oder Esse ete ue e Abed beds Psp beue NI a 32 CD Pack Air Gap 33 CD Pack Removal Installation 2 2 2 33 Flywheel Operation aed ved eR Va et ERR EU 34 Flywheel Removal bade 34 Flywheel Installation 4 35 TABLE OF CONTENTS REWIND STARTER Ime tt eet ek Eu e eS RNC C TERT UE EIUS 37 Gor 37 Removal and 37 Reassembly amp se eu vr TIR Ried baw Pie a See ere 37 ENGINE a ELI xx Se eta ERECTAE ae RI bx uie 39 Ge
11. piston and rings Cylinder worn Remove and replace short block TROUBLESHOOTING Engine Lacks Power Possible Causes Remedies Dull blade Sharpen or replace blade mower only Housing choked with grass and debris Clean housing thoroughly mower only Plugged exhaust system Clean exhaust ports Muffler plugged Flywheel key sheared Clean or replace muffler Replace flywheel key Carburetor dirty Clean carburetor Intake air leak Repair or replace failed components s Low compression See Engine Has Low Compression table Engine Surges Possible Causes Remedies Fouled idle circuit Clean idle circuit Air leak Check sealing surfaces oil seals gaskets and port plugs Restricted fuel flow Check filters and fuel line Engine RPM low Adjust to proper specification Note A slight surge at no load is normal Governor link misadjusted R tek Air vane sticking Adjust Clean or replace Engine Backfires Possible Causes Remedies Flywheel key sheared Replace key Muffler filled with carbon Clean muffler Exhaust ports plugged Clean ports Air leak to crankcase Replace seals or re seal crankcase to cylinder Spark plug partly fouled Clean or replace Engine Overheats TROUBLESHOOTING Possible Caus
12. proper range experimentation within the RPM range may be necessary Exhaust partially plugged Decarbon exhaust port and muffler Rings leaking Break in new engine or repair worn rings cylinder Float height incorrect Re set float Reeds not sealing Repair replace reeds DuraForce only Preliminary Check Removal of DuraForce Carburetor The primer start carburetor used in E Engines has an 1 Disconnect spark plug wire We strongly all Minlon housing with a fixed high speed and pilot jet recommend cleaning the exterior of the carburetor and an adjustable float before removal from the machine This reduces Perform the following preliminary checks to eliminate the chance that dirt can get into the carburetor and some of the possibilities that may contribute to will extend the life of the solvent in your cleaning carburetor malfunction tank 1 Ignition system ensure that all components are 2 Remove fuel line and drain remove the fuel tank adjusted to specs and are the correct components On snowthrowers it will be necessary to remove the lower shroud to access the carburetor and fuel 2 Fueltank filter must not be plugged line 3 Fuel cap vent hole must not be plugged 3 Open and remove air cleaner cover and air filter element mower only See Figure 17 4 Airfilter must be clean and oiled DuraForce engines 4 Detach carburetor from engine by removing two mounting screws Discard the two smaller 5 Crankcase seal Crankcase seals m
13. red wire going to the mower CAUTION Keep hands and feet away from the blade Measure alternator output The reading should be from 190 450 M A Milliampere at 2900 300 RPM If output is not within specification check the alternator air gap Alternator Air Gap Adjustment 1 Rotate the flywheel until the magnets are directly adjacent to the alternator There should be a 010 25 mm air gap If gap is incorrect loosen the alternator mounting bolts slightly allowing the flywheel magnets to pull alternator against the gauge Tighten the bolts to 75 in lbs and recheck the air gap See Figure 104 Fej Figure 104 6 tif 57 Alternator Resistance Check Disconnect the electronic cup assembly from the wiring harness Connect one ohmmeter RX 1 scale lead to the green wire of the wiring harness and the other to the engine block See Figure 105 Measure resistance The resistance should be from 2 7 to 3 3 ohms If specification is not met check resistance at alternator connection If specification is met at the alternator look at the harness for breakage If specification is not met at alternator connection replace the alternator Figure 105 0891 004 Cup Assembly Test The cup assembly consists of a capacitor and diode Its function is to convert alternating current to direct current and increase the voltage Disconnect the electronic cup assembly from the wiring harness Connect one o
14. the vent opening in the top of the cap If water does not drain the vent opening may be plugged or restricted 3 Ifthe fuel cap will not vent properly replace the entire cap assembly 4 Should you encounter a situation where fuel leaks around the threads of the fuel cap not out the vent inspect the top of the neck of the fuel tank and the area in the cap where the fuel tank neck contacts the cap This is the sealing area not the threads See Figure 45 Figure 45 720 021 Cleaning 1 Remove the fuel tank Take it to an appropriate area and wash the tank in clean solvent intended for cleaning engine parts 2 Backwash the filter screen by directing cleaning solvent under moderate pressure through the sediment reservoir and screen opposite the direction of fuel flow 3 Wash the tank again with clean solvent 4 Clean or replace the fuel hose THIS PAGE INTENTIONALLY LEFT BLANK 30 Troubleshooting IGNITION SYSTEM Problem Misfiring no firing engine surges engine dies Note these symptoms may also be caused by fuel system problems Possible Cause Suggested Remedy Spark plug or lead wire loose Tighten plug Spark plug in poor condition Replace plug CD Pack air gap wrong Adjust CD Pack high tension lead loose Secure with GE silicon sealant CD Pack leads loose dirty or grounding Clean and tighten leads replace CD Pack defective Replace CD Pack F
15. 3297 002 A Intake Ports Closed Third Port Open B Ignition D Partial Vacuum 40 Service Tips 1 Oylinder Crankcase Halves The two halves are a matched pair and cannot be exchanged between engines Follow all cleaning and assembly procedures in this subsection Be sure to use Loctite 515 on the mating surfaces Torque the six screws that secure the two halves See specifications 2 Oil Seal Visually inspect for leaky or damaged oil seals two locations See the Seal Service section for the procedure 3 Engine Base Muffler Baffle Lawn mower only This item should be checked and or cleaned every 100 hours maximum to keep carbon from clogging exhaust system power loss and from entering engine causing piston scoring See Cleaning Exhaust see page 15 4 Exhaust Ports The exhaust ports should be inspected and cleaned as necessary see page 15 5 Carburetor Gaskets Carburetor gaskets on either side of the carburetor shield may be leaking or damaged causing air leaks into the engine may cause power fluctuations Ensure that air cleaner carburetor mounting screws are properly tightened see Specifications Disassembly Removal of the shroud recoil starter flywheel ignition coil and carburetor are covered in other parts of this book and will not be repeated here 1 Remove the six crankcase cap screws and separate the halves using a screwdriver See Figure 70 Be careful not to damage the sea
16. 5 mm gap between flywheel and coil Piston Ring Compressor OTC TOR 4089 Compresses piston rings to allow installation into the cylinder Wrist Pin Knockout Tool Toro 602884 Used to drive wrist pin out of piston OTC Tool amp Equipment Division SPX Corporation Industrial Park 2013 4th Street NW Owatonna MN 55060 Telephone 800 533 0492 Fax 507 455 7011 TROUBLESHOOTING TROUBLESHOOTING Engine Will Not Start When Cold Possible Causes Remedies Fuel tank is empty Fill with clean fresh properly mixed unleaded fuel Bad fuel Drain tank and float bowl Fill the tank with clean fresh unleaded properly mixed fuel Fuel filter plugged Replace fuel tank Air cleaner plugged Fouled spark plug Wash and re oil air cleaner element DuraForce only Remove and replace the spark plug No spark at spark plug See Engine Will Not Produce Spark table Insufficient momentum Check for loose blade mower only Incorrect ignition timing Check for sheared flywheel key Low compression Engine flooded with fuel See Engine Has Low Compression table See Engine Flooded With Fuel table Reed valves not closed Replace reed valves DuraForce only Reed valves stuck closed Free up and run engine to clean DuraForce only Primer or choke not operating Fix or replace Engine Will Start When Cold But Not When H
17. At faster speeds about 800 RPM the flywheel magnets induce a large enough charge in the trigger coil to trigger the SCR in the advanced firing position about 28 degrees BTDC See Figure 51 Figure 51 3297 019 A Flywheel Rotation B Crankshaft at 25 BTDC C Charging Leg D Running Leg 25 Advance 33 IGNITION SYSTEM CD Pack Air Gap Adjustment 1 Rotate the flywheel until the magnets are directly adjacent to the CD Pack as shown See Figure Figure 52 Ibv0040a 2 Adjust gap by loosening screws inserting Lawn Boy gauge P N 604659 or a piece of 010 25 mm shim stock and tightening screws Remove the shim stock or gauge CD Removal Installation 1 Disconnect leads and remove mounting screws 2 Replace CD Pack and set gap as outlined in step 1 above Tighten screws See specifications for torque values See Figure 53 Figure 53 lbv0040b IGNITION SYSTEM Flywheel Operation The flywheel is connected directly to the crankshaft secured by a flywheel key and nut and turns at the same speed as the crankshaft Two permanent magnets imbedded in the flywheel rotate past the coil in the CD Pack to begin the generation of electricity Imbedded in the opposite side of the flywheel are steel counterweights which offset the weight of the magnets These counterweights are not magnetic A flywheel key and keyway in the flywheel and crankshaft are used to assure alignment durin
18. R TEK DURAFORCE E ENGINE SERVICE MANUAL Table of Contents Page 1 of 1 PREFACE SAFETY SPECIFICATIONS SPECIAL TOOLS TROUBLESHOOTING MAINTENANCE CARBURETOR FUEL SYSTEM IGNITION SYSTEM REWIND STARTER ENGINE PIVOTING ZONE START BRAKE ELECTRIC START SYSTEM 120 VOLT ELECTRIC START SYSTEM 12 VOLT E DuraForce PREFACE ABOUT THIS MANUAL This manual was written expressly for the E series engines There are two engines in this series One is piston ported R tek and the other is a reed valve DuraForce As these engines are of the same family they will both be covered here Where there are differences between the two versions a heading will state which engine is being discussed We have made every effort to make this information complete and correct We hope that you find this manual a valuable addition to your service shop If you have questions or comments regarding this manual please contact us at the following address The Toro Company Consumer Service Department 8111 Lyndale Ave So Minneapolis MN 55420 1196 The Toro Company reserves the right to change product specifications or this manual without notice TABLE OF CONTENTS TABLE OF CONTENTS eel ER ca v PIN ene ed FR E EAE E PES 1 SPECIFICATIONS ea da o Ger ul Sata e te 27 05 dea te 2 Engine Specifications All dimensions for a new engine
19. RBURETOR 8 Pressure check carburetor Attach pump with pressure gauge to fuel inlet fitting on carburetor see Figure 33 With carburetor upside down float up raise float and lower to its normal position Pump pressure to 5 psi It should hold this pressure indefinitely For practical purposes test for 10 or 15 seconds If it does not hold wet the needle and seat and repeat the test Figure 33 0893 026 9 Install the fuel filter over the fuel nozzle Pressure check before proceeding see Figure 34 Figure 34 0893 22 24 10 Install a new fuel bowl gasket and p fuel bowl with the four bowl retaining screws see Figure 35 Figure 35 2 0893 002 11 Hook the governor spring into the bottom of the governor collar DuraForce engines See Figure 36 Figure 36 0893 050 12 Place the collar and spring over the carburetor fitting DuraForce engines See Figure 37 Figure 37 0893 005 13 14 Install the air vane and throttle shaft into the carburetor body by very carefully pushing the shaft through the collar into the carburetor body See Figure 37 Push the throttle plate into the throttle shaft The plate only inserts one way If the throttle plate does not fit snugly replace the throttle shaft The governor spring can now be attached to the throttle shaft Note Be sure air vane operates smoothly and does not stick or bind Installation DuraForce Assemble the c
20. SHOOTING Engine Pre Ignites Possible Causes Remedies Wrong spark plug too hot Install the correct type of spark plug Low quality fuel old or stale Replace with fresh unleaded regular fuel Carbon buildup in engine Decarbon engine and muffler Excessive alcohol in fuel Replace with fresh unleaded fuel having no more than 10 ethanol Sheared flywheel key Inspect and repair Engine Smokes Excessively Smoke is light colored engine runs well Possible Causes Remedies Slight oil accumulation in crankcase None normal on start up Air cleaner element clogged Clean and re oil or replace air cleaner element mower only Fuel oil mixture too rich Drain fuel tank and fill with fuel of correct mixture Choke is in On position Move to high speed or Off position Engine Smokes Excessively Smoke is dark engine runs poorly Possible Causes Remedies Carburetor running too rich Clean and check carburetor Choke is in On position Move to high speed or Off position 10 Engine Stalls TROUBLESHOOTING Possible Causes Remedies Engine out of fuel Refill with fresh fuel of the correct mixture Engine overloaded Unload engine and restart Fuel filter plugged Clean fuel filter tank Spark plug fouled Fuel cap vent plugged See Spark Plug Fouled table
21. Side play crankshaft near lower main 0006 0003 0006 015mm 008 015 Piston cyl Clearance tightest loc 0035 to 0059 089 to 150mm Wrist pin hole diameter 500 5005 12 705mm 12 712mm Bottom ring thickness new 0600 0005 1 52mm 013 016 008 in 40 20mm Displacement 8 6 cu in 141cc 4 or 5HP 584 Mix ratio oil or NUMA TCW3 Toro 2 cycle oil or NAMA TCW3 4HP runs at 3700 300 CCR 2400 3700 Governed Engine Speed 2900 300 rpm 5HP runs at 3800 300 rpm CCR 2450 amp 2500 3800 rpm CCR 3600 3900 rpm CCR 3650 4000 rpm Snow Commander 4000 rpm All snow engines are 300 rpm cle Speed 2200 2800 rpm Air Cleaner Oiled foam type with Centrifugal pre cleaner N A 2 SPECIFICATIONS Item DuraForce R tek Choke Manual butterfly type Fuel filter In tank and in carburetor Piston rings Cast iron semi keystone top ring Second ring is rectangular Anti rotation pin in piston Piston Permanent mold high silicon aluminum Engine Fastener Torque Requirements Item DuraForce R tek Bolt Head 140 200 in Ibs 16 22 Nm 140 200 in Ibs 16 22 Nm Jet Main 4 Gin lbs 44 66 Nm 4 6 in lbs 44 66 Nm Jet Pilot 10 12 in Ibs 1 1 1 3 Nm 6 8 lbs 66 88 Nozzle Carburetor 16 28 in Ibs 1 7 4 0 Nm 20 30 in Ibs 2 2 3 4 Nm Nut Blade 45 50 ft in 60
22. T 1 rn Pw anne ae ee ee eee eee 51 Troubleshooting 51 Introduction uda eit IRI Maan bois 51 Starter Removal 10044 tese acus vb diee peperisse 51 Starter Disassembly utei Sae Riv P eC ed RR UE oe 52 Startet Assembly 21 22 seme UA Qux eme 52 Starter Installation etos epe EUR Baie eh eS 52 TABLE OF CONTENTS ELECTRIC START SYSTEM 12 VOLT une re RR ad 53 Troubleshooting ete ek ute edes Phe a Ax E Rau tee has 53 Introduction esee E ERE RE Ho alata eg 53 Starter Removal i sete eer ddan 0 beens keds AU dudes 53 Starter Testing eis ave ais Sea Sete oe Ra 54 Starter Disassembly 54 Starter Assembly Be ote ERA MERE ne 55 Starter installation eer ad steed deed teeta EE UE SEE NC RAS 55 Alternator Introduction bre 56 Alternator Output Testing 4 57 Alternator Air Gap Adj stment P REI des cupi nade d pened is 57 Alternator Resistance Check
23. al position See Figure 86 Lowering the bail to the main mower handle opens the switch Switch leads are connected to the primary side of the coil and to ground see Figure 87 When the switch is closed the electronic ignition module is bypassed so that it cannot interrupt primary current flow This action prevents the coil from producing the high voltage necessary to generate spark When the switch is open the ignition coil produces spark Figure 87 0893 043 Stopping the engine and blade is accomplished by means of a brake that is applied to the flywheel The brake spring is in the braked position when the blade control is in the at rest or vertical position When the blade control bail is lowered to the mower handle the brake is retracted and allows the engine to run PIVOTING ZONE START BRAKE There are two versions of this brake The function is the same but they contact different parts of the flywheel Figure 88 is a diagram of the system used on recoil start engines The brake pad engages the bottom of the flywheel Figure 89 is a photo of a slightly different system used on electric start engines On electric start engines the brake pad must contact the side of the flywheel to clear the teeth of the flywheel ring gear Disassembly Recoil Figure 88 3297 023 Plastic rivet self expanding 2 1 Ground strap stop 6 2 Self tapping screw 7 Shoulder screw 10 mm 3 Brake switch
24. an be removed by inserting a small diameter drill bit into the holes to release the jaws Figure 95 1657 021 52 ELECTRIC START SYSTEM 12 VOLT Troubleshooting Starter Motor Fail to Turn Possible Cause Correction Starter motor has failed Check by disconnecting the spark plug wire and starter wiring connector Apply 12 volts directly to the starter motor Note Due to the connector arrangement it is possible that the starter motor will turn backwards during this test This does not harm the motor Battery has low charge or is disconnected Check battery for full charge and ensure it is connected Engine has seized Verify that the engine turns over easily Starter switch malfunction Use a volt ohmmeter to insure there is continuity in the start position Bad ground Check to ensure the ground is secure and not corroded Bad wires between battery and starter Use a volt ohmmeter to ensure that continuity exists Introduction 3 Loosen the Allen head bolt used to secure the starter pin with a 1 4 Allen wrench See Figure 96 It may be necessary to remove the carburetor bolts and lower the carburetor to gain access the needed clearance for the Allen wrench The electric start models of the DuraForce engine utilize a 12 volt starting system consisting of a starter motor battery key switch alternator regulator cup assembly starter relay fuse Starter Removal 1 Un
25. arburetor gaskets heat shield and air filter box Use the two mounting screws to hold the parts together during assembly R tek Assemble the carburetor spit cup heat shield and gaskets Use the mounting screws to hold parts together during assembly DuraForce engines Guide the air vane through the opening in the shroud base from the bottom of the base and attach the carburetor to the engine with two mounting screws Tighten them to specifications DuraForce engines Insert the bent wire of the throttle cable into the vertical tab of the speed control lever Set the throttle to fast and the speed control lever so that the throttle plate is in the full open position The cable is adjusted at the cable clamp on top of the air filter box R tek engines Connect the governor spring to the throttle plate and the tab on the block Connect the governor rod adjusting loop A up to the air vane and connect the choke cable Assure the throttle is in the full open position See Figure 38 and Figure 40 25 CARBURETOR Figure 38 724 004 4 Install the fuel line and primer tube on the appropriate carburetor fittings 5 Checkthat the choke and air vane assembly move freely and is properly adjusted If the air vane requires adjusting see Presetting the Governor on page 26 6 Install the air filter element and cover DuraForce engines only The R tek engine has a spit cup B only Note The opening of the spit cup s
26. ase in match marks on the rod and rod caps Some of the very early engines may not have these marks Use a permanent marker if match marks are not visible 1 Secure wrist pin using snap ring Make sure square edge of snap ring faces out and ring opening faces up toward top of piston See Figure 79 b Figure 79 0893 028 44 Several piston and ring combinations have been used Pistons have been plated and unplated Pistons have used two keystone rings and others used one semi keystone and one standard ring The pistons made for one type of ring will not accept the other type However any piston and ring assembly can be used in any cylinder Install keystone piston ring in top groove with bevel facing up The square bottom ring can be installed either way Note that there are pins in the ring grooves The open ends of the rings must line up with the pins Assemble ball bearings to crankshaft and install crankshaft Note One side of the paper is sticky remove paper carefully while installing needle bearings There should be 32 needle bearings on the lower connecting rod When reinstalling original needle bearings use a little 2 bearing grease to stick the needles to the rod Install rod cap A Ensure that mating marks are aligned Clean old screws B thoroughly and apply Loctite 271 See Figure 80 Torque to specifications Figure 80 0893 023 Oil parts Use ring compressor to install piston with EX mar
27. center passage When air rushes through the venturi air pressure at the center of the passage is lowered By inserting a tube from the carburetor float bowl into the venturi see Figure 14 the lower air pressure at the venturi causes the normal air pressure in the bowl to push fuel up the tube 17 CARBURETOR Venturi Effect Figure 14 3297 012 A Venturi C Air Pressure B Center Passage Area The fuel oil mix is then picked up by and mixed with the moving air the amount of fuel determined by throttle opening and jet size This fuel oil air mixture enters the crankcase through the reed valves DuraForce or ports R tek See Figure 15 and Figure 16 When the piston moves away from the spark plug the cylinder intake ports are opened and the now pressurized crankcase causes the mixture to move into the combustion chamber Reed Valve Figure 15 3297 021 3 A Reed Valve Closed C Second Stroke B Exhaust Gases Piston Ported Figure 16 3297 002 A Intake Ports Closed Third Port Open B Ignition D Partial Vacuum CARBURETOR Troubleshooting Engine Starts Hard Possible Causes Primer malfunction Remedies Repair or replace as necessary No fuel in carburetor Add the proper fuel oil mix Carburetor bolts loose Tighten bolts to 20 30 in Ibs 2 2 6 2 Nm Mislocated gaskets Loosen bolts realign gaskets and tighten Choke not closing fully Adju
28. dings will be incorrect 2 Measure resistance Reading should be less than 10 ohms If high resistance or open circuit infinite resistance is shown replace the starter motor Starter Disassembly 1 Slide the pinion clutch assembly A off the pinion shaft Remove the retaining ring from the pinion Figure 100 1657 019 clutch assembly and disassemble completely Inspect all parts for wear or damage and replace as needed See Figure 98 Figure 98 1657 020 54 ELECTRIC START SYSTEM 12 VOLT Starter Assembly 1 Apply a light coat of Lawn Boy AX grease to the pinion gear thrust washer and driven gear prior to installation Place the pinion gear on small driveshaft in motor housing with either side facing up See Figure 101 Place the thrust washer then the driven gear on the pin Make sure the raised side of the driven gear is facing the cover plate Figure 101 1657 013 tif Install the cover plate with the word OUT facing the pinion clutch assembly and secure with two screws and drag spring stud Make sure you replace the drag spring stud in its original position Torque screws and stud to 20 in Ibs 55 5 Reassemble pinion clutch assembly Apply a small amount of Lawn Boy AX grease to the pin Slide the assembly on to the pin with the drag spring A over the stud See Figure 102 Figure 102 1657 020 Starter Installation 1 Install the starter leaving the bolts loo
29. e Figure 21 Figure 21 0893 005 3 Turn the carburetor over Remove the four bowl retaining screws the bowl gasket and the bowl See Figure 22 Discard the bowl gasket Figure 22 0893 002 21 CARBURETOR 4 The pilot jet is located under the decal on the side of the carburetor Remove the decal and the pilot jet Note The threads have Loctite on them See Figure 23 Figure 23 0893 30 5 Remove the fuel filter from the fuel nozzle see Figure 24 Figure 24 0893 22 CARBURETOR 6 Remove the float hinge pin the inlet valve needle assembly with its clip and the float see Figure 25 Discard the needle and clip Figure 25 0893 18 7 nspect the float for cracks or deterioration of the cork see Figure 26 Figure 26 0893 001 8 Remove the brass inlet fuel valve seat and discard it See Figure 27 2 Figure 27 0893 041 22 1 9 Remove the high speed jet A from the nozzle B It is best to clean the nozzle in place If the nozzle is not sealed into the carburetor body the air fuel mixture will be affected see Figure 28 Note There are two white nylon plugs in each carburetor Do not attempt to remove them or the carburetor will be damaged Figure 28 0893 037 Cleaning and Inspection With the carburetor completely disassembled thoroughly clean all parts in a parts cleaning solution Do not soak the carburetor Leave it in the solvent only lon
30. e cover B and air filter See Figure 1 Figure 1 3297 005 Wash air filter in laundry detergent and water Squeeze filter to remove excess liquid and blot dry with a paper towel or rag see Figure 2 Do not wring out the element or damage may occur Figure 2 3329 006 Apply one tablespoon SAE 30 or similar oil to the air filter see Figure 3 Lightly squeeze filter until oil is distributed evenly throughout the filter Blot lightly with paper towel to remove excess oil Replace filter with cleanest side facing carburetor 14 Note Be sure filter is properly seated in air box and is not puckered allowing direct passage of air and dirt to carburetor Figure 3 3297 007 Spark Plug A spark plug that is dirty pitted carbon covered or has worn electrodes may cause hard starting and poor operation Replace spark plug once a season or every 25 hours which ever occurs first Use NGK BPMR 4A or equivalent 1 Setspark plug gap to 030 76 mm See Figure 4 030 in Figure 4 3297 008 Install spark plug finger tight then torque per specifications See Figure 5 Figure 5 3297 009 Cleaning the Exhaust System Lawn Mower Warning Disconnect the spark plug wire to prevent accidentally starting the engine 1 Mower Using a 1 2 drive with a 15 16 socket remove the blade nut that secures both the mulch fan and blade to the engine Use heavy duty gloves to hold the blade wh
31. epressed Engine has seized Verify that the engine turns over freely Starter motor has failed If all the above conditions are checked and the starter still fails to turn it must be repaired or replaced Introduction Starter Removal The electric start models of the R tek engine use a 120 1 volt starting system When the starter is supplied with voltage the helical shaft spins forcing the pinion gear to slide out on the shaft and engage the ring gear See Figure 92 SWITCH Figure 92 120V 51 Remove the upper housing Remove the starter switch the bolt holding the wire clip and the two bolts which mount the starter to the engine See Figure 93 Figure 93 1657 017 ELECTRIC START SYSTEM 120 VOLT Starter Disassembly Starter Assembly 1 Remove the pinion retaining clip by applying Assemble by reversing the disassembly process constant pressure towards the end of the shaft on one end of the clip and working around the rest of the clip Always replace clip with a new one Starter Installation 2 Slide the stop washer pinion spring and pinion off Install by reversing the removal procedure the shaft 3 Remove the two housing bolts and separate the ends from the body Pay close attention as things come apart easily when disassembling 4 The serviceable items are shown See Figure 94 Figure 94 1657 022 5 The starter switch is also serviceable See Figure 95 Note The wires c
32. es Remedies Cylinder head cooling fins clogged Clean fins thoroughly Restricted carburetor jets Clean carburetor and jet Improper gas to oil mix ratio Ensure mixture is correct Cooling air intake plugged Remove foreign material and clean Engine Vibrates Excessively Possible Causes Remedies Blade out of balance Balance blade or replace if damaged Bent blade Replace blade Loose engine mounting screws Tighten engine mounting screws engine to plate plate to mower housing Bent crankshaft Replace crankshaft Flywheel out of balance damaged Replace flywheel Engine Crankshaft Will Not Turn Possible Causes Remedies Engine brake incorrectly engaged Disengage brake and inspect and repair as necessary mower only Blade jammed in housing Inspect and repair or replace mower only Piston seized in its cylinder Inspect and repair or replace Starter jammed Repair starter Engine Produces Mechanical Knocking Sound Possible Causes Remedies Loose blade Inspect and tighten blade nut to correct torque mower only Loose flywheel Inspect and tighten flywheel nut to correct torque Pre ignition is occurring See Engine Pre Ignites table Loose rod cap Replace rod and bearings Loose engine mounting bolts Tighten bolts TROUBLE
33. fuel mixture to enter the combustion chamber As the exhaust gases continue to exit the exhaust port the engine is readied for another cycle See Figure 69 In a piston ported engine there are no reed valves The fuel air mixture enters the crankcase through a third port that is opened and closed by the piston See Figure 66 All other functions are the same as a reed valve engine Figure 66 3297 001 2 Figure 68 3297 003 A Intake Ports Closed Third Port Closed A Intake Ports Closed C Third Port Open B Compression D Partial Vacuum B Exhaust Port Opening D Pressure Building Up Both Piston Ported and Reed Valve Engines At about 28 degrees before top dead center BTDC the spark plug fires When the engine is functioning properly the air fuel mixture ignites causing a burn that occurs evenly through the power stroke If the compression ratio is too high the air fuel mixture actually explodes which can be heard and is identified as detonation The burn continues as the piston changes direction and begins its travel towards the crankcase See Figure 67 Figure 69 3297 004 A Intake Ports Open C Fresh Fuel Change B Exhaust Port Open D Third Port Closed The 2 cycle engine is always well lubricated as long as the correct oil fuel mixture is maintained in the fuel tank Oil suspended in the fuel vapor adheres to all moving parts keeping them continually coated regardless of operating angle Figure 67
34. g assembly The tapered fit of the flywheel and crankshaft along with the torque of the bolt or nut actually holds the parts together The surfaces of both tapers must be good to obtain a good friction fit The key is designed as a light duty part so that if the engine stops rapidly due to blade impact the key will shear If the key were too hard and the impact occurred the more expensive flywheel could crack Flywheel Removal 1 Remove shroud and fuel hoses 2 Remove flywheel nut and starter cup Reinstall nut flush with the end of the crankshaft See Figure 54 Figure 54 0893 21 34 Remove the flywheel by pulling up on the edge of flywheel while striking the flywheel nut with a soft hammer See Figure 55 Figure 55 Ibv0040b 4 Remove key and check its condition see Figure 56 0893 006 Figure 56 5 Replace crankshaft and or flywheel if keyway is distorted or cracked 6 Inspect the flywheel for cracks or damage and the strength of the magnets using a iron object Replace as necessary See Figure 57 Figure 57 0893 013 Flywheel Installation 1 Make sure flywheel taper crankshaft taper and keyway is absolutely clean and dry 2 Make sure key is installed correctly see Figure 58 3 Locate keyway cutout in flywheel over key and shaft MAKE SURE KEY IS INSTALLED CORRECTLY Figure 58 3297 020 35 IGNITION SYSTEM 4 Torque flywheel nut to specifications see Figu
35. g enough to clean it Inspect for wear or deterioration Use a spray can of carburetor cleaner with the hose and flush all passages with cleaner Blow dry all carburetor passages with compressed air CAUTION If tag wire is used never enlarge or restrict any passageway in the carburetor Always check the carburetor mounting flange and the fuel bowl mounting flange to be sure they are smooth and undamaged Assembly 1 Install the high speed jet into the fuel nozzle If the nozzle has been removed turn the carburetor over Apply one drop of Loctite 242 blue or equivalent to the nozzle threads and install the nozzle assembly into the carburetor body see Figure 29 Figure 29 0893 038 3 Apply one drop of Loctite 242 blue to the threads and install the pilot jet see Figure 30 Figure 30 0893 030 23 CARBURETOR 4 Apply one drop of Loctite 242 or equivalent to the seat threads and install a new brass inlet fuel valve seat see Figure 31 Figure 31 0893 041 5 Install a new inlet valve needle and clip on the float Install the float assembly with a new float hinge pin in the bottom of the carburetor Ensure that the hinge pin is positioned properly to keep the float level The float should be free to move up and down easily in the carburetor body Adjust float so height is 1 2 03 76 mm from bowl flange gasket not in place to top of float see Figure 32 Figure 32 0893 054 CA
36. h both the open ends of the spring facing you Figure 40 3S 001 Presetting the Governor DuraForce Engines Only Note Each click of the governor collar represents approximately 50 75 RPMs 1 Turn the collar clockwise to increase spring tension Figure 42 7 tif and engine RPMs or counterclockwise to decrease spring tension and RPMs See Figure 39 Preset the governor collar 3 or 4 clicks clockwise 26 Servicing the Air Filter DuraForce Engines Only 1 To remove the air filter unsnap the wire holder on the right side of the cover the cover Rotate the cover open The air filter element can now be removed If you wish to remove the cover rotate it full open and unhook it from the hinge See Figure 43 Figure 43 0893 017 Clean and re oil the air filter element according to the procedure in Maintenance section CAUTION Do not operate the engine without a filer element or with a dry element engine life will be shortened Note Snowthrower engines do not have an air filter for two reasons a The snow prevents dirt from getting into the air b In colder weather the snow will blow around Fine particles of snow would clog the air filter The engine will ingest snow but that small amount will not cause a problem 27 CARBURETOR THIS PAGE INTENTIONALLY LEFT BLANK 28 Operation The E engine uses a plastic fuel tank with a non replaceable 75 micron in tank filter screen
37. hmmeter RX 1 scale lead to the green wire of the cup side of the connector and the other lead to the red wire of the connector ELECTRIC START SYSTEM 12 VOLT 3 Measure resistance Reverse leads and measure resistance again The specification is to have different resistance between the two measurements high one way and low the opposite way If specification is not met replace the cup assembly See Figure 106 Figure 106 0891 003 58
38. hould be pointed up See Figure 38 Governor Theory Reed Valve Engine DuraForce Engines Only The shaft of the governor air vane is attached to the throttle disc of the carburetor so that air flow created by the rotating flywheel attempts to close the throttle The governor spring resists this force and attempts to open the throttle The balance between these two forces is the governed engine speed Spring tension may be changed via an adjustable collar which produces a 50 75 RPM change in engine speed for each adjustment click it is moved See Figure 39 CARBURETOR 2 Useatachometer to check engine speed 2900 300 RPM for DuraForce engines on mowers For R tek piston ported engines refer to the specification pages Should the governor link A be bent or replaced adjustment will be necessary See Figure 41 Figure 39 0720 07 Piston Ported Engine R tek Engines Only The piston ported engine does not use the click type adjustment For the piston ported engines the governor is adjusted by bending the bracket that the governor spring is attached to Otherwise the function Figure 41 0893 039 of the governor is the same see Figure 40 A good starting point is about 114 31 75 mm from the casting to the end of the air vane See Figure 42 Then move the air vane until the throttle is full open The air vane must not contact the CD ignition Should the governor spring be removed reinstall wit
39. id fires Wipe up any spilled fuel or oil immediately Avoid asphyxiation Never operate an engine in a confined area without proper ventilation Avoid fires and explosions Use a container designed for gasoline Avoid spilling fuel and never smoke while working with any type of fuel Avoid accidental misuse of fuel Always store fuel in a properly labeled container designed for gasoline Avoid injury due to inferior parts Use only Toro Lawn Boy original parts to ensure that important safety criteria are met Avoid injury to bystanders Always clear the area of bystanders before starting or testing powered equipment Avoid injury due to projectiles Always clear the area of sticks rocks or any other debris that could be picked up and thrown by the powered equipment Keep all safety shields in place Avoid modifications Never alter or modify any part unless it is a factory approved procedure Avoid unsafe operation Always test the safety systems after making adjustments or repairs on the machine SPECIFICATIONS Specifications Engine Specifications All dimensions are for a new engine DuaFoce 2 5000 0005 63 5mm 0127 1 75 4 45mm 5000 0000 0002 12 70mm 000 005 7427 0003 0002 18 85mm 008 005 0 017 0 431mm 1998 Snow End play crankshaft 0 017 0 431mm Walk mower 0 0215 0 533 1999 and later Snow
40. ile removing the nut See Figure 6 Note Removing the blade is merely for convenience while working Figure 6 0893 011 Snowthrower Remove 2 bolts holding the muffler to the engine block Remove the muffler Proceed to step 3 2 Remove the cover and the exhaust pipe under the cover See Figure 7 Figure 7 1657 010 15 MAINTENANCE Figure 8 1657 001 With the cover and exhaust pipe removed you can see into the passage leading to the exhaust port of the engine A and passage to the muffler B If the exhaust requires cleaning remove the engine and separate the engine and base for access to the exhaust ports If the muffler requires cleaning it can be removed by removing the 2 screws on either side of the muffler passage see Figure 8 and one through the side of the muffler see A in Figure 9 Use a stick of wood to scrape the carbon loose Do not use a metal scraper Figure 9 16057 009 The muffler B can be removed from the top of the mower to inspect for carbon buildup See Figure 9 MAINTENANCE Cleaning the Exhaust System Reassembling Exhaust System Snowthrower Mower Only 1 Remove the muffler see Figure 10 Clean as 1 Install the exhaust pipe into the engine base see needed Figure 10 0893 012 2 2 Inspect exhaust port see Figure 11 If cleaning is necessary rotate piston to cover exhaust port and scrape carbon from exhaust port area Use wood only to clean th
41. ine and the R tek is piston ported The design difference affects the path which the incoming fuel air charge takes to get to the firing chamber Two cycle engines have special advantages which make their use more practical in certain applications Two cycle engines are lightweight with an excellent power to weight ratio and can be operated in any position limited only by the carburetor and fuel supply system They are also notably easy to maintain and service because of their uncomplicated design Theory of Operation Reed Valve Engine The illustration below see Figure 64 shows what happens inside the engine during one full crankshaft revolution Fuel intake fuel ignition and the exhaust of burned gases all take place during a single 360 degree rotation of the crankshaft Figure 64 3297 022 2 A Reed Valve Closed B Exhaust Gases Beginning at a point where the top of the piston is just below the exhaust port the piston moves forward toward the crankcase As the transfer port is uncovered the fuel air mixture stored in the pressurized crankcase is forced into the combustion chamber See Figure 65 39 ENGINE Figure 65 A Reed Valve Open 3297 021 2 The crankshaft continues its rotation and the piston begins its travel toward the spark plug As it moves the piston seals off the transfer port first then the exhaust port When both ports are sealed the remaining travel compresses the air fuel mixture
42. is area Figure 11 0893 035 3 Install the muffler and torque the bolts per specifications 16 Figure 12 Figure 12 16547 006 The cover on the exhaust portion of the engine base uses a high temperature silicone to seal the joint Apply a coat of Loctite 598 or equivalent to the sealing surfaces before assembly Torque the four screws per specifications Re install the blade and mulch fan if removed Tighten the nut per specifications Identification The E series engines use two versions of the primer start carburetor One with an air filter box on the mower engines DuraForce and one without an air filter box on the snowthrower engines R tek Differences include a plug in the snowthrower carburetor vent passage and some minor differences in the throttle shafts jetting and throttle valve bleed hole Both carburetors have two circuits and use both a choke and primer for starting See Figure 13 Figure 13 0720 012 Theory of Operation As the crankshaft rotates the piston moves back and forth in the cylinder alternately creating a pressure or a partial vacuum in the crankcase See Figure 16 As the piston moves toward the spark plug the reed valve opens see Figure 15 or the inlet ports are uncovered see Figure 16 This causes air to rush through the carburetor throat to equalize the pressure in the crankcase The carburetor throat is formed into a venturi large at each end but with a smaller
43. k and arrow pointing towards the exhaust port Install seals before fully seating the crankshaft Install new oil seals Clean seal bore with alcohol before installing seals Oil in the bore may cause the seal to blow out when the engine is hot Note Ring Compressor P N TOR 4089 order from OTC see page 5 for address and phone 7 Apply Loctite 515 gasket maker very thinly to the crankcase cover sealing surface A being careful not to get sealant in bearings See Figure 81 Figure 81 0720 018 8 Carefully align the two crankcase halves using the alignment pin A and its matching hole Press the two halves together See Figure 82 Figure 82 0720 015 45 ENGINE Tighten the screws to specifications tightening only 20 in lbs 2 26 Nm increments at a time while tightening modified X pattern See Figure 83 Figure 83 0891 005 Reinstalling External Components 10 Reattach the flywheel brake system 11 Clean the crankshaft and flywheel hub with alcohol and install flywheel 12 Install carburetor and governor assembly 13 Install starter and shroud assembly and starter handle 14 Reconnect fuel lines and electrical system leads 15 Install CD pack and set air gap See Ignition System on page 31 16 Test run engine ENGINE Crankshaft Seal Replacement The crankshaft seals on both the R tek and DuraForce engines are located right on top of a groove in the bore Figure 85 The
44. lead wire 8 Brake plate assembly 4 Ground strap 9 Screw 5 Insulation strap 10 Brake mounting plate Electric Start Figure 89 0893 040 Note Numbers in parentheses in the following procedures refer to the previous illustration see Figure 88 1 If the engine and blade are taking more than seconds to stop when the blade control bail is released inspect the brake pad for excessive wear and replace if necessary Note that the brake pad and the brake plate are replaceable only as an assembly 2 Toreduce the pressure of the spring between brake mounting plate 10 and brake plate 8 squeeze tabs of brake cable that hold it in place at the brake mounting plate Push cable through the hole in brake mounting plate 3 Slide cable out through horizontal slot in brake mounting plate Also slide the ball end of the cable up through the vertical slot in the brake plate Note In step 4 some units may use a 3 8 head with 1 4 diameter screw rather than a 10 mm 4 Remove the 10 mm shoulder screw 7 to remove the brake plate and brake pad attached to it 5 lf the ground strap or any part of this assembly requires replacement remove the second screw 9 to remove the brake mounting plate from the engine PIVOTING ZONE START BRAKE Assembly 6 Operate the blade control bail to verify that the 1 brake mechanism stops within three 3 seconds There is no adjustment needed after this assembly If the
45. ling surfaces 41 ENGINE 2 Remove the entire crankshaft assembly and discard the oil seals Figure 70 1657 012 3 Carefully remove the HSH hex socket head cap screws A see Figure 71 to remove the connecting rod cap and the split bearing liner The needle roller bearings are under the split bearing liner See Figure 72 Figure 71 0720 013 ENGINE 4 Remove the piston and rod assembly Separate 3 Check all parts for wear or damage and replace if the assembly if necessary using a snap ring pliers questionable on the retaining ring 16 Use wrist pin knock out tool P N 602884 to punch out wrist pin 17 See 4 Clean crankcase surfaces with Gel Seal and Figure 72 Gasket Remover See Figure 74 Figure 72 0893 24b Figure 74 0720 014h 5 Remove the two bolts and two nuts retaining the 5 Use a feeler gauge to check that the ring end gap cylinder head to the block Remove the head and is to specifications discard the head gasket See Figure 73 Figure 75 0893 014 Figure 73 720 008 Inspect the piston and cylinder see Figure 75 A good piston will show most of the machining marks Inspection and Repair on the surface Some things that indicate piston and cylinder damage are 1 Check bearings for wear and freedom of movement replace the bearings if questionable 2 Check rings for sticking Remove and check rings for wear or damage replace rings if questionable Clean any carbon build
46. ly we do not stock individual parts Should the recoil fail due to something other than a starter rope we recommend replacing the assembly The replacement recoil will be connected to the shroud with nuts and bolts Reassembly Both the DuraForce and R tek engines use starter ropes about 7 feet long 1 To wind the rope and pretension the spring turn the pulley counterclockwise six 6 turns for the R tek and 5 turns for the DuraForce Insert the rope through the guide then the reel A pair of small needle nose pliers will be helpful See Figure 61 Figure 61 0893 010 REWIND STARTER 2 Tiea single knot in the end of the rope then singe the end with a lighter to prevent the knotted end of the rope from fraying see Figure 62 Tie a simple knot in the rope to prevent too much from retracting until the starter handle is installed Figure 62 Ibv0043d bmp 3 Reassemble the starter and shroud with the four screws and nuts Remember the orientation of the rope outlet 4 The shroud must be assembled by slipping the shroud over the two studs on the cylinder head then rotating the shroud down until the holes on the engine block and shroud align Install the nuts on the studs and two screws on the side opposite the head Note Do not overtighten See Figure 63 Figure 63 0720 002 38 General Information In this section we will cover both versions of the E series engine The DuraForce is a reed valve eng
47. lywheel key damaged or sheared Replace key and check keyway see Servicing the Flywheel in this section Flywheel magnets demagnetized or weak Replace flywheel Engine will not stop Broken ground wire Check the ground wire between the mag and kill switch Look for breaks or loose connections Testing Check the ignition system in the following order 1 Spark plug connection amp wire condition 2 CD Pack air gap connections or spark 3 Flywheel key and magnets Use the table above to aid in diagnosing the problem Spark Plug Operation The spark plug ignites the oil fuel mixture by producing a spark just before the piston reaches top dead center TDC A spark plug is typically constructed as shown See Figure 46 A Metal Shell B Center Electrode C Ground Electrode 31 Figure 46 3297 014 D Head Insulator E Copper core F Leg Insulator G Gap IGNITION SYSTEM Spark Plug Service 1 Check spark plug with the chart in this subsection and replace following the specifications given on this page CAUTION Do not clean plug with a sand blaster 2 Clean with a wire brush removing the carbon buildup Check conditions of the plug for cracking or damage Replace as necessary Item Specification Action Plug type NGK BPMRAA or equivalent Frequency of change As needed Check clean and gap Every 50 hours Gap See specificati
48. mixtures to enter the crankcase on compression strokes and to trap fuel mixtures in the crankcase on power strokes Figure 77 0720 018 1 Check clearance between tip of reed and plate replace reeds if clearance is more than 020 5 mm Figure 76 0893 027 CAUTION Do not use compressed air to clean B Discoloration of a piston is often caused by reeds improper lubrication Without the necessary lubrication friction increases and overheats the 2 piston Often in an engine that failed due to improper lubrication the piston is discolored the rings may be stuck yet the lower rod and crankshaft bearings might appear usable As the piston is the source of the friction and heat the bearings further from the heat source may not appear damaged However we would not recommend re using bearings in an engine that failed due to improper lubrication Clean reeds carefully by hand using carburetor solvent 43 ENGINE 3 When replacing reeds install smooth edge down centered over openings in crankcase see Figure 78 and use Loctite 271 on threads of screws Torque per specifications 2207 1 Figure 78 0720 020 Reassembly Assemble the piston and connecting rod Note the piston has the letters EX and an arrow stamped into the top The arrow should point towards the exhaust port The connecting rod can be assembled to the piston two ways As the rod is symmetrical either way is acceptable We will ph
49. move the lower shroud to access the carburetor and fuel line The carburetor is attached to the intake pipe by two Screws which are screwed into two captured nuts The nuts are held in their pockets by a rubber band during the manufacturing process If the rubber band is no longer in place smear some general purpose grease on the nuts to prevent them from falling out of the pockets Remove the two screws and discard the gasket See Figure 18 Figure 18 0893 009 Disconnect the primer tube from the carburetor fitting see Figure 19 Disconnect the governor spring from the adjustment arm and remove the choke cable See Figure 19 1 Figure 19 0893 039 6 Pullthe carburetor assembly down and away from the engine such that the air vane governor clears the hole in the shroud mounting base Disassembly NOTE The exterior of the carburetor should be cleaned before removal from the machine If this has not been done clean the outside before disassembly At the throat of the carburetor using needle nose pliers gently pull the throttle plate out of the throttle shaft See Figure 20 Notice the orientation of the small protrusions on the throttle plate as you pull it out Figure 20 0893 007 2 Hold the governor collar on the carburetor and lift the air vane throttle shaft out of the carburetor For DuraForce engines only Lift the collar and spring up detaching the spring from the speed control lever Se
50. n can be checked after assembly These seals should be recessed between 040 and 060 1 016 1 524mm Check the depth in about 3 places to ensure the seal is at the proper depth and square in the bore PIVOTING ZONE START BRAKE PIVOTING ZONE START BRAKE DuraForce Engines Only Introduction In 1982 the federal government mandated that all consumer walk behind mowers with a cut of 25 63 5 cm or less be equipped with safety devices There are two primary criteria which these devices must meet 1 Atwo step operation must be performed in order to start the blade rotating The blade must come to a stop within three seconds of the operator leaving the operator s position One of the ways the Lawn Boy Corporation met these requirements was with the zone start system This system utilizes a kill switch and a brake which stops the engine when the operator releases the blade control bail A See Figure 86 The two step blade engagement criteria is met by requiring the operator to pull the bail to the handle first then pull the recoil rope from the operator s position Figure 86 0893 048 47 Operation The pivoting style zone brake system has two main functions The first function of the system is to stop the production of spark and the second is to stop the engine and the blade Stopping spark production is controlled by a switch The switch is closed when the blade control bail is in the at rest vertic
51. neral Information 39 Theory of Opetatloni2s 35 eres ERG eR ER GNU CEA UE s Re MERE Re 39 Reed Valve ENGINE tise 12 s ed eme ea wee ar D eei EY ena doa 39 Piston Ported Engine 1 1 00 40 Both Piston Ported and Reed Valve 40 Semice wees ee tae OPBRPSUECIGeKId ERES Aer Li s rei eter 41 Disassembly mer bui ra EIC epp atu e eb Muere eta ir eai 41 Inspection and Repair 41 4 42 Reed Valve Service DuraForce Engines 2 43 Reassembly 2 0 RET m dere dut md oe ea x oon Hd Bae 44 Reinstalling External Components 45 Crankshaft Seal Replacement 46 PIVOTING ZONE START BRAKE e Rx Ri Rm a RU a 47 Introduction PEEL TC 47 Operation wh see 47 Disassembly duco t bier i sar RE 48 ASSOMDIV i rte e uie e Seen Abe Ee e do es 49 ELECTRIC START SYSTEM 120 VOL
52. ons Torque value See specifications CD Pack Operation The Capacitive Discharge CD system see Figure 47 is breakerless and contains electronic components that replace mechanical points and related accessories such as a breaker cam spark advance assembly etc Figure 47 A CD Ignition Module 3297 015 As the flywheel magnet passes the CD Pack an AC voltage is induced into the charge coil This AC voltage is converted by a rectifier into a DC signal which is then stored in a capacitor See Figure 48 32 SPARK PLUG Figure 48 3297 016 When the SCR is triggered or fires up to 200 volts DC stored in the capacitor travels to the spark coil Here it is stepped up to as much as 25 000 volts and is discharged across the electrodes of the spark plug See Figure 49 Ignition timing when the SCR fires is also determined by the flywheel key and the keyways in the flywheel and crankshaft Damage to any of these parts will affect the ignition timing SPARK PLUG Figure 49 3297 017 At slower speeds the flywheel magnet induces a smaller charge in the trigger coil This action triggers the silicon controlled rectifier SCR enabling easier starting in a retarded firing position about 5 degrees before top dead center BTDC See Figure 50 Figure 50 3297 018 A Pole Shoe D Magnet B Flywheel Rotation E Starting Leg C Crankshaftat 5 BTDC Charging Leg G Pole Shoe
53. ot Possible Causes Engine is flooded Remedies See Engine Flooded With Fuel table Excessive alcohol in fuel Use no more than 1096 ethanol blend Avoid methanol Engine is overheated See Engine Overheats table Clogged bowl vent Fuel percolation vapor lock Clean bowl vent Use current season gas for fuel mixture Engine Will Not Produce Spark TROUBLESHOOTING Possible Causes Remedies Spark plug wire disconnected Reconnect spark plug wire Spark plug fouled or damaged Replace spark plug Spark plug wire damaged Replace CD pack Coil kill wire grounded Ignition coil failed Locate and eliminate the unwanted ground Replace CD pack Flywheel magnets weak Replace flywheel Engine Flooded With Fuel Possible Causes Remedies Overuse of choke position Take throttle off choke Throttle cable misadjusted Adjust throttle cable if present Air cleaner plugged Wash and re oil air cleaner element DuraForce only Fouled spark plug Replace spark plug Carburetor inlet needle stuck open or leaking Clean carburetor replace failed parts and pressure test Carburetor Air Vent Clean Air Vent Engine Has Low Compression Possible Causes Remedies Worn piston rings Replace piston rings or short block Piston ring s stuck in groove Replace
54. plug the wiring connector at the starter Remove the three screws that secure the upper fuel tank shroud assembly and move it off to one side While it is not necessary to disconnect the fuel line the fuel tank should be nearly empty while working on the starting system Figure 96 1657 005 2 Remove the two nuts and two bolts that secure the inner shroud recoil housing and move it off to the side Again it is not necessary to remove the assembly from the unit 53 ELECTRIC START SYSTEM 12 VOLT 4 Remove the bolt that secures the lower bracket to 2 Remove the two screws and drag spring stud A the chassis Remove the starter While removing that secure the gear cover plate to the motor be careful not to move the starter side to side as housing See Figure 99 Remove the cover you may bend the pinion shaft See Figure 97 plate Note that the plate has OUT stamped on the top During installation OUT must face the pinion clutch assembly X Figure 97 1657 004 tif S Figure 99 1657 016 tif tarter Testing 3 Remove the pinion gear driven gear and thrust washer Clean all parts thoroughly and inspect for 1 Connect the red lead of an ohmmeter to the red damage or wear See Figure 100 wire of the starter connector and the black lead of the ohmmeter to the blue wire Slowly rotate the armature through 360 degrees If rotated rapidly the starter acts like a generator and rea
55. re 59 Figure 59 0893 025 THIS PAGE INTENTIONALLY LEFT BLANK 36 Operation The rewind starter operates through a retainer friction disc that causes two engagement dogs to extend from the center of the rewind starter and engage the inside of the starter hub on the flywheel The engagement dogs move into contact with the starter hub when the rewind rope is pulled When the engine starts the starter cup accelerates As the speed of the starter cup exceeds the speed of the recoil starter the ramps on the inside of the starter cup will contact the back side of the starter dogs and push them inward Also if the starter rope is relaxed the spring will cause the dogs to retract Removal and Disassembly Note The rewind starter assembly housing is attached to the shroud with rivets 1 Remove any necessary shrouding to reveal fuel tank Remove the fuel tank 2 Remove the two hex head screws A that attach the shroud to the base Also there are 2 studs B on the cylinder head that are used to attach the shroud Remove the nuts and washers from the studs The shroud can then be rotated towards the cylinder head until there is enough clearance to slide the shroud off the studs See Figure 60 Figure 60 720 002 3 Drill out the rivets connecting the recoil and the shroud Note the orientation of the starter REWIND STARTER 4 This recoil starter is a pressed together assembly Due to the low cost of the assemb
56. rt Self propelled mower only Clean grass clippings and debris under drive belt mechanism cover and drive belt Spark Plug Clean inspect and regap replace if necessary 50 Hours Air Filter Mower only Remove and clean each mowing season or every 50 hours more frequently if operating conditions are dusty Blade Blade Brake Mower only Sharpen or replace maintain more frequently if edge is dulled quickly in rough or sandy conditions Check stopping time every 50 hours or at start of each mowing season Blade must stop within 3 seconds of releasing bail If not repair or replace Lubrication Self propelled mowers only Grease rear height adjuster brackets Exhaust Ports Clean every 50 hours or at least once each season Fuel System Check for leakage and or deterioration of fuel hose Replace if necessary 100 Hours Cooling System Clean grass clippings debris or dirt that clog engine air cooling fins clean more frequently under dirty or high chaff conditions 13 MAINTENANCE Air Filter Mower Only Once every season or every 50 hours clean the air filter housing and element Do so more frequently under dusty conditions Note Do not operate the engine without the air filter in place Doing so may damage the engine or cause excessive engine wear 1 To remove air filter A snap cover latch open swing to side and unhook Remove th
57. rubber on the outer diameter of the seal grips the groove and provides a seal as well as holding the seal in place Only the PTO seal on the DuraForce engine has a snap ring installed after the seal to help hold it in place Figure 84 As both the R tek seals and the DuraForce flywheel seal must set on top of the groove we do not recommend driving a new seal in place Driving the seal over the groove would damage the rubber on the outside of the seal 1657 012 Figure 85 0893 016 46 Separate the crankcase from the cyclinder to replace the seals Slide the seals off the crankshaft and clean the case mating surfaces as previously indicated Clean the block where the seal goes and the outside of the seal with alcohol to ensure they are oil free If oil is in the bore or on the seal O D the lubrication may cause the seal to move when hot Use some type of seal protector to prevent damage to the seal lip and slide the seal down the crankshaft The seal must rest directly on top of the groove in the block Seal the crankcase halves as previously indicated Ensure the seal does not move while assembling the crankcase The snap ring on the DuraForce PTO end should be installed after the six cap screws are torqued down Both R tek seals and DuraForce flywheel end seal The snap ring on the DureaForce PRO end should be installed after the six cap screws are torqued down Both R tek seals and the DuraForce flywheel end seal locatio
58. se 2 Using a feeler gauge gap the end of the pinion clutch assembly away from the engine 019 to 021 48 mm to 53 mm While keeping this air gap tighten the Allen head bolt first then the lower mounting bolt 3 Plug the wiring connector in and install the shrouds and fuel tank ELECTRIC START SYSTEM 12 VOLT Alternator Introduction charge rate it is important to use the 120 volt charger to fully charge the battery before initial use and at the start of each season Frequent starts or hard starting may require using the 120 volt charger to recharge the battery See Figure 103 Electric start DuraForce engines are equipped with an alternator to keep the battery topped off The charge rate of this alternator is 500 milliamps Due to the low 123 O00 REGULATOR ALTERNATOR STARTER SWITCH STARTER Figure 103 12v tif Note Fuse 5 amp 2 blade automotive 56 ELECTRIC START SYSTEM 12 VOLT Alternator Output Testing 1 To check output of the alternator accurately it is necessary to run the engine at operating speed 2900 300 RPM Readjust the governor if necessary Refer to page 26 Presetting the Governor DuraForce Engines Only With the engine running unplug the battery connector and reconnect the plug so that only the black wires are connected Using a multimeter set to read 500 milliamps Connect the red lead to the red wire going to the battery and the black lead to the
59. st choke or throttle choke cable Engine Runs Rich Possible Causes Remedies Dirty air cleaner Clean or replace and re oil air filter element DuraForce engines Dirt in carburetor Clean carburetor fuel line and tank Primer line pinched Dirt in primer vent Inspect and correct problem Clean and or replace as necessary Choke not opening fully Adjust choke or throttle choke cable Engine Runs Lean Possible Causes Carburetor bolts not tight Remedies Tighten bolts to specifications Crankcase gaskets or seals leaking Replace or reseal Main jet partially clogged Clean jet Pilot jet or circuit clogged Clean pilot jet and passages Fuel Leaks From Carburetor Leaking is continuous and fully drains fuel tank Possible Causes Remedies Dirt under inlet needle Remove inlet needle and seat Then clean or replace and pressure check Bowl vent plugged Remove bowl and clean with compressed air Float sinking heavy Replace float Float stuck gummed carburetor Remove bowl and clean carburetor 18 CARBURETOR Fuel Leaks From Carburetor Leaking starts after running stops after shutdown Note This condition which does NOT drain the fuel tank is called spit back Possible Causes Remedies Engine RPM out of proper range Adjust to
60. to prepare it for ignition The travel of piston towards the spark plug is called the compression stroke See Figure 65 The movement of the piston towards the spark plug also has an important effect in the crankcase Once the transfer port is sealed a vacuum is created in the crankcase This action pulls the reed valve open and draws in a fresh charge of fuel air mixture Just before the piston reaches top dead center TDC the spark plug fires When the engine is functioning properly the fuel air mixture ignites causing a burn that occurs evenly through the power stroke The piston changes direction and begins its travel towards the crankcase NOTE If the compression ratio is too high the fuel air mixture actually explodes before it is ignited by the spark plug This can be heard and is identified as detonation also called knock When the piston opens the exhaust port high pressure exhaust gases exit the exhaust port Further movement of the piston towards the crankcase uncovers the transfer port which allows a fresh charge of air fuel mixture to enter the combustion chamber As the exhaust gases continue to exit the exhaust port the engine is readied for another cycle ENGINE Piston Ported Engine When the piston opens the exhaust port high pressure exhaust gases exit the exhaust port See Figure 68 Further movement of the piston towards the crankcase uncovers the transfer port which allows a fresh charge of oil
61. up from the ring grooves before installing new rings It is best to use a piece of hardwood to scrape carbon loose Should you use a metal tool you might damage the piston 42 A Vertical scratches that appear all the way around the piston sometimes is combined with discoloration see Figure 76 Scratches all the way around the piston indicate high hours or dirt ingestion If the scratches are in limited areas look more closely to see if they are in line with the ports On a NEW engine if the ENGINE C Oylinder damage is usually less than the damage to the piston As the cylinder liner is made of harder material it can stand more abrasion However it is generally best to replace the short block if severe piston damage is present as it is the most cost effective repair ports are not properly deburred piston damage can result This can appear ONLY on engines with very few hours on them The damage is immediate If the engine has more than a couple of hours use inspect the carburetor reed area and crankcase for any sign of dirt Much of the dirt that an engine ingests does its damage and goes out the exhaust Any dirt found in these areas indicate that the engine has ingested a great deal more If an engine has ingested dirt the best solution is a short block replacement as the bearings have been exposed to that dirt also Reed Valve Service DuraForce Engines Only The reed assemblies see Figure 77 permit fuel
62. ust be carburetor gaskets on either side of the carburetor installed properly and in good condition torque shield Keep the heat shield for later installation value on the bolts must be correct See Figure 17 6 Carburetor flange gaskets and heat shield must be installed correctly 7 Exhaust ports must not be restricted 8 Fuel mixture must be fresh As gasoline ages it becomes more difficult to ignite 9 Governor air vane must move freely Figure 17 0893 045 19 CARBURETOR Disconnect the primer tube from the carburetor fitting See Figure 19 Pull the carburetor assembly down and away from the engine such that the air vane governor clears the hole in the shroud mounting base Remove the throttle cable screw and nut from the throttle cable mounting bracket CAUTION Be careful in the next step to avoid damage to the delicate governor spring Slide the plastic control lever to either end of its adjustment and snap it to the locked position to help restrict its movement while you disconnect the throttle cable from the control lever Removal of R tek Carburetor Disconnect spark plug wire We strongly recommend cleaning the exterior of the carburetor before removal from the machine This reduces the chance that dirt can get into the carburetor and will extend the life of the solvent in your cleaning tank Remove fuel line and drain remove the fuel tank On snowthrowers it will be necessary to re
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