Robin EX17, EX21, EX27 Service Manual

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SERVICE MANUAL

Models

EX13, 17, 21, 27 ENGINES

PUB-ES1934 Rev. 10/05

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 ...............................................................................................................7

4. GENERAL DESCRIPTION OF ENGINE COMPONENTS........................................ 8

5. DISASSEMBLY AND REASSEMBLY .................................................................... 14

5-1 PREPARATIONS AND PRECAUTIONS............................................................14

5-2 SPECIAL TOOLS .............................................................................................. 14

5-3 DISASSEMBLY PROCEDURE.......................................................................... 15

5-4 REASSEMBLY PROCEDURE........................................................................... 29

6. ENGINE OIL ...........................................................................................................47

7. MAGNETO .............................................................................................................. 48

8. WIRING DIAGRAM................................................................................................. 51

9. ELECTRIC STARTER............................................................................................. 53

10. OIL SENSOR .......................................................................................................... 55

11. AUTOMATIC DECOMPRESSION SYSTEM........................................................... 56

12. CARBURETOR....................................................................................................... 57

13. RECOIL STAR TER................................................................................................. 61

14. INSTALLATION ...................................................................................................... 66

15. TROUBLESHOOTING............................................................................................ 68

16. STANDARD REPAIR TABLES ............................................................................... 74

15-1 STANDARD DIMENSIONS AND LIMITS OF USE ........................................... 74

15-2 TIGHTENING TORQUE .................................................................................... 80

17. MAINTENANCE AND STORAGE ..........................................................................81

1. SPECIFICATIONS

)

Model EX13D EX17D EX21D EX27D

Type

Bore & Stroke

Piston Displacement

Compression Ratio 8.5 8.3

Continuous Output kW(HP)/r.p.m.

Maximum Output kW(HP)/r.p.m. 3.2(4.3)/4000 4.2(5.7)/4000 5.1(7.0)/4000 6.6(9.0)/4000

Maximum Torque

Direction of Rotation Counterclockwise as viewed from the P.T.O.shaft side Valve Arrangement Overhead cam system Cooling System Forced air coo ling system Lubrication System Splash lubrication system

Lubricant

mm (in.)

ml (cu.in.)

N・m/r.p.m. (kgf・m/r.p.m.) (ft・lb./ r.p.m.)

58 x 48

(2.28 x 1.89)

126

(7.69)

1.9(2.6)/3000

2.2(3.0)/3600

8.1/2500 (0.83/2500) (6.01/2500)

Automobile engine oil ;Grade SE or higher (SG,SH or SJ in recomended)

SAE 10W-30-----Under ordinary atmospheric temperatures SAE 5W-30-------In cold areas

Air-Cooled, 4-Cycle, Slant Singl e-Cyl inder,

Horizontal P.T.O. Shaft, OHC Gasoline Engine

67 x 48

(2.64 x 1.89)

169

(10.31)

2.6(3.5)/3000

2.9(4.0)/3600

11.3/2500

(1.15/2500)

(8.34/2500

67 x 60

(2.64 x 2.36)

211

(12.87)

3.2(4.4)/3000

3.7(5.0)/3600

13.9/2500

(1.41/2500)

(10.26/2500

75 x 60

(2.95 x 2.36)

265

(16.17)

4.4(6.0)/3000

5.1(7.0)/3600

18.6/2500 (1.9/2500)

(13.74/2500

Capacity of Lubricant L 0.6 1.0 Carburetor Horizontal draft, Float type Fuel Automobile unleaded gasol ine

Fuel C onsumption Rate

Fuel Supply System Gravity type Fuel Tank Capaci ty L 2.7 3.6 6.1 Ignition System Transistorized magneto Spark Plug NGK BR-6HS (CHAMPION RL86C)

Charging Capaci ty (Option)

Starting System Recoil starter Recoil starter / Electric starter (Option) Governor System Centrifugal flyweight system

Dry Weight

Dimensions (L x W x H)

＊Specifications are subject to change without notice.

g/kW・h (g/HP・h)

V-A ------------- 12-1 A , 3 A , 1 6.7 A (Opt i on)

kg (lb.)

mm (in.)

(11.7x13.4x12.5)

(30.87)

297 x 341 x 318

367 (270) at continuous rated output

(33.08)

304 x 354 x 335

(12.0x13.9x13.2)

(12.2x14.4x13.2)

(35.28)

311 x 366 x 335

(46.31)

351 x 420 x 410

(13.8x16.5x16.1

- 1 -

2. PERFORMANCE

2-1 MAXIMUM OUTPUT

The Maximum output is the output of an engine with its throttle valve fully opened and considering that all the moving parts are properly broken in.

A new engine may not produce full maxim um output while its moving parts are still not broken-in.

NOTE : Pow er curves shown in the follo wing charts are made in conformity with 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 gov erned speed which is most fav orable from the view point of engin’ s life and fuel consumption.

When the engine is installed on a certain equipment, it is recommended that the continuous output required from the equipment to 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 a specific r.p.m..

- 2 -

2-4 PERFORMANCE CURVES

EX13D

9.0

0.9

[HP]

5.0

4.0

3.0

MAXIMUM TORQUE

4.0

3.5

MAXIMUM HORSEPOWER

3.0

2.5

8.0

7.0

0.8

0.7

TORQUE

OUTPUT

2.0

1.0

2.0

CONTINUOUS RATED HP

1.5

RECOMMENDED HORSEPOWER RANGE

1.0

0.5

2000 2400 2800 3200 3600 4000

r.p.m.REVOLUTION

- 3 -

EX17D

12.0

1.2

[HP]

6.0

5.0

4.0

4.5

4.0

3.5

3.0

2.5

MAXIMUM TORQUE

MAXIMUM HORSEPOWER

11.0

10.0

9.0

1.1

1.0

0.9

TORQUE

3.0

OUTPUT

2.0

1.0

CONTINUOUS RATED HP

2.0

RECOMMENDED HORSEPOWER RANGE

1.5

1.0

0.5

2000 2400 2800 3200 3600 4000

r.p.m.REVOLUTION

- 4 -

[PS]

5.5

EX21D

MAXIMUM TORQUE

15.0

14.0

13.0

12.0

1.5

1.4

1.3

1.2

7.0

6.0

5.0

4.0

3.0

OUTPUT

5.0

TORQUE

MAXIMUM HORSEPOWER

4.5

4.0

3.5

3.0

CONTINUOUS RATED HP

2.5

RECOMMENDED HORSEPOWER RANGE

2.0

1.0

1.5

1.0

0.5

2000 2400 2800 3200 3600 4000

r.p.m.REVOLUTION

- 5 -

EX27D

[HP]

9.0

8.0

7.0

6.0

MAXIMUM TORQUE

7.0

6.5

MAXIMUM HORSEPOWER

6.0

5.5

5.0

4.5

4.0

CONTINUOUS RATED HP

19.0

18.0

17.0

16.0

15.0

1.9

1.8

1.7

1.6

1.5

TORQUE

5.0

4.0

OUTPUT

3.0

2.0

1.0

3.5

RECOMMENDED

3.0

2.5

2.0

1.5

1.0

0.5

0 2000 2400 2800 3200 3600 4000

HORSEPOWER RANGE

r.p.m.REVOLUTION

- 6 -

3. FEATURES

3-1 EXTREMELY SILENT - SOFT TONE QUALITY

EX engines are 2dBA quieter and softer in tone than other engines in the same class.

This quiet and soft tone is achieved b y:

- A reduction in mechanical noise realized by emplo ying sophisticated OHC system.

- Employment of an optimized capacity Rigid Muffler.

3-2 EXTREMELY EASY START - NO KICK-BACK

Reliable Starting and Less Pulling Force are achieved by:

- Sophisticated Mechanical Compression Release System as well as newly designed Combustion Chamber.

- EX engines start instantly even at minus (-) 10°C, without any perceptible kick-back.

3-3 EXTREMELY EASY MAINTENANCE

Extreme ease of maintenance is realized by:

- High Parts Commonality

simplifies maintenance & lowers repair cost due to fe w er parts for service. More than 90% of component parts are in common between more than two models, in such as Muffler, Intake and Exhaust Valves, Valve Springs, etc. Furthermore, more than 50% of component parts are in common among EX13, EX17 and EX21, in such as Chain Guide, Air Cleaner, Ignition Coil, etc.

- Only with ordinary tools, routine maintenance, assembly and disassembly can be performed.

3-4 EXTREMELY ADVANCED TECHNOLOGY

Extreme reliability and durability are achieved b y:

- Heavy Duty Chain Driven OHC System

Oval type case-hardened steel links enhance performance and resist stretching, which result in extended maintenance free operation.

- Completely New Main Bearing Cover’s Design

Flush-mounted main bearing cover with lower moment of def ormation significantly increases reliability and engine life.

- Superior Cooling and Lubrication System

Heat reduction is achieved b y more efficient, larger and more numerous cooling fins on cr ankcase, cylinder and mounting base, as well as by outstanding oil delivery system.

- Large Ball Bearings on both ends of crankshaft for maxim um stability under demanding loads .

- Cast Iron Cylinder Liner resists wear

3-5 EXTREME POWER AND PERFORMANCE

Extremely Higher Po wer and Lo wer Fuel Consumption are realiz ed b y :

- High speed and homogeneous combustion achiev ed by sophisticated Pentroof Combustion Chamber which includes Intake and Exhaust Valves located at optimum angle.

- Straight Intake Port with minimal air flow resistance.

Environmentall y friendly

EX engines comply with EPA Phase 2 and CARB Tier II Emission Regulations in the USA.

Extreme application compatibility

With four versatile models, existing slant-cylinder engines can be easily replaced.

- 7 -

4. GENERAL DESCRIPTION OF ENGINE COMPONENTS

4-1 CYLINDER AND CRANKCASE

The cylinder and crankcase are aluminum die-casting as a single piece. A special cast iron cylinder liner is molded into the aluminum die-casting. The crankcase has a mounting surface on the output shaft side to which the main bearing cover is attached. The cylinder is inclined to the right at an angle of 25 degrees from the horizontal as viewed from the output shaft side.

Fig. 4-1

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. By removing the main bearing cover, the inside of the engine can be inspected with ease. Pilots and bosses are machined into the cover to f acilitate the direct coupling of the engine with machines such as generators and pumps. There is an oil filling port, with oil gauge, on either side of the cover.

4-3 CRANKSHAFT

The crankshaft is made of spheroidal graphite cast iron, and the crank pin is high-frequency induction-hardened. The crank sprocket used to drive the chain and the gear used to drive the governor gear are pressed into the output end of the shaft.

4-4 CONNECTING ROD AND PISTON

The connecting rod is a specially heat-treated aluminum alloy die-casting. Its large and small ends function as bearings. A splasher built into the connecting rod lubricates by splashing engine oil. The piston is an aluminum alloy casting with groov es for mounting two compression rings and one oil ring.

Fig. 4-2

Fig. 4-3

- 8 -

Fig. 4-4

4-5 PISTON RINGS

The piston rings are made of special cast iron. The profile of the top ring is a barrel face or tapered face, and that of the second ring is a tapered face. There are 2 types of oil ring depending on the engine specification. As those are interchangeable, the cutter ring with coil expander type can be selected as the spare part.

BARREL

TOP

RING

(EX13/27)

TAPER (EX17/21)

Fig. 4-5

4-6 CAMSHAFT

The camshaft and the sprocket are made of special sintered alloy. They are constructed as a single piece. The camshaft is provided with intake and exhaust cam, and the decompression release lever is mounted on the sprocket shaft end side.

4-7 VALVE ARRANGEMENT

SECOND RING

OIL RING

TAPER

CUTTER RING WITH COIL EXPANDER

THREE-PIECE CONSTRUCTION

Fig. 4-6

EXHAUST VALVE INTAKE VALVE

This engine has a chain-driven overhead cam and overhead valve construction, with a single cam performing both intake and exhaust oper ations.

4-8 CYLINDER HEAD

The cylinder head is an aluminum die-casting with a pent roof combustion chamber construction. The intak e and exhaust ports are arranged in a cross direction to improve combustion efficiency.

Fig. 4-7

Fig. 4-8

- 9 -

4-9 GOVERNOR SYSTEM

GOVERNOR GEAR

This engine is equipped with a centrifugal flyweight type governor that makes it possible to oper ate the engine at a constant speed, even with load variations. (The governor flyweights are mounted on a governor gear .)

Fig. 4-9

4-10 COOLING SYSTEM

The engine uses a forced air-cooling system in which a cooling fan (which also works as a flywheel) forces cooling air into the cylinder and the cylinder head. Baffles are provided to guide the flow of the cooling air. (Model EX21 is provided with a synthetic resin cooling fan that is separate from the flywheel.)

4-11 LUBRICATION SYSTEM

The rotating parts, sliding parts and valv es of the engine are lubricated with oil in the crankcase. The oil is splashed

onto the parts by the oil splasher on the connecting rod.

4-12 TIMING CHAIN

Timing chain system is adopted and designed for lubricating for the upper portion of cylinder head. The timing chain is engaged between the sprocket portion of integrated camshaft in the cylinder head and the crankshaft gear sprocket. The sprocket teeth in particular shape are adopted to enhance the durability and to realize low noise level.

4-13 IGNITION SYSTEM

The ignition system is a transistor controlled magneto system with the ignition timing set at 23 degrees (EX13/ 17/21)[27 degrees (EX27)] before the top dead center . The magneto consists of a flywheel and ignition coil. The flywheel (which also works as a fan) is directly mounted on the crankshaft and the ignition coil is directly mounted on the crankcase.

TIMING CHAIN

OIL SPLASHE

Fig. 4-10

※Model EX13,17,21 and 27D has a smooth advanced

ignition timing system to improve starting performance. (For further details, refer to page 48, section “7. MAGNET O”.)

IGNITION COIL

FLYWHEEL

Fig. 4-11

4-14 CARBURETOR

The engine is equipped with a horizontal draft carburetor. The carburetor setting is calibrated after careful testing for optimum all-round performance (including starting, acceleration, fuel consumption, output power characteristics). Special attention is also paid to the general-purpose use of the engine. (For further information, refer to page 57, section “11. CARBURETOR”.)

Fig.4-12

4-15 AIR CLEANER

The engine uses an air cleaner that is quieter than conventional ones. A semi-wet urethane foam element is used in the STD air cleaner. Dual element air cleaner (with a primary element of d ry type sponge and secondary element of dry type paper) and other types are also provided as special options.

4-16 BALANCER

(PROVIDED ONLY IN MODEL EX27D)

Unbalanced inertia force is cancelled by the balancer which rotates at the same speed as the crankshaft to effectively reduce vibration.

STD Type Dual Element Type

CLEANER COVER

URETHANE FOAM

Fig.4-13

CLEANER COVER

URETHANE FOAM

PAPER ELEMENT

4-17 DECOMPRESSION SYSTEM

The automatic decompression system is mounted on the camshaft. It opens the exhaust valve before the compression top, thereby alle viating the compression pressure and reducing the force required to pull the recoil starter. During engine operation, the decompression system is overpowered by centrifugal force and compression is fully utilized to produce power .

Fig.4-14

RETURN SPRING

ROCKER ARM (EXHAUST VALVE SIDE)

EXHAUST VALVE

CAMSHAFT

Fig.4-15

4-18 SECTIONAL VIEW OF THE ENGINE

Cross sectional view – across the shaft

FUEL TANK

TANK CAP

GOVERNOR SHAFT

BLOWER HOUSING

STARTING PULLEY

RECOIL STARTER

FLYWHEEL CHARGE COIL

(OPTION)

OIL SENSOR

(OPTION)

GOVERNOR LEVER

GOVERNOR GEAR

CRANKSHAFT

CONNECTING ROD

MAIN BEARING COVER

Fig. 4-16

M S

G G

N R

Cross sectional view – along the shaft

FUEL STRAINER

CHAIN GUIDEGOVERNOR LEVER

FUEL TANK

OVERNOR EAR

AGNETIC

WITCH

TIMING CHAIN

STARTING MOTOR (OPTION)

MUFFLER COVER

EXHAUST

VALVE

MUFFLERPISTON

TAIL SCREE or DEFLECTO (OPTION)

SPARK ARRESTER (OPTION)

ROCKER

ARM

CAMSHAFT

INTAKE VALVE

PISTON PIN

PISTON RING

TENSIONER

OIL GAUGE

OIL DRAIN PLUG

FILLER PLUG

CONNECTING ROD

CRANKSHAFTCRANKCASE

OIL SENSOR

(OPTION)

Fig. 4-17

5. DISASSEMBLY AND REASSEMBLY

5-1 PREPARATIONS AND PRECAUTIONS

(1) When disassembling the engine, memorize the location of each part so that you can reassemble the engine

correctly. If necessary , attach identification tags with the required assembly information to the parts. (2) Store groups of parts in separate box es . This will make reassembly easier. (3) To prevent parts from being mislaid, keep each group provisionally assembled after removing the parts from

the engine. (4) Handle the disassembled parts with the utmost care. Clean them with cleaning oil if necessary . (5) Use the correct tools in the correct wa y when disassemb ling and reassembling the engine.

5-2 SPECIAL TOOLS

Tool name Use

Commercially available product

Flywheel puller For pulling off the flywheel

FLYWHEEL PULLER

Fig. 5-1

5-3 DISASSEMBLY PROCEDURE

Step Parts to remove Remarks and procedures Fasteners

1 Drain the engine oill (1) Remove a drain plug (M14×12mm)

located on both sides of the case. Take care not to lose the gaskets.

(2) To discharge oil quickly, remove the oil

guage.

14 mm spanner

OIL GAUGE

GASKET

STEP 1

GASKET

DRAIN PLUG

Fig. 5-2

Step Parts to remove Remarks and procedures Fasteners

Air cleaner cover Remove the air cleaner cover.

Air cleaner Remove the element, and remove the air

cleaner while pulling the breather pipe away from the rocker cover.

STEP 3

AIR CLEANER COVER

URETHANE FOAM

10 mm box spanner M6 nut: 2 pcs. M6×20:1pc.

DUAL ELEMENT TYPESTD TYPE

STEP 3

AIR CLEANER COVER

URETHAN FOAM

PAPER ELEMENT

M6 x 20 FLANGE BOLT : 1 pc.

Fig. 5-3

AIR CLEANER COVER

STEP 2

BREATHER PIPE

M6 FLANGE NUT : 2 pcs.

Step Parts to remove Remarks and procedures Fasteners

Stop switch Disconnect the wire and remove the stop

switch from the blower housing.

Recoil starter Remove the recoil starter from the blower

Blower housing Baffle 2 (head) Baffle 3

housing.

(1)Remove the blower housing from the

crankcase.

(2)Remove the baffle 2 (head) and baffle 3.

STEP 4

M6 x 12 BOLT : 4 pcs.

M4 TAPPING SCREW : 2 pcs.

STOP SWITCH

10 mm box spanner M6 × 8mm : 4 pcs.

10 mm box spanner M6 × 12mm : 4 pcs. 10 mm box spanner or

spanner M6 × 12mm : 2 pcs. (Baffle 2 (head)) M5 tapping bolt : 2 pcs. (Baffle 3)

M6 x 8 BOLT : 4 pcs.

STEP 5

BAFFLE 3

(EX21 ONLY)

M5 TAPPING BOLT : 2 pcs.

RECOIL STARTER

BLOWER HOUSING

STEP 6

BAFFLE 2 (HEAD)

M6 x 12 BOLT : 1 pc.

STEP 6

Fig. 5-4

Step Parts to remove Remarks and procedures Fasteners

Fuel tank (1) Drain fuel from the carburetor drain.

(2) Remove the fuel tank mounting nuts

and bolts from the crankcase.

(3) Disconnect the fuel pipe from the carburetor.

(See Fig. 5-6)

(4) Remove the fuel tank from the crankcase.

Muffler and Muffler cover (1) Remove the muffler cover from the

muffler.

(2) Remove the muffler from the cylinder

head. Take care not to lose the gasket.

※Take care not to cut your hand with the

muffler gasket.

※Seal the exhaust port with adhesive

tape or plug it with cloth to prevent nuts and other objects from falling inside.

STEP 7

FUEL TANK

10 (12) mm spanner or box

wrench M6 nut : 2 pcs. (Models EX13, 17 and 21) M8 nut : 2 pcs. (Model EX 27) M6 × 25mm : 1 pc. (Models EX 13, 17 and 21) M8 × 25mm : 2 pcs. (Model EX27)

12mm box spanner 10mm box spanner or

spanner M6 tapping bolt : 2 pcs. M6 × 8mm : 1 pc. M8 nut : 2 pcs. M8 × 12mm : 1 pc.

M6 x 10 TAPPING BOLT : 2 pcs.

STEP 8

M6 NUT : 2 pcs. (EX13,17,21) M8 NUT : 2 pcs. (EX27)

FUEL PIPE

M6 x 8 FLANGE BOLT : 1 pc.

M8 NUT : 2 pcs.

M6 x 25 BOLT : 1 pc. (EX13, 17, 21) M8 x 25 BOLT : 2 pcs.

(EX27)

MUFFLER

M8 x 12 BOLT : 1 pc.

GASKET

(It has two faces)

FUEL DRAIN

Seal the exhaust port with adhesive tape or plug it with cloth.

Fig.5-6

Fig.5-5

Step Parts to remove

Remarks and procedures

Fasteners

Governor system (1) Loosen the bolt and remove the governor

lever from the governor shaft. There is no

need to remove the bolt. (2) Remove the governor spring. (3) Remove the governor rod and the rod

spring from the carburetor.

Carburetor, Insulator Remove the carburetor from the cylinder head.

Speed control lever and

Bracket

STEP 9

GOVERNOR LEVER

Remove the insulator.

Remove the speed control lever and bracket from the cylinder head.

GOVERNOR ROD and ROD SPRING

GOVERNOR SPRING

10 mm box spanner or

spanner

M6 × 30mm : 1 pc.

10 mm box spanner M6 × 12mm : 2 pcs.

GOVERNOR SHAFT

M6 x 12 BOLT : 2 pcs.

STEP 11

SPEED CONTROL LEVER and BRACKET

GASKET

INSULATOR

GASKET

CARBURETOR

STEP 10

Fig.5-7

Step Parts to remove Remarks and procedues Fasteners

Ignition coil Remove the spark plug cap from the spark plug and

remove the ignition co il from the crankcase.

Starting pulley Remove the starting pulley from the flywheel.

Fit a box wrench or a socket wrench on the flywheel nut and loosen the nut by knocking the wrench sharply with a hammer. (See Fig. 5-10) NOTE:

1) Do not insert a screwdriver or other objectbetween the flywheel blades, otherwise the risk of damaging the blades might be occured.

2) Knock the w rench with a hammer in a counter

clockwise direction.

3) The fan of the Model EX21 engine is made of

synthetic resin. Take the utmost care when handling it.

Flywheel Remove the flywheel from the crankshaft. Leave the nut

temporarily to prevent the flywheel from dropping out.Fit

the flywheel puller as shown in Figure 5-11 and remove the flywheel from the crankshaft by rotating the bolt at the centerin a clockwise direction. (Knock the center bolt witha hammer sometimes)

10 mm box spanner M6 × 25mm : 2 pcs.

19 (24) mm box spanner o socket wrench M14 nut (Models EX13,17 and 21) M18 nut (Model EX27)

Flywheel pull er

FLYWHEEL PULLER

Fig. 5-10 Fig. 5-11

M14 NUT : 1 pc. (EX13,17,21) M18 NUT : 1 pc. (EX27)

STEP 13

STEP 14

FLYWHEEL

STARTING PULLEY

M6 x 25 BOLT an WASHER : 2 pcs.

STEP 12

GROMMET (EX13,17,21 only)

Fig. 5-9

ATTACH NUT TEMPORARILY

Step Parts to remove Remarks and procedures Fasteners

Electric starter (option)

Control box,

Diode rectifier,

Magnetic switch

STEP 15

(1) Disconnect the grounding cable from battery. (2) Disconnect the wire leading from the key

(3) Disconnect the wire that connects the

(4) Remove the electric starter.

ELECTRIC STARTER (option)

switchSTterm inal to the magnetic switch.

positive terminal of the battery to the magnetic switch.

M6 NUT : 1 pc. (EX17,21) M8 NUT : 1 pc. (EX27)

EX27

M8 x 28 BOLT : 2 pcs.

EX17, 21

UPPER SIDE M6 x 30 FLANGE BOLT : 1 pc DOWN SIDE M6 x 20 FLANGE BOLT : 1 pc

12 mm box spanner

M8 nuts 10 mm box spanner 12 mm box spanner

Fig. 5-8

Step Parts to remove Remarks and procedures Fasteners

Baffle 1 (case) Remove the baffle 1 (case) M6 × 12mm : 1 pc.

(Models EX13, 17 and 21) M8 × 12mm : 1 pc. (Model EX27)

Charge coil (option) Remove the charge coil.

(For EX27, remove the wire clamp together)

box spanner M6 × 20mm : 2 pcs. + screwdriver

Spark plug Remove the spark plug from the cylinder head. 21 mm plug wrench

M6 x 12 FLANGE BOLT : 1 pc. (EX13, 17, 21) M8 x 12 FLANGE BOLT : 1 pc. (EX27)

BAFFLE 1 (CASE)

For the model without electric starter.

STEP 16

STEP 17

CHARGE COIL

SPACER

Fig.5-12

STEP 18

SPARK PLUG

CHARGE COIL

VIEW

EX13

EX17

EX21

EX27

(EX27 only)

15W 40W 15W 40W

200W

15W 40W

200W

15W 40W

200W

CLAMP

SPACER

NA NA NA NA

BOLT M6 x 40L M6 x 35L M6 x 35L M6 x 40L M6 x 25L M6 x 35L M6 x 40L M6 x 25L M6 x 20L M6 x 30L M6 x 25L

Step Parts to remove Remarks and procedures Fasteners

Rocker cover (1) Remove the rocker cover from the

cylinder head.

(2) Remove the gasket (rocker cover).

Rocker arm

Remove the pin (rocker arm) and the rocker

arm from the cylinder head at the compression top dead center.(See Fig. 5-14b)

ROCKER ARM (EXHAUST VALVE SIDE)

PIN (ROCKER ARM)

ROCKER ARM (INTAKE VALVE SIDE)

10 mm box spanner M6 × 12mm : 4 pcs.

The position of compression top dead center

Punch marks

Fig. 5-14a

STEP 20

ROCKER ARM (INTAKE VALVE SIDE)

CLOSE-UP A

GASKET (ROCKER COVER)

Fig. 5-14b

ROCKER ARM (EXHAUST VALVE SIDE)

PIN (ROCKER ARM)

STEP 19

Fig. 5-13

ROCKER COVER

M6 x 12 BOLT : 4 pcs.

Step Parts to remove Remarks and procedures Fasteners

Main bearing cover (1) Remove the flange bolts of main bearing

cover from the crankcase. Remove the main bearing cover while

tapping gently around the cover using a plastic hammer or similar tool. (See Fig. 5-16) Be careful not to damage the oil gauge or oil seal or not to lose the pipe knocks.

12 mm box spanner M8 × 35mm : 6 pcs. (Models EX13, 17 and 21) M8 × 35mm : 7 pcs. (Model EX27)

Fig. 5-16

M8 x 35mm : 6 pcs. (MODELS EX13, 17 AND 21) M8 x 35mm : 7 pcs. (MODEL EX27)

STEP 21

MAIN BEARING COVER

PIPE KNOCK

Fig. 5-15

Step Parts to remove Remarks and procedures Fasteners

Tensioner, Camshaft (1) Remove the tensioner. (See Fig. 5-18a)

※Do not lose the pin (tensioner).

(2) Remove the retaining bolt of pin (camshaft)

fromthe cylinder head.(See Fi g. 5-18b)

(3) Remove the pin (cam shaft), taking care not

to scratch the O-ring.

(4) Remove the chain from the camshaft

sprocket and then take out the camshaft. (See Fig. 5-19)

(5) Remove the chain from the crankshaft.

PIN (CAMSHAFT)

M6 x 12 BOLT : 1 pc. Bolt used to prevent the

PIN (TENSIONER)

Fig.5-18a

pin (camshaft) from coming out

Fig.5-18b

M10 box spanner or spanner M6 × 12mm : 1 pc.

Fig.5-19

CHAIN

SPRING (TENSIONER)

PIN (TENSIONER)

CHAIN

CAMSHAFT

TENSIONER

STEP 22

PIN (CAMSHAFT)

Fig. 5-17

CAMSHAFT

STEP 22

M6 x 12 BOLT : 1 pc. Bolt used to prevent the pin (camshaft) from coming out

CHAIN

Step Parts to remove Remarks and procedures Fasteners

Cylinder head, Chain guide

Intake and exhaust valves

(1) Remove the cylinder head from the

crankcase.

(2) Remove the cylinder head gasket from the

cylinder head. Take care not to lose the pipe knocks.

(3) Remove the chain guide from the top side

of the crankcase. (If the chain guide is removed from the inner side of the crankcase, it might be damaged.)

(1) Remove the collet valve from the

spring retainer. (See Fig. 5-21)

(2) Remove the intake valve and the exhaust

valve.

12 mm box spanner M8 × 68mm : 4 pcs. M8 × 35mm : 1 pc.

Fig.5-21

Push

PIPE KNOCK

INTAKE VALVE

EXHAUST VALVE

STEP 24

CHAINGUIDE

M8 x 35 BOLT : 1 pc. (This bolt is same as the main bearing cover bolt).

GASKET

SPRING RETAINER

VALVE SPRING

STEP 23

CYLINDER HEAD

COLLET VALVE

M8 x 68 BOLT : 4 pcs.

STEM SEAL

SPRING RETAINER

VALVE SPRIN

COLLET VALVE

Fig.5-20

Step Parts to remove Remarks and procedures Fasteners

Connecting rod and piston

(1) Scrape off any carbon from the cylinder

and the piston head, then remove the connecting rod bolt.

(2) Remove the connecting rod cap. (3) Rotate the crankshaft until the piston

comes to its top position. Push the connecting rod and remove the piston from the upper part of the cylinder.

Piston and piston rings (1) Remove the piston clips (2 pcs.). Take

out the piston pin and then remove the piston from the connecting rod small end, taking care not to damage the connecting rod

small end.

(2) Remove the piston rings from the piston

by spreading them at the gap. Take special care not to damage the rings when doing this.

STEP 25

CONNECTING ROD CAP

CONNECTING ROD

10 mm box spanner M6 × 33mm :2 pcs. (Models EX13, 17 and 21) M7 × 40mm : 2 pcs. (Model EX27)

STEP 26

PISTON RING

CLIP

PISTON PIN

CLIP

M6 x 33 (EX13, 17, 21) M7 x 40 (EX27) CONNECTING ROD BOLT : 2 pcs.

Fig.5-22

PISTON

Step Parts to remove Remarks and procedures Fasteners

Crankshaft (1) Remove the woodruf fkey (for the flywheel

magneto) .

(2) Remove the crankshaft fromthe crankcase

by tapping its magneto side end with a plastic

Plastic hammer hammer, taking care not to damage the oil seal.(See Fig.5-24)

Oil sensor (option) (1) Remove the clamp.(See Fig.5-25)

(2) Remove the oil sensor from the crankcase.

Fig.5-24

M6 × 12mm : 1 pc.

M6 × 16mm : 2 pcs.

CLAMP

OIL SENSOR

Fig.5-25

M6 x 10 TAPPING BOLT : 1 pc. (EX27 only)

CLAMP

CRANKCASE

WOODRUFF KEY

CRANKSHAFT

STEP 27

Fig.5-23

SHIELD PLATE (For charge coil only)

M6 x 16 BOLT : 2 pcs.

OIL SENSOR

STEP 28

OIL SENSOR

SHIELD PLATE(OS)

M6 x 12 BOLT : 1pc.

M6 x 16 BOLT : 2pcs.

CLAMP

5-4 REASSEMBLY PROCEDURE

POLYVINYL TAPE

5-4-1 NOTES ON REASSEMBLY

(1) Clean the each parts carefully, taking special care with the piston, cylinder, crankshaft, connecting rod and

bearings.

(2) Scrape off any carbon deposits on the cylinder head and the piston head. Be particularly careful when

removing carbon from the piston ring grooves. (3) Inspect the oil seals for any damage to the lip. Replace them if damaged. Apply oil to the lip before reassemb ly . (4) Replace all the gaskets with new ones. (5) Replace the keys, pins, bolts and nuts with new ones, if necessary. (6) Tighten nuts and bolts to the specified torque settings. (7) When reassembling the engine, apply oil to all moving parts. (8) Check clearances and end plays and adjust, if necessary. (9) When mounting any major part during reassembly of the engine, rotate it with your hand to check for any

jamming or abnormal noise.

5-4-2 ASSEMBLY STEPS AND PRECAUTIONS

(1) OIL SENSOR

(a) Mount the oil sensor and fix the wire with the clamp. (b) Mount the shield plate only for charge coil type.

Tightening torque

10.0 N・m

(

100 kgf・cm)

(7.2 ft・lb.)

control unit at the same time.

(See Fig. 5-49a on page 38).

Fig.5-29

(2) CRANKSHAFT

RANKSHAFT

(a) Wrap the key-way portion of the crankshaft with

polyvinyl tape and insert the crankshaft into the

crankcase, taking care not to damage the oil seal lip. (b) Insert the woodruff key (f or the flywheel magneto).

NOTE: Do not insert the woodruff key before inserting

the crankshaft into the crankcase.

Fig.5-30

(3) PISTON AND PISTON RINGS

Install each piston ring in the correct groove of the piston by widening it enough to slide it over the piston.

NOTE: Be careful not to twist the rings too much,

as they may be damaged. Install the oil ring first, followed by the second ring and then the top ring. When installing the second ring, make sure that the ‘N’ mark is face up. (See Fig. 5-33)

OPEN ENDS OF PISTON RING

Fig.5-31

BARREL

TOP

RING

(EX13/27)

TAPER (EX17/21)

MARK "R"

EX13

Fig.5-32

SECOND RING

OIL RING

MARK "N"

TAPER

CUTTER RING WITH COIL EXPANDER

THREE-PIECE CONSTRUCTION

EX17, EX21, EX27

Fig.5-33

(4) PISTON AND CONNECTING ROD

MAG

PISTON RING GUIDE

CONNECTING ROD

"MAG" MARK

FLYWHEEL SIDE

The piston is attached to the connecting rod by

the piston pin.

When assembling the piston and connecting rod,

make sure to align the mark on the piston head with

the ‘MAG’ mark on the connecting rod.

NOTE 1: Before assembling the connecting rod,

apply oil to its small end.

NOTE 2: Be sure to insert the clips in the two ends

of the piston pin and check the clips for any play.

(5) CONNECTING ROD

(a) Install the piston and connecting rod assembly into

the cylinder by holding the piston rings with the

ring guide, with the ‘MAG’ mark on the connecting

rod on the flywheel side. (If y ou do not ha v e a ring

guide, hold the piston rings with the fingers and

tap the upper part of the piston with a piece of

wood.)

NOTE 1: Apply oil to the piston rings, the large end

of the connecting rod and cylinder before installing the connecting rod into the cylinder.

MAG

Fig. 5-34

When assembling the piston and connecting rod, make sure to align the mark on the piston head with the ‘MAG’ mark on the connecting rod.

NOTE 2: The piston ring gaps should be positioned

around the piston at 90-degree intervals. (See Fig. 5-36)

Fig.5-35

SECOND RIN

OIL RIN

TOP RIN

Fig.5-36

(b) Rotate the crankshaft down to the bottom dead center

A M

and lightly tap the piston head until the large end of the connecting rod touches the crank pin.

marks and fit the clinch portions firmly together.

Tightening torque

EX13,17,21 EX27

13.0 - 15.0 N・m

(130 - 150 kgf・cm)

(9.4 - 10.8 ft・

lb.)

17.0 - 20.0 N・m

(170 - 200 kgf・cm)

12.3-14.5

(

ft・

lb.)

(d) Check f or free mo vement of the connecting rod b y

turning the crankshaft slowly.

(6) INTAKE AND EXHAUST VALVES

Take the following points into account when mounting the intake and exhaust valves on the cylinder head.

NOTE 1: Replace the valve with a new one if it shows

signs of wear. (Refer to the “STANDARD REPAIR TABLES” on page 78 and 79.)

NOTE 2:Carefully scrape off any carbon deposits

on the combustion chamber. Apply oil to the valve stems bef ore mounting the intake and exhaust valv es. Insert the valves in the cylinder head and place it on a level workbench. Ne xt, mount the v alve springs, the spring retainers and collet valves. (Mount the stem seal on the intake valve guide.)

INTAKE VALVE

LIGNMENT

ARKS

SPRING RETAINER

VALVE SPRING

CYLINDER HEAD

ALIGNMEN MARKS

Fig. 5-37

Fig. 5-38a

COLLET VALVE

STEM SEAL

EXHAUST VALVE

COLLET VALVE

VALVE SPRING

SPRING RETAINER

Fig.5-38b

(7) CHAIN GUIDE

Mount the chain guide to the crankcase.

Model EX21 mounting position

Models EX13, 17 and 27 mounting positions

CHAIN GUIDE

Fig. 5-39a

Fig. 5-39b

(8) CYLINDER HEAD

Inspect and repair any scratches on mounting surface and replace head gask et to new one bef ore installing.

Tightening Torque

step 2ndstep

Cylinder head bolts

Remarks

25.0 - 27.0 N・m

M8 × 68mm

flange bolt : 4 pcs.

M8 × 35mm

flange bolt : 1 pc.

17.0 - 19.0 N・m

(170 - 190 kgf・cm)

(12.3 - 13.7 ft・lb.)

(250 - 270 kgf・cm)

(18.1 -19.5 ft・lb.)

28.0 - 30.0 N・m

(280 - 300 kgf・cm)

(20.3 - 21.7 ft・lb.)

-------- --------

When replace to new cylinde head and flange bolts

Re-use

Tighten the cylinder head bolts in diagonal order.

(1) Re-use (Oil the screw thread)

●

Tighten all bolts (5pcs) by 18 ± 1 N・m primary, and then tighten longer ones (M8

bolt: 4pcs) by 26 ± 1 N・m.

(2) When replace to new cylinder head and flange

bolts (Oil the screw thread)

●

Tighten all bolts (5pcs) by 18 ± 1 N・m primary, and then tighten longer ones (M8

bolt: 4pcs) by 29 ± 1 N・m.

× 68mm flange

PIPE KNOCK

GASKET

PIPE KNOCK

Fig. 5-40

M8 x 68 BOLT : 4 pcs

CYLINDER HEAD

M8 x 35 BOLT : 1 pc.

(9) SETTING THE TIMING CHAIN

(a) Align the timing mark on the crankshaft sprocket with the mark plate of the timing chain. (b) Align the timing mark on the crankshaft sprocket with the mark plate of the opposite end of the timing chain.

Model EX13 EX17 EX21 EX27

Number of oval steel link 86 88 92 100

Model EX13

TIMING MARK

MARK PLATE

Model EX17, 27

TIMING MARK

CHAIN GUIDE FITTING POSITION

The position of top dead center

CHAIN GUIDE FITTING POSITION

MARK PLATE

The mark plate does not have a camshaft side or crankshaft sprocket side.

TIMING MARK

ROLL PIN

CAMSHAFT SPROCKET

CRANKSHAFT SPROCKET

MARK PLATE

The mark plate does not have a camshaft side or crankshaft sprocket side.

TIMING MARK

ROLL PIN

CAMSHAFT SPROCKET

Model EX21

TIMING MARK

MARK PLATE

CRANKSHAFT SPROCKET

CHAIN GUIDE FITTING POSITION

CRANKSHAFT SPROCKET

Fig. 5-41a

MARK PLATE

The mark plate doe not have a camshaf side or crankshaft sprocket side.

TIMING MARK

ROLL PIN

CAMSHAFT SPROCKET

S (

(10) MOUNTING THE CAMSHAFT ON THE CYLINDER HEAD

P (

S (

Mount the camshaft on the cylinder head by inserting the pin (camshaft) through the head. Fix the bolt to prevent the pin (camshaft) from coming out.

PIN (CAMSHAFT)

CHAIN

PRING

TENSIONER)

TENSIONER

PIN(TENSIONER)

CHAIN

CAMSHAFT

PIN(CAMSHAFT)

M6 x 12 BOLT : 1 pc. Bolt used to prevent the pin (camshaft) from coming out

CAMSHAFT

CHAIN

M6 x 12 BOLT : 1 pc. Bolt used to prevent the pin (camshaft) from coming out

Fig. 5-41b

(11) MOUNTING THE TENSIONER

TENSIONER)

PRING

TENSIONER)

TENSIONER

Fig. 5-42a

PIN (TENSIONER)

Fig. 5-42b

(12) BALANCER SHAFT (OPTION)

(for EX27 only) Mount the balancer shaft on the crankcase, align

BALANCER GEAR

TIMING MARK

the timing marks on the balancer gear and the crankshaft gear.

NOTE:Incorrect alignment of the timing marks

can result in malfunction of the engine, leading to damage due to interference of the parts.

Fig. 5-43

CRANKSHAFT GEAR

(13) MAIN BEARING CO VER

Apply oil to the bearing and the oil seal lip when mounting the main bearing cover. Also apply sealant (Three Bond “1215”) to the surface of the cr ankcase. T o av oid damaging the oil seal lip , wrap the crankshaft key-wa y portion with polyvinyl tape bef ore mounting the main bearing cover.

NOTE: Be careful that the lever portion of governor shaft does not face the main bearing cov er.

Tightening torque

17.0

18.0 N・m

(

170-180 kgf・cm)

(12.3 - 13.0 ft・lb.)

M8 x 35 BOLT : 6 pcs. (EX13, 17, 21) M8 x 35 BOLT : 7 pcs. (EX27)

MAIN BEARING COVER

GOVERNOR SHAFT

CRANKSHAFT

SEALANT (

Three bond "1215"

)

Fig. 5-44

(14) Pass the pin (rocker arm) through the rocker arm

and mount them on the cylinder head.

ROCKER ARM (EXHAUST VALVE SIDE)

PIN (ROCKER ARM)

NOTE 1:

Conduct this job at the compression top dead center. (The position of two punch marks on cam

sprocket is in parallel with the cylinder head surface at a time.)

NOTE 2:

Make sure that the piston is at the compression top dead center by checking mutual position between the flywheel and the ignition coil or by checking that the key way is at the top. (See each Fig.5-46)

(15) VALVE CLEARANCE ADJUSTMENT

Temporarily fit the flywheel. Rotate the crankshaft up to the compression top

dead center and insert the thickness gauge between the valve and the adjusting screw of rocker arm to measure the clearance.

[Adjustment method]

Punch marks

The position of compression top dead center

Fig. 5-45

EX13, 17, 21

EX27

ROCKER ARM (INTAKE VALVE SIDE)

The position of top dead center

Loosen the nut on the adjustment screw and turn the screw to adjust the valve clearance. When the valve clearance is correct, tighten the nut.

Valve clearance (when the engine is cold)

Intake valve side

Exhaust valve side

Tightening

torque

(0.0047 in.)

5.0 - 7.0 N・m

(50 - 70 kgf・cm)

(3.6 - 5.1 ft・lb.)

+0.03

0.12 mm

+0.0012 0

NOTE: After adjusting the valve clearances, rotate

the crankshaft and check again that the intake and exhaust valve clearance are correct.

THICKNESS GAUGE

The key way is at the top

Fig. 5-46

NUT

ADJUSTMENT SCREW

ROCKER ARM (EXHAUST VALVE SIDE)

ROCKER ARM (INTAKE VALVE SIDE)

Fig. 5-47

(16) ROCKER COVER

Replace the gasket with a new one, and mount the rocker cover.

✕ 12mm flange bolt : 4 pcs.

Tightening torque

5.0

7.0 N・m

(50-

70 kgf・cm)

(3.6 - 5.1 ft・lb.)

SPARK PLUG

(17) SPARK PLUG

Remove any carbon deposits from the spark plug and inspect the electrode for damage before mounting. Replace with a new one, if necessary .

Spark plug: NGK BR-6HS

or CHAMPION RL86C

Electrode gap 0.6 mm - 0.7 mm

(18) BAFFLE 1 (CASE)

Align the top and bottom of the baffle 1 (case) with the crankcase and mount it with the bolts.

[

Model without electric starter]

✕ 12 mm bolt : 1 pc.

(Models EX13, 17 and 21)

✕ 12 mm bolt : 1 pc. (Model EX27)

BAFFLE 1 (CASE)

New spark plug Re-tightening torque

12.0 - 15.0 N・m

(120 - 150 kgf・cm)

(8.7 - 10.8 ft・lb.)

[

Model with electric starter]

Mount the electric starter and the charging coil, referring to the illustrations of disassembly.

UPPER

M6 x 12 FLANGE BOLT : 1 pc. (EX13, 17, 21) M8 x 12 FLANGE BOLT : 1 pc. (EX27)

EX13, 17, 21

GASKET (ROCKER COVER)

ROCKER COVER

Fig. 5-48

Tightening torque

23.0 - 27.0 N・m

(230 - 270 kgf・cm)

(16.6 - 19.5 ft・lb.)

Tightening torque

EX13,17,21 EX27

4.0 N・m

(40 kgf・cm)

(2.9 ft・lb.)

TO IGNITION COIL

12.0 N・m

(120 kgf・cm)

(8.7 ft・lb.)

M6 x 12 BOLT : 4 pcs.

LOWER

BAFFLE 1 (CASE)

HOOK

TO OIL SENSOR

Fig. 5-49b Fig. 5-49a

OIL SENSOR UNIT

(19) FLYWHEEL AND STARTING PULLEY

NOTE: When mounting the flywheel, be sure to

wipe off any oil on the tapered portion of the crankshaft and flywheel.

Mount the flywheel on the crankshaft. (Tighten the flywheel together with the starting pulley.)

FLYWHEEL

Tightening torque

59.0

64.0 N・m

(

590-640 kgf・cm)

(

42.7-46.3 ft・lb.)

M14 nut : 1 pc. (EX13, 17, 21) M18 nut : 1 pc. (EX27)

(20) IGNITION COIL

When mounting the ignition coil, insert a thickness gauge between the ignition coil and the flywheel to check the air gap.

STARTING PULLE

Align the 2 bosses of starting pulley with the depression of flywheel.

Fig. 5-50

Fig. 5-51

THICKNESS GAUGE

‑‑

0.3

Air gap

‑ 0.5 mm

‑‑

Tightening torque

7.0 - 9.0 N・m

(70 - 90 kgf・cm)

(5.1 - 6.5 ft・lb.)

M6 ✕ 25 bolt and washer : 2pcs.

IGNITION COIL

Fig. 5-52

To STO SWITCH

Fig. 5-53

(21) SPEED CONTROL LEVER, BRACKET AND BAFFLE

Mount the speed control lever and bracket, baffle 2 (head) and baffle 3 on the crankcase. NOTE : The baffle 3 is used f or Model EX21 only.

(22) CARBURETOR

(a) Replace the gasket of insulator with a new one and mount the insulator on the cylinder head intake

side.

(b) Mount the carburetor.

M6 x 12 BOLT : 2 pcs.

SPEED CONTROL LEVER and BRACKET

CARBURATOR

INSULATOR

GASKET

BAFFLE 2 (HEAD)

GASKET

M6 x 12 BOLT : 1 pce.

BAFFLE 3 (EX21 ONLY)

M5 TAPPING BOLT : 2 pcs.

Fig. 5-54

Detail A

(23) GOVERNOR LEVER

(a) Pass the governor rod through the rod spring, then connect to the throttle lever of the carburetor. (b) Attach the governor rod and rod spring to the governor lev er , then mount the go vernor le ver on the go vernor

shaft. Do not adjust the bolt on the governor lever yet.

NOTE : See page 42 for details on the adjustment method after mounting air cleaner base.

Variation of the governor spring

The dimensions of the governor spring are different each other according to the Hz. The governor spring for the standard engine is same as that for the engine to be connected to the 60Hz generator.

Discrimination according to the dimensions:

EX13, 17 / 50Hz

10 20

Color : Gold

EX13, 17, 21, 27 / 60Hz (STD)

26 15

Color : Silver

GOVERNOR LEVER

Long length side

Short length side

EX21, 27 / 50Hz

15 15

(Speed con. side)

GOVERNOR ROD and ROD SPRING

Color : Gold

GOVERNOR SPRING

(Governor lever side)

Fig. 5-55

SPEED CONTROL LEVER and BRACKET

G S

(24) AIR CLEANER BASE

M6 x 20 FLANGE BOLT : 1 pc.

M6 FLANGE NUT : 2 pcs.

AIR CLEANER BASE

BREATHER PIPE

Insert the breather pipe into the rocker cover and then mount the air cleaner base.

M6 flange nut : 2 pcs. M6 x 20 mm flange bolt : 1 pc.

Tightening torque

6.0

8.0 N・m

(60-

80 kgf・cm)

(4.3 - 5.8 ft・lb.)

Fig. 5-57

■ Governor system adjustment method

The governor unit is a centrifugal flyweight type and is installed on the governor gear . Since it automatically adjusts the throttle valve of the carb uretor by means of a link mechanism, it is possib le to

maintain a constant engine speed, even with load variations. (1) Turn the speed control lever to the full speed position, making sure that the carburetor throttle valv e is fully

open.

(2) Hold the top of the governor shaft with the plier and turning it clockwise as far as it will go . Tighten the bolt on

the governor lev er.

Tightening torque

8.0

10.0 N・m

(80-

100 kgf・cm)

(5.8 - 7.2 ft・lb.)

GOVERNOR LEVER

GOVERNOR ROD and ROD SPRING

GOVERNO SPRING

OVERNOR

HAFT

Fig. 5-58

(25) MUFFLER

)

Mount the muffler and the gasket on the cylinder head.

(1)

GASKET (Attention to the wrong side and right side)

MUFFLER SIDE (RIGHT SIDE)

M6 x 10 TAPPING BOLT : 2 pcs.

M6 x 8 FRANGE BOLT : 1 pc.

CYLINDER SIDE (WRONG SIDE)

Take utmost care not to cut your hand with the muffler gasket

M8 ✕12 mm bolt : 1 pc. M8 nut : 2 pcs.

Tightening torque

18.0

22.0 N・m

(

180-220 kgf・cm)

(

13.0-15.9 ft・lb.)

(2) Mount the muffler cover on the muffler.

M6 ✕ 8 mm flange bolt : 1 pc. M6 ✕ 10 mm tapping bolt : 2 pcs.

NOTE : Be sure to remove any tape or cloth used

to cover the e xhaust port when the engine was disassembled

M8 NUT : 2 pcs.

M8 x 12 BOLT : 1 pc.

GASKET (Attention to the wrong side and right side)

Fig. 5-59a

MUFFLER

(26) FUEL TANK

(1) Mount the fuel strainer to the fuel tank.

Tightening torque for fuel strainer

3.0

4.0 N・m

(30-

40 kgf・cm)

(

2.2-2.9 ft・lb.)

(2) Connect the fuel pipe and fix it with a clamp.

Model EX13 EX17 EX21 EX27

Fuel pipe length

mm(in.)

145(5.7) 150(5.9) 155(6.1) 195(7.7

NOTE : Make sure the fuel pipe is located on the boss ,

as shown in the illustration, in order to prev ent the pipe from attaching to the flywheel In case the pipe is routed improperly, the pipe might be hit by the flywheel and will be damaged.

FUEL STRAINER

FUEL PIPE

M6 NUT : 2pcs.

HOSE CLAMP

M6 x 25 BOLT : 1pc.

(EX13, 17, 25)

M8 x 25 BOLT : 2pcs.

(EX27)

Fig. 5-59b

(3) Mount the fuel tank on the crankcase.

M6 nut : 2 pcs. M6 ✕ 25 mm bolt : 1 pc.

(Models EX13, 17 and 21)

FUEL PIPE

M8 ✕ 25 mm bolt : 2 pcs. (Model EX27)

Fig. 5-59c

(27) BLOWER HOUSING AND RECOIL STARTER

(1) Mount the ignition coil cord on the crankcase by aligning it with the baffle 1 (case). (2) Mount the blower housing on the crankcase .

× 12 mm bolt : 4 pcs.

(3) Mount the recoil starter on the blower housing.

× 8 mm bolt : 4 pcs.

M6 x 12 BOLT : 4 pcs.

M6 x 8 BOLT : 4 pcs.

BOSS

Fig. 5-60

RECOIL STARTER

BLOWER HOUSING

(28) STOP SWITCH

STOP SWITCH

(1) Mount the stop switch on the blower housing. (2) Refer to the wiring diagram (See page 51 and 52) for

wiring details.

(29) AIR CLEANER

Fig. 5-61

Mount the air cleaner element and cleaner cover .

Fig. 5-62

STD

Type

Dual element

(30) EXTERNAL INSPECTION

Reassembly is completed. Chec k that the wiring is correct and that there are no loose nuts and bolts or any other faults visible on the outside of the engine.

(31) FILLING WITH ENGINE OIL

Use the automobile engine oil of API service class SE or higher grade. The amount of oil depends on the engine model. Refer to the table below.

Model

EX13

Engine oil volume 0.6 L 1.0L

Model

EX17

Model

EX21

Model

EX27

(32) BREAK-IN OPERATION

A new engine or 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

Step 1

Model

EX13

Model

EX17

No Load 2500 r.p.m. 10 min.

Model

EX21

Model

EX27

Engine

Speed

Time

Step 2

Step 3

Step 4

Step 5

No Load 3000 r.p.m. 10 min.

No Load 3600 r.p.m. 10 min.

1.5 HP 2 HP 2.5 HP 3.5 HP 3600 r.p.m. 30 min.

3 HP 4 HP 5 HP 7 HP 3600 r.p.m. 30 min.

6. ENGINE OIL

Using engine oil of the correct grade and viscosity greatly lengthens engine life and improv es perf ormance. Too much or too little oil can also result in serious problems, including engine seizure.

6-1 CLASSIFICATION BY OIL GRADE

API (American Petroleum Institute)

Classification SA SB SC SD SE SF SG SH SJ

Grades suited for Robin Engine: SE or higher (SG,SH or SJ in recomended)

6-2 CLASSIFICATION BY OIL VISCOSITY

SAE (Society of Automotive Engineers)

10W

Single grade

20W

#20

#30

#40

10W

Multigrade

Ambient temperature

10W

Be sure to use automobile engine oil of the viscosity shown in the table abov e, depending on en vironmental air temperature. When the air temperature falls below –20°C or rises above 40°C , be sure to choose engine oil of appropriate viscosity and grade, according to the prevailing conditions. ※Care must be tak en when using multi-gr ade engine oil, because the oil consumption rate tends to increase

when the air temperature is high.

6-3 ADDING AND CHANGING ENGINE OIL

○ Engine oil inspection and filling up............. Every time you use the engine

(add engine oil up to the designated maximum level)

○Engine oil change ..................................... First time ............After 20 hours’ use

Thereafter ...........Every 100 hours’ use

7. MAGNETO

7-1 MAGNETO

The Robin Engine uses a T.I.C. type breakerless magneto ignition system. (1) T.I.C. (TRANSISTOR IGNITER CIRCUIT) has the ignition coil outside the flywheel, which is the standard

specification. A charge coil system is available as an option. (The flywheel is a specialized piece of equipment.) As for the lighting coil, the ignition coil is outside the flywheel and a lighting coil is inside.

7-2 INSPECTING THE MAGNETO

If the engine does not start, has difficulty starting, or does not run smoothly, check the magneto for defects according to the following procedure: (1) Carefully check the high-tension cable for any damage or short circuiting. (2) Chec k the sparking.

① Take the spark plug out of the cylinder head, connect the spark plug with the plug cap and ground it

on the cylinder head or any other metallic part of the engine. (The gap between the electrodes of the spark plug should be between 0.6 mm and 0.7 mm).

② Rotate the engine by pulling the recoil starter and check the spark plug gap for sparking. If the spark

plug is sparking, check the intensity of the spark. (Before checking the spark plug, disconnect the primary wire from the connector.)

③ Next, disconnect the spark plug from the plug cap and check the end of the high-tension cable for

sparking.

7-3 IGNITION SYSTEM (EX13 ,17, 21)

7-3-1 TYPE OF IGNITION SYSTEM

EX13, 17 and EX21 have the T.I.C. (Transister, Igniter, Circuit) pointless ignition system. As optional parts, these ignition system may be implemented with lamp coil, charge coil and excitor coil.

Resister

LowSpeed

Ignition

Timing

Control Circuit

Automatic

Advancing

Signal Transistor

Control

Circuit

Signal Transistor

Power Transistor

Primary Coil

Secondary Coil

Ignition Coil

Fig. 7-1(a)

7-3-2 B ASIC THEORY

To ensure the easy star tability of the engine, the

(B.T.D.C)

23ࠑ

ELECTRONIC ADVANCING FLYWHEEL

MAGNETO SYSTEM

step advancing ignition timing system is incorporated in the ignition coil. This system

STEP ADVANCING

enables the engine to hav e basically tw o different ignition timings according to the engine speed. Following are the e xplanation how the system w orks.

IGNITION TIMING

1) At lower speed of the engine Rotation of the flywheel induces current I1, as this current flows through the base terminal of the power transister, it is activated and the current I2 starts flowing.

15ࠑ

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

ENGINE REVOLUTION

Fig. 7-1(b)

As the engine reaches the ignition timing, the ignition timing control circuit for the lower engine speed is activated and lets the current I

3 flow through the base terminal of the power transistor .

This generates the collector current I4 which will bypass the current I1 and abruptly shut off the current I2 because the power transistor is turned off. This sudden current change generates a big voltage on the secondary side of the ignition coil and which sparks the spark plug.

Spark Plug

2) At the higher engine speed Rotation of the flywheel generates the current I

1 as this current flows through the base terminal of the power

transistor, it is activated and the current I2 starts of flow. As the engine reaches the ignition timing, the ignition timing control circuit for the higher engine speed is activated and provides the base current I

5 to the power transistor. This current induces the collector current

I6 and will bypass the current I1 to shut down the current I2 abruptly because the power transistor is turned off.

This sudden current change generates a big voltage on the secondary side of the ignition coil and which will spark the spark plug. The ignition timing control circuit for the higher engine speed is activated, sooner than the control circuit for the lower speed and not activated when the engine speed is in a low er range.

7-4 IGNITION SYSTEM (EX27)

7-4-1 IGNITION COIL INTERNAL CIRCUIT

Base Resister

Low Speed Ignition Timing Control Circuit

Advancing Control Circuit

7-4-2 IGNITION TIMING CHARACTERISTIC

35 30 25 20 15

B.T.D.C. ( )

IGNITION TIMING

5 0

0 500 1000 1500 2000 2500 3000 3500 4000

LINEAR ADVANCING

I1 I2

Control thyristor

Fig.7-2a

Fig.7-2b

Power T ransistor

Revolution Sensing

Resister

ENGINE REVOLUTION (R.P.M.)

Primary Coil

Secondary Coil

Spark Plug

7-4-3 B ASIC THEORY

(a) Rev olution of the flywheel generates electricity on the primary side of the ignition coil (①), and the base

current I current I

1 flows to the power transistor ( 2 flows. This is the same situation when the contact breaker is closed in a case of breaker point

). Current I1 turns the power transistor “ON” and the electric

②

type ignition system.

(b) At lower engine revolution, the low speed ignition timing control circuit (③)operates to run the gate

current I

3 to turn the control thyristor (

At this moment, the power transistor (②) turns “OFF” and the current I

) “ON”, thus the current I1 bypass the thyristor as current I5.

⑤

2 is shut off abruptly resulting

in the high voltage generated in the secondary coil (⑦)which produces sparks at the spark plug. The ignition timing at lower engine revolution is less advanced as shown in the abov e chart.

4 to turn the control thyristor (

At this moment, the power transistor (②)turns “OFF” and the current I

)“ON”, thus the current I1 bypass the thyristor as current I5.

⑤

2 is shut off abruptly resulting

in the high voltage generated in the secondary coil (⑦)which produces sparks at the spark plug. At over 2,000rpm, ignition timing on each engine rev olution is controlled b y adv ancing control circuit (④) that receive electrical information from revolution sensing resister (⑥). The advancing of ignition timing from lower to higher engine revolution changes lineally as shown in the above chart.

8. WIRING DIAGRAM

K 0

8-1 MODEL WITHOUT ELECTRIC STARTER (Models EX13, 17, 21 and 27)

Spark plug

Black

Ignition coil (with built-in transistor)

Flywheel

Fig. 8-1

Stop switch

8-2 MODEL WITH ELECTRIC STARTER (Models EX17 and 21)

Spark plug

Black

Magneto

Charge coil

ey switch

66-00003-30

-M +M BS

OFF ON START

Ignition coil

Diode rectifier

LA306

Electric starter

Key switch

LA106 LA406

Magnetic switch

Red

Battery (12V24AH)

Fig. 8-2

8-3 MODEL WITH ELECTRIC STARTER (Model EX27)

S p

Spark plug

Black

agneto

Charge coil

Key switch 066-00003-30

-M +M BS

OFF ON START

8-4 MODEL WITH OIL SENSOR

To LED Lamp

Ignition coil

Diode rectifier

Yellow Yellow / Red

Fig. 8-3

Black

Black / White

Key switch

LA108 LA408

Electric starter

Oil sensor control unit

Red

Battery (12V24AH)

Orange Orange

Oil senso

LA106

Black

park

lug

To stop switch

※※

※Oil sensor as option

※※

Body earth

Fig. 8-4

9. ELECTRIC STARTER

9-1 SPECIFICATIONS

Models EX17,21 Model EX27

Voltage (V) 12 Power (kW) 0.6 0.6 Weight (kg) 1.6 3.4

9-2 OPERATING PRINCIPLES

EX 17, 21

EX 27

129.5

157.8

Fig. 9-1

Pinion ge

PINION GEAR

The battery is connected to the 6 or 8 mm diameter terminal of the magnetic switch. The figure below shows the state when the starter is ON.

ELECTRIC STARTER

MAGNETIC SWITCH

BATTERY

KEY SWITCH

Fig. 9-2

There are two energized circuits: the magnetic s witch (M) circuit and the starter motor (S) circuit. When the ke y switch is ON, the (M) circuit is closed, the current flows in the direction of the arrows, the coil of the magnetic switch is magnetically excited and the contactor is pulled. As a result, a low current flows through the (M) circuit and a high starter current flows through the (S) circuit. This energizes the starter motor and cranks the engine. ◇ Engagement of the pinion gear (EX17,21)

When the starter motor is started, the weight built into the spiral splines located on the shaft mov es in the direction of the axis driven by centrifugal force and pushes out the pinion gear , and the pinion gear engages the ring gear .

9-3 COMPONENT PARTS

(Models EX17 and EX21)

MAGNETIC SWITCH

BATTERY CABLE

FRONT COVER

O - RING

PINION AY

PINION STOPPER SET

THROUGH BOLT (2 pcs

REAR COVER

(Model EX27)

O - RING

YOKE AY

WASHER

ARMATURE AY

BRUSH

SPRING (BRUSH)

BRUSH HOLDER

MAGNETIC SWITCH

PINION A

ARMATURE AY

SPRING (BRUSH)

BRUSH

CASE METAL

THROUGH BOLT (2 pcs.)

YOKE AY

BRUSH HOLDER

REAR COVER

Fig. 9-3

PINION STOPPER SET

FRONT COVER

FRONT METAL

10.OIL SENSOR

10-1 SPECIFICATIONS

Type

Resistance (at FULL oil level)

Operating Temperature

Float type (with lead switch incorporated)

100 M ohms or over

-30 to +180 degree Celsius

10-2 CONSTRUCTION AND OPERATION

The oil sensor is composed of the float, permanent magnet incorporated into the float and the oil sensor. In accordance with the oil level, the float mo ves up and down. When the oil level is upper level, the float moves up.

OIL SENSOR

Fig.10-1

FLOAT

When the oil level is lower level, the float moves down. The permanent magnet is close to the lead switch, and the lead switch is activated by the magnetic force.

NOTE : With regards to the wiring diagram,

please refer to the section 8-4 (page52).

PERMANENT MAGNET

LEAD SWITCH

Fig.10-2

MAGNETIC FORCE

Fig.10-3

11.AUTOMATIC DECOMPRESSION SYSTEM

11-1 FUNCTIONS AND CONSTRUCTION

EX series engines employ an automatic decompression system as a standard feature. This enables easy starting of the engine, with lighter recoil pull. The automatic decompression system releases the compression of the engine by lifting up the exhaust v alve at cranking speed. The following is the explanation of the function.

At the end of the compression process, the release lev er lifts up the roc k er arm (exhaust) which in turn opens up the exhaust valv e slightly to release the compression. The release lever has a flyw eight on its end and another end of the lever is a crescent cam. When the engine is cranked, the crescent cam projects above the cam profile and lifts up the rocker arm (exhaust) because the force of the return spring on the weight is larger than the centrifugal force on the weight.

ROCKER ARM (EXHAUST)

ROCKER ARM (INTAKE)

CAM

CRESCENT CAM

RELEASE LEVER

CAMSHAFT

ROCKER ARM (EXHAUST)

Fig. 11-1

DETAIL

When the cranking speed reaches a specified r.p.m., the crescent cam is retracted under the cam profile because the centrifugal force applied to the flyweight becomes larger than the force of the return spring on the weight and thus it is shifted to the position shown in the illustration below.

ROCKER ARM (EXHAUST)

ROCKER ARM (INTAKE)

RELEASE LEVER

ROCKER ARM (EXHAUST)

CAM

CRESCENT CAM

RELEASE LEVER

Fig. 11-2

11-2 INSPECTION

When assembling the release lever, make sure that it works smoothly.

DETAIL

CAMSHAFT

12.CARBURETOR

P P

12-1 SPECIFICATIONS

EX13 EX17 EX21 EX27

A/C Type STD DUAL STD DUAL STD DUAL STD DUAL Main Jet 70.0 68.8 81.3 80.3 86.3 83.8 98.0 96.0

ilot Jet 40.0 40.0 40.0 40.0 41.3 ilot Screw Turning 1-3/4

12-2 FUNCTIONS AND CONSTRUCTION

12-2-1 FLOAT SYSTEM

The float chamber is located below the carburetor body. Through the operation of the float and the needle valve , the float chamber maintains a constant fuel level while the engine is working. The fuel flows from the tank into the float chamber through the needle valve. When the fuel rises to a specific level, the float rises. When the buoyancy of the float is balanced with the fuel pressure , the needle valve shuts off the fuel passage, thereby maintaining the fuel at the predetermined level.

←

1-1/4

←

40.0

1-1/2

← ←

12-2-2 PILOT SYSTEM

The pilot system supplies fuel to the engine during idling and low-speed operation. Fuel is initially metered by the main jet and then metered once again by the pilot jet. At the pilot jet, the fuel is mixed with air metered by the pilot air jet and then the fuel/air mixture is f ed to the engine through the pilot outlet and the bypass. During idling, fuel is fed to the engine mainly through the pilot outlet.

12-2-3 MAIN SYSTEM

The main system feeds fuel to the engine at medium and high speed operation. Fuel is metered by the main jet and flows into the main nozzle. Air metered by the main air jet is mixed with fuel through the bleed holes of the main nozzle. The fuel/air mist is injected into the V enturi and mixed once again with air from the air cleaner. This fuel/air mixture is now of optimum concentration and is fed into the combustion chamber of the engine.

12-2-4 CHOKE SYSTEM

The choke system is for easier start of the engine in cold weather conditions. When the engine is started with a closed choke, the negative pressure applied to the main nozzle increases. This causes a larger amount of fuel to be drawn into the carburetor, which in turn makes it easier to start the engine.

FUEL SYSTEM OUTLINE

FLOAT

FLOAT CHAMBER

FUEL

NEEDLE VALVE

PILOT OUTLET

BYPASS

PILOT AIR JET

MAIN AIR JET

Fig. 12-1

PILOT JET

MAIN NOZZLE

AIR INTAKE PORT

CHOKE VALVE

FLOAT

MAIN JET

Fig. 12-2

12-3 DISASSEMBLY AND REASSEMBLY

Mechanical failures aside, most carburetor malfunctions occur when the fuel/air ratio of the mixture is not correct. This is usually caused by clogged jets, air passages and fuel passages, or by variations in the fuel level. To get the best possible performance from the carburetor, ensure that the each passages are k ept clean so that air and fuel can flow freely through them.

MODEL EX13, 17, 21 MODEL EX27

22 23

26 25

18 20

13 14

24 25

2223

1920

18 17 16

27 28

12 11

5 6

6 7

9 8

Fig. 12-3

The procedures for overhauling the carburetor are described below. (Refer to Fig. 11-3.)

12-3-1 THROTTLE SYSTEM

(1) When the throttle stop screw  is removed, the spring  can be taken out. (2) Remove the phillips screw  and the throttle valve , then take out the throttle shaft .

23 24

When removing the throttle valve , take care not to damage the valve edge.

12-3-2 CHOKE SYSTEM

(1) Remove the choke v alve ⑭. Then pull out the choke shaft ⑬. (2) When reassembling the choke shaft, be sure to position the cutout on the choke v alv e facing the pilot air

jet.

12-3-3 PILOT SYSTEM

(1) Remove the pilot jet ⑱. Use the correct tool so as to avoid damaging the jet. (2) When reassembling the pilot jet, be sure to firmly tighten it, otherwise fuel may leak, leading to engine

malfunction.

12-3-4 MAIN SYSTEM

(1) Remove the bolt ⑧ and remov e the float chamber body ⑤. (2) Remove the main jet ⑪ from the body ①. (3) Remove the main nozzle ② from the body ①. (4) When reassembling the main system, be sure to fasten the main jet and main nozzle firmly to the body,

otherwise the fuel concentration in the fuel/air mixture may become too rich, leading to engine malfunction.

(5) The tightening torque of the bolt ⑧ is 9 N・m (90 kgf・cm / 6.5 ft・lb.). Be sure not to forget to mount the

washer .

12-3-5 FLOAT SYSTEM

(1) Take out the float pin ⑩ and then remove the float ④ and the needle valve ⑫.

※Since the needle valve ⑫ is linked to the float ④, take care when assemble. ※Do not use drill or similar objects for cleaning the jets, as these are likely to damage the orifices, which

in turn can impair fuel flow. Use compressed air to clean the jets.

※The float pin is pressed into the carburetor body. When removing the needle valve and the float, a rod

or a similar tool slimmer than the float pin should be used. T ap the reverse side gently and remove .

13.RECOIL STARTER

13-1 RECOIL STARTER

Tools required: Screwdriver, pliers and protective glasses

NOTE: Put on the protective glasses prior to start disassembly.

13-1-1 DISASSEMBLY PROCEDURE

(1) Release the reel spring power

-1 Hold the star ter knob and pull out the star ter rope.

-2 Pull out the rope fully and align the rope knot in the reel with the rope guide.

-3 Hold the reel down firmly with both thumbs, taking care not to allow it to spring back. (Fig. 12-1)

-4 Remove the knot from the reel, untie the knot and pull the rope out toward the starter knob. Note: This procedure requires 2 people.

-5 While controlling the reel with the thumbs, slowly wind it back as far as it will go.

NOTE: When the rope is pulled out to its full length, the f orce stored in the spring reaches its maxim um.

Be careful not to drop it or release your grip on it suddenly.

Fig. 13-1

(2) Remove the components. (Fig. 13-2)

-1 Grip the case and loosen the set screw.

-2 Take out the set screw, the ratchet guide, the friction spring and the ratchet in that order.

(3) Remove the reel. (Fig. 13-2)

-1 Hold down the reel gently to keep it from escaping from its case and rotate it slowly back and forth by quarter turns until it moves smoothly.

-2 Lift the reel up little by little and take it out of the case.

-3 If the spr ing is about to pop out of the reel, repeat steps (3)-1 and (3)-2.

NOTE: Since the spring is stored in the reel, make sure

not to drop or shake the reel after removing it. Place it on a level surface such as a table.

SET SCREW

RATCHET GUIDE

FRICTION SPRING

RATCHET

REEL

STARTER CASE

Fig. 13-2

Disassembly is completed.

NOTE: Put on the protective glasses prior to start reassembly.

13-1-2 REASSEMBLY PROCEDURE

(1) Put the reel back into the case

-1 Apply grease to the surface of the case. (Fig.13-3)

-2 Adjust the position of the inner end of the spring in the reel. (Fig. 13-4)

-3 Hold the reel in such a way that the inner end of the spring hooks onto the shaft hook and then place the reel carefully back into the case.

-4 Turn the reel gently counterclockwise to confirm that the spring is hooked.

GREASE

SHAFT HOOK

Fig. 13-3

Position where the inner end of the spring touches to the rib of the bearing

Fig. 13-4

(2) Mount the components

APPROX. 200 MM

FROM THE REEL

ROPE HOLE IN REEL

ROPE GUIDE

-1 Mount the ratchet into the reel. (Fig. 13-5)

THE RATCHET SHOULD BE IN THE CLOSED POSITION

Fig. 13-5

-2 Mount the ratchet guide assembly, taking care

not to move the ratchet. (Fig.13-6)

(3) Tighten the set screw

-1 Hold the ratchet guide gently by your hand to

prevent it from rotating, then tighten the set screw.

Tightening torque(M6)

5.5 N・m

(55 kgf・cm)

(4.0 ft・lb.)

Set screw

Ratchet guide

Friction spring

Ratchet guide sub-assembly

Fig. 13-6

(4) Tension the reel spring

NOTE: The spring force reaches its maxim um value when the reel is w ound up. Be careful not to drop

it or release your grip on it suddenly.

-1 Grip the case and turn the reel 6 times

counterclockwise.

-2 Fix the reel so that the rope hole in the reel is

aligned with the rope guide. (Fig. 13-7)

Fig. 13-7

(5) Install the rope

NOTE: This procedure requires 2 people.

-1 Pass the rope end through the rope guide and the rope hole of the reel and pull through approximately 20 cm out of the reel. (Fig. 13-7)

-2 Tie a knot in the rope end . (Fig. 13-8)

-3 Put the rope into the reel, taking care that the rope end does not stick up. (Fig. 13-9)

-4 Grasp the rope firmly with one hand at approximately 50 cm from the rope guide and keep the rope tense, taking care that the rope is not pulled into the reel.

-5 Release the reel carefully and allow the rope to be wound back slowly by the f orce of the spring until the knob reaches the rope guide.

Assembly is completed.

Approx. 20mm

Fig. 13-8

Fig. 13-9

※ The disassembly and the reassembly are completed, howev er , carry out the follo wing to check if the necessary

components have surely been assembled.

13-1-3 CHECKING THE RECOIL ST ARTER AFTER REASSEMBLY

(1) Pull the starter knob about 2-3 times.

(a) If the starter knob is too heavy to pull, check that each parts have been assembled as specified. (b) If the ratchet does not work, check for missing parts such as the friction spring.

(2) Pull out the starter knob as far as it will go.

(a) If the starter rope remains in the rope slot in the reel, the spring may be over-stressed. T o fix this , pull

out the starter rope approximately 30 cm, and, controlling the rotation of the reel with your thumb, allow the starter rope to rewind about 1 or 2 turns.

(b) If the starter rope rewinds slowly or only partially, apply grease or oil to the rotary parts or the friction

surfaces. If this does not help , try winding up the spring 1 or 2 turns, taking care not to over-stress the spring.

back, reassemble the recoil starter from the beginning.

13-1-4 OTHER GUIDES

(1) If the spring escapes from the reel during

disassembly

SPRING

STARTER REEL

(a) Hook the outer end of the spring onto the gap

in the reel, and rewind the spring, holding the spring with your fingers so as to prevent it from springing out of the housing unit. (Wear protective gloves when doing this.)

Hook the outer end of the spring onto the gap in the reel.

Fig. 13-10

(b) Hook the inner end of the spr ing onto the

TARTER REEL

SPRING

projection on the starter case.

※ Refer to the assembly procedure for more

details.

(2) About lubrication

Lubricate the rotating and frictional par ts and the spring with grease (heat-resistant grease recommended) or engine oil when the starter is disassembled and prior to long term storage.

APPLY GREAS

STARTER CASE

Fig. 13-11

14.INSTALLATION

Installation has a decisive influence on engine life , ease of maintenance and inspection, frequency of inspection and repair, running costs and other related aspects. Before installing the engine, be sure to plan the installation with care, taking the points below into account.

14-1 INSTALLING

When installing the engine, pay special attention to the position of installation, the method for coupling with working equipment, and the foundations and supports for the engine. Position the engine so that tasks such as gasoline and oil replenishment and inspection, spark plug inspection, air cleaner maintenance, oil drainage and so on can be carried out as easily as possible.

14-2 VENTILATION

An engine requires fresh air for cooling and for burning fuel. When an engine is covered with a bonnet or is operated in an enclosed space, the temperature around the engine rises and this causes such problems as vapor lock, oil deterioration, increased oil consumption, power loss, engine seizure, and reduced engine lif e, making it difficult f or the engine to function normally. It is thus necessary to install ducts and dampers to guide fresh air, so as not to recycle the hot air used to cool the engine and to prevent the working equipment from heating up . Be sure to keep the engine room temperature below 50°C all year round and to pre v ent the accumulation of hot air in the engine room.

14-3 EXHAUST EQUIPMENT

Exhaust gas is noxious. When operating the engine indoors, make sure that exhaust gases are discharged outdoors. However, if the exhaust pipe is long, resistance increases and this lowers engine output. Therefore, the longer the exhaust pipe the larger its inner diameter should be.

Exhaust pipe length: Less than 3 m Pipe inner diameter: 30 mm Exhaust pipe length: 3 - 5 m Pipe inner diameter: 33 mm

The ideal solution is forced exhaustion (outdoors) b y installing a blower on the exhaust pipe. ※ Install a safety cover on the exhaust pipe, muffler and other related parts.

14-4 FUEL SYSTEM

If the fuel tank is detached from the engine, the height from the bottom of the fuel tank to the fuel joint of the carburetor should be between 5 cm and 50 cm. When using a fuel pump, the bottom of the fuel tank can be up to 20 cm below the carburetor. P osition the fuel tank carefully because, when it is low, fuel is not fed to the carburetor and when it is high, it can cause an overflow in the carb uretor. When piping the fuel, the hose should be as short as possible and attention should be paid to heat transmission, size, bending, leakage at hose joints and so on. Care should also be taken to prevent air loc k and vapor lock.

14-5 POWER TRANSMISSION TO DRIVE MACHINES

14-5-1 BEL T DRIVE

Note the following:

• Use a V-belt rather than a flat belt.

• The drive shaft of the engine must be parallel to the drive shaft of the driven machine .

• The drive 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. ※ A belt tensioner or similar should be installed if no clutch is used.

14-5-2 FLEXIBLE COUPLING

When using a flexible coupling, run-out and misalignment between the driven shaft and the engine shaft should be minimized. The permissible margin of run-out and misalignment is specified by the flexible coupling manufacturer.

15.TROUBLESHOOTING

If the engine shows any sign of malfunction, the cause should be determined immediately and appropriate countermeasures should be taken to prevent the prob lem from worsening. This section describes certain known problems, their possible causes and appropriate countermeasures. Note, however, that the list of problems presented here is not all. Generally speaking, since there is the possibility of multiple causes for a single problem, please use your e xperience and common sense when deciding on what action to take .

15-1 ENGINE

The following three conditions must be fulfilled f or 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 .

Problem and possible cause Remedy

1. Ignition system problems

2. Fuel system problems 1) No fuel in fuel tank Refill

Starting difficulties

3. Engine core components problems

1) Spark plug

・ Improper spark plug gap ・ Insulation defect ・ Carbon deposits

2) Ignition coil

・ Insulation defect or discontinuity ・ Poor contact or broken wire

3) Improper air gap between ignition coil and flywheel Adjust

2) Fuel hose clogged or pinched Clean or replace

3) Air in fuel lines Check and retighten joints

4) Poor quality gasoline or water in gasoline Replace

5) Carburetor

・ Overflow ・ Clogged or damaged ・ Throttle valve malfunction

(does not close fully)

1) Insufficient tightening of cylinder head bolts Check and retighten

2) Wearing of piston, piston rings and/or cylinder

Adjust the gap Replace Clean

Replace Repair or replace

Adjust Overhaul Check and adjust

Repair or replace

3) Improper contact of valve and seat Repair

4) Valve sticking Repair

5) Improper valve clearance Adjust

6) Leakage from intake manifold gasket Retighten; replace gasket

7) Leakage from carburetor gasket Retighten; replace gasket

8) Insufficient tightening of spark plug Retighten

Problem and possible cause Remedy

1. Insufficient compression 1) Loosen spark plug Retighten; replace gasket

2) Leakage from cylinder head gasket Retighten; replace gasket

3) Piston ring 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 problems

Poor output

3. Fuel system malfunction

4. Low air intake volume

1. Engine 1)Cooling air flow obstructed at inlet or cylinder

OverheatRough Idling

1) Faulty spark plug Replace

2) Faulty ignition coil Replace

3) Improper air gap between ignition coil and flywheel

4) Demagnetization (flywheel magneto) Replace

1) Carburetor clogged Overhaul, clean

2) Fuel strainer and/or hose clogged Clean or replace

3) Air in fuel lines Check and retighten joints

4) Poor quality gasoline or water in gasoline Replace

1) Air cleaner clogged Clean or replace

2) Throttle valve malfunction Repair or replace

baffle portion

2) Poor quality engine oil Replace

3) Lean fuel/air mixture

4) Excessive back pressure of exhaust system Checkand clean or replace

Adjust

Clean

Check and adjust carburetor

1. Carburetor system

2. Intake system

3. Cylinder head

4. Valve system

5. Ignition system

5) Overloading Adjust to rated load

1) Low idling speed Adjust

2) Slow system passage clogged Check and clean

1) Air mixing from air intake system joints

1) Gasket faulty (blow-by) Replace

1) Improper valve clearance Adjust

2) Leakage from valve seat Repair

3) Excessive clearance between valve stem and guide

1) Weak spark

Check and tighten; replace gasket

Replace

Check; adjust or replace plug

Problem and possible cause Remedy

1. Oil leakage

2. Oil up

Excessive engine oil consumptionHigh fuel consumptionAbnormal engine noise

1. Fuel system

1) Loose oil drain plug Tighten

2) Faulty oil drain gasket Replace

3) Loose main bearing cover bolts Tighten

4) Faulty main bearing cover gasket Replace

5) Crankshaft oil seal (front, rear) defect

1) Faulty piston oil ring Replace

2) Piston ring seizure, wear or poor contact Replace

3) Excessive wear of piston and/or cylinder Replace

4) Faulty stem seal Replace

5) Excessive oil level Adjust oil level

6) Breather defect Repair or replace

1) Clogged air cleaner Clean or replace

2) Faulty needle valve and/or high fuel level in float chamber

Replace

Repair or replace

2. Engine core components

1. Ignition system problems

2. Fuel system problems

3. Cylinder head

4. Valve system problems

3) Choke does not open fully Repair or replace

1) Low compression Check and repair

2) Overcooling

1) Loose ignition system wiring Inspect and tighten

2) Improper or faulty spark plug Clean or replace

1) Lean or rich fuel/air mixture

2) Carburetor contamination Overhaul or clean

3) Dirty or clogged fuel lines Clean or replace

4) Air mixing from air intake system joints Tighten; replace gasket

1) Carbon deposit in combustion chamber Clean

2) Leakage from cylinder head gasket Replace

1) Improper valve clearance Adjust

2) Valve heat deterioration Replace

Check and adjust load and/or engine speed

Clean, adjust or replace carburetor

3) Worn or broken valve spring Replace

4)Improper valve timing Adjust

LECTRIC STARTER

Engine does not start

Does the crank run?

NG NG NG

Does the starter run?

Check engagement of pinion and ring gear

Check pinion roller clutch for damage or replace.

Check battery charged state and battery terminal connection or corrosion for any abnormality.

Operation sound of magnetic switch of starter

With starter alone, connect the battery (+) terminal and the M or K terminal of the starter and check if motor runs.

There is any contact failure of starter magnetic switch. Please replace.

Charge or replace the battery. Repair connection or corrosion of battery terminals.

Key switch Connected state Check/repair wiring to the starter magnetic switch. Repair or replace starter magnetic switch.

Check settling of spring and sliding of pinion. Replace if pinion/ring gear end face is worn. Correction of pinion gap

Replace motor (brush holder or armature).

Normal rotation?

Check ignition system and fuel system.

When the starter continuously runs (Immediately remove the (-) terminal of the battery)

Motor does not stop even when the key switch is turned off.

(Too slow)

Check battery charged state and battery terminal connection or corrosion for any abnormality.

Check viscosity of engine oil for any abnormality.

Replace the starter with a new one and check if it runs.

Repair or replace the starter.

Repair or replace the key switch or starter magnetic switch.

Charge or replace the battery. Repair connection or corrosion of battery terminals.

Change the engine oil.

Check the engine interior.

Problem and check item Description Remedy

1. Checking of continuity of wiring

Check S terminal and B terminal for deformation, looseness, rusting, or dust sticking. Carefully check inserting method of the S terminal. If not abnormal, set the key switch to START position while cranking (no ignition of engine) and check if voltage is applied to the S terminal and B terminal of starter motor.

2. Battery checking

Check battery voltage and specific gravity of battery fluid.

[Voltage]

Normal value : 12.4 to 12.8V Limit (charging required): 12.4V

or lower

Staring limit : 12V (at 20ﾟC)

[Specific gravity]

Normal value : 1.22 to 1.29

Limit (Charging required)

: 1.22 or lower

[Service life]

Var iance in specific gravity among cell : 0.04 or more

3. Checking of pinion operation

Check if the pinion operates or sound of magnetic switch contactor is heard. If the pinion does not operate or magnetic switch sound is not heard, check continuity of each coil of magnetic switch.

(1) Starter does not run or only “click” sound is heard.

4. Checking of magnetic

(1) Operate the magnetic switch

and check B-M terminals

switch

(2) Check the magnetic switch

plunger and bobbin interior for dust sticking or rusting.

5. Motor checking Connect the (+) side of the

battery to the M terminal of magnetic switch and check if the motor runs.

(1) When no voltage is applied to the S

KEY SWITCH

(+)

)

(

terminal and B terminal, check continuity of the terminals and key switch and repair or replace if necessary.

(2) If voltage is applied to the S terminal

and B terminal, go to “2. Battery checking.”

(1) Charge or change the battery when

voltage is lower than 12.4V or specific gravity is lower than 1.22 (at 20°C).

(2) If the wiring and batter y are normal,

GRAVITY METE

remove the starter and go to “3. Checking of pinion operation.”

BATTERY

(1) If the pinion operates or contactor sound

is heard, step to “4. Checking of magnetic switch (1).”

(2) In case of no continuity

Replace the magnetic switch.

(3) When continuity is OK

Step to “4. Chec king of magnetic switch (2).”

(1) In case of no continuity

Contact continuity failure. Replace the magnetic switch.

(2) When continuity is OK

Step to “5. Motor checking.”

(1) Clean the plunger. If the bobbin interior

is contaminated, replace the magnetic switch.

(+)

(

)

(1) If the motor does not run, check electric

circuit inside the motor, field coil, armature, and brush and replace faulty parts.

Problem and check item Description Remedy

Check engaged state of pinion and ring gear.

(2) Starter runs but engine not

(3) Both starter

and engine run, but the engine does not start.

Motor idles and engine does not run.

If pinion and ring gear do not engage with each other and abnormal noise is heard between end faces of pinion and ring gear, check the starter pinion and ring gear.

Check if the rotation speed is normal or slow. If slow, check the battery and engine oil viscosity.

RING GEAR

PINION GEA

(1) Remove and check the starter. Check

or replace the pinion clutch if necessary.

(2) Check battery charged state and

battery terminal connection or corrosion for any abnormality.

(1) Remove the starter and check pinion

and ring gear end faces. If worn, replace the pinion and ring gear.

(2) In case of sliding fault of the pinion,

correct it.

(3) If shift lever or spring is deformed,

replace it.

(1) When the rotation speed is normal

Check the ignition system and fuel system.

(2) When the rotation speed is slow

(a)Check the battery. (b)Check the viscosity of engine oil. If

not normal, change the oil.

Remove and check the starter.

16.STANDARD REPAIR TABLES

“STD” in the following table is the parts dimension from the brand new engine or the spare parts. Whereas, “Limit” shows the maximum allowance f or the parts to be used on the engine. If the measurement exceeds beyond the “Limit”, the part needs to be replaced and/or repaired.

16-1 STANDARD DIMENSIONS AND LIMITS OF USE

ITEM STD Limit

CYLINDER HEAD *Flatness

EX13 EX17 EX21 EX27

* Intake/exhaust valve seat

contact width

Intake

Exhaust

* Intake/exhaust valve guide inner diameter

EX13 EX17 EX21 EX27

0.05

(0.002)

0.7 - 1.0

(0.0276 - 0.0394)

Unit: mm (in.)

0.1

(0.004)

----------------------

* Rocker arm pin outer diameter

D1D

* Rocker arm pin support inner d iameter

Intake

Exhaust

Pin outer diameter

1,D2

Support

inner

diameter

3,D4

EX13 EX17 EX21 EX27

5.500 - 5.518

(0.2165 - 0.2172)

5.970 - 5.980

(0.235 - 0.235)

6.00 - 6.018

(0.236 - 0.237)

----------------------

5.9

(0.232)

6.05

(0.238)

Unit: mm (in.)

ITEM STD Limit

CYLINDER * Inner diameter

* Roundness after reboring

Standard

First

reboring

Second

reboring

EX13

EX17 EX21

EX27

EX13

EX17 EX21

EX27

EX13 EX17

EX21 EX27

EX13 EX17 EX21 EX27

58.000 - 58.019

(2.2835 - 2.2842)

67.000 - 67.019

(2.6378 - 2.6385)

75.000 - 75.019

(2.9528 - 2.9535)

58.250 - 58.269

(2.2933 - 2.2941)

67.250 - 67.269

(2.6476 - 2.6484)

75.250 - 75.269

(2.9626 - 2.9633)

58.500 - 58.519

(2.3031 - 2.3039)

67.500 - 67.519

(2.6575 - 2.6582)

75.500 - 75.519

(2.9724 - 2.9732)

Less than 0.01

(0.0004)

To be rebored when the difference between max. and min. of diameter reached to

0.1 (0.004).

Ditto

* Cyli ndrici ty after reboring

PISTON

* Outer diameter at skirt in thrust

direction

Standard

Oversize

+0.25

Oversize

+0.50

EX13 EX17 EX21 EX27

EX13 EX17

EX21 EX27

EX13 EX17

EX21

EX27

EX13 EX17

EX21 EX27

Less than 0.015

(0.0006)

57.980 - 58.000

(2.2827 - 2.2835)

66.960 - 67.000

(2.6362 - 2.6378)

74.980 - 75.000

(2.9520 - 2.9527)

58.230 - 58.250

(2.2925 -2.2933)

67.210 - 67.250

(2.6461 - 2.6476)

75.230 - 75.250

(2.9618 - 2.9626)

58.480 - 58.500

(2.3024 - 2.3032)

67.460 - 67.500

(2.6559 - 2.6575)

75.480 - 75.500

(2.9717 - 2.9724)

57.89

(2.2791)

66.88

(2.6331)

74.89

(2.9484)

58.14

(2.2890)

67.13

(2.6429)

75.14

(2.9583)

58.39

(2.2988)

67.38

(2.6528)

75.39

(2.9681)

Unit: mm (in.)

ITEM STD Limit

PISTON

* Ring groove side clearance

* Piston pin hole

* Piston pin outer diameter

* Clearance between piston and cylinder

at skirt

Top

Second

Oil ring

Coil exp

Oil ring

(three-piece)

EX13 EX17 EX21 EX27

EX13

EX17 EX21

EX27

EX13

EX17 EX21

EX27

EX13

EX17 EX21

EX27

EX13

EX17 EX21

EX27

EX13

0.035 - 0.080

(0.0014 - 0.0031)

0.02 - 0.075

(0.0008 - 0.0031)

0.01 - 0.065

(0.0004 - 0.0026)

0.01 - 0.065

(0.0004 - 0.0026)

0.060 - 0.165

(0.0024 - 0.0065)

0.0300 - 0.185

(0.0012 - 0.0073)

0.0100 - 0.205

(0.0004 - 0.0081)

12.991 - 13.009

(0.5115 - 0.5122)

15.991 - 16.009

(0.6296 - 0.6303)

17.991 - 18.009

(0.7083 - 0.7090)

12.992 - 13.000

(0.5115 - 0.5118)

15.992 - 16.000

(0.6296 - 0.6299)

17.992 - 18.000

(0.7083 - 0.7087)

0.040 - 0.079

(0.0016 - 0.0031)

0.15

(0.0059)

0.15

(0.0059)

-------------------------------------------------------

13.035

(0.5132)

16.035

(0.6313)

18.035

(0.7224)

12.960

(0.5102)

15.960

(0.6283)

17.960

(0.7071)

* Piston ring end gap

Top

Second

Oil

(Coil exp)

EX17 EX21 EX27

EX13 EX17

EX21 EX27

EX13 EX17

EX21 EX27

EX13 EX17

EX21 EX27

0.050 - 0.089

(0.0020 - 0.0035)

0.15 - 0.35

(0.0059 - 0.0138)

0.15 - 0.3

(0.0059 - 0.0118)

0.1 - 0.3

(0.0039 - 0.0118)

0.15 - 0.35

(0.0059 - 0.0138)

0.2 - 0.4

(0.0078 - 0.0157)

0.2 - 0.4

(0.0078 - 0.0157)

0.05 - 0.25

(0.0020 - 0.0098)

0.1 - 0.3

(0.0039 - 0.0118)

0.25

(0.010)

1.5

(0.0591)

1.5

(0.0591)

1.5

(0.0591)

CONNECTINGROD



* Large end inner diameter

Unit: mm (in.)

ITEM STD Limit

EX13 EX17 EX21

30.000 - 30.016

(1.1811 - 1.1817)

30.1

(1.1850)

* Clearance between large

end and crank pin

* Small end inner diameter

* Clearance between small

end and piston pin

* Large end side clearance

EX27

EX13 EX17 EX21 EX27

EX13 EX17

EX21 EX27

EX13 EX17 EX21 EX27

34.500 - 34.516

(1.3386 - 1.3392)

0.020 - 0.049

(0.0008 - 0.0019)

13.010 - 13.021

(0.5122 - 0.5126)

16.010 - 16.021

(0.6303 - 0.6307)

18.010 - 18.021

(0.7091 - 0.7095)

0.010 - 0.029

(0.0004 - 0.0011)

0.100 - 0.780

(0.0040 - 0.307)

34.1

(1.3425)

0.2

(0.0078)

13.08

(0.5150)

16.08

(0.6331)

18.08

(0.7118)

0.12

(0.0047)

1.0

(0.0394)

CRANKSHAFT * Crank pin outer diameter

* Journal outer diameter

EX13 EX17 EX21

EX27

EX13 EX17 EX21

EX27 EX13

EX17 EX21

EX27

29.967 - 29.980

(1.1798 - 1.1803)

34.467 - 34.480

(1.3570 - 1.3575)

27.988 - 27.997

(1.1019 - 1.1022)

29.988 - 29.997

(1.1806 - 1.1810)

24.988 - 24.997

(0.9838 - 0.9841)

29.988 - 29.997

(1.1806 - 1.1810)

29.85

(1.1752)

34.35

(1.3524)

ITEM STD Limit

CAMSHAFT * Cam peak height (intake and exhaust)

Cam peak

height

EX13 EX17 EX21 EX27

29.028 - 29.128

(1.1428 - 1.1468)

Unit: mm (in.)

28.98

(1.1409)

* Cam sprocket inner diameter * Pin (cam sprocket) outer diameter

D1 D

INTAKE/EXHAUST VALVES

* Valve stem outer diameter

Cam inner

diameter

1,D2

Pin outer

diameter

3,D4

Intake

Exhaust

EX13 EX17 EX21 EX27

9.0 - 9.036

(0.3543 - 0.3557

8.953 - 8.975

(0.3525 - 0.3533)

5.440 - 5.455

(0.2142 - 0.2148)

5.426 - 5.444

(0.2136 - 0.2143)

9.05

)

(0.3563)

8.95

(0.3524

)

5.35

(0.2106)

5.35

(0.2106)

* Clearance between valve stem and

valve guide

* Valve clearance (in cold state)

Intake

Exhaust

Intake

Exhaust

EX13 EX17 EX21 EX27

0.045 - 0.078

(0.0018 - 0.0031)

0.056 - 0.092

(0.0022 - 0.0036)

0.12 - 0.15

(0.0047 - 0.0059)

0.12 - 0.15

(0.0047 - 0.0059)

0.3

(0.0118)

0.3

(0.0118)

ITEM STD Limit

VALVE SPRING FREE LENGTH

VALVE SEAT ANGLE (INTAKE AND EXH AUST) * Valve cutter angle (a) * Valve co ntact width (b)

Intake Exhaust

EX13 EX17 EX21 EX27

27.4

(1.0787)

a:90°

b:0.7 - 1.0

(0.0276 - 0.0394)

Unit: mm (in.)

2.0

(0.0787)

CHAIN LENGTH

160N (16kgf.)

Compression pressure (kg ・cm

Fuel consumption Continuous load / 3600 rpm (L / Hr)

Capacity (L)

EX13

EX17

EX21

EX27

/ 500 rpm)

263.1

(10.3583)

269.0

(10.5906)

281.7

(11.0906)

307.1

(12.0906)

EX13 EX17 EX21 EX27

266.0

(10.4726)

272.1

(10.7126)

284.9

(11.2165)

310.6

(12.2284)

3.5 4.0 4.0 4.0

1.2 1.6 1.9 2.6

0.6 1.0

Lubricant

Efficacy (mL)

Consumption (mL / Hr)

※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

350 500

5-10 8-13

16-2 TIGHTENING TORQUE

Tightening Torque

ITEM

N・mkgf・cm ft・lb.

Re-use 25.0 - 27.0 250 -270 18.1 - 19.5

M8×68flangebolt

Cylinder head bolts

M8 × 35 flange bolt 17.0 -19.0 170 - 190 12.3 - 13.7

Connecting rod cap

bolts

Flywheel nut 59.0 - 64.0 590 - 640 42.7 - 46.3 Main bearing cover bolts 22.0 - 24.0 220 - 240 16.2 - 17.7

Spark plug

Muffler nut 18.0 - 22.0 180 - 220 13.0 - 15.9 Ignition coil 7.0 - 9.0 70 - 90 5.1 - 6.5

EX13,17,21 13.0 - 15.0 130 - 150 9.4 - 10.8 EX27 17.0 - 20.0 170 - 200 12.3 - 14.5

New 12.0 - 15.0 120 - 150 8.7 - 10.8 Re-tightening 23.0 - 27.0 230 - 270 16.6 - 19.5

When replace to new cylinder head and flange bolts

28.0 - 30.0 280 - 300 20.3 - 21.7

17.MAINTENANCE AND STORAGE

The maintenance jobs described below apply to correct use of the engine under normal conditions. The maintenance intervals mentioned in this section are not a guarantee that no maintenance is required during those intervals. For example, when the engine is used in dusty conditions, the air cleaner should be cleaned every day, rather than ev ery 100 hours.

17-1 DAILY MAINTENANCE (EVERY 8 HOURS OF USE)

MAINTENACE ITEMS REASON / REMARKS

(1) Clean dust from engine.

(2) Check for fuel leakage.Tighten or replace parts,

if necessary.

(3) Check all parts are securely fastened.Tighten,

if necessary.

(4) Check oil l evel and add up to full mark.

(5) Check that the air cleaner el ement is clean.

Clean or replace, if necessary.

(1) D ust can impair operation of various parts.

Governor linkage is especially sensitive to dust

(2) Uneconomical and dangerous.

(3) Looseness can result in vibration and

accidents.

(4) Running the engine with insufficient oil can

result in serious problems, including engine seizure.

(5) A clogged ai r cleaner can cause power loss

and malfunction.

17-2 INSPECTION AND MAINTENANCE AFTER THE FIRST 20 HOURS

MAINTENACE ITEMS REASON / REMARKS

(1) Change the crankcase oil. (1) Sludge is deposited during running-in.

17-3 INSPECTION AND MAINTENANCE EVERY 100 HOURS (EVERY 10 DAYS)

MAINTENACE ITEMS REASON / REMARKS

(1) Change the crankcase oil. (2) Clean the air cleaner.

(1) Contaminated oil quickens wear. (2) A clogged air cleaner can cause engine

malfunction.

(3) Inspect the spark plug. Clean with gasoline or

polish with sandpaper if dirty.

(3) A faulty spark plug can cause low power output

and poor starting performance.

17-4 INSPECTION AND MAINTENANCE EVERY 100 TO 200 HOURS (EVERY MONTH)

MAINTENACE ITEMS REASON / REMARKS

(1) Clean the fuel strainer and fuel tank. (2) Change the air cleaner element.

(1) Contaminated fuel can cause engine

malfunction.

(2) A clogged air cleaner can cause engine

malfunction.

17-5 INSPECTION AND MAINTENANCE EVERY 300 HOURS

MAINTENACE ITEMS REASON / REMARKS

(1) Inspect the intake and exhaust valve clearance.

Adjust if necessary.

(1) Incorrect clearance can cause low power output

and engine malfunction.

17-6 INSPECTION AND MAINTENANCE EVERY 500 TO 600 HOURS (EVERY 6 MONTHS)

MAINTENACE ITEMS REASON / REMARKS

(1) Remove the cylinder head and remove any carbon. (2) Disassemble and clean the carburetor.

(1) Carbon deposits can cause engine malfunction. (2) A faulty carburetor can cause engine malfunction.

17-7 MAINTENANCE EVERY 1,000 HOURS (ANNUAL MAINTENANCE)

MAINTENACE ITEMS REASON / REMARKS

(1) Overhaul the engine. Clean and correct the

engine parts, replacing if necessary. (2) Replace the piston rings. (3) Replace the fuel hose.

(1) Dirty, misaligned or worn parts can cause low

power output and engine malfunction.

(2) Faulty piston rings can cause low output power

and engine malfunction.

(3) To prevent fuel leakage and attendant dangers.

17-8 ENGINE STORAGE

(1) Carry out the maintenance jobs described in step 16-1 above. (2) Drain fuel from the fuel tank and carburetor float chamber. (3) To prevent rust in the cylinder bore, inject oil through the spark plug hole, pull the recoil starter knob

gently 2 or 3 times and then put back the spark plug. (4) Pull the recoil starter knob until the resistance is heavy . Leave it in that position. (5) Clean the exterior of the engine with an oiled cloth. Place a plastic co v er or similar o v er the engine, and

store the engine in a dry place.

PRINTED IN THE USA

Robin EX17, EX21, EX27 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual