Snapper 311 User's Manual
Contents
1. Service Manual for SNAPPER Model 310 amp 311 Trimmer Engine INDUSTRIES Company SNAPPER POWER EQUIPMENT McDonough GA 30253 07115 9 85 Printed in U S A2. O jum c Q gt im o 5 MODEL 310 amp 311 TRIMMER ENGINE H 10 T N o m Z lt McDonough GA 30253 SNAPPER POWER EQUIPMENT SNAPPERS TABLE OF CONTENTS FOREWORD FAMILIARIZATION ccccecceececcsssceccsssaecesscescesseucnececs 2 Section AIR FILTER amp CHOKE BASE 3 Section Il CARBURETOR cccsscscceccecerseccesssascuscesceccecaucsseccens 3 5 Fuel PUI PG E es ree 3 4 Fuel Me Or iG scie ele be nine 4 High Low RPM Adjustments ccccssssececsececscaccessreccecessuceuecensece 5 Section 111 CARBURETOR MOUNT amp REED 1 5 Section IV FUEL TANK 6 Fuel Tank NERONE 6 Fuel Line amp di ee EE 6 Section V MUFFLER amp 7 Section VI CLUTCH ccscsscsccssceneeccvceccecscceccecaccesssssscacauseccssces 7 8 Housing eo rien cavea nn vei nid ee ccce oe Eee 7 Cl teli DEI ies RE ks E o aga ones 7 Cl teh S088 Deren eu ca caesa e id 8 Section RECOIL STARTER 8 11
3. Dry the carburetor body with air and inspect the operation of the throttle valve and lever 2 5 Re assemble the carburetor in reverse order of disassembly Replace all damaged and ques tionable parts Replacement parts kits are listed below O E M Repair Kit 1 Filter Screen 2 Needle Valve 3 Metering Lever 4 Metering Lever Pin 5 Metering Lever Spring B Gasket Diaphragm Kit 1 Fuel Pump Diaphragm 2 Fuel Pump Gasket 3 Metering Diaphragm 4 Metering Gasket Before re assembling the carburetor onto the engine remember to inspect the carburetor moun ting gasket If any damage is suspected replace the gasket Model 310 amp 311 TRIMMER ENGINES Section 111 Carburetor Mount and Reed Assembly 3 1 With the carburetor removed Ref section 2 remove the four screws from the rear of the car buretor mount These screws have a thread locking material but they can be used again for re assembly See Figure 3 1 Se ee URDU ER FIGURE 3 1 A Remove the mount from the rear of the engine Care should be taken not to damage the gasket B Visually inspect the large center hole for excessive debris If excessive debris is present disassemble the reed assembly from the carburetor mount for cleaning 3 2 To disassemble the reed assembly from the car buretor mount remove the two screws in the forward end of the mount Notice for re assembly the ar rangement of the outside backup plate bowed out and t
4. body See Figure 2 3 FIGURE 2 3 B With the metering diaphram and clean and inspect for damage The diaphragm should be free of holes and debris The gasket should show no breaks or deformities C The main needle valve can now be removed from the carburetor body Being careful not to loose the spring retained under the lever remove the screw re taining the lever pin Remove the lever pin spring and needle valve Care should be taken not to dam age the point of the needle valve or distort the spring See Figure 2 4 FIGURE 2 4 D Note for re assembly of the needle valve and lever group the lever end should be adjusted to 1 16 below the level of the outside surface of the carburetor body See Figure 2 5 FIGURE 2 5 removed v 2 3 On the top left side of the carburetor body are located the low speed and high speed adjustment screws These are marked on the carburetor body as L and H The high speed screw is covered with silicon patch at the factory Remove the silicon and then remove the two screws with their springs Notice for re assembly the long screw and long spr ing are for the low speed adjustment side See Figure 2 6 FIGURE 2 6 To re assemble seat screws gently and back out 1 and 1 4 turns for initial adjustment 2 4 Thoroughly clean the carburetor body with sol vent and air gun removing all debris Give special at tention to all small openings and orifices
5. TRIMMER ENGINES B The cylinder bore inside should be 1 3790 1 3805 inches measured top and bottom at three points around the circle of the bore Note that the cylinder is tapered at the extreme bottom for ease of instali ing the piston assembly Measurements must be taken above this taper for accurate readings 9 6 Remove the piston and connecting rod assembly from the crank shaft assembly Note for re assembly that the piston skirt has a large circular notch in the forward area for crank shaft counter weight clearance Clean excessive carbon from the piston and inspect for scars or signs of wear Inspect the piston ring for chips cracks or signs of wear Insure the ring is free moving in the ring groove Be sure the ring gap is located at the ring stop pin in the piston Do not disassemble the piston and connecting rod it is a factory assembly Inspect the bearings for any feeling of tightness or roughness FIGURE 9 6 A Refer to the dimensional specifications chart in section 10 If the piston ring is within specifications but the ring to groove is not replace the piston and connecting rod assembly The piston and connecting rod assembly is furnished with a new ring installed B If the piston ring gap is within specifications but the cylinder end gap is not replace the cylinder with Snapper P N 42024 The cylinder is furnished with a new cylinder gasket and two new mounting screws C If the piston ring is not within sp
6. an ohm meter or continuity tester See Figure 8 1 FIGURE 8 1 8 2 Remove the two mounting screws from the igni tion module and set the screws and module aside until final re assembly Note that the ground tab for the switch is mounted under one of the module mounting screws 8 3 For re assembly of the ignition module align the flywheel magnets with the module and adjust the air gap to 010 inches Tighten the mounting 5 5 to 28 inch pounds torque Section IX Complete Block Assembly Remove the crank shaft sleeve and set it aside until final re assembly See Figure 9 1 d FT FIGURE 9 1 9 2 On top of the flywheel over the area of the magnets is an elongated mark that indicates the location of the crank shaft key Rotate the flywheel until the mark is opposite the ignition module moun ting area This positions the flywheel counter weight at the module area Using a soft faced mallet sharply tap the side of the counter weight at a place directly across from the key to loosen the flywheel from the crank shaft See Figure 9 2 FIGURE 9 2 12 A Do not strike the side or the end of thecrank shaft Severe damage might result to the shaft or the inter nal bearings B For re assembly the flywheel need only be set over the crank shaft aligned with the crank shaft key 9 3 On top of the flywheel are two starter dog assemblies These are permanently assembled onto the flywheel an
7. Recoil 5 9 10 Recoll nto els cute E ce Ud uuu 10 11 Section VIII SWITCH amp IGNITION MODULE eee rennen 11 Section IX COMPLETE BLOCK 12 13 i re EEEMX 12 Flywheel Housing Leu rena Tw ciega e E aU RD SOR RES 12 Crankcase Assembly Cylinder 13 Piston amp Connecting Rod Assembly nn eene nnne 13 Section X CHARTS eene eee onera a parra naa n v a oua Eae 14 15 Dimensional Specifications cccecccececucecececscecececerecerscneacecsees 14 Tune Up Specifications issues cit eh er er FRUI 14 Torque Requirements ceniccascaceivecccitnnecncccceteasdnuaaaesesescewsdcutarean 14 Engine Troubleshooting 14 Carburetor Troubleshooting nnns 15 SNAPPER POWER EQUIPMENT __ McDonough GA 30253 2 Section AIR FILTER amp CHOKE BASE Caution Before proceeding with engine disassembly empty fuel from the fuel tank Remove the spark plug For re assembly all parts of questionable condition should be replaced with new parts 1 1 Remove air filter cover by depressing top and bottom of cover between your f
8. arter housing from the engine Pull the starter rope to check for proper pulley and recoil spring function and inspect for worn or frayed rope 7 2 If repair is required remove the screw pulley retainer from inside the housing Carefully lift up on the pulley If the recoil spring is being lifted with the pulley replace the pulley to its position Pull the rope handie out a few inches Hold the pulley from recol ing and drop the rope free See Figure 7 2 e FIGURE 7 2 Continue holding the pulley and work the slack rope to the inside of the housing and unwind the rope from around the pulley See Figure 7 3 FIGURE 7 3 If the pulley still will not l ft free repeat the pro cedure With the pulley free from the recoil spring lift the pulley out being careful not to unwind the spring See Figure 7 4 Model 310 amp 311 TRIMMER ENGINES FIGURE 7 4 A If the recoil spring does come out of the housing it can be re installed using two pair of locking pliers such as vise grip or equivalent small enough to insert through the side louver openings of the housing Remembering that the spring winds a clockwise direction from the outside winding working inward Place the hooked end of the spring around the post inside the housing Insert one of the pair of pliers through the side louver of the housing across the top of the post and extending approximately 3 8 inch to the inside Clamp the pliers firm but
9. d should never be removed However the dog springs can be replaced if necessary With the hooked end facing up place the spring over the pin and on top of the dog Pass the lower end of the spring under the dog and lift the spring end over and past the flywheel fins ina clockwise rotation Continue this procedure until the whole spring is under the dog From the under side of the dog hook the hooked end of the spring around the dog Place the lower end of the spring in front of the flywheel fin adjacent to the dog See Figure 9 3 FIGURE 9 3 9 4 Remove the crank shaft key from the crank shaft and the four screws from the flywheel housing Lift the flywheel housing off the crank shaft housing and set these aside until final re asembly For re asembly tightened the housing mounting screws to 120 inch pounds torgue See Figure 9 4 w N FIGURE 9 4 9 5 Remove the two screws from the crank case housing and separte the crank case assembly from the cylinder block by pulling in a straight line direc tion Avoid a twisting motion this could cause the ends of the piston ring to scar the cylinder wall For re assembly tighten the crank case to cylinder Screws to 120 inch pounds torque See Figure 9 5 O FIGURE 9 5 A Inspect the cylinder for scars or signs of excessive wear clean out excessive carbon and gasket residue In ali cleaning care should be taken not to scar the surfaces 13 Model 310 amp 311
10. e screw centered on the cover plate of the filter side Care should be taken in removing the plate not to damage the gasket or the fuel pump diaphragm Note for re assembly the arrangement of gasket outside diaphragm inside against the car buretor body See Figure 2 1 FIGURE 2 1 B Carefully remove and visually inspect the gasket and the diaphragm The gasket should show no breaks or deformities The diaphragm should be in spected for flatness and continuity with no holes The flapper valves in the diaphragm should be flat and free from curling C Thoroughly clean the cover plate with solvent wash and air gun Blow through the internal pulse hole of the cover to insure that there are no obstructions D The filter screen can now be removed from the car buretor body using the sharp point of a needle or knife and working it against the inside edge in an up ward motion Do not pry between the outside edge and the carburetor body This practice would result in deforming the filter screen See Figure 2 2 FIGURE2 2 E Wash the filter screen with solvent and blow clean with air gun from the inside surface outward 2 2B METERING SIDE A Remove the four screws in the metering side plate Care should be taken in removing the plate not to damage the gasket or the metering diaphragm Note for re assembly the placement of the diaphragm outside with its small metal center fac ing out and the gasket inside against the carburetor
11. e shaft Lift the drum off and inspect the inside for any wear on the clutch surface or the center bearing See Figure 6 2 A For re assembly use thread locking compound and tighten the screw to 150 inch pounds torque Note Later model clutch drums use a lockwasher on the screw and do not require this compound FIGURE 6 2 However if using thread locking compound it should be used on engine shaft threads only NOT on clutch screw it will lock head to drum 6 3 The clutch shoe assembly is removed as a whole unit and should never be taken apart With Special SNAPPER Spanner Wrench inserted into the center hub tap the wrench handle sharply in a counter clockwise direction Care should be taken not to scar the engine shaft Remove the assembly and in spect for wear See Figure 6 3 Note for re assembly the outside face of the clutch shoe assembly is marked OUT Hand tighten only 6 4 If either the clutch drum or the clutch shoe assembly show excessive wear or are of ques tionable condition replace both with new parts FIGURE 6 3 Section VII Recoil Starter Assembly 7 1 With the clutch assembly removed from the front of the engine Ref section 6 remove the four screws from the upper perimeter of the starter housing and C the one screw from the lower center retaining the _ lower shroud extension Set the lower shroud aside until final and re assembly See Figure 7 1 um FIGURE 7 1 A Lift the st
12. ecifications replace with a new ring 9 7 The crank case assembly is a factory assembled unit and should never be dis assemble However in dividual parts for this assembly are available for parts sales Section X CHARTS Inspect the connecting rod end of the crank shaft for any signs of wear scratches or dark burn spots For additional information to determine the ser viceability of internal engine parts see the dimen sional specifications chart below Dimensional Specifications Chart Crankshaft run out 010 Piston diameter 1 375 1 376 inches Cylinder bore diameter 1 3790 1 3805 inches Piston ring width 580 680 inches Piston ring thickness 0615 0625 inches Cylinder ring end gap 0670 0770 inches Ring piston groove side clearance 005 inches max Engine compression 90 120PSI Tune up Specifications Ignition module air gap 010 inches Spark plug gap 025 inches ChampionDJ8 Engine idle speed 2800 3400 RPM Engine high speed 6800 7200 RPM RPM readings taken with Snapper Bump head installed and lines fully extended to line cutter Torque Specifications Chart e Cylinder head bolts 120in Ibs Muffler screws 56in Ibs Carburetor mount mounting bolts 15in Ibs Choke base mounting screws 40in Ibx Flywheel housing bolts 120in Ibs Ignition module mounting screws 28in Ibs Starter housing screws 40in 1 5 Clutch drum retaining screw 150in Ibs Spark plug 150in 165 Clutch shoe assemb
13. he inside reed plate bowed inward against the carburetor mount See Figure 3 2 3 3 Wipe the debris from the carburetor mount and reeds and re assemble 3 4 For final re assembly of the carburetor mount to the engine tighten the mounting screws evenly in a criss cross pattern to a final torque of 15 inch pounds FIGURE 3 2 Section IV Fuel Tank Assembly 4 1 With the carburetor mount removed Ref section 3 1A the fuel tank assembly can be lifted freely from the engine The front and rear rubber mounting pads can be retained for re assembly if no damage is apparent 4 2 Remove the fuel tank cap The cap is a vented cap and should be inspected Looking at the inside face of the cap locate the end of the rubber vent By squeezing the long ends toward each other open the vent passage and inspect the opening to insure it is free of debris See Figure 4 1 VENTED FUEL FIGURE 4 1 4 3 The fuel line and filter assembly is disassembled from the tank by first carefully removing the retain ing ring from around the fuel line The end of the filter is left projecting out the bottom of the fuel tank With the ring removed force the line and filter assembly inside the tank Next reach inside the tank through the neck and pull the assembly free from the tank See Figure 4 2 FIGURE 4 2 A To test the line and filter assembly submerge the filter portion in a container of water and force air through the f
14. hield onto the engine it is advisable to always use a new gasket Apply thread locking compound to the screw threads and tighten the muffler screws to 56 inch pounds torque Section VI i Clutch SNAPPER s special service bulletin No 1985 C dat ed 7 1 85 covers replacement of an undersized bush ing in clutch drum P N 42068 This undersized bush ing may allow the clutch drum to slip forward rub ing the plastic clutch cover P N 42070 Bushing fail ures of this type will usually occur during the first hour of machine operation and can be solved by re placement of the clutch drum and clutch cover with the corrected parts See 6 1 and 6 2 for instructions When reassembling earlier model clutch drums apply thread locking compound to the crankshaft threads only not clutch screw Then install the clutch drum and tighten the screw to 150 inch pounds torque The later model clutch drums have retaining screws fitted with lockwashers which eliminates the need for thread locking compound 6 1 Remove the four screws from the clutch housing Leave the loose screws inserted into the housing and set the clutch housing and engine stand aside until final re assembly See Figure 6 1 FIGURE 6 1 6 2 With the clutch drum now exposed insert a 3 16 standard screw driver such as a Stanely No 1008 8 or equivalent into the drive shaft hole and loosen the screw The screw is retained inside the drum but will come free from the engin
15. ingers thus releasing the locking tabs FIGURE 1 1 1 2 The foam air filter can be removed from the air filter cover Wash the filter and cover in solvent or soapy water Allow to dry Saturate filter thoroughly with light oil Squeeze excess oil from the filter and re install it into the air filter cover 1 3 Take out the two screws mounting the choke base Note the placement of the spring washer under the choke lever fingers out for re assembly Wash in solvent or soapy water Re assemble lever and spring washer onto choke base by re installing the screws through the holes and set aside until final re assembly 1 4 To re assemble the choke base onto the engine care should be taken not to cross thread the screws With the choke base assembly and screws in posi tion turn the screws backwards counter clockwise until you feel the thread drop into place then pro ceed to tighten by turning clockwise Tighten the screws to 40 inch pounds torque Model 310 amp 311 TRIMMER ENGINES Section CARBURETOR 2 1 With the air filter and choke base removed ref section 1 remove the throttle cable from the car buretor throttle arm Using a screw driver carefully remove the fuel line from the carburetor 2 2 CARBURETOR DISSASSEMBLY The carburetor has two main areas of concern As viewed from the rear the right side is the fuel pump and filter side The left side is the metering side 2 2A FUEL PUMP AND FILTER SIDE Remove th
16. ly Hand tight ENGINE TROUBLESHOOTING Engine does not start or is hard to start Engine turns smoothly NO Recoil starter obstructed Engine damaged internally YES Section 9 ram NO r Fuel is in fuel tank Fill with proper mixture using fresh fuel YES NO Spark plug shows fuel Fuel supply blocked Carburetor malfunction YES Section 3 amp 14 Spark plug damaged Spark plug fires Damaged wire grounded or oil fouled YES Section 11 SI low Compression 90 120 PSI NO Spark plug loose Cylinder screws loose Section 12 YES PSI high Excessive carbon build up Sections 5 amp 9 Engine flooded Section 14 ES Air gap incorrect Ignition module damaged Section 8 Carburetor base loose Damaged reed Internal engine wear Sections 3 amp 12 Ignition module weak Rod bearings damaged Dn pz wi 14 CARBURETOR TROUBLESHOOTING CHART START Hard starting Fuel dumping from carburetor Floods engine when not running Rich idle Idles with needle closed Erratic idle L Needle needs frequent adjustment ds up while idling Will not accelerate 15 Over rich acceleration Low power Will not 4 cycle No rich drop off MAINTENANCE RECORD NAME MECHANIC WEEKLY MONTHLY QUARTERLY 16 5
17. not tight enough to damage the housing Now locate the second pair of pliers directly across on the opposite side and clamp them firm allowing to extend approximately 3 8 inch to the inside Wind the spring one coil at a time placing it under the extended jaws of the pliers When completely wound carefully remove the pliers See Figure 7 5 FIGURE 7 5 B If it is necessary to replace the spring the replacement is furnished pre wound for assembly Leave the retainer on the new spring to keep it wound and place the spring into the housing Position the hooked end of the outer winding of the spring around the post inside the housing Remember that the spring winds in a clockwise direction from the outside sinding working in inward With the spring in position carefully remove the retainer Refer to Figure 7 5 7 3 To replace the rope or the pulley remove the rope and pulley from the starter housing as described in paragraphs 7 1 and 7 2 Separate the rope from the pulley and replace with new parts as necessary A To re assemble the rope onto the pulley use a 33 inch length of I 8 inch diameter rope Insert one end of the rope through the larger hole in the side of the pulley and under the stop pin inside the pulley Tie a knot securely in the opposite end of the rope then pull the rope through the pulley seating the knot in to the hole and against the stop pin See Figure 7 6 ee 4 3 FIGURE 7 6 B Inser
18. pe does not completely retract pull the rope handle approximately 8 inches and hold the pul ley to prevent it from recoiling Pull the slack rope to the inside of the housing and wind the pulley one additional turn Pull the slack rope to the outside of the housing and slowly release the pulley Refer to Figure 7 2 B With the recoil tensioned enough to completely retract the rope pull the rope handle until all of the rope is extended Hold the rope to prevent it from retracting Continue to hold the rope and attempt to turn the pulley clockwise If the pulley will turn the spring tension is correct If the pulley will not turn the spring tension is too tight un wrap one coil of rope gt C If the spring is properly tensioned but will not completely retract the rope check for pulley drag rope too long or recoil spring to weak D For final re assembly of starter housing onto the engine the mounting screws should be tightened to 40 inch pounds torque install the pulley retainer and screw See Figure 7 9 11 Model 310 amp 311 TRIMMER ENGINES Section VIII Switch and Ignition Module Assembly NOTE Since condition of ignition module is more easily checked while engine is assembled all other probable causes of weak spark such as faulty or broken wires fouled plug etc should be checked before any engine disassembly 8 1 Disconnect switch from the ignition module Test the switch for continuity and function with
19. t the free end of the rope through the guide hole of the starter housing from the inside of the housing Thread the rope through the starter rope handle and tie a knot securely See Figure 7 7 10 FIGURE 7 7 C If the starter rope has simply come untied inside the pulley it can be re installed in reverse order to that mentioned above 7 4 With the starter rope and pulley together and the rope through the guide hole of the starter housing apply a small amount of grease onto the top face of the recoil spring and onto the center shaft inside the starter housing Turn the pulley so the six teeth are facing up and place the pulley down onto the housing shaft If the hub of the pulley will not drop freely into the recoil spring use a small screw driver and while applying slight downward force on the pulley reach through the side louvers of the housing and under the pulley Pull the inside coils of the spring from under the pulley hub See Figure 7 8 FIGURE 7 8 7 5 To wind the spring for retracting the starter rope pull the rope through the rope guide to the inside of the housing While holding the rope to prevent it from wrapping around the pulley wind the pulley in a clockwise direction 4 turns Hold the pulley from re coiling and pull the rope through the rope guide to the outside of the housing Carefully allow the pulley to slowly re coil winding the rope onto the pulley Re FIGURE 7 9 A If the ro
20. uel line A steady flow of bubbles should result B For re assembly the replacement fuel line and filter are already assembled together To re install the line and filter form a loop in a length of small diameter stiff wire and pass the loop through the bottom hole of the tank and out through the fill neck Insert the tip end of the line inside the wire loop and draw the wire through the bottom hole seating the filter base inside the tank See Figure 4 3 C Re install the retaining ring over the fuel line and firmly seat it against the bottom of the fuel tank FIGURE 4 3 Section V Muffler and Shield 5 1 The muffler and shield can be removed from the engine at any time without respect to any other engine components Remove the two screws at the top of the muffler and shield Remove the muffler and shield from the engine Inspect the inlet and outlet of the muffler and the exhaust port of the engine for excessive carbon buildup It is preferred that carbon build up be removed by using a piece of wood as a scrape However if necessary a metal ob ject can be used but care should be taken not to scar the piston See Figure 5 1 FIGURE 5 1 Model 310 amp 311 TRIMMER ENGINES 5 2 The muffler and shield can only be separated after the two screws mounting them onto the engine have been removed If necessary to separate the shield from the muffler remove the last remaining screw 5 3 When re assembling the muffler and s
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