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UEL

YSTEM

AND

OVERNOR

The function of the fuel system is to store fuel, mix the fuel with air in the correct ratio and deliver it to the intake

port. The fuel system consists of the following components:

•

Fuel tank

•

Fuel lines

•

Fuel filter

•

Carburetor and insulator block

NOTE:

When working on the fuel systems, look at the whole system. A problem will rarely be isolated to one

component.

Fuel Line

The fuel line used by MTD is GREENBAR

. This is

a multi-layer fuel line that meets the current EPA guide-
lines.

NOTE:

This fuel line has a thin inner liner. If a tear

forms in this inner liner, fuel can get between
the liner and the hose. This will cause the
liner to collapse, cutting off the fuel flow.

NOTE:

The fuel line must be replaced every time it

is disconnected from the brass barb on the
carburetor.

NOTE:

Replace the fuel line only with GREEN-

BAR

700 series fuel line.

Inspect the fuel lines

•

Are they cracked?

•

Are they clogged?

•

Are they brittle?

NOTE:

If the answer to any of the above is yes,

replace the fuel lines. When replacing fuel lines, low permeable fuel line must be used in order to meet
EPA and CARB standards.

NOTE:

The nipple has a sharp edge that will damage the inner lining of the fuel line. Replace the fuel line

every time it is removed from the carburetor fuel nipple.

•

Drain the fuel tank or clamp the fuel line before starting work to prevent spillage.

•

Dispose of drained fuel in a safe and responsible manner.

Figure 4.1

NBR inner liner

THV barrier layer

NBR intermediate layer

Reinforcement

CSM Cover

Picture courtesy of Avon Automotive

When working around the fuel system, do not bring any sources of heat, spark, or open flame
near the work area.

! WARNING

CHAPTER 4: THE FUEL SYSTEM AND GOVERNOR

Summary of Contents for 61 series

Page 1: ...the product s Oper ators Manual supplied with the equipment No liability can be accepted for any inaccuracies or omission in this publication although care has been taken to make it as complete and a...

Page 2: ......

Page 3: ...ine 15 General torque specifications 15 Definitions 17 Chapter 2 Basic Troubleshooting Introduction 17 Steps to troubleshooting 17 Define the problem 17 Identify factors that could cause the problem 1...

Page 4: ...Autochoke 52 Temperature compensating auto choke 53 Primer 54 Carburetors 55 Inspecting the carburetor 55 Disassembly and rebuilding the carburetor 56 Governor 61 Governor shaft 62 Governor cup and t...

Page 5: ...96 Chapter 8 Exhaust To remove replace the conventional muffler 99 Catalytic converter muffler 101 Chapter 9 Cylinder Head Cylinder Head 103 Valves 106 Chapter 10 Crankshaft piston and Connecting Rod...

Page 6: ...IV...

Page 7: ...ent shall MTD be liable for poor text interpretation or poor execution of the procedures described in the text If the person using this manual is uncomfortable with any procedures they encounter they...

Page 8: ...vents Respirator when working with chemical or solvents Appropriate tinted eye protection when cutting or welding Flame resistant headgear jacket chaps when cutting or welding WARNING WARNING CAUTION...

Page 9: ...ation Whichever method is more appropriate will be used In many cases both will be used so that the manual is handy as a quick refer ence guide as well as a step by step procedure guide that does not...

Page 10: ...d d e r h S r e p p i h C C D Mower long shaft M1 N Mower short shaft M0 E Mower short shaft M1 P Mower long shaft M0 F Mower short shaft no shroud Q Mower short shaft M0 G Garden Cart Side Discharge...

Page 11: ...lways start with the model number Maintenance The recommended maintenance intervals listed in this manual are a guideline They are adjustable for local con ditions First oil change at 5 hours If equip...

Page 12: ...ing failure no start occurs 3 Cleaning the spark plug NOTE MTD does not recommend cleaning spark plugs Use of a wire brush may leave metal deposits on the insulator that causes the spark plug to short...

Page 13: ...ition it can be cleaned and reused The paper pleated filters can be shaken or lightly tapped to free the debris from the filter NOTE Never use compressed air on a paper air filter Compressed air will...

Page 14: ...oil To simply look at synthetic oil and to compare it with Petroleum based oil there is very little difference However when you look at the two through a microscope it is easy to see the difference Sy...

Page 15: ...ading it in to get the oil level reading See Figure 1 5 4 The oil level is determined by the lowest point on the dipstick that is completely covered with oil To check the oil with a 1 4 turn dip stick...

Page 16: ...n the bottom of the dipstick tube A Place an approved oil drain pan next to the base of the dip stick B Remove the drain plug using a 1 4 extension See Figure 1 8 C Allow all of the oil to drain into...

Page 17: ...pment should be no more than 30 days old Because it may already have been stored at the refinery or gas station for a week or more fuel should be purchased in small quantities and stored in safety app...

Page 18: ...s were equipped with a fuel filter placed between the fuel tank and the car buretor See Figure 1 10 2 Currently the engines are equipped with a fuel filter installed in the fuel tank where the fuel li...

Page 19: ...bolts that secure the valve cover using a 10mm wrench and remove the valve cover from the engine NOTE If care is used not to damage the valve cover gas ket it can be re used 5 Confirm that the piston...

Page 20: ...e fulcrum nut with a 14mm wrench tighten the jam nut to a torque of 80 106 in lb 9 12 Nm using a 10mm wrench 11 Double check the clearance after tightening the jam nut to confirm that it did not shift...

Page 21: ...N 5 9 1 6 9 3 3 m N 7 1 8 6 4 2 l a c i t i r c n o N n i s r e n e t s a F m u n i m u l A 4 1 M 2 1 M 0 1 M e z i s 8 M 6 M 5 M 4 M e z i s 3 4 7 2 6 1 s b l t f 3 9 8 3 2 2 1 1 s b l n i 8 4 e d a...

Page 22: ...61 65 and 70 Series Vertical Shaft Engines 16...

Page 23: ...to troubleshooting NOTE The steps and the order of the steps that follow are a suggested approach to troubleshooting the MTD engine The technician does not necessarily have to follow them as described...

Page 24: ...cally accept that the customer is correct with their description of the problem Try to duplicate the problem 2b Check the general condition of the equipment visually I Cleanliness of the equipment wil...

Page 25: ...n in the cylinder occurring at the right time II Compression enough pressure in the cylinder to convert combustion into kinetic motion It also needs sufficient sealing to generate the vacuum needed to...

Page 26: ...governor setting or stuck governor a Check RPMs using a tachometer b RPMs should not droop under moderate to heavy loads V Low compression a Check valve lash b Check compression c Check leak down to...

Page 27: ...il to exit the engine via any low resistance paths Piston rings Confirm with leak down test Smoke will be more pronounced under load Repair may not make economic sense Valve guides and intake valve st...

Page 28: ...ope and see if the spark goes away at the same time the engine dies 4 Engine over speed A Continual over speed Binding or damaged external governor linkage or carburetor throttle Mis adjusted governor...

Page 29: ...paired equipment confirming that the initial diagnosis was correct If it was wrong start the troubleshooting process over again NOTE Sometimes the engine will have multiple problems at the same time B...

Page 30: ...mber with an external air source and will allow the technician to listen for air leaking at the valves piston rings and the head gasket NOTE These are general instructions Read and follow the instruct...

Page 31: ...head gasket Air escaping from the exhaust Leaking exhaust valve Air escaping from the carburetor Leaking intake valve Gauge reading low Cylinder and piston rings are in good condition Gauge reading mo...

Page 32: ...combustion chamber will result in an artificially high compression reading 1 Install a compression gauge in the spark plug hole 2 Confirm that the gauge is zeroed then pull the starter rope repeatedl...

Page 33: ...air filter housing See Figure 2 3 To measure the crankcase pressure 1 Remove the dipstick 2 Attach a manometer to the dipstick tube 3 Start the engine 4 Read the measurement on the manometer See Fig u...

Page 34: ...61 65 and 70 Series Vertical Shaft Engines 28...

Page 35: ...61 65 and 70 series engines Paper filer with a thumb screw door Paper filter with a snap fit door Oval foam filter housing Round foam filter housing Paper filter with a thumb screw To access the air f...

Page 36: ...control bracket using a 10mm wrench See Fig ure 3 4 3 Remove the two nuts that hold the air filter body to the carburetor mounting studs using a 10 mm wrench See Figure 3 4 4 Disconnect the crankcase...

Page 37: ...steps in reverse order Foam air filter housing To remove the air filter housing 1 Remove the air filter by following the steps described in the previous section 2 Remove the screw that holds the air f...

Page 38: ...mer out of the housing See Figure 3 10 NOTE Behind the filter housing is a steel plate with formed rubber gaskets vulcanized to each surface See Figure 3 11 NOTE Mark or note the orientation of the pl...

Page 39: ...rs will col lapse the inner lining cutting off fuel flow 2b Double nut the studs for removal with a washer between the serrated faces of the nuts See Figure 3 12 2c After the second stud is removed th...

Page 40: ...nhook the stabilizer spring that takes up the play between the governor arm the governor rod and the throttle arm on the carburetor NOTE The carburetors are not inter changeable from one engine model...

Page 41: ...e gasket to the shape of the intake port The bowl vent channel in the insulator faces the carburetor with the exit toward the bottom There is a small hole in the insulator to carburetor gasket The hol...

Page 42: ...61 65 and 70 Series Vertical Shaft Engines 36...

Page 43: ...cted from the brass barb on the carburetor NOTE Replace the fuel line only with GREEN BARTM 700 series fuel line Inspect the fuel lines Are they cracked Are they clogged Are they brittle NOTE If the a...

Page 44: ...some parts of the United States Fuel make up varies sea sonally and geographically Ethanol is the primary additive used to oxygenate fuel Ethanol in fuel creates a lot of problems for gasoline engines...

Page 45: ...ilter is located in the fuel tank It can be removed and cleaned with a can of carb cleaner or replaced See Figure 4 4 NOTE On some early production engines an in line filter was used See Figure 4 5 Fi...

Page 46: ...o pull a vacuum on the fuel tank with the gas cap in place 4 Attempt to pressurize the fuel tank with the gas cap in place NOTE The tank should not hold any pressure nor any vacuum Replace the cap if...

Page 47: ...nbolt and remove the tank See Figure 4 8 5 Install by following the previous steps in reverse order Charcoal canister fuel tank To remove replace the fuel tank 1 Drain the fuel out of the fuel tank in...

Page 48: ...Slanted neck tank To remove the fuel tank 1 Drain the fuel out of the fuel tank into an approved container 2 Disconnect the fuel line from the tank 3 Remove the recoil starter by following the proce d...

Page 49: ...ree systems that can be used Charcoal canister fuel caps Charcoal canister system with the canister snapped into the tank Charcoal canister system with the canister snapped into the shroud NOTE All fu...

Page 50: ...vapors 2 The vapors exit the fuel tank through the roll over valve vent NOTE The fuel cap used with the charcoal canister system is not vented If a vented cap is used the EVAP system will not work Se...

Page 51: ...as follows 1 The gasoline evaporates letting off vapors 2 The vapors exit the fuel tank through a vacuum hose 3 The vapors are routed through the charcoal canister See Figure 4 20 4 The activated char...

Page 52: ...nister or between the canister and the tank Engine runs rich Raw gasoline in the charcoal canister A blockage in the line between the char coal canister and the carburetor insulator plate Engine runs...

Page 53: ...e Figure 4 22 3 Inspect the rubber grommet replace if damaged 4 With the grommet on the roll over valve install the roll over valve by pressing it into the opening in the tank See Figure 4 23 5 Instal...

Page 54: ...following the steps described above 2 Connect a vacuum pump to the roll over valve 3 Hold the roll over valve in an inverted position 4 Apply a vacuum to the roll over valve See Figure 4 24 NOTE The r...

Page 55: ...ter snapped into the shroud 1 Remove the recoil starter by following the procedures described in Chapter 6 Starters 2 Remove the fuel cap and tether by unscrewing them 3 Remove the fuel tank nut 4 Rem...

Page 56: ...handle bar depending on the applica tion If the choke plate fails to close fully when the knob is pulled the mower will be difficult or impossible to start when cold NOTE The rod connecting the choke...

Page 57: ...ake adjustments if the choke is not opening or closing fully 1 Remove the ignition module by following the steps described in Chapter 7 Ignition System 2 Loosen the screw that secures the air vane bra...

Page 58: ...replace the air door 1 Remove the starter and blower housing by following the steps described in Chapter 6 Starters NOTE The air door is mounted to the underside of the blower housing See Figure 4 34...

Page 59: ...ure compensator is installed on the muffler As the muffler heats up a bi metallic coil inside will expand The expand ing coil will rotate a lever towards the muffler pulling on a rod This rod will ove...

Page 60: ...tors that use a primer are easily identified by the lack of a choke plate and the addition of a primer port See Figure 4 40 To remove replace the primer 1 Remove the air filter housing by following th...

Page 61: ...d runs ok then that was the problem If it does not start move on to the car buretor Inspecting the carburetor 1 Remove the float bowl and check for dirt and or varnish 2 Inspect the needle valve and n...

Page 62: ...4 43 3 Remove the bowl bolt using a 10mm wrench See Figure 4 44 NOTE From this point an assessment can be made about the viability of rebuilding the carbure tor If extensive corrosion is evident repla...

Page 63: ...ect to wear it is suggested that technicians replace the valve and spring any time the carbure tor is disassembled for cleaning A square cross section gasket seals the bowl to the body of the carburet...

Page 64: ...ation NOTE The main jet secures the emulsion tube in the central column of the carburetor See Figure 4 49 7 The throttle stop screw has a large pliable lip around the head of the screw That lip secure...

Page 65: ...ut away view the passage by the metering port is visible See Figure 4 53 NOTE The pilot screw regulates how much of this pre mixed fuel air emulsion is allowed to enter the throat of the carburetor to...

Page 66: ...able is 1 800 RPM 160 RPM set using throttle stop screw See Figure 4 55 For mower applications the idle speed is not normally critical because the operator is not provided with a throttle control 16 C...

Page 67: ...n index mark to orient the shaft to the arm on installation remove the arm and go to step 3 1d Carefully slide the Governor arm off of the governor shaft 2 If the governor arm is being installed witho...

Page 68: ...d steps 3 Remove the sump by following the steps described in Chapter 10 Disassembly 4 Remove the hair pin clip from the governor shaft See Figure 4 60 5 Slide the governor arm out of the engine block...

Page 69: ...gine rpm and usually presents as an over speeding engine 11 Install the sump by following the steps described in Chapter 10 Disassembly 12 Rotate the governor shaft clockwise as far as it will go 13 P...

Page 70: ...ngle screw models Inspect the plate for any deformity discard if any is found 4 Slide the gear shaft out of the gear and cup See Figure 4 66 5 Install by following the above steps in reverse order NOT...

Page 71: ...le alternative but it does not extend service intervals NOTE MTD recommends the use of petroleum oil during the break in period to ensure the piston rings cor rectly break in Synthetic vs Petroleum ba...

Page 72: ...e dipstick without threading it in to get the oil level reading See Figure 5 2 4 The oil level is determined by the lowest point on the dipstick that is completely covered with oil To check the oil wi...

Page 73: ...p stick tube 1 Remove the dip stick 2 Remove the screw at the top of the dip stick tube See Figure 5 4 3 Pull the dip stick tube out of the engine block 4 Inspect the O rings on the dip stick and the...

Page 74: ...forcing addi tional oil up to the cylinder head See Figure 5 7 The second oil passage runs along the bottom side of the cylinder This is the oil return passage As the name implies it allows the oil c...

Page 75: ...ystem 2 Remove the two screws that hold the PCV chamber cover to the engine block using a 10mm wrench See Figure 5 9 3 The cover and gasket can be separated from the chamber See Figure 5 10 NOTE The d...

Page 76: ...gure 5 12 6 Inspect the oil drain back port Make sure it will allow oil to drain back into the engine See Figure 5 13 NOTE Starting in the 2012 model year some engines where equipped with a new PCV br...

Page 77: ...the breather port of the engine requiring the crankshaft to be removed to get it out 7 Reassemble the PCV 8 Tighten the cover bolts to a torque of 27 in lbs 3 Nm 9 Inspect the PCV tubing for cracks b...

Page 78: ...61 65 and 70 Series Vertical Shaft Engines 72...

Page 79: ...shroud to the engine See Figure 6 1 3 Remove the fuel cap 4 Lift the shroud off of the engine 5 Remove the engine cover and replace the fuel cap 6 Remove the three nuts that secure the recoil assem b...

Page 80: ...el or starter cup NOTE If the flywheel or starter cup is replaced the complete starter should be replaced as well to prevent a repeat failure 2 If the engine has a steel starter cup remove it by remov...

Page 81: ...tight to seat the knot firmly in the recess in the back of the pulley See Figure 6 6 6 Wind the spring completely Then relieve it minimum 1 full turn counting when the pulley knot aligns with the rop...

Page 82: ...djusted there is room between the recoil housing and the pulley to wind on more tension See Figure 6 8 10 Install the starter and tighten the starter nuts to a torque of 80 106 in lbs 9 12 Nm Figure 6...

Page 83: ...that are held in the disengaged position by two torsion springs 3 Inspect the pawls and torsion springs for wear and damage See Figure 6 10 4 Carefully lift the spring and pulley out of the recoil ho...

Page 84: ...on springs and pawls so that the long arm of the spring reaches outside of the pawl and draws it toward the center of the assembly See Figure 6 12 NOTE The rolled end of the pawl fits in the recess in...

Page 85: ...lace the starter relay 1 Unplug the starter harness See Figure 6 13 2 Remove the screw that secures the relay and dip stick tube using a 10mm wrench 3 Disconnect the two 12 AWG wires from the bottom o...

Page 86: ...d lead from the middle tab of the blade brake switch See Figure 6 14 5 Connect a Digital MultiMeter DMM that is set to the Ohms scale to the two terminals on the bot tom of the relay See Figure 6 16 N...

Page 87: ...y back wire on it See Fig ure 6 18 8 Reconnect the DMM with it still on the Ohms scale See Figure 6 19 NOTE The DMM should read less than 0 2 Ohms This relay has a burnt contact 9 If the test results...

Page 88: ...emove the dip stick 4 Remove the two screws that secure the starter using a 10mm wrench See Figure 6 21 NOTE If replacing the starter make sure both dowel tubes are in the engine block See Figure 6 22...

Page 89: ...Starters 83 Schematic 12V Charger connection 40A Fuse 12V Battery Motor Module Blade brake switch Starter relay Key switch...

Page 90: ...61 65 and 70 Series Vertical Shaft Engines 84...

Page 91: ...e full throttle position 4 Squeeze the safety bail if equipped and pull the starter rope If sparks can be seen in the spark tester the ignition system is working NOTE If there are sparks present in th...

Page 92: ...4 NOTE If the reading is low the module is shorted to ground and may not produce a spark The wire will need to be traced back to the mod ule to find the short 7d Alternatively a jumper wire could be...

Page 93: ...erly and the connection is good at the spade terminal but releasing the bail or turning off the switch fails to stop the engine then the problem lies within the module 9 The module 9a Normal performan...

Page 94: ...e ignition should produce voltage approaching 12 000 See Figure 7 9 9e At pull over speed 600 RPM voltage should be at least 10 000V See Figure 7 10 NOTE Flash over voltage will vary with spark plug c...

Page 95: ...laminations was observed to be in the 8K 9K range See Figure 7 12 NOTE There may be slight variation in specification due to production variation and other factors such as temperature Resistance figur...

Page 96: ...d to confirm opposite polarity of the flywheel mag nets See Figure 7 13 11 Inspect the flywheel The flywheel is a frequently forgotten component of the ignition system It holds the magnets that induce...

Page 97: ...amage may result Inspection of the spark plug Inspection of the spark plug can provide indications of the operating condition of the engine Light tan colored deposits on insulator and electrodes is no...

Page 98: ...of the flywheel in relation to the crankshaft Proper timing is main tained by a steel key NOTE Regardless of which type of magneto is used the test procedures are the same Module removal 1 Unplug the...

Page 99: ...er gauge between the mod ule and the flywheel See Figure 7 16 NOTE The air gap should be 0 012 0 020 0 3 0 5 mm 4 Rotate the flywheel so that the magnets align with the legs of the module while holdin...

Page 100: ...e by 4a Squeeze the barbs together at the engine end of the cable housing and push it through the brake assembly 4b Unhook the Z fitting from the brake assembly See Figure 7 18 5 Disconnect the connec...

Page 101: ...vot point and the bolt by the dip stick is in a slot See Figure 7 20 4 Use a spring clamp to hold the safety bail against the upper handle bar 5 Position the brake assembly so that the edge of the bra...

Page 102: ...emove the flywheel 1 Remove the recoil assembly by following the steps described in Chapter 6 Starter 2 Lift the fan shroud off of the three studs that locate it See Figure 7 23 3 Loosen the flywheel...

Page 103: ...e Figure 7 27 NOTE If the key is damaged it must be replaced If there is damage to the crankshaft key way the engine must be short blocked because crankshafts are not available as a service part 6 On...

Page 104: ...el nut to a torque of 47 52 ft lbs 64 70 Nm NOTE If the engine has a cast iron flywheel install a starter cup by placing the starter cup on the flywheel Allow the protrusion on the bot tom of the star...

Page 105: ...lers a standard muffler covered here or a catalytic converter muf fler that will be covered later in this chapter To remove replace the conventional muffler 1 Remove the muffler cover that is secured...

Page 106: ...ust gasket is made of a graphite material It will stick to the sealing surfaces when pressure is applied tearing when pressure is relieved The gasket can only be used one time 3 Clean the cylinder hea...

Page 107: ...converter so that it can complete its chemical reaction inside the muffler NOTE Stoichiometric point is defined as the point where the mass ratio of fuel to air is chemically balanced For gasoline th...

Page 108: ...Burned clean using a butane or propane torch 3 Install the inlet screen cover and tighten the screws to a torque of 44 in lbs 5 Nm 4 Clean the gasket material from the air injector and the muffler See...

Page 109: ...iod of time The oil will seep into the breather chamber NOTE It is not absolutely essential to remove the fan shroud but taking the engine cover off if equipped will ease access to some components 1 D...

Page 110: ...their original locations on engine with substantial 100 hours operat ing time 7 Remove the muffler by following the steps described in Chapter 8 Exhaust 8 Double nut and remove the exhaust studs using...

Page 111: ...ad bolts are loosened 14 Position the cylinder head on the engine block 15 Install the 4 head bolts and tighten them to a step torque of 212 in lb 24 Nm in an alternating diagonal pattern See Figure 9...

Page 112: ...lve repairs are to be accomplished by replacing the cyl inder head 1 Remove the cylinder head by following the steps described earlier in this chapter 2 Remove the rocker arms by 2a Remove the jam nut...

Page 113: ...6 mm 9 Install the valves in the cylinder head by following steps 2 5 in reverse order 10 Test the valves for leaks by 10a Place the cylinder head on a couple of wood blocks with the valves facing up...

Page 114: ...61 65 and 70 Series Vertical Shaft Engines 108...

Page 115: ...pter 4 Fuel system and Governor 3 Remove the starter by following the steps described in Chapter 6 Starter systems 4 Remove the flywheel and ignition module by following the steps described in Chapter...

Page 116: ...ure 10 2 NOTE Align the timing marks to allow easier removal of the cam shaft and to help protect the compression relief from damage NOTE Early production of the 1P70 series engines had a steel cam sh...

Page 117: ...he proper orientation NOTE Rotating the crank shaft after the connecting rod bolts are removed will help to separate the connecting rod from the cap See Figure 10 6 14 Push the piston out of the cylin...

Page 118: ...5 Check the crank shaft for straightness by measuring the run out The crank shaft run out can be check by 5a Place the crank shaft on a pair of matched V blocks or in the engine block with the sump i...

Page 119: ...pter See Fig ure 10 11 4 Repeat steps 3 and 4 on the other rings NOTE Piston rings are not available as service parts If any of the end gaps are out of spec the engine must be short blocked 5 Install...

Page 120: ...ing rod and compare the measurements to those listed in the chart at the end of this chapter See Figure 10 15 NOTE Take two measurements 90 degrees apart This will check the out of roundness of the co...

Page 121: ...Compare the measurements to those that are listed in the chart at the end of the chapter 3 Inspect the cylinder cross hatch See Figure 10 18 NOTE The X65 series engine has a smooth aluminum bore no cr...

Page 122: ...OTE Do not de glaze an X65 series engine cylin der If the cylinder needs to be de glazed replace the cylinder block Bearings There are two bearings to inspect a plain bearing in the sump and a ball be...

Page 123: ...ankshaft into the cylinder block bearing NOTE Pre lube the crank shaft with clean 10W 30 motor oil or engine assembly lube NOTE Use an old piece of microfiche or a seal protector to protect the oil se...

Page 124: ...e lube the connecting rod with clean 10W 30 motor oil or engine assembly lube 4f Install the connecting rod cap Apply a small amount of releasable thread locking compound such as Loctite 242 blue to t...

Page 125: ...marks See Figure 10 28 7 If removed install the governor arm by following the steps described in Chapter 4 Fuel systems and Gov ernor 8 If removed install the oil return deflector See Figure 10 29 9...

Page 126: ...ribed in Chapter 9 Cylinder head 12 Install the muffler by following the steps described in Chapter 8 Exhaust 13 Install the fuel tank by following the steps described in Chapter 4 Fuel systems and Go...

Page 127: ...und P61 0 000 0 000 0 000 0 005 0 000 0 005 P65 0 000 0 000 0 000 0 005 0 000 0 005 X65 0 000 0 000 0 000 0 005 0 000 0 005 P70 0 000 0 000 0 000 0 005 0 000 0 005 Cylinder taper P61 0 000 0 000 0 000...

Page 128: ...020 1 026 26 060 P70 1 182 30 015 1 182 30 025 1 184 30 061 Connecting rod ID piston side P61 0 520 13 204 0 520 13 212 0 521 13 232 P65 0 520 13 204 0 520 13 212 0 521 13 232 X65 0 512 13 004 0 512 1...

Page 129: ...551 13 984 0 547 13 898 P65 0 550 13 966 0 551 13 984 0 547 13 898 X65 0 550 13 966 0 551 13 984 0 547 13 898 P70 0 550 13 966 0 551 13 984 0 547 13 898 Cam shaft OD sump side P61 0 550 13 966 0 551...

Page 130: ...511 1 091 27 711 1 081 27 465 P65 1 085 27 561 1 089 27 661 1 079 27 416 X65 1 085 27 561 1 089 27 661 1 079 27 416 P70 1 092 27 740 1 096 27 840 1 086 27 593 Compression ring end gap P61 0 006 0 150...

Page 131: ...0 200 P65 0 006 0 150 0 008 0 200 X65 0 006 0 150 0 008 0 200 P70 0 005 0 130 0 007 0 170 Spark plug gap P61 0 024 0 600 0 031 0 800 P65 0 024 0 600 0 031 0 800 X65 0 024 0 600 0 031 0 800 P70 0 024...

Page 132: ...lbs 12 14 Nm Flywheel nut 48 52 ft lbs 64 70 Nm 48 52 ft lbs 64 70 Nm 48 52 ft lbs 64 70 Nm 48 52 ft lbs 64 70 Nm Head bolt 20 22ftlbsstep 28 30 Nm 20 22ftlbsstep 28 30 Nm 20 22ftlbsstep 28 30 Nm 20 2...

Page 133: ...asive Ingestion is when hard particles are introduced into the engine Particles can be introduced into the engine by leaks in the air intake system through a dirty oil fill plug or by particles of met...

Page 134: ...ottom will show this Other sources of abrasives that get into the engine includes carbon that builds up on the top side of the piston metal shavings from the wear of engine parts or dirt enter ing thr...

Page 135: ...are trapped in the oil will cause the lower portion of the combustion chamber to wear ing more than the upper portion NOTE Wear of only one bearing surface on a new engine could be a sign of a manufa...

Page 136: ...s It forms a cushion between moving parts protecting them from contact with each other When an engine is properly lubricated all of the moving parts glide on a thin film of oil If that film breaks dow...

Page 137: ...of the failure Larger size abrasive particles can render the lubricants ineffective leading to an engine failure An overheated engine can cause the oil to break down leading to a failure In an engine...

Page 138: ...mage to it Usually the connecting rod will be in several pieces after it breaks making it hard to find where the first failure was 2 All engines create a certain amount of vibration when they are oper...

Page 139: ...like cylinder heads the hottest part of the engine As they try to expand they fight against the head bolts The head bolts will not move to allow the expansion so the head warps to allow the expan sion...

Page 140: ...n of the fuel spontaneously igniting the combustion chamber prior to the spark plug firing In this state the flame front from the detonation will start to travel through the combustion chamber and a s...

Page 141: ......

Page 142: ...MTD Products Inc Product Training and Education Department FORM NUMBER 769 03354 02 12 2013...

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