Robin EH72 Service Manual

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SERVICE MANUAL

Model

EH72 ENGINES

PUB-ES1545 Rev. 09/03

940 Lively Blvd. • Wood Dale, IL 60191 • Phone: 630-350-8200 • Fax: 630-350-8212

e-mail: sales@robinamerica.com • www.robinamerica.com

CONTENTS

Section Title Page

1. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2. PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3. FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4. GENERAL DESCRIPTION OF ENGINE COMPONENTS . . . . . . . . . . . . . . . . . . . . 5

5. DISASSEMBLY AND REASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5-1 PREPARATIONS AND SUGGESTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5-2 SPECIAL TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5-3 DISASSEMBLY PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5-4 REASSEMBLY PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5-5 BREAK-IN OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6. MAGNETO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

7. LUBRICATION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

8. CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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

12-3 OIL GRADE CHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

13. MAINTENANCE AND STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

13-1 DAILY MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

13-2 PERIODIC MAINTENANCE SCHEDULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

13-3 ENGINE STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

– 1 –

1. SPECIFICATIONS

Model EH72D

Type

Air-Cooled, 4-Stroke, V-Twin Cylinder,

Horizontal P.T.O. shaft, OHV Gasoline Engine Bore×stroke mm (in.) 2 - 84 x 65 (3.31 x 2.56) Displacement cm3(cu. in.) 720 (43.9) Compression Ratio 8.1 Continuous Output kW (HP) / r.p.m. 13.4 (18.0) / 3600 Maximum Output kW (HP) / r.p.m. 18.6 (25.0) / 3600

Maximum Torque N•m / r.p.m.

(kgf•m / r.p.m.) (ft•lb. / r.p.m.)

53.6 / 2500

(5.5 / 2500)

(39.78 / 2500)

Direction of Rotation Counterclockwise as viewed from P.T.O. shaft side Cooling System Forced Air 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 Charging Capacity V - A 12 - 15 or 12 - 30 Starting System Electric Starter Governor System Centrifugal Flyweight Type Air Cleaner Double Element Type Dry Weight kg (lb.) 46 (101.3) Dimension (L×W×H)

mm (in.)

317 × 477 × 475 (12.5 × 18.8 × 18.7)

＊ Specifications are subject to change without notice.

– 2 –

2. PERFORMANCE

2-1 MAXIMUM OUTPUT

The maximum output is the output of an engine with its throttle valve fully opened under the condition that all the moving parts are properly worn in after the initial break-in period. A new engine may not produce full maximum output while its moving parts are still not broken-in.

NOTE : Power curves shown in the following charts are made 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 below this continuous rated output.

2-3 MAXIMUM TORQUE

The maximum torque is the torque at the output shaft when the engine is producing maximum output at certain revolution.

– 3 –

2-4 PERFORMANCE CURVES

EH72D

55 (5.61

N-m

(

)

kgf-m

)

(

26.8

(HP)

(20.1)

HORSEPOWER

45 (4.59

MAXIMUM TORQUE

)

MAXIMUM HORSEPOWER

CONTINUOUS RATED HP

)

TORQUE

(13.4)

(

)

6.7

2000 2400 2800 3200 3600

REVOLUTION r.p.m

RECOMMENDED HORSEPOWER RANGE

– 4 –

3. FEATURES

Highly rigid structure

●

High-carbon steel, forged crank shaft

●

Light-weight , tough alminum forged connectiong rod

●

Ball-bearing

●

Special cast iron cylinder liner

Long-lasting structure

●

Forced pressure lubrication of crankshaft by directly connected trochoid pump

●

Standard equipped oil cooler 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 stability and reduced gas emissions

Compact

●

Center height 133.3mm and 25HP

●

90°V2 cylinder built in crankcase

– 5 –

Fig. 4-1

Fig. 4-2

Fig. 4-3

4. GENERAL DESCRIPTION OF ENGINE COMPONENTS

ROBIN EH72D engine is air-cooled, 4-stroke, twin-cylinder, OHV arrangement gasoline engine. The twincylinder is located in the angle of 90 degree; #1 cylinder is in the RH side and #2 cylinder in LH side as viewed from flywheel (cooling fan) side.

4-1 CYLINDER AND CRANKCASE

The twin-cylinder and crankcase is single piece aluminum die-casting. The cylinder liner, made of special cast iron, is molded into the aluminum casting. The crankcase 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 removing the main bearing cover.

4-3 CRANKSHAFT

The crankshaft is forged carbon steel, and the crank pin is induction-hardened. The output end of the shaft has a crankshaft gear pressed into position. Engine oil passages are provided onto the journal and pin portions of crankshaft for lubrication.

4-4 CONNECTING ROD AND PISTON

The connecting rod is forged aluminum alloy, and its large and small ends function as bearings. The piston is an aluminum alloy casting, and carries two compression rings and one oil ring.

– 6 –

Fig. 4-4

4-5 PISTON RINGS

The piston rings are made of special cast iron. The profile of the top ring 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 crankcase and main bearing cover.

Fig. 4-5

Fig. 4-6

TOP RING

SECOND RING

OIL RING

BARREL

TAPER

COMBINATION RING

– 7 –

4-7 CYLINDER HEAD

The cylinder head is an aluminum die-casting which utilizes semi-spherical type combustion chamber for the high combustion efficiency.

Fig. 4-7

4-8 VALVE ARRANGEMENT

The intake valve is located on flywheel side of the cylinder head. The cooling 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.

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 bearing cover and driven by the crankshaft.

Fig. 4-9

INTAKE VALVEEXHAUST VALVE

GOVERNOR GEAR

– 8 –

4-10 COOLING SYSTEM

The large fins on the flywheel provide sufficient cooling air capacity for cylinder and cylinder head. The cylinder baffle helps the cooling air flow efficiently.

4-11 LUBRICATION SYSTEM

The engine is furnished with full pressure lubrication system. The trochoid type oil pump is driven by crankshaft and delivers pressurized engine oil through the fullflow 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.

Fig. 4-10

Fig. 4-11b

Fig. 4-11a

4-13 CHARGING SYSTEM

Multipolar charging coil is provided inside of flywheel. Charging capacity is 12V-15A or 12V-30A.

(12V-15A) (12V-30A)

IGNITION COIL

FLYWHEEL

CABLE, EXTENDED

CHARGE COIL

REGULATOR

CHARGE COIL

– 9 –

4-14 CARBURETOR

The engine is equipped with a down draft carburetor that has a float controlled fuel system and a fixed main jet. The carburetors are calibrated carefully for the sure starting, low fuel consumption and sufficient output. Fuel cut solenoid valve is provided to prevent engine running on when 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.

Fig. 4-12

Fig. 4-13

4-16 FUEL PUMP

The engine is equipped with a diaphragm type fuel pump which is operated by the crankcase inside vacuum pressure.

Fig. 4-14

FUEL CUT SOLENOID VALVE

ACCELERATOR-PUMP

CLEANER COVER

WING NUT

ELEMENT

URETHANE FOAM

FUEL PUMP

– 10 –

4-17 SECTIONAL VIEW OF ENGINE

Fig. 4-15

CARBURETOR

INTAKE MANIFOLD

IGNITION COIL

OIL PUMP

FLYWHEEL

P.T.O.SHAFT

MAIN BEARING COVER

OIL PUMP FILTER

– 11 –

Fig. 4-16

– 12 –

5. DISASSEMBLY AND REASSEMBLY

5-1 PREPARATIONS AND SUGGESTIONS

When disassembling the engine, memorize the locations of individual parts so that they can be reassembled correctly. If you are uncertain of identifying some parts, it is suggested that tags be attached to them. Have boxes ready to keep disassembled parts by group. To prevent losing and misplacing, temporarily 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 popular in the market place as shown in the illustration is needed.

Fig. 5-1

Tool No. Tool Use

228-95001-17

Flywheel puller with bolt

EH63,64,65,72 / DY30,35,41,42

FLYWHEEL PULLER

– 13 –

5-3 DISASSEMBLY PROCEDURES

Step Parts to remove Remarks and procedures Fasteners

1 Engine oil drain

Drain engine oil by removing plugs located on both side of crankcase.

2 Muffler cover

M6 x 12 : 6 pcs.

3 Muffler M8 nut : 4pcs.

4 Muffler bracket

M8 x 16 bolt and washer : 2pcs.

Fig. 5-2

OIL LEVEL GAUGE

M6 FLANGE BOLT : 2 pcs.

STEP 2

OIL FILLER CAP

GUIDE, oil level

MUFFLER COVER

M6 FLANGE BOLT : 2 pcs.

MUFFLER

STEP 3

MUFFLER BLACKET

M8 BOLT & WASHER : 2 pcs.

M6 FLANGE BOLT : 2 pcs.

STEP 4

GASKET

M8 SUS FLANGE NUT : 4 pcs.

GASKET

OIL DRAIN PLUG (

ON BOTH SIDE

STEP 1

)

– 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.

Fig. 5-4

Fig. 5-3

BREATHER PIPE

M6 FLANGE BOLT :

3 pcs.

STEP 6

WING NUT

CLEANER

COVER

STEP 5

CLEANER ELEMENT

CLEANER BASE

HOSE CLAMP

BREATHER PIPE

HOSE CLAMP

– 15 –

Step Parts to remove Remarks and procedures Fasteners

7 Blower housing

M6 x 12 : 2 pcs. M6 x 14 : 6 pcs.

8 Chock control lever and link

(1) Remove the choke knob. (2) Remove the choke contol link.

M6 bolt : 1 pc.

Fig. 5-5

LINK PIVOT

CHOKE CONTROL ROD

RETURN SPRING

STEP 8

CHOKE CONTROL LINK

WAVED WASHER

M5 TAPPING SCREW : 1 pc.

CLAMP

CHOKE KNOB

BLOWER HOUSING

M6 FLANGE BOLT : 2 pcs

STEP 7

M6 FLANGE BOLT : 6 pcs

– 16 –

Step Parts to remove Remarks and procedures Fasteners

Carburetor

At first remove fuel pipe. Take out carburetor along with governor rod and rod spring.

M8 x 80 : 2 pcs.

Fig. 5-7

Fig. 5-6

M8 FLANGE BOLT : 2 pcs.

STEP 9

CARBURETOR

FUEL PIPE

GASKET, carburetor

– 17 –

Step Parts to remove Remarks and procedures Fasteners

Governor lever and Speed control lever

Governor lever ; Remove bolt and take out lever. Speed control lever ; (1) Governor spring (2) Self lock nut (3) Stop plate (4) Spring washer (5) Speed control lever

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.

Fig. 5-8

M6 NUT : 1 pce.

M6 BOLT AND WASHER : 1 pce.

M6 SELF LOCK NUT : 1 pce.

ROD SPRING

GOVERNOR ROD

STOP PLATE SPRING WASHER

STEP 10

FRICTION WASHER

SPEED CONTROL LEVER

M8 FLANGE BOLT : 2 pcs.

STARTING MOTOR

STEP 12

SPACER

GOVERNOR LEVER

GOVERNOR SPRING

FRICTION WASHER

M6 FLANGE BOLT : 3 pcs.

STEP 11

BRACKET UNIT, speed control

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.

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.

Fig. 5-10

PLUG TERMINAL

SPARK PLUG CAP

IGNITION COIL

TO STOP DIODE

M6 BOLT AND WASHER ASSY : 2 pcs.

STEP 14

IGNITION COIL

PLUG TERMINAL

SPARK PLUG CAP

IGNITION COIL

BRACKET, fuel pump

HOSE CLAMP

PULSE PIPE

STEP 13

M6 FLANGE BOLT : 2 pcs.

HOSE CLAMP

FUEL PIPE

M6 FLANGE BOLT : 2 pcs.

FUEL PUMP and FUEL FILTER ASSY

HOSE CLAMP

– 19 –

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

Fig. 5-13

M5 BOLT AND WASHER : 4 pcs.

STEP 15

M6 BOLT AND WASHER : 4 pcs.

M18 NUT : 1pce.

SPRING WASHER

WASHER

CHARGE COIL

STEP 16

FLYWHEEL PULLER

COOLING FAN

FLY WHEEL

RING GEAR

– 20 –

Step Parts to remove Remarks and procedures Fasteners

Cylinder baffles (#1, #2, #3 & #4)

M6 flange bolt x 12 : 10 pcs.

Fig. 5-15

18 Regulator and Stop diode

M6 flange bolt x 12 : 1 pce.

CYLINDER BAFFLE #1

CYLINDER BAFFLE #3

M6 FLANGE BOLT : 2 pcs.

TO OIL PRESSURE SWITCH

STEP 18

TO IGNITION COIL

M6 FLANGE BOLT : 1 pce.

TO IGNITION COIL

STOP DIODE

CYLINDER BAFFLE #4

M6 FLANGE BOLT : 3 pcs.

WIRING HARNESS

STEP 18

M6 FLANGE BOLT : 2 pcs.

REGULATOR

M6 FLANGE BOLT : 3 pcs.

STEP 17

M6 FLANGE BOLT : 3 pcs.

CYLINDER BAFFLE #2

– 21 –

Step Parts to remove Remarks and procedures Fasteners

19 Oil cooler Take out oil hoses M6 Flange bolt : 4 pcs.

Fig. 5-16

BRACKET UNIT

M6 FLANGE BOLT : 2 pcs.

OIL COOLER

HOUSE CLAMP

OIL HOUSE#2

M6 FLANGE BOLT : 2 pcs.

HOUSE CLAMP

STEP 19

HOUSE CLAMP

OIL HOUSE#1

– 22 –

Step Parts to remove Remarks and procedures Fasteners

20 Intake manifold M8 flange nut : 4 pcs.

21 Spark plug NGK : BPR6ES (or CHAMPION : RN9YC)

Fig. 5-17

M8 FLANGE

SPARK PLUG

NUT : 2 pcs.

STEP 21

GASKET

STEP 20

INTAKE MANIFOLD

M8 FLANGE NUT : 2 pcs.

GASKET

SPARK PLUG

STEP 21

– 23 –

Step Parts to remove Remarks and procedures Fasteners

22 Rocker cover M6 x 12 : 8 pcs.

Cylinder head and Push rod

1. Bolt, pivot

2. Rocker arm

When removing “rocker arm” and “Bolt,pivot”, turn and adjust flywheel at TDC with the marking “T” faced to “1” or “2” on each cylinder head. Put the marking of original position onto each push rod, rocker arm and valve for reassembly.

M10 x 65 : 8 pcs.

Fig. 5-18

M6 FLANGE BOLT : 4 pcs.

NUT

STEP 22

PIVOT

ROCKER ARM

PUSH ROD

HOOK

ROCKER COVER

M10 FLANGE BOLT : 4 pcs.

GUIDE PLATE

PUSH ROD

ROCKER COVER

ROCKER ARM

PIVOT

NUT

BOLT, PIVOT

STEP 22

M6 FLANGE BOLT : 4 pcs.

BOLT, PIVOT

GUIDE PLATE

CYLINDER HEAD 1

GASKET 1

STEP 23

GASKET, rocker cover

GASKET 2

CYLINDER HEAD 2

GASKET, rocker cover

M10 FLANGE BOLT : 4 pcs.

HOOK

STEP 23

– 24 –

Step Parts to remove Remarks and procedures Fasteners

Intake & exhaust valves Breather cover Breather plate

M6 x 00 : 2 pcs.

Fig. 5-20

Fig. 5-19

COLLET-VALVE

SPRING RETAINER

VALVE SPRING

COLLET-VALVE

SPRING RETAINER

VALVE SPRING

SEAL-INTAKE VALVE

(BLACK)

STEP 24

GASKET , breather plate

BREATHER PLATE

GASKET , breather plate

BREATHER COVER

M6 FLANGE BOLT : 2 pcs.

INTAKE VALVE

EXHAUST VALVE

– 25 –

Step Parts to remove Remarks and procedures Fasteners

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

WASHER : 2 pcs.

GOVERNOR GEAR SHAFT

GOVERNOR GEAR

THRUST BEARING

GOVERNOR SLEEEVE

M8 FLANGE BOLT : 10 pcs.

STEP 25

GASKET

MAIN BEARING COVER

– 26 –

Step Parts to remove Remarks and procedures Fasteners

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

STEP 26

TAPPET

CAMSHAFT

TAPPET

– 27 –

Step Parts to remove Remarks and procedures Fasteners

Piston and Connecting rod *Piston pin clip *Piston pin *Piston rings

(1) Remove connecting rod bolts. (2) Take out connecting rod cap. (3) P us h t he co nn ec ti ng r od up wa rd s a nd

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

Fig. 5-25

STEP 27

PISTON RING SET

PISTON

CLIP

M8 CONNECTING ROD BOLT : 2 pcs.

PISTON PIN

CLIP

CONNECTING ROD CAP

CLIP

CONNECTING ROD

PISTON RING SET

PISTON

CLIP

SPACER

PISTON PIN

CONNECTING ROD

CONNECTING ROD CAP

M8 CONNECTING ROD BOLT : 2 pcs.

STEP 28

STEP 27

CRANKSHAFT

– 28 –

Step Parts to remove Remarks and procedures Fasteners

Crankcase *Oil pump *Oil filter *Oil pressure switch *Oil pump filetr *Oil relief spring & ball *Governor lever shaft

M6 x 00 : 3 pcs. 10-32 x 11

Fig. 5-26

M6 FLANGE BOLT : 4 pcs.

OUTER

ROTER INNER ROTOR

O RING

SNAP PIN WASHER

OIL PUMP COVER

WASHER

GOVERNOR LEVER SHAFT

10-32 FLANGE BOLT (Inch) : 1 pce.

OIL PUMP FILTER

STEEL BALL SPRING, relief valve GASKET, aluminum PLUG, oil relief

OIL FILTER

STEP 29

O RING

M6 FLANGE BOLT : 3 pcs

ADAPTER, oil cooler

OIL PRESSURE SWITCH

– 29 –

5-4 REASSEMBLY PROCEDURES

5-4-1 PRECAUTIONS FOR REASSEMBLY

1) Clean parts thoroughly before reassembly. Pay most attention to cleanliness of piston, cylinder, crankshaft, connecting rod and bearings.

2) Scrape off all carbon deposits from cylinder head, piston top and piston ring grooves.

3) Check lip of oil seals. Replace oil seal if the lip is damaged. Apply oil to the lip before reassembly.

4) Replace all the gaskets with new ones.

5) Replace keys, pins, bolts, nuts, etc., if necessary.

6) Torque bolts and nuts to specification referring to the "TORQUE SPECIFICATIONS".

7) Apply oil to rotating and sliding portions.

8) Check and adjust clearances and 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 governor lever shaft with clip. (4)Tighten oil drain plugs on both side of crankcase.

Tightening torque

11.8 - 14.7 N・m

(150 - 250 kgf・cm)

(10.9 - 18.1 ft・lb.)

Fig. 5-27

SNAP PIN WASHER

OIL DRAIN PULG

GASKET

WASHER

GOVERNOR LEVER SHAFT

OIL PUMP FILTER

GASKET

M6 FLANGE

BOLT : 3 pcs

O RING

ADAPTER,

oil cooler

10-32 FLANGE BOLT (Inch) : 1 pce.

STEEL BALL SPRING, relief valve GASKET, aluminum PLUG, oil relief

OIL DRAIN PULG (ON BOTH SIDE)

OIL PRESSURE

SWITCH

OIL FILTER

– 30 –

B. CYLINDER HEAD, VALVES and ROCKER ARM

(1)Attach oil seal only onto intake valve guide. (2)Apply oil to washer, valve spring and valve stem.

Place cylinder head on flat table 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 to SERVICE DATA for clearance specifications. ) If exceeds, draw valve guides out and press new guides in. After replacing valves and guides, lap valves in place until a uniform ring shows around the face of the valve.

Fig. 5-28

ROCKER ARM

COLLET-VALVE

SPRING RETAINER

VALVE SPRING

COLLET-VALVE

SPRING RETAINER

VALVE SPRING

SEAL-INTAKE VALVE

(BLACK)

GASKET , breather plate

BREATHER PLATE

GASKET , breather plate

BREATHER COVER

INTAKE VALVE

EXHAUST VALVE

M6 FLANGE BOLT : 2 pcs.

– 31 –

C. PISTON and CONNECTING ROD

(1) Install oil ring first, then second ring and top ring. Spread ring only far enough to slip over piston and

into correct groove. Use care not to distort ring.

(2) Apply enough oil to small end of connecting rod and piston pin, and fix connecting rod to piston with

piston pin.

(3)Use clips on the both side of the piston pin to secure piston pin in position.

Fig. 5-31

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 with punched mark beside the gap on the top side. * Top ring can be fit either way. * As for oil ring, rails should be placed on and below the expander.

TOP

RING

BARREL

SECOND RING

OIL RING

GOVERNOR GEAR SHAFT

TAPER

COMBINATION RING

WASHER : 2 pcs.

GOVERNOR SLEEEVE

GOVERNOR GEAR

THRUST BEARING

MAIN BEARING COVER

– 32 –

5-4-3 Re-assembly

1) CRANKSHAFT

Install crankshaft onto crankcase.

Fig. 5-32

2) PISTON and CONNECTING ROD

(1)Install piston and connecting rod assembly into

cylinder by using a piston ring compressor to hold piston rings.

(2)Temporary fit key and flywheel and turn

crankshaft to BTDC (bottom dead center). Lightly tap the top of piston until large end of the rod meet the pin portion of crankshaft.

(3)Set connecting rod cap to connecting rod with

the alignment marks mated and the clinching portion 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.

Fig. 5-33

Fig. 5-34

NOTE ; Apply enough oil to bearing portion of crankcase. For easy installation, put crankcase on box or wood blocks.

NOTE ; * The "1" mark of the connecting rod for #1

cylinder and "2" mark for #2 cylinder should be faced to the flywheel side when assembled.

* Apply enough oil to piston rings,

connecting rod bearings (large end) and cylinder bore before assembly.

* Set gaps of piston rings as shown in

the illustration.

CRANKSHAFT

PISTON RING COMPRESSOR

CONNECTING ROD

MARK "1"

TOP RING

OIL RING

ALIGNMENT MARKS

SECOND RING

– 33 –

3) TAPPET and CAMSHAFT

(1)Apply oil to tappets and install in their original

position. Push in fully to avoid damage during camshaft installation.

(2)Lubricate bearing surfaces of camshaft. Install

camshaft into the crankcase with the timing mark on both crankshaft gear and camshaft alined.

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)

Fig. 5-36

)

Fig. 5-37

CAUTION: Incorrect alinement will cause malfunction of the engine.

CAMSHAFT GEAR

TIMING MARK

HEIGHT GAUGE

READING

CRANKCASE

CRANKSHAFT GEAR

READING

CRANKSHAFT

MAIN BEARING COVER

CRANKSHAFT GEAR

SPACER

CRANKCASE

0.36 mm

(

THICKNESS WITH

GASKET TIGHTENED

– 34 –

5) MAIN BEARING COVER

(1)Put a oil seal guide onto PTO shaft portion to avoid damaging the main bearing cover oil seal. (2)Place gasket onto the mating surface of crankcase. (3)Lubricate oil seal lip portion and bearing surfaces, and install main bearing cover.

Tighten bolts evenly to the specified torque.

6) OIL PUMP and COVER

(1) Apply oil to inner and outer rotors of oil pump

and attach them in position. (2)Set O-ring in position. (3)Install oil pump cover with the allow marking

upwards.

Tightening torque

23 - 26 N・m

(235 - 265 kgf・cm)

(17.3 - 19.5 ft・lb.)

Fig. 5-38

7) CYLINDER HEAD

(1)Place new head gasket onto crankcase. (2)Install #1 and #2 cylinder heads. Tighten 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 with a soft hammer until tacthing the crankcase mating surface, engaging with

governor gear and camshaft gear properly.

* Rotate crankshaft slowly to check for smooth operation and side clearance.

NOTE

;;

Be sure to check dowel pin, and replace with new one if damaged.

OUTER ROTOR

Cylinder head bolts

M10 x 65 mm Flange bolt : 8 pcs.

INNER ROTOR

Tighten the cylinder head bolts in diagonal order.

1st step Final step2nd step

25 N・m

(255 kgf・cm)

(18.4 ft・lb.)

OIL PUMP COVER

O-RING

Tightning Torque

35 N・m

(357 kgf・cm)

(25.8 ft・lb.)

" "MARKING

45 N・m

(459 kgf・cm)

(33.2 ft・lb.)

– 35 –

(3)Insert push rods into the concave portion of tappet and set the other end to the concave portion of rocker

arm adjust screw with valve spring depressed.

(4)Temporally tighten adjust screw.

9) VALVE CLEARANCE ADJUSTMENT

(1)

Rotate crankshaft clockwise to the TDC (top dead center) of compression stroke by matching the mark "T" of flywheel with the mark "1" of #1 cylinder head.

(2)Loosen lock nut on rocker arm and turn adjusting

screw to adjust the 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.)

Fig. 5-39

Fig. 5-40

NOTE ; Temporally fit the flywheel in position for easy operation.

10) ROCKER COVER

Install rocker cover with new gasket.

Tightening torque

2.9 - 4.9 N・m

(30 - 50 kgf・cm)

(2.2 - 3.6 ft・lb.)

Valve Clearance (Cold condition)

0.085 - 0.115 mm

(0.0033 - 0.0045 in.)

THICKNESS GAUGE

#1 CYLINDER

MARK"1"

MARK" I "

FLYWHEEL

14) STARTER MOTOR

Install starter motor.

Tightening torque

16.7 - 18.6 N・m

(170 - 190 kgf・cm)

(12.3 - 13.7 ft・lb.)

– 36 –

11) BREATHER PIPE and COVER

Attach breather plate (breather valve) and

breather cover to crankcase using proper

gaskets.

Put breather plate in such position as its reed

valve opens outside.

Tightening torque

2.9 - 4.9 N・m

(30 - 50 kgf・cm)

(2.2 - 3.6 ft・lb.)

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.)

Fig. 5-42

NOTE

;;

Never tighten the bolts over the specified torque, or gasket is damaged and cut. Replace gaskets with new ones if they are torn or damaged.

Current plug

15) CYLINDER BAFFLE

Attach cylinder baffle #1, #2, #3 and #4.

11.8 - 14.7 N・m

(120 - 150 kgf・cm)

(8.7 - 10.8 ft・lb.)

22.5 - 26.5 N・m

(230 - 270 kgf・cm)

(16.6 - 19.5 ft・lb.)

GASKET , breather plate

BREATHER PLATE

GASKET , breather plate

CHARGE COIL

BREATHER COVER

PULLING

M6 FLANGE BOLT : 2 pcs.

M8 FLANGE BOLT : 2 pcs.

ELECTRIC

STARTER

– 37 –

Fig. 5-43

Fig. 5-44

16) INTAKE MANIFOLD

Set gasket (stainless steel) onto both #1 and #2 cylinder head and install intake manifold.

Tightening torque

16.7 - 18.6 N・m

(170 - 190 kgf・cm)

(12.3 - 13.7 ft・lb.)

17) 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 tighten flywheel nut with spring washer and washer.

Tightening torque

83.3 - 93.1 N・・m

(850 - 950 kgf・・cm)

(61.5 - 68.7 ft・・lb.)

Fig. 5-45

GASKET, muffler

M8 FLANGE NUT : 2 pcs.

INTAKE MANIFOLD

M8 FLANGE NUT : 2 pcs.

GASKET, muffler

CYLINDER BAFFLE #4

BRACKET UNIT

HOSE#2

M6 FLANGE BOL T : 4pcs.

OIL COOLER

HOSE CLAMP

HOSE#1

STOP DIODE

– 38 –

20) IGNITION COIL

Temporally fit ignition coil to crankcase.

Adjust air gap between ignition coil and flywheel

using a thickness gauge and tighten bolts.

Fig. 5-46

Fig. 5-47

Fig. 5-48

Connect 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

shaft. Tighten locking bolt temporarily.

Tightening torque

6.9 - 8.8 N・m

(70 - 90 kgf・cm)

(5.1 - 6.5 ft・lb.)

Ignition coil air gap

0.3 - 0.5 mm

(0.012 - 0.020 in.)

THICKNESS GAUGE IGNITION COIL

WIRE

STOP DIODE

M5 BOL T and WASHER : 4 pcs.

COOLING FAN

GOVERNOR SHAFT

GOVERNOR LEVER

ROD SPRING

GOVERNOR ROD THROTTLE LEVER

– 39 –

24) SPEED CONTROL LEVER

Install speed control bracket onto intake manifold. Attach return spring, spacer, friction washer, wing nut, etc. to speed control lever as shown 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

CARBURETOR

GOVERNOR GEAR

GOVERNOR LEVER

5 4 3 2 1

SPEED CONTROL LEVER

ROD SPRING

FULL CLOSE

GOVERNOR SPRING

HIGH SPEED

GOVERNOR ROD

FULL OPEN

LOCK NUT

ADJUSTING SCREW

LOW SPEED

– 40 –

25) ADJUST GOVERNOR SYSTEM

(1)Push speed control lever all the way to the high

speed position and fix it by tightening nut. (2)Check that governor lever is pulled by governor

spring and carburetor throttle valve is fully open. (3)Turn governor shaft counterclockwise all the

way and tighten lock bolt to secure 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 cleaner cover with knob.

Fig. 5-50

Fig. 5-51

Fig. 5-52

GOVERNOR LEVER

GOVERNOR SHAFT

FUEL PUMP

AIR CLEANER BASE

– 41 –

29) OIL PRESSURE SWITCH

Install oil pressure switch onto crankcase.

Tightening torque

5.9 - 9.8 N・m

(60 - 100 kgf・cm)

(4.3 - 7.2 ft・lb.)

Fig. 5-53

Fig. 5-54

30) OIL FILTER

Apply oil to O-ring and install oil filter by tightening 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.

OIL PRESSURE SWITCH

OIL FILTER

3/4 TURNS

O RING

– 42 –

Fig. 5-56

Fig. 5-55

33) ENGINE OIL

Refill engine oil and start the engine. Engine oil

will be lubricated oil passages and oil filter.

Check the engine oil level and refill again to the

upper level of oil level gauge.

NOTE ;

* Use “SE” (API classification) or higher

grade engine oil.

5-5 BREAK-IN OPERATION

An engine that has been completely overhauled by being 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 engine operating speed.

Step Load Engine Speed Time

Step 1 No Load 2,500 r.p.m. 10 min. Step 2 No Load 3,000 r.p.m. 10 min. Step 3 No Load 3,600 r.p.m. 10 min. Step 4 9HP 3,600 r.p.m. 30 min. Step 5 18HP 3,600 r.p.m. 30 min.

Standard Option

Oil Capacity

1.55 liter (0.41 U.S. gal.)

OIL GAUGE

UPPER LEVEL

OIL GAUGE

UPPER LEVEL

OIL GAUGE

UPPER LEVEL

LOWER LEVEL

– 43 –

6. MAGNETO

OPERATION AND FUNCTION

The ignition system is pointless flywheel magneto with automatic advancing characteristic. Being different from the breaker point type ignition system, this system is completely free from such troubles as starting-up failure owing to dirty, burnt or corroded point surface. The electronic automatic advancing ensures extremely easy starts and stable high performance at operating speed by advancing 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

1 flows to the power transistor. Current I1 turns the power transistor "ON" and the electric current I2 flows.

Fig. 6-1 (a)

Fig. 6-1 (b)

Low Speed

Ignition

Timing

Control Circuit

Resister

Power Transistor

Primary Coil

Automatic

Advancing

Control

Signal Transistor A

Circuit

Signal Transistor B

Secondary Coil

Spark plug

ELECTRONIC ADVANCING FLYWHEEL

(

B.T.D.C.

)

MAGNETO SYSTEM

STEP ADVANCING

IGNITION TIMING

500 1000 2000 3000 (r.p.m.)

ENGINE REVOLUTION

– 44 –

(2)At lower engine revolution, when the flywheel reached the ignition point the low speed ignition timing control

circuit operates to run the base current I

3 to turn the signal transistor A "ON" allowing the current I1 to

bypass as current I

At this moment the power transistor turns "OFF" and the current I

2 is abruptly shut resulting in the high

voltage generated in the secondary coil which produces sparks at the spark plug.

(3) At higher engine revolution, the advancing control circuit operates at the ignition timing to run the base

current I

5 to turn the signal transistor B "ON" allowing the current I1 to bypass as current I6.

At this moment the power transistor turns "OFF" and the current I

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 wirings of proper gauge as shown by the dotted lines in the wiring diagram.

Fig. 6-2

OIL WARNING LAMP

CARBURETOR

IGNITION COIL #2

SPARK PLUG

CHARGE COIL

GRAY

OIL PRESSURE SWITCH

RED

IGNITION COIL #1

REGURATOR

SPARK PLUG

GREEN

RED

BLACK BLACK

ELECTRIC STARTER

STOP DIODE

BLACK

YELLOW

RED

YELLOW

BLACK / WHITE

BLACK

WHITE

TACHO / HOUR METER

(HIGH TENSION CORD)

BATTERY

12V

KEY SWITCH

Terminal

Key Position

GMBL S

OFF RUN

START

Key switch (Option parts)

– 45 –

7. LUBRICATION SYSTEM

OPERATION AND FUNCTION

Full lubrication system is adopted, in combination with large-size torchoid oil pump and cartridge type oil filter.

* The large-size trochoid type oil pump is driven directly by crankshaft, and delivers pressurized engine oil to

the journal and pin portions of crankshaft, camshaft etc.

* The engine oil in the oil pan is fed through the oil pump filter into oil pump and the engine oil 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 case that the oil filter element is

clogged, the engine oil is fed through the by-pass valve into the crankcase oil passage.

Fig. 7-1

OIL PRESSURE SWITCH

OIL COOLER

CAMSHAFT

OIL FILTER

CRANKSHAFT

RELIEF VALVE

OIL PUMP

OIL PUMP FILTER

– 46 –

Oil

Fig. 7-2

relief valve

Oil puressure switch

1 Oil relief Valve opening pressure : 3.8 kg/cm2 (373KPa) 2 Oil filter relief Valve opening pressure : 1.0 kg/cm2 (98KPa)

Camshaft journal

Oil pan

Oil strainer

3 Oil pressure switch

Normally close type Contact pressure : 1.0kg/cm2 (98KPa)

Oil pump

Oil cooler

Element

Relief valve

Crankshaft journal (Flywheel side)

Crankpin & Connecting rod large end

Cylinder Crankpin &

Connecting rod small end

Cam & Tappet Rocker arm &

Valve stem

Crankshaft journal (P.T.O. side)

Splash

– 47 –

8. CARBURETOR

8-1 OPERATION AND FUNCTION

Fig. 8-1

LEAK JET

FUEL

AIR

MIXTURE

DIAPHRAGM SPRING

AIR

CHECK VALVE SPRING

MAIN EMULSION TUBE

MAIN AIR BLEED JET

ACCELERATION NOZZLE

SLOW AIR BLEED JET

OUTLET CHECK VALVE

PUMP DIAPHRAGM

MAIN JET

SLOW JET

IDEL SCREW

BACUUM CUSHION JET

MIXTURE

AIR VENT

CHOKE VALVE

FLOAT

FLOAT VALVE

FUEL INLET PIPE

FLOAT VALVE SEAT

FUEL

MAIN NOZZLE

THROTTLE VALVE

SLOW PORT

IDEL PORT

BACUUM PORT

– 48 –

8-1-1 FLOAT SYSTEM

The float system is consists of a float and a needle valve, and maintains a constant fuel level during engine operation. The fuel flows from the fuel tank into the float chamber through needle valve. When the fuel rises to a specific level, the float rises, and when its buoyancy and fuel pressure are balanced, the needle valve closes to shut off the fuel, thereby keeping the fuel at the predetermined level. Air vent hole of float chamber is provided around the carburetor air hone and the fuel vapor is sucked into the combustion chamber. This closed system has unti-dust feature.

8-1-2 PILOT SYSTEM

The pilot system feeds the fuel to the engine during idling and low-speed operation. The fuel is fed through the main jet to the pilot jet, where it is metered, and mixed with the air metered by the pilot air jet. The fuel-air mixture is fed to the engine through the pilot outlet and the by-pass. At idling speed, the fuel is mainly fed from the pilot outlet.

8-1-3 MAIN SYSTEM

The main system feeds the fuel to the engine at medium-and high-speed operation. The fuel is metered by the main jet and fed to the main nozzle. The air metered by the main air jet is mixed with the fuel through the emulsion tube, and the mixture is atomized out of the main bore. It is mixed 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 the throttle is opened rapidly for acceleration, air flow and manifold vacuum change almost instantaneously. Because fuel is heavy and lags behind air flow, a momentary leanness results. The accelerator-pump supplies extra fuel for smooth operation during this condition. At constant load condition, a vacuum passage in the carburetor applies manifold vacuum to the pump diaphragm and the pump diaphragm is held to pull position. When the throttle is opened rapidly for acceleration, the manifold vacuum is dropped, the pump diaphragm moves by the diaphragm spring, the fuel in the pump chamber push out by the pump diaphragm and the fuel gush out from the accelerator-pump nozzle.

8-1-6 FUEL CUT VALVE

Fuel cut valve, operated with starter key switch, is equipped with main system of carburetor for preventing engine running on and after burning. When the key switch is on, the valve is activated and the plunger is pulled in to open the main jet. When the key switch is off, the power source to the valve is off. The plunger is pushed out by the return spring and stop the fuel flow of main jet.

– 49 –

8-2 COMPORNENT PARTS

1. BODY, lower

2. GASKET, air horn

3. BODY, upper

4. LEVER ASS'Y, choke

5. RING, choke lever

6. SPRING, choke

7. COLLAR, choke

8. FILTER, choke shaft

9. SHAFT ASS'Y, choke

10. CHOKE VALVE

11. SCREW, valve set

12. SCREW, air horn set

13. VALVE, float

14. FLOAT ASS'Y

15. FLOAT PIN

16. SCREW, float pin set

17. MAIN JET (#138)

18. GASKET

19. SOLENOID VALVE ASS'Y

20. JET, slow (#48)

21. SPRING, 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, holder set

44. CLAMP, SOLENOID WIRE

45. JET

Fig. 8-2

29 12

– 50 –

9. ELECTRIC STARTER

9-1 OPERATION AND FUNCTION

When key switch is turned ON, lower electric current (M →) flows through coil of magnetic switch and the coil is excited. The plunger is pulled and higher current (S→) flows through electric starter.

When electric starter is operated, pinion gear is pushed out by means of centrifugal force of weight located in the spline of armature shaft. The pinion gear is engaged with ring gear and flywheel and crankshaft are rotated.

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.

Fig. 9-1

OIL WARNING LAMP

CARBURETOR

IGNITION COIL #2

SPARK PLUG

GRAY

OIL PRESSURE SWITCH

RED

IGNITION COIL #1

BLACK BLACK

SPARK PLUG

RED

STOP DIODE

BLACK

YELLOW

RED

YELLOW

BLACK / WHITE

BLACK

WHITE

TACHO / HOUR METER

(HIGH TENSION CORD)

KEY

SWITCH

CHARGE COIL

REGURATOR

GREEN

ELECTRIC STARTER

BATTERY

12V

Terminal

Key Position

GMBL S

OFF RUN

START

Key switch (Option parts)

STARTING MOTOR

MAGNETIC SWITCH

KEY SWITCH

BATTERY

ELECTRIC STARTER

– 51 –

9-2 COMPONENT PARTS

1. STARTING MOTOR ASS'Y

2. ARMATURE ASS'Y

3. THRUST WASHER KIT

4. PINION STOPPER SET

5. YOKE ASS'Y

6. REAR COVER 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

Fig. 9-3

– 52 –

10.TROUBLESHOOTING

The following three conditions must be fulfilled for satisfactory engine start.

(1) The cylinder filled with a proper fuel-air mixture. (2) Good compression in the cylinder. (3) Good spark, properly timed, to ignite the mixture.

The engine cannot be started unless these three conditions are met.

There are also other factors which make engine start difficult, e.g., a heavy load on the engine when it is about to start at low speed, and a high back pressure due to a long exhaust pipe.

The most common causes of engine troubles are given below:

10-1 NO ENGINE OPERATION

Phenomenon Possible 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 magnetic switch faulty Check, clean, repair or replace

7) Starter motor faulty Repair or replace

8) Crankshaft seizure Check, repair or replace

9) Seizure between piston and cylinder Check, repair or replace

2. Electric starter operates, but engine does not start.

1) No fuel Refill

2) Poor connection or discontinuity of ignition system wirings

Check, repair or replace

3) Electric starter faulty Repair or replace

– 53 –

Phenomenon Possible causes Remedy

1. Low engine speed at starting

1) Battery discharged Charge battery

2) Poor connection between battery and starter motor Clean or repair

3) Poor connection between battery and ground Clean or repair

4) Electric starter faulty Repair or replace

5) Improper engine oil

Replace with recommended engine oil

2. Ignition system malfunction

Spark plug

* Improper spark plug gap * No insulation * Carbon deposits

Adjust Replace Clean

Ignition coil

* No insulation or discontinuity * Poor connection or discontinuity of ignition code

Replace Repair or replace

Improper air gap between ignition coil and flywheel Adjust

3. Fuel system malfunction

1) No fuel in fuel tank 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 components malfunction

1) Insufficient tightening of cylinder head bolts Check and retighten

2) Wear of piston, piston ring and/or cylinder Repair or replace

3) Improper contact of valve and seat Repair

4) Valve seizure Repair

5) Improper valve clearance Adjust

6) Intake manifold gasket leakage

Retighten intake manifold bolts or replace gasket

7) Carburetor gasket leakage

Retighten carburetor bolts or replace gasket

8) Insufficient tightening of spark plug Retighten

10-2 STARTING DIFFICULTIES

– 54 –

Phenomenon Possible causes Remedy

1. Low compression

1) Loosen spark plug Retighten or replace gasket

2) Cylinder head gasket leakage Retighten or replace gasket

3) Piston ring(s) seizure or wear Replace

4) Piston or cylinder wear Repair or replace

5) Incorrect valve and seat contact Repair or replace

6) Valve stem seizure Repair or replace

7) Improper valve clearance Adjust

2. Ignition system malfunction

1) Spark plug faulty Replace

2) Ignition coil faulty Replace

3) Improper air gap between ignition coil and flywheel Adjust

4) Magneto demagnetization 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 replace

10-3 INSUFFICIENT OUTPUT

10-4 OVERHEAT

Phenomenon Possible causes Remedy

Overheating

1) Cooling air flow obstructed at inlet or cylinder baffle portion

Clean

2) Improper engine oil Replace

3) Lean air/fuel mixture Check and adjust carburetor

4) Excessive back pressure of exhaust system Check, clean or replace

5) Over-load Change to rated load

– 55 –

Phenomenon Possible causes Remedy

1. Carburetor

1) Low idling speed Adjust

2) Carburetor slow system passage clogged Check and clean

2. Intake system 1) Air mixing from connecting portion of air intake system Check, tighten or replace gasket

3. Cylinder head 1) Cylinder head gasket faulty (blow-by) Replace

4. Valve system

1) Improper valve clearance Adjust

2) Leakage from valve seat Adjust valve seat contact

3) Excessive clearance between valve stem and guide Replace

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

2. Oil dilution

1) Piston oil ring faulty Replace

2) Piston rings seizure, wear or poor contact Replace

3) Excessive wear of piston and cylinder Replace

4) Excessive wear of valve stem Replace

5) High oil level Adjust oil level

6) Breather faulty Repair or replace

– 56 –

10-7 HIGH FUEL CONSUMPTION

Phenomenon Possible causes Remedy

1. Fuel system

1) Over-size main jet Replace

2) Needle valve faulty and/or high fuel level in float chamber

Adjust or replace

3) Chock valve does not open fully. Repair or replace

2. Engine core components

1) Low compression Check or repair

2) Over cooling

Check and adjust load and/or engine speed

10-8 DETONATION

Phenomenon Possible causes Remedy

1. Ignition system malfunction

1) Poor connection 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) Carbon deposit in combustion chamber Remove and clean

2) Cylinder head gasket faulty (blow-by) Replace

4. Valve system

1) Improper valve clearance Adjust

2) Valve heat deterioration Replace

3) Valve spring deterioration Replace

4) Improper valve timing Adjust

– 57 –

10-9 ENGINE MISFIRE

Phenomenon Possible causes Remedy

1. Ignition system

1) Improper spark plug gap or damaged electrode Cealn, adjust or replace

2) Ignition coil faulty Replace

3) Damaged ignition system wirings Replace

4) Poor connection of 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

3) Low compression Check, adjust or replace

– 58 –

11. INSTALLATION

Engine life, ease of maintenance and inspection, frequency of checks and repairs, and operating cost all depend on the way in which the engine is installed. Review the following instructions carefully for installing the engine.

11-1 INSTALLING

When mounting the engine, carefully examine its position, the method of connecting it to a machine, the foundation, and the method of supporting the engine. When determining its mounting position, in particular, make sure that gasoline and oil can easily be supplied and checked, the spark plug can easily be checked, the air cleaner can easily be serviced, and that the oil can easily be discharged.

11-2 VENTILATION

Fresh air is necessary for cooling the engine and burning the fuel. In the case the engine is operated under a hood or in a small room, temperature rise in the engine room can

cause vapor lock, oil deterioration, increased oil consumption, loss of power, piston seizure, shorter engine life, etc., making it impossible to operate the engine properly. It is necessary, therefore, to provide a duct or baffle to guide cooling air to the engine to prevent recirculation 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. Thus pipe inside diameter must be increased in proportion to exhaust pipe length.

Exhaust pipe : Less than 3 m long --- pipe inside diameter 30 mm.

Less than 5 m long --- pipe inside diameter 33 mm.

11-4 POWER TRANSMISSION TO DRIVEN MACHINES

11-4-1 BELT DRIVE

Take the following notes into consideration.

* V-belts are preferable to flat belts. * The driving shaft of the engine must be parallel to the driven shaft of the machine. * The driving pulley of the engine must be in line with the driven pulley of the machine. * Install the engine pulley as close to the engine as possible. * If possible, span the belt horizontally. * Disengage the load when starting the engine. If no clutch is used, use a belt tension pulley or the like.

11-4-2 FLEXIBLE COUPLING

When using a flexible coupling, run out and misalignment between the driven shaft and engine shaft must be minimized. Run out and misalignment tolerance are specified by the coupling manufacturer.

– 59 –

12.SERVICE DATA

"STD" in the following table is the parts dimension from the brand new engine or the spare parts. Whereas, "Limit" shows the maximum allowance for the parts 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.)

– 60 –

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)

Unit : mm(in.)

16 mm

– 61 –

ITEM

EH72D

STD Limit

PISTON * Ring groove side clearance

* Piston pin hole

* Piston pin outside dia.

* Clearance between piston and cylinder at skirt

area.

* 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.)

– 62 –

ITEM

* Journal dia.

E72D

CRANKSHAFT * Crankpin outside dia.

STD Limit

CONNECTING ROD * Big end inside dia.

* Clearance between big end and crankpin

* Small end inside dia.

* Clearance 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)

———

Unit : mm(in.)



D1 D2

– 63 –

ITEM

VALVE * Valve stem outside dia.

* Clearance between valve stem dia. and valve

guide

* Valve clearance

EH72D

EX.

STD Limit

CAMSHAFT * Cam height (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.)

– 64 –

ITEM

EH72D

VALVE SPRING FREE LENGTH

STD Limit

TAPPET * Stem outside dia.

* Guide inside dia.

* Tappet guide clearance

8.954 - 8.979

(0.3525 - 0.3535)

8.924

(0.3513)

39.5

(1.5551)

9.00 - 9.015

(0.3543 - 0.3549)

9.08

(0.3575)

———

0.021 - 0.061

(0.000827 - 0.002402)

0.15

(0.0059)

VALVE SEAT ANGLE (IN. EX.) * Valve cutter angle (a) * Valve contact width (b)

a: 90˚ b: 0.7 - 1.0

(0.028 - 0.039)

2.0

(0.079)

Unit : mm(in.)

Compression pressure Fuel consumption

Lubricant

Continuous load / 3600 rpm Capacity Efficacy Consumption

(kg / cm (L / Hr ) (L) (mL) (mL / Hr)

※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 break-in operation has been finished.

• Oil : 10W-30 (Grade SE)

• Load : Continuous load / 3600 rpm

470 rpm )

EH72D

7.0

1.55 930

15 - 20

– 65 –

ITEMS

Breather cover

N・・m kgf・・cm ft・・lb.

Breather cover 2.9 - 4.9 30 - 50 2.2 - 3.6

Carburetor bolts 16.7 - 18.6 170 - 190 12.3 - 13.7

Charge coil 1.5 - 3.4 15 - 35 1.1 - 2.5

Connecting rod cap bolts 22.1 - 27.0 225 - 275

Tightening Torque

16.3 - 19.9

Cylinder head bolts 41.2 - 49 400 - 500 29.4 - 36.8

Flywheel nut 83.3 - 93.1 850 - 950 61.5 - 68.7

Ignition 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 8.7 - 10.9

Current one 22.5 - 26.5 225 - 275 16.6 - 19.5

Starter motor bolts 16.7 - 18.6 170 - 190 12.3 - 13.7

12-2 TIGHTENING TORQUE

– 66 –

12-3 OIL GRADE CHART

Use oil classified as SE or higher. Multi-grade oil tends to increase its consumption at high ambient temperature.

Comparison between oil viscosity and temparature

10W

Specified

Lubricant

Quality

Single

grade

Multigrade

20W

#20

#30

#40

10W-30

10W-40

10 50

20 68

30 86

40 °C

104 °F

– 67 –

13.MAINTENANCE AND STORAGE

13-1 DAILY MAINTENANCE

Every day before operating engine, check the following items :

13-2 PERIODIC MAINTENANCE SCHEDULE

Periodic maintenance is vital to safe and efficient operation of engine. Check the table below for periodic maintenance intervals. It is also necessary to conduct the maintenance and adjustments on the emission-related parts listed below to keep the emission control system effective;

(1) Carburetor and internal parts (2) Choke system (3) Fuel strainer (4) Air cleaner elements (5) Intake pipe (6) 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 dust and chaff from engine. Governor linkage is especially sensetive to dust.

2) Check fuel leakage from fuel system. If any, retighten fasteners or replace necessary parts.

3) Inspect for loose hardware and retighten if necessary.

Loose bolts and nuts may come off and result in breakage of other parts.

4) Check oil level and add to full level.

– 68 –

Maintenance Items

Every 8

hours

(Daily)

Every

hours

Every

hours

Every

200

hours

Every

500

hours

Every

1000

hours

Clean engine and check bolts and nuts

× (Daily)

Check and refill engine oil

(Refill daily

to upper level)

Change engine oil (*Note 1)

(Intial)

Replace engine filter (*Note 1)

(Intial)

Check battery electrolyte fluid level

Clean spark plug

Clean air cleaner

Replace air cleaner element

Clean fuel strainer

Clean and adjust spark plug and electrodes

Replace spark plug

Remove carbon from cylinder head

Clean and adjust carburetor

Clean engine base (oil pan)

Check and adjust valve clearance

Replace fuel lines

(Yearly)

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 give you more detailed instructions on proper disposal.

*Note 2 : As to the procedures, please refer to the Service Manual or consult your nearest ROBIN service

dealer.

*Note 3 : More frequent oil changing, oil filter replacement and air cleaner service or replacement may be

necessary depending on operating conditions such as dusty environment, high ambient temperature, heavy engine loading etc.

Periodic Maintenance Schedue Table

– 69 –

13-3 ENGINE STORAGE

(1)Change the engine oil and perform the daily maintenance items above mentioned. (2)Drain fuel from carburetor float chamber. (3)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.

PRINTED IN THE USA

Robin EH72 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual