Robin America EH72 Service Manual Download Page 64

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ITEM

EH72D

STD

Limit

CYLINDER
* Inside dia.

* Roundiness after reboring.

* Cylindricity after reboring.

STD

84.000 - 84.022

(3.3071 - 3.3080)

To be rebored when the
difference between
max. and min. of
diameter reached to
0.1 (0.004).

0.01

(0.004)

1st

reboring

84.250 - 84.272

(3.3169 - 3.3178)

Ditto

—

2nd

reboring

84.500 - 84.522

(3.3268 - 3.3276)

—

0.015

(0.0006)

—

PISTON
* Piston size (At skirt in thrust direction)

STD

83.980 - 84.000

(3.3063 - 3.3071)

83.890

(3.3028)

1st o/s

84.230 - 84.250

(3.3161 - 3.3169)

84.140

(3.3126)

2nd o/s

84.480 - 84.500

(3.3260 - 3.3268)

84.390

(3.3224)

16 mm

Unit : mm(in.)

Summary of Contents for EH72

Page 1: ...SERVICE MANUAL EH72 ENGINES Model PUB ES1545 Rev 09 03 ...

Page 3: ...BURETOR 47 9 ELECTRIC STARTER 50 10 TROUBLESHOOTING 52 10 1 NO ENGINE OPERATION 52 10 2 STARTING DIFFICULTIES 53 10 3 INSUFFICIENT OUTPUT 54 10 4 OVERHEAT 54 10 5 ROUGH IDLING 55 10 6 HIGH ENGINE OIL CONSUMPTION 55 10 7 HIGH FUEL CONSUMPTION 56 10 8 DETONATION 56 10 9 ENGINE MISFIRE 57 11 INSTALLATION 58 12 SERVICE DATA 59 12 1 STANDARD DIMENSIONS AND SERVICE LIMITS 59 12 2 TIGHTENING TORQUE 65 12...

Page 4: ......

Page 5: ...r Cooling Valve Arrangements Overhead Valve OHV Lubrication Full pressure type with oil Cooler Lubricant Automotive Engine Oil SAE 20 30 or 10W 30 Class SE or higher Capacity of Lubricant L U S gal 1 55 0 41 Carburetor Down Draft Float Type With Accel Pump Fuel Automotive Unleaded Gasoline Fuel Feed System Diaphragm Pump Pulse type Ignition System Flywheel Magneto Solid State Spark Plug NGK BPR6ES...

Page 6: ...ade in conformity to SAE internal combustion engine standard test code J1349 2 2 CONTINUOUS RATED OUTPUT The continuous rated output is the output of an engine at optimum governed speed which is most favorable from the view point of engine s life and fuel consumption When the engine is installed on a certain equipment it is recommended that the continuous output required from the engine be kept be...

Page 7: ...E CURVES EH72D 2000 2400 2800 3200 3600 10 13 4 5 6 7 15 20 1 20 26 8 REVOLUTION r p m HORSEPOWER kW HP TORQUE N m kgf m 55 5 61 45 4 59 CONTINUOUS RATED HP RECOMMENDED HORSEPOWER RANGE MAXIMUM TORQUE MAXIMUM HORSEPOWER ...

Page 8: ...ensures a good lubrication environment Ball bearing installed in the throttle bearing of the carbureter Reliability Unusually high dust proofing by a double compartment air cleaner and inner vent type carbureter Carbureter equipped with acceleration pump and receives excellent throttle response A fine distribution suction pipe and effective combustion chamber shape provide greater cubustion stabil...

Page 9: ...rankcase has a mounting surface on the output shaft side where the main bearing cover is attached 4 2 MAIN BEARING COVER The main bearing cover is an aluminum die casting which is mounted on the output shaft side of the crankcase Pilots and bosses are machined on the cover for direct mounting of the engine onto such machines as generators and pumps It is easy to inspect inside of the engine after ...

Page 10: ...ng is barrel face and the second ring has a tapered face The oil ring is designed for better sealing and less oil consumption in combination with 3 pieces 4 6 CAMSHAFT The camshaft is made of special cast iron and camshaft gears are casted together in one piece Each 2 cam robs are provided for intake and exhaust valves correspondingly Both sides of the shaft fit into the plane bearings on the cran...

Page 11: ...ng fins and passages design lead cooling air to the exhaust valve area for the optimum cooling Hard alloy valve seats are molded in the cylinder head INTAKE VALVE EXHAUST VALVE Fig 4 8 4 9 GOVERNOR SYSTEM The governor is a centrifugal flyweight type which ensures constant operation at the selected speed against load variations The governor gear with governor weights is installed inside of main bea...

Page 12: ...ngine oil through the full flow type oil filter to the journal and pin portions of crankshaft and camshaft 4 12 IGNITION SYSTEM The ignition system is a transistor controlled magneto ignition system which consists of a flywheel and an ignition coil with a built in transistor installed onto the crankcase FLYWHEEL IGNITION COIL Fig 4 10 CHARGE COIL CABLE EXTENDED REGULATOR Fig 4 11b CHARGE COIL REGU...

Page 13: ...the key switch is turned to off Accelerator pump is provided for obtaining quick and good throttle response 4 15 AIR CLEANER The air cleaner is a heavy duty type with a dual element system primary side is urethane foam half wet and secondary side is dry type ACCELERATOR PUMP FUEL CUT SOLENOID VALVE Fig 4 12 URETHANE FOAM ELEMENT WING NUT CLEANER COVER Fig 4 13 4 16 FUEL PUMP The engine is equipped...

Page 14: ... 10 4 17 SECTIONAL VIEW OF ENGINE CARBURETOR OIL PUMP IGNITION COIL FLYWHEEL INTAKE MANIFOLD OIL PUMP FILTER MAIN BEARING COVER P T O SHAFT Fig 4 15 ...

Page 15: ... 11 Fig 4 16 ...

Page 16: ...assemble each group of disassembled parts Carefully handle disassembled parts and clean them with washing oil if necessary Use the correct tools in the correct way When disconnecting electric wirings be sure to hold and disconnect the connector housing 5 2 SPECIAL TOOLS No Special Tool is needed for disassembling and reassembling the engine For pulling off the flywheel universal type puller being ...

Page 17: ... 2 Muffler cover M6 x 12 6 pcs 3 Muffler M8 nut 4pcs 4 Muffler bracket M8 x 16 bolt and washer 2pcs STEP 4 STEP 3 STEP 2 A MUFFLER BLACKET MUFFLER COVER M6 FLANGE BOLT 2 pcs M6 FLANGE BOLT 2 pcs M8 BOLT WASHER 2 pcs M6 FLANGE BOLT 2 pcs GASKET MUFFLER M8 SUS FLANGE NUT 4 pcs STEP 1 GASKET OIL DRAIN PLUG ON BOTH SIDE OIL FILLER CAP GUIDE oil level OIL LEVEL GAUGE A Fig 5 2 ...

Page 18: ...ER BASE HOSE CLAMP M6 FLANGE BOLT 3 pcs BREATHER PIPE HOSE CLAMP 14 Step Parts to remove Remarks and procedures Fasteners 5 Air cleaner cover and elements Remove breather pipe from 1 cylinder head 6 Air cleaner base M6 x 12 3 pcs BREATHER PIPE Fig 5 4 Fig 5 3 ...

Page 19: ... 6 pcs 8 Chock control lever and link 1 Remove the choke knob 2 Remove the choke contol link M6 bolt 1 pc CHOKE CONTROL ROD RETURN SPRING WAVED WASHER LINK PIVOT CHOKE CONTROL LINK CHOKE KNOB CLAMP M5 TAPPING SCREW 1 pc BLOWER HOUSING M6 FLANGE BOLT 6 pcs M6 FLANGE BOLT 2 pcs STEP 7 STEP 8 Fig 5 5 ...

Page 20: ...cs CARBURETOR GASKET carburetor 16 Step Parts to remove Remarks and procedures Fasteners 9 Carburetor At first remove fuel pipe Take out carburetor along with governor rod and rod spring M8 x 80 2 pcs FUEL PIPE Fig 5 7 Fig 5 6 ...

Page 21: ...ver M6 x 12 3 pcs M6 self lock nut 11 Speed control bracket unit M6 x 12 3 pcs 12 Starting motor At first remove wiring M8 x 65 2 pcs STOP PLATE SPRING WASHER SPEED CONTROL LEVER M6 FLANGE BOLT 3 pcs M8 FLANGE BOLT 2 pcs M6 SELF LOCK NUT 1 pce FRICTION WASHER FRICTION WASHER BRACKET UNIT speed control STEP 11 STEP 10 STEP 12 GOVERNOR SPRING GOVERNOR ROD ROD SPRING GOVERNOR LEVER M6 BOLT AND WASHER...

Page 22: ... AND WASHER ASSY 2 pcs TO STOP DIODE IGNITION COIL PLUG TERMINAL SPARK PLUG CAP M6 BOLT AND WASHER ASSY 2 pcs Fig 5 9 18 Step Parts to remove Remarks and procedures Fasteners 13 Fuel pump Remove pluse pipe at first M6 x 12 2 pcs 14 Ignition coil 1 Take out plug cap 2 Remove ignition coil 3 Cut out stop wire fixing bands 4 Disconnect stop wires from ignition coil M6 x 30 bolt washer 4 pcs IGNITION ...

Page 23: ...HER WASHER M5 BOLT AND WASHER 4 pcs Step Parts to remove Remarks and procedures Fasteners 15 Flywheel Remove key from crankshaft and then pull out flywheel by using puller M18 nut washer spring washer 16 Charge coil M5 x 20 4 pcs 15A coil M5 x 25 4 pcs 30A coil Fig 5 12 Fig 5 14 Fig 5 11 FLYWHEEL PULLER Fig 5 13 ...

Page 24: ...GE BOLT 3 pcs M6 FLANGE BOLT 3 pcs M6 FLANGE BOLT 3 pcs CYLINDER BAFFLE 2 CYLINDER BAFFLE 4 CYLINDER BAFFLE 1 CYLINDER BAFFLE 3 M6 FLANGE BOLT 2 pcs STOP DIODE M6 FLANGE BOLT 1 pce WIRING HARNESS M6 FLANGE BOLT 2 pcs REGULATOR TO IGNITION COIL TO IGNITION COIL TO OIL PRESSURE SWITCH Fig 5 15 18 Regulator and Stop diode M6 flange bolt x 12 1 pce ...

Page 25: ...arks and procedures Fasteners 19 Oil cooler Take out oil hoses M6 Flange bolt 4 pcs OIL COOLER HOUSE CLAMP HOUSE CLAMP OIL HOUSE 1 OIL HOUSE 2 HOUSE CLAMP BRACKET UNIT M6 FLANGE BOLT 2 pcs M6 FLANGE BOLT 2 pcs STEP 19 A A Fig 5 16 ...

Page 26: ...s and procedures Fasteners 20 Intake manifold M8 flange nut 4 pcs 21 Spark plug NGK BPR6ES or CHAMPION RN9YC STEP 21 STEP 21 SPARK PLUG GASKET INTAKE MANIFOLD M8 FLANGE NUT 2 pcs GASKET SPARK PLUG STEP 20 M8 FLANGE NUT 2 pcs Fig 5 17 ...

Page 27: ...head Put the marking of original position onto each push rod rocker arm and valve for reassembly M10 x 65 8 pcs STEP 22 STEP 22 STEP 23 STEP 23 M6 FLANGE BOLT 4 pcs ROCKER COVER ROCKER COVER HOOK PIVOT NUT PUSH ROD ROCKER ARM BOLT PIVOT GASKET rocker cover M10 FLANGE BOLT 4 pcs GUIDE PLATE CYLINDER HEAD 2 GASKET 2 M6 FLANGE BOLT 4 pcs ROCKER ARM PIVOT NUT PUSH ROD GUIDE PLATE CYLINDER HEAD 1 GASKE...

Page 28: ...plate BREATHER COVER M6 FLANGE BOLT 2 pcs INTAKE VALVE EXHAUST VALVE SPRING RETAINER VALVE SPRING COLLET VALVE COLLET VALVE SPRING RETAINER STEP 24 24 Step Parts to remove Remarks and procedures Fasteners 24 Intake exhaust valves Breather cover Breather plate M6 x 00 2 pcs Fig 5 20 Fig 5 19 ...

Page 29: ...MAIN BEARING COVER M8 FLANGE BOLT 10 pcs STEP 25 THRUST BEARING Step Parts to remove Remarks and procedures Fasteners 25 Main bearing cover Take out key from PTO shaft Rap PTO shaft with polyvinyl tape not to damage oil seal by key groove edge M8 x 45 10 pcs Fig 5 22 Fig 5 21 ...

Page 30: ...rts to remove Remarks and procedures Fasteners 26 Camshaft and tappet Mate the markings both on crankshaft gear and camshaft gear and then take out camshaft Put the marking of original position onto each tappet for reassembly Fig 5 24 Fig 5 23 ...

Page 31: ...take out along with piston Put the marking of original position onto each piston ring clip piston pin connecting rod and cap for reassembly M8 4 pcs 28 Crankshaft STEP 27 STEP 27 STEP 28 PISTON PISTON PISTON RING SET CLIP CONNECTING ROD PISTON PIN CLIP CONNECTING ROD CAP M8 CONNECTING ROD BOLT 2 pcs CLIP PISTON RING SET PISTON PIN CLIP CONNECTING ROD CONNECTING ROD CAP M8 CONNECTING ROD BOLT 2 pcs...

Page 32: ...rnor lever shaft M6 x 00 3 pcs 10 32 x 11 STEP 29 STEEL BALL OIL PUMP FILTER SPRING relief valve GASKET aluminum PLUG oil relief 10 32 FLANGE BOLT Inch 1 pce GOVERNOR LEVER SHAFT WASHER SNAP PIN M6 FLANGE BOLT 4 pcs OIL PUMP COVER O RING INNER ROTOR OUTER ROTER WASHER M6 FLANGE BOLT 3 pcs ADAPTER oil cooler OIL PRESSURE SWITCH OIL FILTER O RING Fig 5 26 ...

Page 33: ... end plays where specified in this manual 9 When there are many bolts fasten opposing bolts Do not fasten bolts in a circular order In other words after tightening one place go to the opposite side and tighten this place next 5 4 2 Pre assembly A CRANKCASE 1 Fix oil pump filter in position 2 Insert ball and spring into the oil relief valve hole and tighten plug to the specified torque 3 Fit govern...

Page 34: ...able and install washer valve spring valve and spring retainer 3 Install rocker arm Fig 5 29 NOTE Clean valves and wash cylinder head thoroughly Remove carbon and gum deposits from the valves seats ports and guides Inspect valves valve seats and valve guides Replace valves that are badly burned pitted or warped Valve guides should be replaced when valve stem clearance exceeds specifications Refer ...

Page 35: ...on pin to secure piston pin in position TOP RING SECOND RING OIL RING 1 2 3 BARREL TAPER COMBINATION RING 1 2 3 MAIN BEARING COVER GOVERNOR SLEEEVE GOVERNOR GEAR GOVERNOR GEAR SHAFT WASHER 2 pcs THRUST BEARING Fig 5 31 D MAIN BEARING COVER and GOVERNOR GEAR 1 Insert washer into governor gear shaft 2 Insert governor gear along with sleeve into governor gear shaft Fig 5 30 NOTE Install second ring w...

Page 36: ... clinched Tighten bolts to the specified torque Tightening torque 22 1 27 0 N m 225 275 kgf cm 16 3 19 9 ft lb 4 Check for free movement of piston and connecting rod by turning crankshaft slowly CONNECTING ROD PISTON RING COMPRESSOR MARK 1 1 SECOND RING OIL RING TOP RING Fig 5 33 ALIGNMENT MARKS Fig 5 34 NOTE Apply enough oil to bearing portion of crankcase For easy installation put crankcase on b...

Page 37: ...h crankshaft gear and camshaft alined CRANKSHAFT GEAR CAMSHAFT GEAR TIMING MARK Fig 5 35 4 Adjust side clearance Measure end play of crankshaft and camshaft Adjust end play to 0 using the proper spacer SPACER mm A 0 36 B 1 2 HEIGHT GAUGE CRANKSHAFT READING READING CRANKCASE Fig 5 36 SPACER A B CRANKCASE MAIN BEARING COVER 0 36 mm CRANKSHAFT GEAR THICKNESS WITH GASKET TIGHTENED Fig 5 37 CAUTION Inc...

Page 38: ...n bolts evenly in steps to the specified torque Tightening torque 41 2 49 N m 400 500 kgf cm 29 4 36 8 ft lb 8 PUSH RODS 1 Rotate crankshaft to the position in the no lifted condition of tappet 2 Be sure to loose the rocker arm adjust screw NOTE Before installing main bearing cover be sure to check the installation of governor lever shaft and oil pump filter in the crankcase in position Tap cover ...

Page 39: ...e clearance between rocker arm and valve stem end and then tighten lock nut to the specified torque 3 Adjust valve clearance of 2 cylinder side in the same manner 4 Rotate crankshaft several times and be sure to check valve clearance again Adjust valve clearance if necessary Tightening torque 7 8 9 8 N m 80 100 kgf cm 5 8 7 2 ft lb THICKNESS GAUGE Fig 5 39 1 MARK 1 1 CYLINDER MARK I FLYWHEEL Fig 5...

Page 40: ...GE BOLT 2 pcs Fig 5 41 12 SPARK PLUG Install spark plug to each cylinder head Spark plug NGK BPR6ES Tightening torque New plug 13 CHARGE COIL Install charge coil with the wiring located at 2 o clock position Tightening torque 1 5 3 4 N m 15 35 kgf cm 1 1 2 5 ft lb CHARGE COIL ELECTRIC STARTER PULLING M8 FLANGE BOLT 2 pcs Fig 5 42 NOTE Never tighten the bolts over the specified torque or gasket is ...

Page 41: ...OIL COOLER Before connecting hoses apply seal tape onto the engine side fittings as shown by arrows 18 REGULATOR and STOP DIODE Install regurator and stop diode onto cylinder baffle 1 and 4 correspondingly 19 FLYWHEEL 1 Put woodruff key in the keyway of crankshaft 2 Wipe off oil and grease thoroughly from tapered portion of crankshaft and flywheel center hole 3 Install flywheel to crankshaft and t...

Page 42: ... wiring from stop diode to the primary terminal of ignition coil 21 COOLING FAN Attach cooling fan onto flywheel 22 CARBURETOR Set gasket onto intake manifold and install carburetor Tightening Torque 16 7 18 6 N m 170 190 kgf cm 12 3 13 7 ft lb 23 GOVERNOR LEVER Attach governor rod and rod spring between governor lever and carburetor throttle lever and insert the governor lever to governor lever s...

Page 43: ...hown in the ilustration Attach governor spring between governor lever and speed control lever Attach chock control link between carburetor chock lever and chock control lever Fig 5 49 GOVERNOR GEAR GOVERNOR SPRING ADJUSTING SCREW SPEED CONTROL LEVER GOVERNOR LEVER CARBURETOR GOVERNOR ROD ROD SPRING FULL OPEN FULL CLOSE A B LOCK NUT HIGH SPEED LOW SPEED 5 4 3 2 1 ...

Page 44: ...re the lever on the shaft 26 BLOWER HOUSING Attach blower housing to crankcase 27 FUEL PUMP Install fuel pump onto 2 cylinder baffle Connect fuel pipe between carburetor and fuel pump 28 AIR CLEANER 1 Connect breather pipe to air cleaner base 2 Fit air cleaner base onto carburetor 3 Connect breather pipe to 1 cylinder head 4 Set air cleaner element along with urethane foam onto base 5 Install air ...

Page 45: ...L FILTER Fig 5 54 30 OIL FILTER Apply oil to O ring and install oil filter by tighte ning about 3 4 turns after attaching crankcase surface Tightening torque About 12 3 N m About 125 kgf cm About 9 0 ft lb 31 FUEL PUMP PLUSE PIPE Connect fuel pipe between fuel pump and crankcase nipple 32 FINAL CHECK Be sure to check loosen bolts and nuts and also electric wiring connections ...

Page 46: ...fitted with a new piston rings valves and connecting rod should be thoroughly RUN IN before being put back into service Good bearing surfaces and running clearances between the various parts can only be established by operating the engine under reduced speed and loads for a short period of time While the engine is being tested check for oil leaks Make final carburetor adjustment and regulate the e...

Page 47: ...ng the ignition timing to the most suitable point BASIC THEORY 1 Revolution of the flywheel generates electricity on the primary side of the ignition coil and the base current I1 flows to the power transistor Current I1 turns the power transistor ON and the electric current I2 flows Low Speed Ignition Timing Control Circuit I3 I4 Signal Transistor A Automatic Advancing Control Circuit I5 I6 Signal...

Page 48: ... the power transistor turns OFF and the current I2 is abruptly shut resulting in the high voltage generated in the secondary coil which produces sparks at the spark plug The operating timing of the advancing control circuit advances in accordance with the increase of engine speed resulting in the advancing of ignition timing WIRING DIAGRAM Connect key switch magnetic switch and battery with wiring...

Page 49: ...pressure is adjusted by the relief valve after discharging from oil pump Through the oil cooler and cartridge type oil filter the engine oil is provided onto the rotating portions such as journal and pin portion of crankshaft and camshaft The splashed engine oil is provided to the cylinder piston cylinder head valve system The by pass valve is incorporated into the cartridge type oil filter In cas...

Page 50: ...ng rod large end Cam Tappet Rocker arm Valve stem Oil relief valve Oil cooler Oil pump Oil strainer Oil pan Relief valve Element Oil puressure switch 3 1 1 Oil relief Valve opening pressure 3 8 kg cm2 373KPa 2 Oil filter relief Valve opening pressure 1 0 kg cm2 98KPa 3 Oil pressure switch Normally close type Contact pressure 1 0kg cm2 98KPa 2 Fig 7 2 ...

Page 51: ...OAT FLOAT VALVE FUEL INLET PIPE FUEL MAIN NOZZLE THROTTLE VALVE SLOW PORT MIXTURE MAIN EMULSION TUBE ACCELERATION NOZZLE FLOAT VALVE SEAT CHECK VALVE SPRING OUTLET CHECK VALVE MAIN JET SLOW JET IDEL SCREW BACUUM CUSHION JET DIAPHRAGM SPRING PUMP DIAPHRAGM LEAK JET IDEL PORT BACUUM PORT FUEL AIR MIXTURE Fig 8 1 ...

Page 52: ...d again with the air taken through the air cleaner into an optimum fuel air mixture which is supplied to the engine 8 1 4 CHOKE The choke is used for easy start when engine is cold When the starter is operated with a choke valve fully closed the negative pressure applied to the main nozzle increases and draws much fuel accordingly thus easily start up the engine 8 1 5 ACCELERATOR PUMP SYSTEM When ...

Page 53: ...ING adjust screw 22 SCREW throttle adjust 23 NEEDLE idle adjust 24 THROTTLE SHAFT ASS Y 25 FILTER throttle shaft 26 COLLAR 27 THROTTLE VALVE 28 VALVE SET SCREW M3 5mm 29 O RING 30 PLUG ANTI TAMPER 31 SCREW and WASHER ASS Y 32 SPRING 33 DIAPHRAGM ASS Y 34 COVER ASS Y 35 BODY ASS Y 36 U RING 37 HOLDER 38 SCREW and WASHER ASS Y 39 SCREW body set 40 PIPE connector 41 PIPE connector 42 SPACER 43 SCREW ...

Page 54: ... and crankshaft are rotated STARTING MOTOR ELECTRIC STARTER S S M M M M M KEY SWITCH MAGNETIC SWITCH BATTERY Fig 9 2 NOTE For Electric starter operation electric wiring should be connected among electric starter key switch and battery as shown in the diagram CARBURETOR OIL PRESSURE SWITCH IGNITION COIL 1 STOP DIODE IGNITION COIL 2 SPARK PLUG SPARK PLUG CHARGE COIL ELECTRIC STARTER REGURATOR OIL WA...

Page 55: ...VER ASS Y 7 STARTER METAL 8 BRUSH HOLDER ASS Y 9 BRUSH 10 BRUSH SET 11 BRUSH SPRING 12 PINION ASS Y 13 GEAR CASE ASS Y 14 STARTER METAL 15 GEAR CASE METAL COVER 16 DUST COVER KIT 17 SHIFT LEVER KIT 18 MAGNETIC SWITCH ASS Y 19 THROUGH BOLT 20 BOLT 21 M TERMINAL COVER 15 20 9 11 17 16 3 10 6 12 4 13 7 19 8 5 2 21 18 1 14 Fig 9 3 ...

Page 56: ...causes Remedy 1 Electric starter does not operate 1 Poor connection of key switch wiring Check repair or replace 2 Wiring discontinuity between key switch and starter motor Replace 3 Wiring discontinuity between battery and starter motor Replace 4 Improper battery low capacity or dicharged battery Charge or replace battery 5 Poor connection of battery terminal Check clean or replace 6 Starter magn...

Page 57: ...Refill 2 Fuel pump clogged Clean 3 Fuel hose clogged or pinched Clean or replace 4 Air mixing into fuel lines Check and adjust connecting portion 5 Improper gasoline or water infiltration Replace 6 Carburetor Overflow Clogged or damaged Improper operation of throttle valve Adjust Disassembly and clean Check and adjust 7 Poor connection of fuel cut valve wiring Check and repair 4 Engine core compon...

Page 58: ...ion Replace 3 Fuel system malfunction 1 Carburetor clogged Disassembly and clean 2 Improper fuel pump operation Disassembly and clean 3 Fuel strainer or fuel hose clogged Clean or replace 4 Air mixing into fuel lines Check and adjust connecting portion 5 Improper gasoline or water infiltration Replace 4 Low intake air volume 1 Air cleaner clogged Clean or replace 2 Throttle valve faulty Repair or ...

Page 59: ...eplace 5 Ignition system 1 Weak ignition spark Check and replace spark plug 10 5 ROUGH IDLING 10 6 HIGH ENGINE OIL CONSUMPTION Phenomenon Possible causes Remedy 1 Oil leakage 1 Loosen drain plug Tighten 2 Drain plug gasket damaged Replace 3 Incorrect oil filter fitting Repair 4 Loosen main bearing cover bolts Tighten 5 Main bearing cover gasket damaged Replace 6 Crankshaft oil seal damaged Replace...

Page 60: ...nection of ignition system wirings Check and connect properly 2 Improper or damaged spark plug Clean or replace 2 Fuel system malfunction 1 Lean or rich air fuel mixture Clean adjust or replace 2 Carburetor damaged Disassembly and clean 3 Fuel lines clogged or damaged Clean or replace 4 Air mixing from connecting portion of air intake system Connect properly or replace gasket 3 Cylinder head 1 Car...

Page 61: ... ignition system wirings Check and connect properly 2 Fuel system 1 Lean or rich air fuel mixture Disassembly and repair 2 Carburetor clogged Disassembly and repair 3 Improper idling adjustment of carburetor Adjust 4 Improper gasoline or water infiltration Replace 3 Engine core componets 1 Valve heat deterioration or improper valve adjustment Adjust or replace 2 Valve spring deterioration Replace ...

Page 62: ...on of he hot air used for engine cooling and temperature rise of the machine Keep the engine room temperature below 50 C even in the hottest period of the year 11 3 EXHAUST GAS DISCHARGE Exhaust gas is noxious When operating the engine indoors be sure to discharge the exhaust gas outdoors If a long exhaust pipe is used in such a case the internal resistance increases causing loss of engine power T...

Page 63: ... to be used on the engine If the measurement exceeds beyond the Limit the part needs to be replaced and or repaired 12 1 STANDARD DIMENSIONS AND SERVICE LIMITS ITEM EH72D STD Limit CYLINDER HEAD Flatness Valve seat contact width Valve guide inside dia 0 05 or less 0 002 or less 0 1 0 004 IN EX 0 7 1 0 0 028 0 039 2 0 0 079 6 035 6 053 0 2376 0 2383 6 15 0 242 Unit mm in ...

Page 64: ...een max and min of diameter reached to 0 1 0 004 0 01 0 004 1st reboring 84 250 84 272 3 3169 3 3178 Ditto 2nd reboring 84 500 84 522 3 3268 3 3276 0 015 0 0006 PISTON Piston size At skirt in thrust direction STD 83 980 84 000 3 3063 3 3071 83 890 3 3028 1st o s 84 230 84 250 3 3161 3 3169 84 140 3 3126 2nd o s 84 480 84 500 3 3260 3 3268 84 390 3 3224 16 mm Unit mm in ...

Page 65: ...Piston ring end gap Top 0 05 0 09 0 0002 0 0035 0 15 0 006 20 989 21 002 0 8263 0 8269 2nd 0 03 0 07 0 0012 0 0028 0 15 0 006 21 035 0 8281 Oil ring 0 057 0 175 0 0022 0 0069 0 15 0 006 20 991 21 000 0 8264 0 8268 20 960 0 8251 0 0 042 0 0 001654 0 25 0 0098 Top 2nd 0 2 0 4 0 0079 0 0157 1 5 0 0591 Oil ring 0 2 0 7 0 0079 0 0276 1 5 0 0591 Unit mm in ...

Page 66: ...e between small end and piston pin Big end side clearance 39 000 39 016 1 5354 1 5361 39 100 1 5394 0 010 0 032 0 0004 0 0013 0 030 0 060 0 0012 0 0024 0 2 0 079 0 12 0 0047 21 010 21 023 0 8272 0 8277 21 080 0 8299 0 1 0 4 0 0039 0 0127 1 0 0 0394 38 956 38 970 1 5337 1 5343 38 90 1 5315 D1 44 984 45 000 1 77102 1 77165 D2 44 986 44 997 1 77110 1 77154 D1 D2 Unit mm in ...

Page 67: ...eight IN and EX Journal outside dia D type 35 35 35 37 1 392 1 393 35 20 1 385 5 970 5 985 0 2350 0 2356 19 967 19 980 0 7861 0 7866 19 950 0 7854 5 85 0 2303 IN 5 970 5 985 0 2350 0 2356 5 85 0 2303 IN 0 050 0 083 0 00197 0 00327 0 30 0 0118 EX 0 050 0 083 0 00197 0 00327 0 30 0 0118 IN EX cold 0 085 0 115 0 0034 0 0045 Unit mm in D D ...

Page 68: ... a Valve contact width b a 90 b 0 7 1 0 0 028 0 039 2 0 0 079 Unit mm in EH72D 7 0 12 1 55 930 15 20 Continuous load 3600 rpm Capacity Efficacy Consumption L Hr kg cm2 470 rpm L mL mL Hr Compression pressure Fuel consumption Lubricant 1 Above values are rough standard They will be changed by the engine condition and the environment 2 Oil consumption has been measured under following condition Good...

Page 69: ...nition coil 6 9 8 8 70 90 5 1 6 5 Intake manifold bolts 16 7 18 6 170 190 12 3 13 7 Main bearing cover bolts 23 26 235 265 17 3 19 5 Oil filter 12 3 100 150 9 Oil pressure switch 5 9 9 8 60 100 4 3 7 2 Oil relief plug 11 8 14 7 150 250 10 9 18 1 Rocker arm Lock nut 7 8 9 8 80 100 5 8 7 2 Pivot bolt 18 6 20 6 190 210 13 5 15 2 Rocker cover 6 9 8 8 70 90 5 1 6 5 Spark plug New one 11 8 14 7 120 150 ...

Page 70: ...r Multi grade oil tends to increase its consumption at high ambient temperature 5W 10W 20W 20 30 40 10W 30 10W 40 Single grade Multi grade Specified Lubricant Quality Comparison between oil viscosity and temparature 20 4 10 14 0 32 10 50 20 68 30 86 40 C 104 F ...

Page 71: ...Spark plug 7 Magneto 8 Fuel hoses clamps and sealing gaskets The following maintenance schedule is based on the normal engine operation Should the engine be operated in extremely dusty condition or in heavier loading condition the maintenance interval must be shortened depending on the contamination of oil clogging of filter elements wear of parts and so on MAINTENANCE ITEMS REMARKS 1 Clean away d...

Page 72: ...y Overhaul engine Note 2 Note 1 Initial oil change and oil filter replacement should be performed after 20 hours of operation Thereafter change oil every 50 hours and replace oil filter every 200 hours Before changing oil check for a suitable way to dispose of old oil Do not pour it down into sewage drains onto garden soil or into open streams Your local zoning or environmental regulations will gi...

Page 73: ...To prevent rust in the cylinder bore apply oil through the spark plug hole and turn the crankshaft several turns by hand Reinstall the plug 4 Turn the crankshaft by hand and leave it where the resistance is the heaviest 5 Clean outside of the engine with oiled cloth 6 Put a plastic cover or the like over the engine and store the engine in dry place ...

Page 74: ...PRINTED IN THE USA ...

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