Snapper 410 User's Manual
Contents
1. 6 15 CARBURETOR See Section III CARBURETOR CONSTRUCTION amp SERVICE for maintenance instructions A Mount carburetor gasket and metal mounting fiange at one time Insure that pulse hole in gasket is aligned with hole in cylinder B Mount carburetor plastic mounting flange and gasket to metal mounting flange Tighten screws alternately to prevent breakage of part Insure that pulse hole is in alignment with metal flange C Mount carburetor D Attach fuel line 6 16 AIR FILTER A If required disassemble check and clean air filter Reassemble B Mount air filter FASTENER TYPE SECTION Vill ENGINE TROUBLESHOOTING CHART Bl SYMPTOM PROBABLE CAUSE REMEDY Fuel System Fuel level If low add fuel Fuel filter Clean or replace Fuel mixture Using ratio of 32 1 fresh fuel Air in fuel line Prime while depressing tickler button Remove and replace Tighten spark plug Replace gasket and torque according to Section VII Replace Refer to Section II pages 10 11 Using ratio of 32 1 fresh fuel WEAK COMPRESSION Fuel leak from oil seal Fuel leak around spark plug Fuel leak between block and cylinder Piston rings excessively worn Fuel mixture Weak or No Fire Kill switch off Spark plug fouled Ignition Coil Turn on Clean or replace Set air gap Section 11 page 14 Check with coil tester repla2. timing mark on one of the cooling fins Its match mark for firing is the arrow and P mark on the drive side of the crankcase See Figure 2 29 C FIGURE 2 27 NOTE If timing mark is damaged during flywheel removal replace flywheel 14 SECTION II ENGINE COMPONENTS CONSTRUCTION A SERVICE 1 Checking Coil Performance Using a coil tester measure the Sparking performance of the coil Replace coil if spark length is less than specified value COIL TESTING CHART 0 27 500 DEM 0 31 1 000 RPM 2 Adjusting Ignition Coil Air Gap The air gap clearance between the ignition coil and outer circumference of the flywheel is a very important factor which affects engine startability Therefore air gap adjustments should be made with care FIGURE 2 29 a Loosen ignition coil mounting screws 2 If flywheel becomes deformed or unbalanced b Use a brass plastic or otherwise non it should be replaced Otherwise the main magnetic feeler gauge and insert gauge bearings will be quickly worn out between flywheel and ignition coil c Adjust coil up or down until the air gap 3 When reinstalling flywheel torque to measures 015 019 See Figure 2 31 1 0 3kg m 2 2 6 6 Ibs inch B IGNITION COIL The ignition coil is waterproof and has a primary wire low voltage and secondary wire wound in the interior The primary wire connects to the breaker points or MTI unit and stop switch The
3. Section V RECOIL STARTER REPAIR 26 27 DISASSOMDIY discs Zeeche Coe aad ew eae Medea ee 26 Starter Rope Removal Installation 26 F easss oare ria eee dies See Gat nave eaten 26 27 Section Vi SEQUENCE OFREASSEMBLV 28 29 ae WEE 28 EES DKCH fie assess eee ie Fb ia 6 28 Eller eegend e ege RN WEG Ee ee d 28 FIYWHEEI dzee aco Maes acs geht ante acorn ge a gin E 28 E Der EE 28 IONIN e EE 28 Clutch ASSOMDIY ere See de dad ede daisies es wee Meee 28 Breaker POINTS EE EA NEE ENNEN 6 acd oe oe a bus ome ae ENEE 28 29 MAT PUI EE 29 Recoil Starter vince Ee Ae ade aa dean ae bad e 29 Cylinder G erd Zeng he 29 Spark PLUG i4 sv sees phase 29 Fuel Vanes wie oe wate cutive tte hale Aro ees 29 Mute ker ad 6 29 Carburetor i cities Sees cee NEE Shae vies baa ea ete os 29 AWOFI seed EE 29 Section VII TORQUE SPECIFICATIONS CHART 30 Section VIII TROUBLESHOOTING 31 32 Section D PARTS 33 35 SECTION I FAMILIARIZATION 1 1 This catalog was prepared to expedite service repairs on the SNAPPER Model 410 Trimmer Engine At the time of writing the data contained her
4. diameter D Add drop of oil to felt lubricator 6 9 MTI UNIT If not fitted with points then mount MTI unit 6 10 RECOIL STARTER A With flat washer underneath screw recoil starter pulley onto crankshaft 1 Lightly tap pawls of pulley with rubber mallet to tighten pulley 2 Indert screwdriver through crankcase air inlet into fan area Place against crankshaft housing and fan casting not against cooling fin to keep engine from turning 3 Tighten pulley retaining nut to torque specifications B Mount recoil starter assembly 1 NOTE Parts to be mounted with the recoil starter assembly are a Fuel tank hanger band b Two rubber pads c Overflow pipe bracket 2 Do not tighten the mounting screw that will be used to retain the muffer guard 6 11 CYLINDER GUARD A Mount cylinder guard B Insure that spark plug wire dust seal is properly mounted NOTE Cylinder guard should be only loosely attached as its fasteners are also used for mounting muffler guard 6B A2ZSPARKPLUG T2 VER BMA RAS A Check spark gap for correct setting and install spark plug B Press on spark plug wire and twist to the right to seat connector 6 13 FUEL TANK A Mount rubber pads to crankcase B Mount fuel tank and tighten hanger strap C Tighten hanger strap lock nut 6 14 MUFFLER A Mount muffler gasket with angled part towards cylinder B Mount muffler C Mount muffler cover D Mount muffler guard
5. is pushed lowering float valve 7 and fuel flows into float chamber 3 Because of negative pressure in the venturi fuel in the metering chamber sprays out of needle jet 12 and is pulled into the engine as an air fuel mixture A When the engine is stopped negative pressure in the venturi is reduced to zero and float arm 6 is pushed upward by inlet spring 5 closing float valve 7 Flow of incoming fuel is shut off preventing overflow At time of engine starting fuel is fed under pressure to metering chamber through diaphragm pump 15 and float valve 7 when tickler button 19 is pushed and primer is operated 17 3 2 CARBURETOR COMPONENTS amp ADJUSTMENTS A THROTTLE VALVE amp NEEDLE JET The piston type throttle valve provides easy transition from low to high speeds Its bottom profile is designed with a large air inlet area and a smaller air outlet area Because of the venturi effect of this design the flow of air fuel mixture is very fast and atomization of fuel occurs rapidly even when the throttle is barely opened See Figure 3 2 THROTTLE VALVE AIR OUT Ke UNDERSIDE VIEW FIGURE 3 2 1 Cut away CA and recessed R portion of each throttle valve are match machined to stabilize the fuel flow during engine idling See Figure 3 3 SECTION VIEW OF THROTTLE VALVE VAG AS FIGURE 3 3 2 The supply rate of air fuel mixture to the combustion chamber is controlled by cha
6. ERVICE I MAIN ADJUSTING SCREW Diaphragm Type The main aajusting screw controls fuer tiow rate when engine is at high speed under heavy loading See Figure 3 12 A DISASSEMBLY See Figure 3 13 THROTTLE CABLE THROTTLE ADJUSTMENT SCREW LOW RPM S MAIN ADJUSTMENT SCREW HIGH SPEED FUEL CONTROL SCREW TICKLER BUTTON FIGURE 3 12 1 Adjustment Adjust screw so that highest output is produced when a large load is applied at high speed a Move throttle to full open position b By turning adjusting screw clockwise and counterclockwise two or three revolutions set the main adjusting screw to where the engine revolutions are most stabilized 1 Air fuel mixture becomes lean when screw is turned clockwise GI Air fuel mixture becomes rich when screw is turned counterclockwise c Checking Acceleration Deceleration 1 Quickly move throttle to open close posi tion Check to see if acceleration deceleration is made smoothly 2 If engine stalls or if acceleration is not satisfactory then air fuel mixture is too lean Adjust main adjusting screw until acceleration is correct J THROTTLE WIRE REPLACEMENT Fully assembled engine 20 qA ee Li FIGURE 3 13 1 Remove mixing chamber cap 2 and pull out throttle wire 9 spring 3 throttle valve 5 and needle 6 as a unit 2 Remove throtile wire 9 from throttle valve 5 by compressing mixing chamber cap 2 and throttl
7. LED TOWARDS ENGINE 23 SECTION IV SEQUENCE OF ENGINE DISASSEMBLY B Remove 3 pronged starter pulley Fit screw B Use flywheel puller to remove flywheel See driver between pawis of pulley to prevent turning Figure 4 4 See Figure 4 2 Turn pulley counter clockwise STARTER PULLEY 4 9 POINTS l 4 11 SPARK PLUG A Remove points and condenser A Remove spark plug O B Remove MTI unit electronic ignition 4 12 CYLINDER 4 10 FLYWHEEL A Remove cylinder A Remove flywheel retaining nut by inserting a 4 13 CRANKCASE 7 5mm 29 dia pin into cast hole in flywheel and fitting a screwdriver between pin and A Split crankcase by removing four 4 screws clutch mounting boss to prevent flywheel from and washers ing Fi 3 EE B Separate crankcase CLUTCH A Remove piston pin snap rings B Remove piston pin and piston C Remove piston rings FIGURE 4 3 24 SECTION IV SEQUENCE OF ENGINE DISASSEMBLY 4 14 INSPECTION AFTER DISASSEMBLY D Muffler Remove excessive carbon within muffler using 3 A Cylinder heavy gauge wire or screwdriver If this method Remove all carbon deposits using a flat head screw doesn t work remove gasket and burn out the car driver CAUTION Be careful not to scar cylinder bon with a torch See Figure 4 6 walls or any machined surface B Piston Remove all carbon deposits from piston surface and ring grooves If piston is badly pitted or scar
8. OPEN lock button by which the operator controls engine speed As use of the engine Increases the throttle cable will stretch and become slack and the carburetor throttle valve opening about 30 at time of starting will change in relatior to control setting Since this seriously affects engine starting efficiency the throttle cable should be periodically checked and adjusted to proper tension with the adjusting and lock nuts See Figure 2 23 FIGURE 2 23 QO SECTION Il ENGINE COMPONENTS CONSTRUCTION A SERVICE oe SE 25 ZS 22 8 2 fs 23 2 g 235 ba 0 O g en a g o o EI S Sf Eo o aa gt DR ES e LG 26 THE TH 5 of S _ 255 are S Ss 229 ba D z FE Ss Sy amp o8S5E dEr Zo xu 2 eg ce Q r5 ezag A 3 ON n ra oD E oart 25888 sS PT gt EFE 2o o E 28 E KEES regs os o 3 EEFE E o S om 7 O oO SE 3 H a G D Zeg E 2 S Geeks S SA o e gez i os e KEEN EOD aa EES Sco BS oe Oo BG g TE sresea eis Oss SEES EE xD se 2 0 e 09 i ee SS SetGuae BES 2e svs SO o zn ag Gs SE BS 5s Be ae EFEC cO Lorgo azz co QO gI 5352 S Oot o o DH o GER OI o v E Re sos KEIER WooBxD Gr sa ud oztE z Fa Wei sess lt a e o e 2 FIGURE 2 24 13 SECTION Il ENGINE COMPONENTS CONSTRUCTION amp SERVICE D Primer Pump 2 10 MUFFLER The manually operated primer pump is used to The muffler is an expendable item and cannot feed fuel to the carburetor
9. SERVICE 17 23 Operation of Carburetor 17 Diaphragm Piston Type Carburetor 17 Carburetor Components A Adjustments 17 21 Throttle Valve amp Needle Jet 18 Throttle Valve amp Needle Jet Adjustment 18 19 Malin Set gege trates 19 Mall Diaphragm tc eseis EE 19 El 19 Float NEEN EE ANE 20 Float Valve Replacement 20 Diaphragm Check Valves 21 Main Adjusting Screw 21 Throttle Wire Replacement 21 Carburetor Troubleshooting Chart 22 23 SNAPPER POWER EQUIPMENT D McDonough GA 30253 2 Q TABLE OF CONTENTS Section IV SEQUENCE OF ENGINE DISASSEMBLY 24 25 Air Cleaner ee Ba Sees EE Sia UR Rare cw E 24 Eet kamk enge te tae 24 Carburetor ER 24 Uuffeee Ge OSs Bah d DEN AGW ee 24 Cylinder Gover errimea aie SBS FE BN te eee Ne bs 24 Fan Cas n rediens sive at tis are EE RA Ta aS Hw e EE Eer 24 Centrifugal Ouut eeee 24 EE 24 25 POMS 2 ege A EE ange vec EE bis MG Sala BOIS Seo ee aera ts 25 Flywheel 5 eewer ge nie 25 Spark Plug Ae Nee AE Ee 25 Oyunn ose heideger e EE ENEE SE ambled ned Rane aw 25 EE PRETT 25 PISTON eaa EE 25
10. Service Manual for SNAPPER Model 410 Series TRIMMER ENGINES SNAPPER POWER EQUIPMENT A McDonough GA 30253 MANUAL No 07215 11 85 SNAPPER TABLE OF CONTENTS Section l FAMILIARIZATION PE 4 Nomenclature 2 Comte ge intiiesee Fak ove E EAE Ee dau ANEREN aa 5 Ee EE 5 Performance Rating Chart 5 Section li ENGINE COMPONENTS CONSTRUCTION amp SERVICE 6 16 ERREECHEN ee d 6 Crankshaft and Connecting Rod 6 8 VE ll DEE 8 9 Piston and Piston gggggggggg 9 11 Centrifugal Cl teh gees eetand ccedeyweee SEENEN EE 12 RECO Starter isis sissies oe EE ENNEN RN EE Se E dee 12 Throttle Cable vele sense ERNEIEREN deeds NIE a EEN 12 Fuel Systema EE EE 13 14 ir Filtar ee Matias stout aad AA A EE EE 14 Muffler ca scene chat yada pha sot hatte eene erer deet E 14 Flywheel Magneto Inspection amp Adjustments 14 Bis NEE 14 15 B Ignition Golly ecesas torrone inir geet e gu 15 C Breaker POINtS EE 15 16 D Timing Adcjustenttttt 16 E eu TEE 16 E MTP ee ien De 16 Section Ill CARBURETOR CONSTRUCTION amp
11. a condenser capacity tester test the condenser for proper insulation resistance capacity Replace condenser if tested values are less than those shown in chart below CONDENSER CAPACITY CHART F MTI UNIT The MTI Unit is an electronically controlled contact free ignition system Since ignition tim ing is controlled with an electrical circuit pro blems due to fouling wear and rust common to a point system are eliminated A basic circuit of the MTI Unit is shown by Figure 2 35 Voltage variation Sensitive circuit Spark plug Ignition coil Secondary L MTI BASIC CIRCUIT FIGURE 2 35 NOTE The MTI Unit if suspected to be faulty can be tested with standard semiconductor testing apparatus If found to be faulty replace unit as it cannot be repaired Q SECTION lil CARBURETOR CONSTRUCTION amp SERVICE 3 1 OPERATION OF CARBURETOR The carburetor works on the spray principle It mixes air and fuel in a suitable ratio to meet engine requirements through all ranges of operation A DIAPHRAGM PISTON TYPE CARBURETOR FIGURE 3 1 FIGURE 3 1 1 Diaphragm pump 15 is activated by pressure variation in crankcase and pulls fuel through fuel inlet 21 Fuel is then fed under pressure to float valve 7 2 Engine intake pressure is applied to main diaphragm 4 by needle jet 12 while atmospheric pressure pushes on the opposite side of the diaphragm As a result float arm 6
12. agm type carburetor 1 Adjustments a Adjust the float arm height to within 0 5 0 6 of the body See Figure 3 9 HEIGHT GAUGE FIGURE 3 9 19 b Check to see that float and float valve operate smoothly after adjustment c Check free length of inlet valve spring It should measure 31 d Check pressure required to open vaive It should be 1 98 4 Ib sq in 2 Replacement a Hook the float arm around end of new float valve b Install inlet valve spring checking to make sure that spring is correctly mated with float arm guide c As float arm is being installed insert float pin to point where it is completely under set screw See Figure 3 10 OVERFLOW VALVE SEAT FLOAT ARM INLET VALVE SPRING GUIDE FLOAT PIN FLOAT VALVE FLOAT PIN SET SCREW FIGURE 3 10 d Tighten set screw NOTE Care should be taken when installing float pin If the float pin is not correctly seated and tightened then the specified float lever height cannot be obtained and the valve opening pressure will be lost H DIAPHRAGM CHECK VALVES The diaphragm check valves work in conjunction with the diaphragm pump float valve and throttle needle valve to supply proper air fuel mixture to engine See Figure 3 11 DIAPHRAGM CHECK VALVES FIGURE 3 11 1 Inspection Inspect check valve membrane for flatness and damage Replace if required SECTION II CARBURETOR CONSTRUCTION amp S
13. al allowable crankshaft runout at points B and B is shown in the chart below See Figure 2 3 amp 2 4 Sees oe FIGURE 2 3 CRANKSHAFT RUNOUT CHART 8 Lues iF aa 0019 Max Standard Dimension 2 Replace the crankshaft assembly if runout exceeds the allowable limit SECTION Il ENGINE COMPONENTS CONSTRUCTION A SERVICE C Measuring Clearance Between Connecting Rod and Crank Throw Mount crankshaft in a fixture similar to Figure 2 6 Place a mounted dial gauge over the rod end as shown and move the rod up and down for dial reading If reading exceeds allowable limit shown in chart replace crankshaft assembly FIGURE 2 4 B Measuring Clearance Between Rod and Crankshaft With connecting rod pushed against crankshaft counterweight insert feeler gauge into clearance side and take measurement Take this same measurement at four places 90 degrees apart around the rod base and if clearance exceeds the allowable limit at any point replace crankshaft assembly See Figure 2 5 and chart D Measuring Clearance Between Connecting Rod Needle Bearing and Wrist Pin 1 Using cylinder gauge measure inside diameter of connecting rod needle bearing as shown in Figure 2 7 7 FIGURE 2 7 SECTION Il ENGINE COMPONENTS CONSTRUCTION A SERVICE 2 Measure outside diameter of wrist pin with a 2 Replace main bearings and crankshaft microm
14. atio of 32 1 refill fuel tank Clean or replace Clean or replace Remove and replace Adjust timing Section II page 16 Replace Replace See Section II SECTION IX PARTS Cylinder Cover Cylinder Muffler Mounting Studs Cylinder Gasket Muffler Guard Muffler Muffler Gasket Piston Rings Piston Wrist Pin Connecting Rod Crankshaft Assembly Needle Bearing Crankcase Gasket Crankcase Starter Side Oil Seal Recoil Starter Pulley Recoil Starter Housing Recoil Starter Handle Rope Assembly Spiral Spring Reel Friction Spring Ratchet Friction Plate Recoil Starter Gasket Shim Set of 3 Bearing ON OA AON ITEM DESCRIPTION NO DESCRIPTION Woodruff Key Snap Ring Oil Seal Tank Hanger Band Support Bar Tank Band Tank Pad Fuel Tank Point and Condenser Assembly Crankcase Drive Side Flywheel Flywheel Housing Centrifugal Clutch Carburetor Air Cleaner Cover Wire Mesh Foam Element Baffle Spark Plug Boot Gasket A Intake Flange A Gasket B intake Flange B Carburetor Gasket Overflow Tube ignition Coil Assembly SECTION IX PARTS SERVICE MANUAL for SNAPPER TRIMMER ENGINES de SNAPPER POWER EQUIPMENT A KI McDonough GA 30253 07215 11 85 Printed in U S A
15. ce if necessary Clean or replace ENGINE HARD TO START Breaker points fouled Condensor bad Replace Primary or secondary wires bad Replace MTI unit bad Replace Point gap Reset point gap Section 11 page 15 16 Choke on Fuel mixture Turn off Using ratio of 32 1 fresh fuel Remove spark plug pull starter rope to clean excessive fuel Spark Plug Wet Excessive fuel suction Tickler is not fully engaged Insufficient Power or Operation Occasionally Interrupted Ingition out of time Adjust timing Section II page 16 Spark plug fouled Excess carbon build up in exhaust port Clean or Replace regap Remove muffler Clean out carbon build up in port Backfiring Ignition out of time Adjust timing Section II page 16 Remove muffler clean or re place Clean carbon build up from exhaust port Excessive carbon build up in exhaust port and or muffler TROUBLE DURING OPERATION 31 BEES SECTION VIII ENGINE TROUBLESHOOTING CHART Suddenly Stalls Inadequate Firing Knocking Within Engine ENGINE STALLS DURING OPERATION SYMPTOM PROBABLE CAUSE Out of fuel Fuel filter stopped up Fuel line stopped up Diaphragm worn or damaged Ingition out of time Primary and or secondary wires damaged Worn or damaged parts REMEDY Using r
16. diameter x 33 long braided nylon rope as replacement starter rope FIGURE 5 1 5 2 STARTER ROPE REMOVAL INSTALLATION A Pull the starter rope out about 12 until the notch in the reel lines up with the starter rope outlet Hold the reel securely to prevent its turning and pull starter rope out from inside of case See Figure 5 2 5 2 REASSEMBLY O A If spring requires replacement mount new spring in recoil starter case NOTE If existing spring jumped out of position during disassambly it can be rewound by forming a wire of slightly smaller diameter than starter case spring seat and rewinding spring inside See Figure 5 4 FIGURE 5 2 gt B Continue nolding the pulley and unwind the rope in the direction of the arrow shown in SS i DH s 26 FIGURE 5 4 Section V RECOIL STARTER REPAIR B Adjust spring inside starter housing until inner NOTE Allow reel to recoil starter rope slowly end of spring is positioned about 1 8 inch from Otherwise reel assembly and spring shaft as shown in Figure 5 5 This positions the may jump out of starter case amp spring end for easy engagement with reel hook INNER END OF SPRING OUTER END OF SPRING FIGURE 5 5 C Apply a small amount of GP grease to under FIGURE 5 7 side wear surface of reel G Install return spring D Wind starter rope on reel in direction of arrow H Install ratchet friction spring and friction shown in Fig
17. e valve 5 together As wire cap protrudes remove it from bottom end of slotted hole 3 Loosen lock nut 7 and unscrew throttle wire ferrule 8 from pipe elbow 4 4 Remove throttle wire from elbow and cap assembly 5 Replace throttle wire with new assembly B REASSEMBLY Reassemble in reverse order of above NOTE Make sure that spring plate 11 is on top of C clip 10 and centering spring 12 If assembled incorrectly engine will not function properly SYMPTOM FAILURE TO START SECTION lll CARBURETOR CONSTRUCTION amp SERVICE 3 3 CARBURETOR TROUBLESHOOTING Fuel not being fed into cylinder Excessive fuel feed Idling is unstable RPM s cannot be increased engine Stalls or engine RPM s become unstable when they are increased PROBABLE CAUSE Air leak around carburetor mount Choke not fully closed Fuel passage plugged Main jet float plugged Main adjusting screw too tight Float arm adjustment is too low Faulty assembly of inlet valve spring Incorrect installation of float arm pin Fuel level too high Dirt between float valve and seat Air filter dirty Main adjustment screw is at incorrect setting Float arm adjustment too high Needle jet clip set in too low groove location F aulty assembly of inlet valve spring Rubber cap on carburetor loose or worn Float valve dirty Incorrect setting of throttle adjusting screw Float arm incorrectly adjusted Needle
18. ein was completely up to date However due to SNAPPER S continued im provement in design requirements it is possible that the appearance of component parts may vary slightly from those of the actual engine being repaired This merely indicates that the engine has been improved to better fulfill its intended requirements 1 2 NOMENCLATURE The nomenclature drawings below Figure 1 1 show the essential parts of the SNAPPER Model 410 Trimmer Engine It is recommended that all mechanics and other repair personne become throughly familiar with the controls compo nents and operation of this engine before attempting any repairs FIGURE 1 1 4 SECTION FAMILIARIZATION 1 3 SPECIFICATIONS 78mm 76mm 3 07 3 00 S 1 4 PERFORMANCE RATING CHART SE S D A Maximum Output SS On a completely run in broken in engine Le S maximum output means the amount of power produced when the carburetor throttle valve 2 S is fully opened 1 H 5 B Continuous Rated Output e H i That power output which can be continuously 1 EA CONTINUOUS maintained Also it is the output level 1 ANGE CUTE recommended by the manufacturer for BEN H maximum performance efficiency and engine 9 durability ie EL C Maximum Torque K E J That amount of torque produced at the point ZA ae of maximum output g am D Recommended Output Range 0 9 a That output range in which the engine can be os
19. eter as shown in Figure 2 8 assembly if measurements exceed allowable E 7 TT limit shown in chart Crankshaft Journal Dimension 2 3 CYLINDER The combination cylinder cylinder head is made from a single piece of diecast aluminum for better heat dissipation and reduced weight FIGURE 2 wa A The cylinder casting contains an intake port exhaust port and two scavenging ports The inside surface is porous chrome plated for 3 If the difference between measurements 1 and 2 exceed the allowable limit shown in improved durability See Figure 2 10 chart replace the wrist pin and needle bearing And if required replace the piston and piston rings as a set O E Measuring Clearance Between Crankshaft and Main Bearings 1 Measure the outside diameter of each crankshaft journal with a micrometer See Figure 2 9 FIGURE 2 10 FIGURE 2 9 SECTION II ENGINE COMPONENTS CONSTRUCTION amp SERVICE B The operative relationship between intake scav enging and exhaust ports is shown below Figure 2 11 FIGURE 2 11 C The cylinders carburetor mounting surface intake is provided with an air hole pulse hole which transmits the pressure variation in the crankcase to the diaphragm pump in the carburetor This pulse hole is used ONLY for engines with a diaphragm valve type carburetor D Type It is NOT to be used with a float valve type carburetor See Figure 2 12 FIGURE 2 12 D Mea
20. il and check to see that piston ring ends are correctly located at drive pin position B Install gasket in correct position on crankcase C Using ring compression band mount cylinder to piston DO NOT ROTATE CYLINDER WHEN MOUNTING ONTO PISTON If cylinder is rotated during installation open ends of piston rings may catch in cylinder parts and be broken D Tighten cylinder screws securely 6 4 FLYWHEEL A Clean keyed and tapered bore section of flywheel DO NOT USE STEEL WOOL B Fit key onto crankshaft C Mount flywheel to crankshaft and tap into place if required with rubber mallet Check to make sure key is properly seated in keyway D Insert a 29 diameter bar into hole cast in flywheel Place a screwdriver between bar and clutch mounting boss to prevent fly wheel from turning E install spring washer flat washer and nut to threaded end of crankshaft Tighten securely 6 5 CENTRIFUGAL CLUTCH A Determine which clutch shoe mounting surface r M is to face outward B install a flat washer between each shoe and mounting boss C Apply thread locking compound to each clutch bolt Install and hand tighten D Place screwdriver between clutch mounting bosses to prevent flywheel from turning while tightening clutch bolts E Torque bolts to required specifications 6 6 IGNITION COIL A Mount ignition coil loosely inside flywheel housing Screws should be finger tight B Insert spark plug wire du
21. iston wrist pin hole See Figure 2 17 FIGURE 2 15 A Clearance Between Piston and Cylinder 1 Measure the maximum diameter of piston with a micrometer See Figure 2 16 FIGURE 2 17 10 SECTION Il ENGINE COMPONENTS CONSTRUCTION amp SERVICE 2 Measure the outside diameter of the wrist 2 Measure the clearance between open ends pin with a mircometer See Figure 2 18 dimension A of ring with feeler gauge 3 Replace rings if clearance exceeds allowable limit PISTON RING ENDS CLEARANCE CHART Standard Dimension 0 0 0118 D Clearance Between Piston Ring and Ring Groove 1 Measure clearances between piston rings and grooves with feeler gauge See Figure 2 20 FIGURE 2 18 3 If the clearance between piston and wrist pin exceeds allowable limit replace both as a unit PISTON WRIST PIN CLEARANCE CHART Ge S C Clearance Between Open Ends of Piston Rings 1 Using a piston for seating purposes install a piston ring inside cylinder as shown in Figure 2 19 FIGURE 2 20 2 Replace piston and rings if clearance exceeds allowable limit Standard Dimension 0 0019 0 0035 E Cleaning Piston Remove any carbon deposited on head and ring grooves Finish with No 400 fine sandpaper FIGURE 2 19 11 SECTION Il ENGINE COMPONENTS CONSTRUCTION amp SERVICE 2 5 CENTRIFUGAL CLUTCH The centrifugal clutch consists of two weighted shoes held together b
22. jet clip set in wrong groove Faulty assembly of inlet valve spring Choke partly closed Worn float valve Main jet float plugged Main adjustment screw clogged Main adjusting screw is at incorrect setting Incorrect installation of float arm pin Float arm incorrectly adjusted Faulty assembly of inlet valve spring Deteriorated diaphragm Slack throttle wire 21 REMEDY Tighten mounting screws Close choke Disassemble amp clean Disassemble amp clean Readjust Readjust Reassemble Reassemble Adjust tloat Disassemble amp clean Disassemble amp clean Readjust Readjust Disassemble amp reset clip Reassemble Fit securely or replace Disassemble amp clean Readjust Readjust Disassemble amp reset clip Resassemble Open choke Replace Disassemble amp clean Disassemble amp clean Readjust Reassemble Readjust Reassemble Replace Adjust SECTION lll CARBURETOR CONSTRUCTION amp SERVICE 3 3 CARBURETOR TROUBLESHOOTING SYMPTOM PROBABLE CAUSE REMEDY Engine stalls or Filter in fuel tank is clogged Diaphragm Type skips under load conditions but runs well for a short time when engine is restarted Faulty ventilation of fuel tank cap Pulse hole clogged Diaphragm Type Air fuel mixture too rich at high speed even with main adjusting screw all way in Worn main adjusting screw Diaphragm Type Repalce parts Main adjus
23. m flywheel Fit screwdriver between clutch mounting boss and flywheel protrusion to prevent flywheel from turning See Figure 4 1 4 3 CARBURETOR A Remove overflow pipe from retaining clip leave pipe attached to carburetor carburetor mounting screws B Using Phillips screwdriver remove the two CLUTCH C MOUNTING C Remove carburetor NOTE It may be necessary to lightly tap sides of carburetor to loossen it from gasket CAUTION If throttle control is attached to carburetor at this point then remove throttle lever contro assembly from shaft handle and remove carburetor amp THROTTLE CONTROL ASSEMBLY AS A UNIT D Loosen two retaining screws and then remove carburetor insulator mount Note that the insulator mount and its gaskets have a pressure relief hole which faces towards the crankcase this is vital during reassembly FLYWHEEL E Remove mounting screws and carburetor FIGURE 4 1 mount B If clutch is disassembled make sure that marked sides of shoes P M are matched during reassembly 4 8 RECOIL STARTER See Section Ill for carburetor disassembly 4 4 MUFFLER A Remove three screws and washers and muffler A Remove recoil starter assembly guard Parts removed with recoil starter 1 Fuel tank strap B Using 5 16 socket or wrench remove two f 2 Over flow pipe clamp muffler retaining nuts KC C Remove muffler gasket D Remove muffler gasket shield NOTE THAT LEG IS INSTAL
24. nging the opening of the throttle valve This action not only controls intake of air fuel mixture into the engine but also meters the fuel flow rate from the needle jets See Figure 3 4 UR MA MN ODDO 8 0 01918 0 8 Lote keane N N a FIGURE 3 4 B THROTTLE amp NEEDLE JET ADJUSTMENT 1 Throttle Valve and Throttle Adjusting Screw engine idling ajust engine to desired RPM s with the throttle adjusting screw stop screw See Figure 3 5 a Clockwise adjustment increases RPM s b Counterclockwise adjustment decreases RPM s FIGURE 3 5 STANDARD IDLING RPM S 2300 2700 18 2 Jet Needle Adjustment The head of the needlejet has three grooves in which a retaining clip is installed to control fuel flow from the needlejet body The clip is usually in the second groove readjustment is not usually required See Figure 3 6 DIAPHRAGM TYPE THROTTLE VALVE CLIP BAR CLIP JET NEEDLE CLEARANCE THREE GROOVES f FIGURE 3 6 a When clips are set in upper grooves the clearance between needie jet and body become less and the air fuel mixture becomes lean b Installation of clips in lower grooves increases the clearance between needle jet and body and causes the air fuel mixture to become rich D MAIN DIAPHRAGM Differential pressure between engine intake atmoshperic pressures is converted into vertical movement by the diaphragm This operate
25. red replace See Figure 4 5 REMOVE ALL CARBON INSIDE OF MUFFLER BY SCRAPING OR HEATING REMOVE ALL CARBON DEPOSITS ON TOP AND IN RING GROOVES FIGURE 4 6 E Spark Plug Clean spark plug with glass bead blaster or some other means of carbon removal After cleaning electrode and insulator re gap spark plug to 0 6 0 7 mm See Figure 4 7 FIGURE 4 5 CLEAN amp C Routine Inspection v REGAP Check the normal performance of all sliding and SPARK PLUG rotating surfaces piston piston rings cylinder crankshaft bearings oil seals etc FIGURE 4 7 Troubleshooting Chart CRANKSHAF SYMPTOM PISTON PISTON RINGS ASSEMBLY CYLINDER OIL SEAL BEARING Low eAbrasion eAbrasion eCarbon eCracked or Compression eSeize eCarbon build up chipped Scratch build up ePulse hole Not seated clogged Internal eWrist Pin eBroken eAbrasion of Worn out Engine Noise Worn Ring s pin and both bearing s ends of Rod 25 Section V RECOIL STARTER REPAIR 5 1 DISASSEMBLY A Remove binding screw B Remove friction plate 2 friction spring 3 and ratchet 4 as a unit C Remove return spring 5 See Figure 5 1 RECOIL SPRING FIGURE 5 3 C After the starter rope is completely unwound the reel should lift free from the recoil spring See Figure 5 3 NOTE Remove the reel carefully to avoid causing spring to jump out of position D Remove old rope from starter handle and reel E Use a 1 8
26. s the float valve and float arm and meters the incoming fuel flow to the carburetor See Figure 3 7 NEEDLE JET BODY LOCATING PIN HOLES THRUST PIN RUBBER DIAPHRAGM RECEIVER PAN FIGURE 3 7 1 Servicing Diaphragm Periodically the diaphragm should be visually inspected for damage and to see that the receiver pan is free of any deformation a When reinstalling diaphragm to carburetor make sure locating pins and holes are correctly aligned b Use care when handling and installing diaphragm Tighten screws in alternate cross pattern to prevent deformation of receiver pan SECTION Ill CARBURETOR CONSTRUCTION A SERVICE F FLOAT VALVE The float valve is operated by the vertical move ment of the diaphragm and when opened allows fuel to flow into the chambers See Figure 3 8 DIAPHRAGM TYPE HOOK BODY SEAT RUBBER FIGURE 3 8 Adjustment It is imperative that the float valve operate smoothly at all times and that it maintain air tightness when fully closed If the valve seat becomes damaged by dirt grit etc or shows signs of wear stepping after long periods of use then it should be replaced 2 Repair No attempt to repair a defective float valve should be made If the valve loses its airtight intergrity it should be replaced G FLOAT VALVE REPLACEMENT The following adjustment and assembly procedures should be adhered to when replacing the float valve in a diaphr
27. secondary wire connects to the spark plug See figure 2 30 FIGURE 2 31 C BREAKER POINTS If engine is equipped with breaker point type ignition the points should be checked for fouling or corrosion Clean the contact points with fine grain emery paper and if FIGURE 2 30 15 SECTION II ENGINE COMPONENTS CONSTRUCTION amp SERVICE required use a fine file to grind away any protrusions on the point surfaces Before reinstalling points apply a small amount of Molykote GP Paste or equivalent to contact arm bearing post Moisten the felt lubricator with a drop or two of oil See Figure 2 32 FIGURE 2 32 1 Breaker Point Location and Deviation Deviation within 0 007 in all directions Location within 2 3 of the center of the diameter See Figure 2 33 D 2 3D CONTACT AREA MAXIMUM OF CONTACT POINT DEVIATION FIGURE 2 33 2 Adjusting Point Gap Turn crankshaft until crankshaft cam has opened points to widest position Insert feeler gauge between points and adjust to 013 7 002 by loosening and tightening point mounting screw See Figure 2 34 FIGURE 2 34 16 D TIMING ADJUSTMENT Adjust the breaker point mounting plate screw until the point contacts begin to open as the mark on the flywheel fin lines up with the arrow and P mark on the drive side of the crankcase The ignition timing is adjusted to 25 3 BTDC as a result of these adjustments o E CONDENSER Using
28. st seal into slot in flywheel housing NOTE Spark plug outlet from coil and ground wire should face outwards from the engine C Place a brass shim or strip of paper of correct tolerance 016 020 0 5 mm across magnetic section of flywheel D Install flywheel housing with ignition coil installed to crankcase Insert holding screws finger tight E Working from behind flywheel housing adjust coil to shim thickness Tighten ignition coil retaining screws F Remove housing and remove shim G Install housing and torque screws to required specifications NOTE Install wire lead clamp and fuel tank band to crankcase when installing flywheel housing 6 7 CLUTCH ASSEMBLY A If applicable mount clutch drum assembly inside clutch housing B Attach clutch housing to drive side of engine 6 8 BREAKER POINTS A Mount breaker points and condenser B Adjust ignition timing 1 Adjust to where points begin to open as match mark on flywheel fines up with designated mark M or P on crankcase 2 Ignition timing 25 tg BTDC 28 SS Section VI SEQUENCE OF REASSEMBLY C Adjust point gap to 011 015 when point leg is located on high point of cam See Figure 6 1 FIGURE 6 1 1 Check position and offset of both points See Figure 6 2 D 2 30 008 CONTACT AREA ee OF CONTACT POINT MAXIMUM FIGURE 6 2 2 OFFSET 008 Max in all directions POSITION 2 3 Max at center of
29. sure the cylinder bore with a cylinder gauge as shown in Figure 2 13 0 E Using a screwdriver or knife clean carbon deposits from combustion chamber and exhaust port Use care not to damage or scratch chrome plated cylinder wall 2 4 PISTON AND PISTON RINGS The piston is made from a special aluminum alloy to reduce weight and bearing load during operation Its crown is semi spherical in shape to facilitate flow of exhaust gases and scavenging air as in all 2 cycle engines the scavenging ports open up before the end of the exhaust stroke to allow the pressurized air fuel mixture from the crankcase to feed into the combustion chamber This also assists in dispelling any remaining exhaust gases See Figure 2 14 SECTION I ENGINE COMPONENTS CONSTRUCTION amp SERVICE a ZA KI A FIGURE 2 16 FIGURE 2 14 2 Calculate the difference between piston Piston rings are made from a special cast iron diameter and cylinder bore and then surface treated by parkerization for e improved wear resistance They are kept in 3 GE a nee 2 location on the piston by roll pins which prevent their open ends from being caught in the cylinder ports The piston wrist pin is kept in place by a PISTON CLEARANCE CHART lock ring on each side See Figure 2 15 7 1 5354 0 0014 0 0 0019 B Clearance Between Piston and Wrist Pin 1 Using a cylinder gauge measure the inside diameter of the p
30. ting screw has been overtightened Diaphragm Type Replace Parts Main jet plugged Clean Float arm incorrectly adjusted Diaphragm Type Readjust Tighten Tighten or replace Faulty acceleration Loose diaphragm cover plate Diaphragm leaking Plugged needle jet Clean Idling RPM s too low Incorrect assembly installation of float arm and valve spring Increase RPM s Reassemble Worn float valve Replace Carburetor over Float valve operates incorrectly Clean flows Incorrect assembly of diaphragm REassemble Float arm adjustment too high Diaphragm Type Readjust SECTION IV SEQUENCE OF ENGINE DISASSEMBLY NOTE Before disassembling engine remove all 4 5 CYLINDER COVER fuel from tank 4 1 AIR CLEANER A Remove Air Cleaner Parts removed with air cleaner A Remove spark plug wire from plug B Remove cylinder guard 4 6 FAN CASE A Remove ignition wires from retaining clamp Remove clamp B Remove flywheel housing Parts removed with flywheel housing 1 Fuel tank retaining strap 2 Ignition coil 1 Filter Element 2 Baffle plate 3 Wire mesh 4 Air cleaner cover 4 1 FUEL TANK A Disconnect fuel line from carburetor 4 7 CENTRIFUGAL CLUTCH B Loosen fuel tank retaining strap C Remove Fuel tank D Remove rubber shock pads by sliding towards center of crankcase A Remove centrifugal clutch fro
31. ure 5 6 After 3 rounds bring plate O the rope out at the reel notch L Apply thread locking compound to binding screw and tighten in place WIND STARTER ROPE 3 1 2 TURNS FIGURE 5 6 E Mount reel onto spring Make sure there is positive engagement between reel and spring hook C F Holding reel wind starter rope an additional t EXPLODED VIEW OF RECOIL three turns on reel Pull slack out recoil port STARTER ASSEMBLY See Figure 5 7 27 Section VI SEQUENCE OF REASSEMBLY 6 1 PISTON A Mount piston rings in ring grooves with open ends fitted to drive pins Top side of piston rings are marked T B Assemble piston to connecting rod making sure hole in piston crown is facing intake side of engine C Insert snap rings securely on each side of wrist pin 6 2 CRANKCASE A Fit starter side of crankcase to crankshaft 1 Apply oil to mounting pins on crankcase 2 Insure that mating surfaces of crankcase are clean Apply gasket ce ment to gasket and mating surfaces of crankcase 3 Appiy GP grease to oil seal lip B Combine crankcase halves and tighten screws Wipe away any excess gasket cement C Check axial play of crankcase CRANKSHAFT AXIAL PLAY CHART Standard Dimension 0008 001 Allowable Limit Adjustment shims for eliminating excessive axail play are 0004 002 004 008 6 3 CYLINDER A Coat piston with a light coat of o
32. when starting the be repaired It should however have any engine Because the internal parts of the carbon buildup removed by using a screwdriver primer pump are very small care should be or heavy wire brush taken not to lose or incorrectly reassemble them when repairs are being made See Figure 2 26 2 11 FLYWHEEL MAGNETO INSPECTION A ADJUSTMENTS The flywheel magneto contains an Ignition system which includes the coil contact breaker and flywheel The contact breaker can be one of two types MTI unit or points Instructions for inspection adjustments and servicing of parts is contained in the following text A Flywheel Magnetic steel for power generation is cast into the flywheel Its fins serve as the cooling mech anism for the engine and it also serves as the clutch mount Since the flywheel serves various functions care should be taken not to drop it on the floor during repairs See Figure 2 28 FIGURE 2 26 2 9 AIR FILTER The Model 410 engine uses an air filter made of plastic with a polyurethane foam filter element which requires cleaning every 25 hours or less of operation To clean the element wash thoroughly in solvent or detergent squeeze and immerse in engine oil Squeeze again ejecting most of the oil and then remount in case See Figure 2 27 FIGURE 2 28 29 e 33 24 Take Off Hole 1 Timing Mark On the flywheel designed for breaker points there is a red colored
33. y used with stability It is also the best working A TI range for maximum economy and durability oF T of the engine 0 6 BR 3000 4000 5000 6000 7000 8000 Crank Shaft Revolution RPM SECTION I ENGINE COMPONENTS CONSTRUCTION amp SERVICE 2 1 CRANKCASE The crankcase is diecast aluminum and has an internal compression ratio of 1 3 to 1 5 Complete airtightness of the crankcase must be maintained in order to properly compress the airfuel mixture from the intake port before it is fed to the combustion chamber Locating pins are cast into the flywheel housing for proper mating with the drive side of the crankcase Because the flywheel housing and crankcase are machined as a unit the whole assembly all three parts must be replaced should any one part need replacing See Figure 2 1 FIGURE 2 1 2 2 CRANKSHAFT AND CONNECTING ROD The crankshaft is made of forged steel with carburized and ground finished crankpin and journals for increased wear resistance The connecting rod is an integral part of the crankshaft assembly and cannot be removed Should either the crankshaft or rod require replacing then the entire crankshaft assembly must be replaced Replacement items for the crankshaft assembly are wrist pin needle bearing main bearings key washers and nuts See Figure 2 2 FIGURE 2 2 A Measuring Crankshaft Runout With crankshaft supported at points A and A in a suitable fixture the tot
34. y a spring of predetermined tension As the engine RPM s begin to exceed holding tension of the spring the shoes rotate outward due to centrifugal force and make contact with the clutch drum on the work side of the machine See Figure 2 21 FIGURE 2 21 A Clutch Drum Diameter and Clutch Revolution Clutch IN revolution is defined as that engine speed at which the clutch begins to transmit rotary power to the clutch drum with a loading of 0 02 IN LBS CLUTCH CHART Clutch Drum Inside Diameter Weight Tightening Torque 1 8 2 2Ibs inch NOTE Take care not to get any thread locking compound on any clutch parts or fasteners 2 992 or 3 070 2 9 3 1 B The clutch shoes are stamped P and M on either side Make sure that the letters are matched on whichever side is being used C If clutch has been operated at overload conditions for a long period of time then glazing of the shoes will probably occur Roughing of the shoes with sandpaper will remedy this situation D Clutch shoes should properly cared for last indefinitely if 12 2 6 RECOIL STARTER The recoll starter is a separate subassembly of engine When the starter rope which is wound on the reel by the tension of the spiral spring is pulled the ratchet linked with the reel opens causing the starter pulley to turn See Figure 2 22 At the operators end the throttle cable has an adjustable control lever and FULLY
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