Robin EH17-2, EH25-2 Service Manual

CONTENTS

Section Title

1

.

2

.

3

.

4

.

5

.

6

.

7

.

8

.

Page

4-1
4-2
4-3

4-4

4-5
4-6
4-7
4-8
4-9
4-1

0

4-1

1

4-1

2

4-1 3
4-1 4
4-1

5

4-1 6
4-1 7

I.

SPECIFICATIONS

~~ ~ ~~~ ~ ~ ~~ ~~ ~~~ ~~~~ ~~ ~~~ ~ ~

Model

EH12-2B

EH

12-2

EHl2-2D EH12-2BS

EH12-2DS

TY

Pe

X

Bore
Piston Displacement

Max.

Nem (kaf*m)/rDm

I

Direction
Cooling system
Valve Arrangement

Lubrication
Lubricant
Capacity of Lubricant

I

Carburetor

Stroke

Torque

of

Rotation

~~ ~ ~~~~~ ~~ ~

Air-Cooled, 4-Cycle, Single-Cylinder, Horizontal

x

43 rnm (2.36 x 1.57 in.)

60

cm3

(7.38 cu.in.)

As

Viewd From

Splash Type

L

(0.16

U.S.

I

52)

15 (1

Counterclockwise

~~ ~

Automobile

/1300

Oil

SAE

121

Forced Air Cooling

Overhead Valve

#20, #30 or 1 OW-30 ; Class SE, SF

0.6

Horizontal Draft, Float Type

P.T.O.

P.T.O.

gal.)

Shaft, Gasoline Engine

7.5 (0.76) /2600
Shaft Side

or

higher

I

Fuel

I

Fuel Feed System
Fuel Tank Capacity

I

Spark Plug
Charging Capacity

I

Speed Reduction
Governor System

Dry

Weight

Length

I

310 g/KW*h (230 gr/HP*h) At Continuous Rated Output

~~~~~~~ ~~

I

-

Recoil Starter Starting System

2:l Cam Shaft Drive

15.5 kg (34.2Ib.)

299 mm (1 1.77 in.)

Recoil and Electric

Starter

I

18.0 kg (39.7 Ib.)

I

299 mm (1 1.77 in.) I 297 mm (1 1.69 in.) I 297 mm(ll.69 in.)

Automobile Gasoline

~ ~~~

Gravity Type

U.S.

3.6 L (0.95

Flywheel Magneto (Solid State) Ignition System

NGK BGES

12V - 1.3A

Centrifugal Flyweight System

gal.)

-

Recoil

I

15.0 kg (33.1 Ib.)

330mrn (12.99in.)
366 mm (14.41 in.)

Starter

12V

Starter

Recoil and Electric

I

17.5 kg (38.6Ib.)

341 mm (13.43in.)
366 mm (14.41 in.)

-

1.3A

-1-

Model

EH17-2B

EH17-2BS

EH17-2

EH17-2D

EH17-2DS

TY

Pe

X

Bore

Compression Ratio 8.5

Output

Kw

Max.

Nom

Direction of Rotation

I

Cooling system

I

Valve Arrangement

I

Lubrication
Lubricant

Capacity of Lubricant

Stroke

(HP)/rpm

Torque

(kgf*m)/rpm

Continuous
Max.

~ ~~ ~~ ~

Air-Cooled, 4-Cycle, Single-Cylinder, Horizontal

~~ ~~

(3.5)

2.6

I I

I

I

I

Automobile Oil

~~ ~~~~ ~ ~

67

/

1500 2.9 (4.0) / 1800

4.4 (6.0) /2000

21.4 (2.1 8)
Counterclockwise

/

1300

~~~~~~~ ~

SAE

#20, #30

Horizontal Draft, Float Type Carburetor

x

49

mrn

172 cm3 (10.50 cu.in.)

As

Viewd From P.T.O. Shaft Side

Forced

~~

Overhead Valve

Splash Type

L

0.65

(0.17

P.T.O.

(2.64

X

1.93 in.)

2.6

Air

Cooling

~_____

or

1OW-30 ; Class

U.S.

gal.)

Shaft, Gasoline Engine

.

(3.5)

/3000 2.9 (4.0) /3600

4.4 (6.0) /4000

1

0.7

(1

-09) / 2600

_____

~ ~

SE,

SF

or higher

Fuel
Fuel Consumption Rate
Fuel Feed System
Fuel Tank Capacity

Spark

Charging Capacity

I

Starting System
Speed Reduction

Plug

Dry

Weight

Dimensions

Length

Width

Height 380mm (14.96in.)

310g/KW-h (230 gr/HP*h) At Continuous Rated Output

-

2:l

Cam Shaft Drive

16.5 kg (36.4 Ib.)

mm

mm

(1 1.85 in.)
(12.99in.)

301

Automobile Gasoline

Gravity Type

3.6 L (0.95

Flywheel Magneto (Solid State)

12V - 1.3A

NGK

US.

B6HS

gal.)

-

-

Centrifugal Flyweight System Governor System

19.0

kg (41.9

mrn

341

rnrn

380rnm (14.96in.) 380mm (14.96in.)

Ib.)

(1

1.85 in.)

(13.43in.) 330

16.0 kg (35.3

299

mm

rnm

330

Ib.)

(1 1.77 in.) 301
(12.99in.)

18.5 kg

299 mm(ll.77in.)

341
380rnm (14.96in.:

12V

rnm

-

1.3A

(40.8

Ib.)

(13.43in.:

-2-

Model

EH25-2

6

EH25-26s

EH25-2

~~~~~~ ~~ ~

EH25-2D

EH25-2DS

TY

Pe

x

Bore
Piston Displacement
Compression Ratio

output

Kw

Max.

Nom (kgf*m)/rpm
Direction

Cooling system

Valve Arrangement

Lubrication

Capacity of Lubricant
Carburetor

Fuel

Stroke

(HP)hm

Torque

of

Rotation

Continuous
Max.

Air-Cooled, 4-Cycle, Single-Cylinder, Horizontal P.T.O. Shaft, Gasoline Engine

75 X 57

mm

(2.95

251

cm3 (15.31 cu.in;)

X

2.24 in.)

8.5

(5.5)

/3000 4.7 (6.4) /3600

(8.5)

SE,

SF

/4000

/

2600

or

higher Lubricant

6.3

16.6 (1.69)

I

4.0

(5.5)

I1

500

4.7 (6.4) / 1800

(8.5)

6.3

33.1 (3.38)

Automobile Oil SAE #20, #30 or

/2000

/

1300

Counterclockwise As Viewd From P.T.O. Shaft Side

Horizontal Draft, Float Type

4.0

Forced Air Cooling

Overhead Valve

Splash Type

1

OW-30 ; Class

1

.O

L

(0.26

U.S.

gal.)

~ ~~~ ~ ~ ~ ~~~~~

Automobile Gasoline
Fuel Consumption
Fuel Feed System
Fuel Tank Capacity
Ignition System
Spark Plug
Charging Capacity

Starting System Recoil Starter
Speed Reduction

Governor System
Dry Weight

Dimensions

Rate

I

Length

Width

Height

31

-

I

2:l Cam Shaft Drive

I

24.0 kg (52.9

333mm (13.11 in.)
380mm (14.96in.)

440mm

Ib.)

(17.32in.)

0

g/KW*h (230 gr

6.0

Flywheel Magneto (Solid State)

12V - 1.3A

Recoil and Electric

Starter

Centrifugal Flyweight System

28.0 kg (61.7 Ib.)
333mm (13.11 in.)
380mm

440mm

(14.96in.)
(17.32in.)

/

HP-h)

At Continuous Rated Output

Gravity Type

L

(1

59

U.S.

NGK

B6HS

I

Recoil

23.0

gal.)

kg

-

Starter

(50.7

Ib.)

~~~ ~~

-

12V

1

Starter

Recoil and Electric

1.3A

-

27.0 kg (59.5

332mm(l3.07in.) 332mm (13.07in.)

380mrn (14.96in.) 380mm (14.96in.)

440mm

(17.32in.) 440mm (17.32in.)

Ib.)

-3-

2-1

MAXIMUM OUTPUT

The maximum output is the output of an engine with its throttle valve fully opened under the condition
that all the moving parts are properly

A

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

2-2

CONTINUOUS

RATED

OUTPUT

worn

in after the initial break-in period.

The continuous rated output is the output

favorable from the view point

is

When the engine

installed

of

engine’s life and fuel consumption.

on

a certain equipment,

of

an engine at optimum governed speed which is most

it

is

recommended that the continuous output

required from the engine be kept below this continuous rated output.

2-3

MAXIMUM

The maximum torque

TORQUE

is

the torque at the output shaft when the engine is producing maximum output at

certain revolution.

-4-

2-4

PERFORMANCE CURVES

8

0

EHlPD,

B

HP

4

3

kW

2

for

B

type

+

3

l2

n

+

3

0

1

0

1

2000

(1

000)

REVOLUTION

3000

(1

500)

-

r.p.m.

4000

(2000)

-5-

0

EH17D,

6

for

B

tvDe

N.m

kgfam

(1

000)

REVOLUTION

3000

(1

500)

-

-6-

4000

(2000)

r.p.m.

EH25D,

B

kW

HP

-6

8

7

I

t:

$4

I-

&

5

4

r

"

I

I I

"

I

I

I

MAXIMUM

I

I

MAXIMUM

I

I

I

I

I

"-

I

TORQUE

I

HORSEPOWER

RECOMMENDED

1

AL\

I I

I I

'(NET)

I

16.5

15.5

14.5

N.m

(33)

(31)

(29)

c

kgf-m

1.7

(3.4)

1.6

(3.2)

1.5

(3.0)

1.4 (2.8)

2

1

0

2000

(1

000)

I

i

REVOLUTION

3000

(1

500)

-

-7-

'

r.p.m.

4000

(2000)

3.

FEATURES

1.

The overhead valve design offers

a

compactness, light weight and ideal combustion characteristics

resulting in more power from Iess fuel and prolonged engine life.

2.

An

optimum lubrication and better tilted operation thanks to upright cylinder design.

3.

A crossflow arrangement

of

intake and exhaust ports ensures stable performance under high ambient

temperature.

4.

The automatic decompressiom system lightens
conventional

5.

An easy operation thanks to integrated engine control system.
Improved throttle mechanism

6.

Combustion and mechanical noises have been analyzed acoustically and improved for better tonal

SV

engines.

is

adopted for easy starting.

the

recoil pull force by

40%

quality and lower engine noise.

7.

Optimally designed reciprocating parts reduce the vibration level of the engine.
equips single through-balancer shaft as an option.

4.

GENERAL DESCRIPTION

4-1

CYLINDER

AND

CRANKCASE

OF

ENGINE COMPONENTS

comparing to the

EH25-2

engine

,

,

The cylinder and crankcase

is

single piece aluminum
diecasting. The cylinder liner, made of special cast
iron,

is

molded into the aluminum casting.

The crankcase has a mounting surface. on the output

shaft side, where the main bearing cover is attached.

4-2

MAIN

The main bearing cover
which

BEARING

is

mounted on the output shaft side of the

COVER

is

an aluminum diecasting,

crankcase.
Remove the main bearing cover to inspect the inside

of

the engine.
The pilots and bosses are machined on the cover for
direct mounting of the engine onto such machines

as

generators and pumps.

Oil gauge (fillers) are on both sides of the cover for
easy maintenance.

Fig.

/"-

\

4-1

/"

-8-

OIL GAUGE

Fig.

4-2

OIL

GAUGE

4-3

CRANKSHAFT

The crankshaft is forged carbon steel, and

W

pin is induction-hardened.

the

crank

B

TYPE

The output end of the shaft has a crankshaft gear, and
balancer gear for

EH25-2

which are pressed into

position.

D

TYPE

Fig.

4-3

44

CONNECTING

ROD

AND

PISTON

The connecting rod is an aluminum alloy diecasting,

and

its

large and smalI ends function as bearings.
The piston
two compression rings and one

is

an aluminum alloy casting, and carries

oil

ring.

4-5

PISTON RINGS

The piston rings are made
The profile of the top ring
second ring has a tapered
The

oil

ring consists

of

special cast iron.

is

barrel face and the

face.

of

a cutter ring and a

coil

expander for better sealing and less oil consumption.

-9-

I

fig.

4-4

TOP

RING

fig.

SECOND

OIL

4-5

RING

RING

4-6

CAMSHAFT

The camshaft

for

the D-type engine is made

of

special cast iron and camshaft gears are casted to-

gether

in

one piece.
Both sides of the shaft fit into the plane bearings on
the crankcase and main bearing cover.
The camshaft for the B-type engine is made of
forged carbon steel and also functions as PTO shaft.
The cam gear
bearings are employed

is

press fitted on the shaft and the ball

on

both sides for supporting

the shaft.

4-7

VALVE ARRANGEMENT

The intake valve is located

on

flywheel side

of

the

cylinder head.
The hard alloy valve seats axe molded in the cylinder
head and stellite is fused to the exhaust valve face.
The cylinder baffle leads cooling air to the exhaust
valve area for the optimum cooling.

B

Fig.

TYPE

4-6

n

D

lYPE

INTAKE

/

4-8

CYLINDER HEAD

The cylinder head is an aluminum die casting which

utilizes wedge

type

combustion chamber

for

the

highest combustion efficiency.

-

10

Fig.

4-7

Fig.

4-8

-

4-9

GOVERNOR SYSTEM

The governor

is

a centrifugal flyweight type which
ensures constant operation at the selected speed
against load variations.
The governor gear with governor weights is installed

on the main bearing cover.

4-10

COOLING SYSTEM

The large fins on the flywheel provide sufficient
cooling air capacity

for

the inlet and exhaust area
and cylinder.
The cylinder baffle helps the cooling air flow effi­ciently.

4-1

1

LUBRICATION

All the rotating and sliding parts are splash­lubricated by the oil scraper on the connecting rod.

/

GOVERNOR

GEAR

Fig.

4-9

4-1

2

-IGNITION SYSTEM

The ignition system is a transistor controlled mag­neto ignition system which cosists of a flywheel and
an ignition coil with a built in transistor.
This system has an ignition timing advance for easy
starting.

-

11

-

I

OIL

SCRAPER

Fig.

Fig.

4-10

4-1

7

4-13

The engines are equipped with a horizontal draft
carburetor that has a float controlled fuel system and
a
The carburetors are calibrated carefully for easy
starting, good acceleration, low fuel consumption
and sufficient output.

CARBURETOR

fixed

main jet.

4-14

The air cleaner is a
element type is available.

AIR

CLEANER

single

CLEANER
CASE

Single

4-15

Unbalanced inertia force
which rotates at the same speed with the crankshaft
to effectively reduce vibration.

BALANCER

(Option

urethane foam element system.

element type

Fig.

4-

1

3-

I

for

EH25-2)

is

balanced by the balancer

As

an option, heavy duty type with

Double element type

Fig.

4-

13-2

BALANCER

a

CLEANER COVER

I

double

-

-

12-

Fig.

4-14

4-16

DECOMPRESSION

An

automatic decompression mechanism which

SYSTEM

opens exhaust valve before the piston reaches com­pression top

is

assembled on the camshaft for easy

starting.

AUTOMATIC

DECOMPRESSOR

Fig.

4-14

SYSTEM

-

13-

4-1

7

SECTIONAL

VIEW

OF

ENGINE

FUEL

TANK

FLYWHEEL

-

14-

MAIN

BEARING

COVER

a

ROCKER

ARM

PUSH ROD

-

15

-

5.

DISASSEMBLY

5-1

PREPARATIONS AND SUGGESTIONS

1)

When disassembling the engine, memorize the locations

reassembed correctly. If yor are uncertain

AND

REASSEMBLY

of

identifying some parts, it

of

attached to them.

2)

Have boxes ready to keep disassembed parts by group.

3)

To

prevent losing and misplacing, temporarily assemble each group

4)

Carefully handle disassembed parts, and clean them with washing oil

5)

Use

the correct tools in the correct way.

5-2

SPECIAL

Tool

TOOLS

No.

Tool

individual parts

is

of

disassembed parts.

if

necessary.

Use

so

that they can be

suggested that tags be

209

Market

-

95004-

parts

07

Flywheel

Flywheel puller

FLYWHEEL PULLER

puller with

bolt

For
For

pulling

pulling

off

off

FLYWHEEL

the flywheel
the flywheel

PULLER

EH25-2

EH12-2,

EH17-2

/"-

Fig.

-

16

5-1

-

5-3

DISASSEMBLY PROCEDURES

Step

1

Part

to

remove

(1)

Remove

(2)

To

gauge.

oil

drain

plug

and drain oil. Oil drain

discharge oil quickly, remove oil

Remarks Procedures

Be careful
gasket.

not

to

lose the

14mm

Tool

box

I

wrench

Fig. 5-2

-

17

-

GASKET

I

DRAIN

PLUG

Step

2

Part

Fuel

to

remove

tank

Procedures

1

(1)

Close

fuel

valve.

(2) Disconnect fuel hose between fuel strainer

and carburetor.

(3)

Remove fuel
M6X14mm bolt
M8X20mm bolt

tank

from cylinder

*.--

0-

head.

4pcs. (EH12-2,17-2)
4pcs. (EH25-2)

~ ~ ~~ ~~

Wipe

Remarks

off

spilt

thoroughly.

fuel

1

Omm

socket

Tool

(1

2mm)

wrench

I

(EH12-2,

(EH25-2)

FUEL

HOSE

17-2)

-

-*

Fig.

18

5-3

-

Step

I

Part

to

remove

I

Procedures

I

Remarks

I

Tool

Recoil starter

housing

I

5

Oil sensor
(Option)

I

(1)

Remove recoil
M6

X

8mm

(1)

Remove blower housing

M6X

i2mm

(1)

Remove oil sensor probe.
to damage stick and sensor since these are
sensitive and

result.

from

blower housing.

flange

bolt

-

-

4pcs.

from

crankcase.

flange bolt 4pcs.

Be

an

erratic operation

careful not

may

BLOWER

1

Omm

lOmm

HOUSING

box

box

wrench

wrench

Fig.

-

19

5-4

-

)art

to remove

Procedures

Remarks

Tool

Muffler cover,
Muffler and
Exhaust pipe
cover

(1) Remove muffler cover

cover.

M6X

lOmm flange

(2) Remove

cylinder head.
M8 nut 2pcs.
M6
(EHl2-2,17-2)

M8X

muffler

X

12mm

flange bolt

16mm flange

and

bolt

from crankcase and

bolt

exhaust pipe

0..

Spcs.

-

1

PC.

-

1 pc.

(EH25-2)

I

Be careful
muffler gasket.

not

to

8mm, lOmm

lose

12mm socket wrench

and

M8

NUT

:

2

pcs.

MUFFLER

c

COVER

Fig.

-

20.-

5-5

Procedures

Remarks

Tool

Control

box

and Electric
(Option)

(1)

Disconnect wires.
blue
light blue
black

(2)

Remove black wires from electric starter.

(3)

Remove control

(4)

Loosen

1

(diode rectifier

***

1

two

)

1

(diode rectifier

(magnetic switch)

box.

bolts

and

remove electric

)

starter.

M8

bolt 2pcs.

Fastened together with
fuel

tank.

12mm socket wrench

to

-

21

-

Head cover

Air

cleaner

(1)

(1)

1

(2)

L

Procedures

Remove head cover from crankcase.

M6

X

12mm flange bolt

Remove cleaner cover and cleaner
element.
Remove cleaner case.

M6

flange

nut

2pcs.

1

pc.

Remarks

Fastened together with
carburetor.

.GASKET

\

CLEANER CASE

Tool

1

Omm

socket wrench

lOmm

socket wrench

c

c

-

Fig.

22

c

57

-

Step

10

-

11

12

-

13

-

Part

to

remove

I

~

Procedures

Governor
lever,
Governor rod
and Governor
spring

Carburetor

(1) Unhook governor spring from speed

control lever.

(2) Remove governor lever from governor

shaft.

M6X30mm

bolt and washer

-e

lpc.

(3)

Detach governor lever, governor rod and
rod spring from carburetor.

(1)

Remove carburetor from

intake

pipe.

Bolt and washer on
governor lever

only

needs to be loosened.

1

Omm

socket wrench

Speed control (1) Remove stop plate, friction plate and
lever speed control lever.

M6

X

14mm flange bolt

. - -.

1

PC.

lOmm

socket wrench

Intake pipe (1) Remove

intake

pipe from cylinder head. Be careful not

to

lose 10mm, 12mm

M6 flange nut

-

-

2pcs. (EH12-2,17-2) insulator and gasket. socket wrench

M6

X

25mm

flange bolt

-

-

1 pc.

M8 X28mm bolt and washer

(EH12-2, 17-2)

-.-a

~PCS.

(EH25-2)

STOP

PLATE

M6

FLANGE NUT : 2

PCS.

(EH12-2, 17-2) GASKET (INSUMTOR)

M6

FLANGE BOLT

1

PC.

(EH12-2, 17-2)

FRICTION PLATE

M8

BOLT

and

WASHER

:

3

pcs.

(EH25-2)

SPEED CONTROL LEVER

ARBURETOR

ROD

SPRING

GOVERNOR

ROD

GOVERNOR

LEVER

M6

BOLT

and

WASHER : 1

PC.

Fig.

5-8

-

23

-

14

Ignition coil

l-

“

(1)

Disconnect ignition
ignition coil
M6X25mm bolt and washer

”

(1)

Remove starter pulley
Place socket wrench on flywheel fastening
nut and strike
hammer. Refer to the illustration below.
(See Fig.

14mm nut lpc. (EHl2-2, 17-2)
18mmnut

Procedures

from

5-9.)

****

plug cap

crankcase.

...-

from

flywheel.

tip

of the lever

1pC. (EH25-2)

and

remove

2pcs.

with

I

Do not place bar
driver in flywheel
loosen flywheel nut.

I

Remarks

or

screw

fin

to

1

9mm(EH12-2,17-2)
24mm(EH25-2)
socket wrench

(EH12-2,

(EH25-2)

c

17-2)

Fig.

5-70

-

24

-

Fig.

5-9

Step

Part

to

remove

Procedures

Remarks

Too

I

16

Flywheel

17

Charge

~

I

coil

(Option)

18

Spark

plug

(1)

Remove flywheel

(2)

Remove

(See

(1)

Remove charge

M6

(1)

Remove spark

Fig.

X

25mm

key

5-12.)

from

crankshaft.

Use flywheel puller

from crankshaft. illustrated below.

(See Fig.

coil.

Screw

plug

2pcs.

from

cylinder head.

5-1

1.)

as

Flywheel puller

21

mrn

socket wrench

Fig.

5-1

1

FLYWHEEL

-

25

-

step

19

20

~~~ ~

Part

to

remove

Rocker cover

Cylinder head

Procedures

(I)

Remove rocker cover
M6X 12mm flange bolt

(2)

Remove gasket. (rocker cover)

(1)

Remove cylinder head from crankcase.

M8x65mm flange bolt
MIOX75mmflangebolt

(EH25-2)

(2)

Detach cylinder head gasket from cylinder
head.

(3)

Remove

M6

push

FLANGE

rods.

BOLT

:

4

pcs.

from

cyIinder head.

..-.

4pcs.

....

4pcs.

(EH12-2,

--.-

4pcs.

17-2)

Remarks

Tool

1

Omm

socket

wrench

12mm, 14mm

socket wrench

Fig.

-

26

5-74

-

!

Step

-

-

I

Part

21

Main bearing

to

cover

remove

Procedures

(1) Remove main bearing cover fastening

bolts.

M6X30mm bolt and washer

(EH

M8X30mm bolt and washer

(2)

Remove main bearing cover using plastic

hammer.

(See Fig.

5-15)

-

8pcs.

12-2, 17-2)

-.-.

8pcs.

(EH25-2)

Remarks

Be careful

oil

seal.

not

to

damage

I

-

1

Omm,

12mm

socket wrench

L

L

MAIN

Fig.

5-15

M6
M8

BOLT

BOLT

-

and

and

Fig.

27

WASHER

WASHER

5-1

6

-

:

8

:

8

pcs.

(EH12-2,

pcs.

(EH25-2)

17-2)

Step

-

22

-

23

I

Part

to

remove

Cam shaft and
Balancer shaft
(Option for

EH25-2)

Tappet

I

,

1

(1)

Remove cam shaft from crankcase.

(2)

Remove balancer shaft.
(Option for

(1)

Remove tappets

Procedures

EH25-2)

from

crankcase.

Remarks

To

prevent

tappets

from
getting damaged, put the
crankcase upside down.
(See

Fig.

5-17.)

Put a

tag

on

tappets to
identify intake and
exhaust.

,.

Tool

t

-

28

-

Step I Partto

24

Connecting
rod and

Piston M6

,

,

i

~

25

Piston and
Piston rings

remove

PISTON RING

I

Procedures

(1)

Remove connecting rod bolt after scraping

off

carbon from cylinder and piston.

X

34mm flange bolt 2pcs. (EHI 2-2)

M7X37mm flange bolt 2pcs. (EH17-2)

M8x46mm

flange bolt 2pcs. (EH25-2)

(2) Remove connecting rod cap.

(3)

Remove connecting

of

crankcase after rotating crankshaft

rod

from upper side

that piston comes up to top dead center.

(1)

Remove clips and piston pin.

(2)

Remove piston from connecting rod.

(3) Remove piston

rings

from piston.

~~~

Remarks

Tool

lOmm

socket wrench

so

Do

not damage the

smaller end of connecting

rod.

Do

not expand or twist

piston

rings.

PISTON PIN

CLIP

CONNECTING

PISTON

ROD

,

/-

&N\

CONNECTING

,

c

/

I

-

Fig.

29

5-79

-

M6

FLANGE BOLT

M7 FLANGE BOLT 2

M8

FLANGE

BOLT

:

2

PCS.

PCS.

2

PCS.

(EH12-2)
(EH17-2)
(EH25-2)

Step

Part

to

remove

Procedures

Remarks

Too!

26

Crankshaft

(1)

Fig.

Remove

flywheel

5-20

crankshaft

end.

tapping

Be

oil

careful

seal.

at the

not

to

damage

c

CRANKSHAIT

(D

c

type)

-

fig.

30

c

5-21

-

Step

'art

to

remove

Procedures

Remarks

Tool

27

Intake valve
and Exhaust
valve

(1)

Loosen

(2)

Remove

(3)

Press down spring retainer, take

nut

and remove bolt (pivot).

rocker

arms.

out

valve, and then remove spring retainer
and valve spring

(4)

Remove intake

.(See

Fig.

5-23.)

and

exhaust valve.

collet

Inspect valves, valve
seats and guide.

Do

not remove valve
guides unless they are
worn beyond the limit
shown

in

page

58.

.

M6

NUT

EXHAUST

/

VALVE

Fig.

5-24

INTAKE

VALVE

-

31

-

5-4

REASSEMBLY

0

PRECAUTIONS

1)

Clean parts throughly before reassembly.
Pay most attention to cleanliness

off

Scrape
Check
Apply oil

4)

Replace all the gaskets with new ones.

all carbon deposits from cylinder head, piston top and piston ring grooves.

lip

of

to

the lip before reassembly.

5)Replace keys,

6)Torque bolts and nuts to specification referring to the

PROCEDURES

FOR

oil

seals.

pins,

bolts, nuts, etc.,

REASSEMBLY

of

piston, cylinde :r, crankshaft, connectin

Replace oil

seal

if

if

the

lip is damaged.

necessary.

“TORQUE

7)Apply oil to rotating and sliding portions.

8)

Check and adjust clearances

and

end plays where specified

SPECIFICATIONS”.

in

this manual.

g

rod and bearings.

54-1

(1)

CRANKSHAFT

Install crankshaft on crankcase lapping the shaft
with polyvinyl tape to avoid damage to oil seal.

(2)

Install

woodruff

key for the flywheel on critnk-

shaft.

54-2

(1)

PISTON

AND

PISTON

RINGS

Install the oil ring first, then second ring and top
ring.
Spread the ring only far enough to slip over the
piston and into the correct groove.

Use

to distort the ring.

Install the second ring with the punched mark
“R”or

Fig.

“N”

5-29.)

beside the gap on the top side. (See

care not

OPEN

Fig.

ENDS

5-26

OF

/

PISTON

RING

-

32

-

Fig-

5-27

Fig.

5-28

"R"

"N"

Fig.

MARK

(EH12-2,EH17-2)

MARK

(EH25-2)

5-29

5-4-3

(1)

PISTON

AND

CONNECTING,

ROD

When installing the piston on the connecting rod,
place the valve rcess
shown in the illustration to the

of

the piston crown as

"MAG"

side of the
connecting rod.
Apply oil to the small end

of

the connecting rod,
piston and piston pin before installation.
Be sure to use clips on the both
pin

to

secure the pin in position.

end

of the piston

I

"MAG"

Fig.

SIDE

5-30

VALVE

RECESS

-

33

-

(2)

Install the piston and connecting rod assembly
into the cylinder.

Use a piston ring compressor

to

hold

rings.

Place

magneto side

[NOTES]

(1)

Apply

rod bearings
assembly.

(2)

from each other before assembly.

“MAG”

enough oil to piston rings, connecting

Set gaps of the piston rings

side of the connecting rod on the

of

the crankcase.

and

cylinder bore before

90

degrees

the piston

apart

PISTON RING COMPRESSOR

CONNECTING

CRANKCASE (FLYWHEEL

Fig.

5-3

1

ROD

SIDE)

54-4

(1)

CONNECTING

Turn crankshaft
top

of

the piston until large end

ROD

to

bottom dead center, lightly tap

of

the rod meet

crankpin.

(2) Install the connecting rod cap to the connecting

rod

matching alignment marks.

Torque

M6

M7

M8 X 46

connecting

X

34

mm

X

37

mm

mm

rod

bolts

flange bolt 2pcs.
flange bolt
flange

-0..

bolt

to specification.

(EH12-2)

2pcs.
2pcs.

(EH17-2)

(EH25-2)

./=<

Fig.

ALIGNMENT MARK

0

5-32

SECOND

RING

RING

CONNECTING

I

(3)

Check

EH

1

2-2

for

ROD

BOLT TIGHTENING TORQUE

EH

17-1

9.5

free movement

by turning crankshaft slowly.

17-2

Nom

EH25-2

22-27

of

connecting rod

N*m

1

-

34

-

Fig.

5-33

5-4-5

Install balancer shaft aligning the timing mark

BALANCER

SHAFT

(Option

for

EH25)

on

the
balancer shaft gear and the balancer gear on the
crank shaft as shown in the illustration.

TIMING

MARKS

Incorrect timing
matfunction
damage due to interference

5-4-6

(1)

TAPPET AND CAMSHAFT

Oil the tappets and install them in their original

of

of

the engine and may result in

position.
Push in fully to avoid damage during the installation

(2)

Lubricate the bearing surfaces of camshaft.
Align the timing mark on the crankshaft gear with the timing mark on the camshaft
camshaft in the crankcase

I

Incorrect valve timing will cause engine's

malfunction.

m'

5-4-7

(1)

ADJUST CRANKSHAFT AND CAMSHAFT END PLAY

Adjust end play to the specified values using the proper spacer.

The

proper spacer may be determined following manner.

the gears

will

cause

of

the parts.

as

shown in the illustration.

I

of

the camshaft.

Fig.

5-34

and

install the

B1

t

I

11

I

GASKET

7

t

I

CRANKSHAFT

Fig.

-

7

I

5-35

35

MAIN BEARING

\"I

II

-

COVER

A2

t

+

0.3

82

5-4-7-1

(1)

(2)

CRANKSHAFT

Measure the depth “Al” (From the mating surface to the inner race of the ball bearing.)
Measure the height “Bl”
(Al+

0.3)

-

Bl=SIDE CLEARANCE
(SIDE CLEARANCE) - 0.2=THICKNESS OF CRANKSHAFT
(A+
SIDE

0.012”)

CLEARANCE - 0.008”=THICKNESS

-

Bl=SIDE CLEARANCE

END

PLAY

(From

(For

D

type

and B type)

the mating surface to the crank gear.)

(mm)

SHIM

(in)

OF

CRANKSHAFT

SHIM

(mm)

(in)

5-4-7-2

(1)

(2)

CAMSHAFT

Measure the depth
Measure the height
(A2+

0.3)

-

B2=SIDE CLEARANCE (mm)
(SIDE CLEARANCE)
(A2+ 0.012”) - B2=SIDE CLEARANCE (in)

SIDE

Following are availalbe spacer shims.

EH12-2, EH17-2 type

EH25-2

CLEARANCE - 0.008”=THICKNESS

SPACER

SHIMS

type

r-“-

SPACER

SHIMS

END

PLAY

“AT’

(From the mating surface to the inner race of the camshaft bearing.)

“B2”

-

CRANKSHAFf(For D type)

(Model

(From

0.2=THICKNESS

the mating surface to the camgear inner

CRANKSHAFT

T=0.6
T=0.8

T=l

T=0.6
T=0.8 mm

T=l

.O

.O

rnm

mm

mm

mm

mm

I

B=2:1

OF

(0.024”)

(0.031

”)

(0.039”)

(0.024”)

(0.031

”)

(0.039’3

Reduction

CAMSHAFT

OF

CAMSHAFT

1

CRANKSHAFT(For

T=2.7

T=2.9

T=3.1

type

only)

boss.)

SHIM

CAMSHAFT

T=0.6 mm (0.024”)
T=0.8

T=l

.O

mm

mm

rnm

(mm)

SHIM (in)

mm

(0.031

mrn

(0.039’3

B

type)

(0.1

06”)

(0.1

147

(0.1227

”)

-

I

T=0.6
T=0.8 mm

T=l

CAMSHAFT

mm

(0.024”)

(0.031’)

.O

rnrn

(0.039”)

I

-

36

-

MAIN

Fig.

5-36

(2)

Lubricate the

oil

seal

and

bearing surfaces.

Add

a

light film

of

oil

on

the

main

bearing cover face
hold the gasket in place.
Place spacers chosen at procedure

(1)

on crankshaft and camshaft.
Use an oil seal guide when installing the main bearing cover to avoid damaging the seal.
Tap the cover into place with a soft hammer.

Main bearing cover EH12-2, 17-2

EH25-2

Tightening torque

80-1

M6

X

M8

X

(EH12-2,17-2)

00

kgwn

30

mm bolt and washer

30

mm bolt and washer

Tightening torque

-

37

-

....

8

.-e-

8

17-1

8.5

170-1

90

12.5-13.5

pcs.

pcs.

(EH25-2)

Nom

kgocrn

ftelb

to

5-4-8

(1)

CYLINDER HEAD

Clean carbon and gum deposits from the valves, seats, ports and guides. Inspect the valves, valve
seats and valve guides.

(2) Replace valves that are badly burned, pitted or warped.

(3)

When installing the valves in the cylinder head, oil the valve stems and insert them into the valve
guide.

Then place the cylinder head

a flat

table,

install the valve springs, spring retainers

on

valves.

(4)

Valve guides should be replaced when the valve stem clearance exceeds specifications (See
"SERVICE

DATA").

Draw the valve guides out and press the new guides in.
Refer to"SERV1CE
After replacing the valves and guides, lap valves

DATA"for

clearance specifications.

in

place until a uniform ring shows around the face

of the valve. Clean valves and wash cylinder head thoroughly.

(5)

Install cylinder head to cylinder with new head gasket.
Tighten four flange bolts evenly in three steps by the following tightening torque:
Cylinder head

M8

M10

X

65

mm flange bolt

X

75

mm

flange bolt

-

-

-

4

4

PCS.

(EH12-2, 17-2)

pcs.

(EH25-2)

and

collet

Tightening torque

1

st

step final step

5

Nom

50

kgwn

3.6

ft-lb

54-9

(1)

ROCKER

ARMS

Insert push rods into crankcase.

2nd step

100

AND

Put push rod tip in the hollow

(2)

Apply oil to the rocker arms and assemble them to the cylinder head using pivot bolt and guide plate.

5-4-10

(1)

VALVE

CLEARANCE ADJUSTMENT

Position the piston at the top dead center of the compression stroke. The top dead center may be
obtained by placing the key slot

I

12

o'clock

10

7.2

(EH12-2,

Nom

kgcm

ft-lb

PUSH

of

17-2)

23-26

230-270

17-30

RODS

tappet top.

on

the power take

I

Nm

kgcm

ft-lb

10 o'clock

off

1

100

shaft

st

step

9.8

7.2

to

Tightening torque

2nd step

Nom

kgecrn

ft-lb

:

19.6

200

14.5

(EH25-2)

Nom

kgcm

ft4b

final

33.3-41.2
340-420

24.6-30.4

step

Nom

kg-cm

ft*lb

n

I

EH12-2B,17-2B,25-2D

I

EH12-2D,17-2D,25-2B

-

38

-

(2)

Loosen the nut under the rocker arm and turn the bolt
rocker arm and the valve stem end.
Tighten the nut under the rocker arm.

I

Valve clearance

0.08-0.1

2

mm

I

(pivot)

to adjust the clearance between the

0.0031

I

Check operation
Recheck valve clearance.

(3)

Install rocker cover and gasket.
Rocker cover

5-4-1

1

SPARK PLUG

Install spark plug

Spark

plug

EHl2-2

EH17-2,25-2

New

11.8-1

:

spark

4.7

-0.0047

plug

N*m

in.

of

valves

M6

X

12

to

the cylinder head.

:

NGK

:

NGK

Tightening

B6ES

B6HS

I

by

turning crankshaft.

mm bolt

torque

.-..

4

Retightening

~____

2216-26.5

pcs.

Nom

Fig.

5-38

120-150

8.7-1

5-4-12

(1)

Be careful not
coil and crankcase.

(2)

(3)

FLYWHEEL MAGNETO

Install the charge coil to the crankcase. (Option)

Put the woodruff key in the key way of crank­shaft.
Wipe off oil and degrease thoroughly from the
tapered portion
center hole.
Install the flywheel to crankshaft.
Tighten the flywheel nut with the starter pulley.

0.9

kg-cm

fblb

to

pinch coil wire between charge

of

[

the crankshaft and the flywheel

230-270

16.6-1

9.5

kg-crn

fblb

Fig.

5-39

-

39

-

1

Tightening

torque

I

I

54-13

Install the ignition coil
Adjust the air
flywheel using a thickness gauge (filler gauge) and
tighten the bolts.

8.8-10.8

5-4-14

(1)

59-63

IGNITION

INTAKE PIPE,

Install the intake pipe to the cylinder head with gasket.
EH12-2,

EH25-2 M8 X 28mm bolt and washer

N-m

COIL

gap

between the ignition

Tightening torque

Nom

I

90-1

17-2

M6 flange nut
M6

I

to

the crankcase.

10

kgecrn

lNSULATOR

600-650

6.5-8.0

..---.....-.......-.

X

25mm flange bolt

kgocm

coil

ft4b

.-.......

and the

A

I

2 pcs.

1

PC.

3

pcs.

43-47

ft*lb

Fig.

I

5-40

Tightening torque

9.8-1

3.7

Nm

Then put the gasket and the insulator on the intake pipe.

54-15

Install the gasket and the carburetor to the intake pipe.

54-16

(1)

(2)

CARBURETOR

GOVERNOR

Connect the governor lever and the throttle lever
on carburetor with governor rod and rod spring.
Install the governor lever

Install the speed control lever to the cylinder
head.

SYSTEM

100-1

40

kgocm

on

the governor shaft.

7.2-10.1

GOVERNOR

ft4b

LEVER

Fig.

5-4

1

-

40

-

’

(3)

Connect the speed control lever and the governor lever with the governor spring. The governor spring

2

should be hooked to the number

Refer to the illustrations below. (See Fig.

(4)

Turn the speed control lever all the way toward the high speed position and make sure that the throttle

valve

(5)

Turn the governor shaft clockwise all the way using a screw driver, and tighten the lock bolt and nut.

(See

For the generator applications, there are two different governor springs existing according to the speed

setting of the engine. The governor springs may be distinguished

The

cations.

r

I

in

the carburetor is at the wide open position.

Fig.

5-43.)

governor spring employed on the

SPEED

CONTROL

LEVER

hole on the speed control lever for the regular specifications.

5-42.)

by

the following table.

6OHz

application is same as the one from the standard specifi-

\\

e

D

‘l)t--”

GOVERNOR

GOVERNOR

50

Hz

(3000

rprn)

49

(1.9’7

(0.35”)

EH

SPRING

LEVER

1

2-2

(3600

8.1

60

Hz

rpm)

t

(0.32”) 9.1

N

;

50

(3000

38

(1.5‘7

10.7

(0.42”)

SPRING

EHl7-2

HZ

rprn)

WOUND

60

(3600

9.6

Hz

rpm)

t

(0.38”)

Fig.

50

(3000

43

8.7

5-43

EH25-2

HZ

rpm)

(1

-73

(0.34”)

60

Hz

(3600

t

t

rpm)

I

Color

~

Gold Silver Gold

-

41

-

Silver

~~~

Gold

Silver

54-17

AIR CLEANER

Install the air cleaner gasket and the cleaner case and tighten them with 2-M6 flange nuts.
Then install the element and the cleaner cover.

5-4-1 8 HEAD COVER

Install the head cover

M6

X

12mm flange

to

the cylinder head.

bolt

..a-

1

PC.

54-19

MUFFLER, MUFFLER COVER

and

EXHAUST

PIPE

COVER

Install the muffler to the cylinder head.

M8

flange

nut

....

230-270

16.6-1

9.5

2

pcs.

kgcm

ft-lb

Then tighten the muffler bracket portion.

M6 X 12mm flange bolt

M8

X

16mm flange bolt

--.a

1

PC.

(EH12-2, 17-2)

1

PC.

(EH25-2)

Install the muffler cover and exhaust pipe cover.

M6

X

10mm flange bolt

54-20 BLOWER

HOUSING,

e-..

RECOIL

5

pcs.

Install the blower housing and the recoil. Insert the high tension cord from the ignition coil into the notc
of

the

blower

housing

so

that

not

to

pintch the

cord.

:h

54-21 FUEL TANK

Install the fuel tank. Connect the fuel strainer and the fuel inlet

M6

X

14mm bolt and washer

M8

X

20mm bolt and washer

-

End of the reassembly

-.--

4

pcs. (EH12-2,17-2)

4

pcs.

(EH25-2)

-

-

42

-

on

carburetor with the fuel hose.

c

5-5

BREAK-IN

OPERATION

An

engine that has been completely overhauled by being fitted with a new piston, rings, valves and

connecting rod should be throughly

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.

Steps

10

min

3600

rpm

No

load

Step

3

10

min

3000 rpm

No

load

Step

2

10

min

2500 rpm

No

load

Step

1

Time

Engine

speed

Load

1

Step

4

EH12-2
EH17-2
EH25-2

1

1.5

KW

b.OHPI

1

3600 rpm

1.OKW

1.4HP

2.4KW 3.2HP

30 min

Step

5

EH12-2
EH25-2

EH17-2

1

$:A

f::

1

3600 rpm

60 min

4.7KW

6.4HP

6.

IGNITION

SYSTEM

6-1

TYPE

OF

IGNITION SYSTEM

EH12-2

employs the

U.

T.

C.

I.

(Universal type Transistor Controlled Ignition) pointless ignition system.

EH17-2

and

EH25-2

have the

T.

I.

C. (Transistor, Igniter, Circuit) pointless ignition system.

AS

optional parts, these ignition system may be implemented with lamp.coi1, charge coil and excitor coil.

6-2

BASIC

THEORY

To

ensure the easy startability

of

the engine, the step advancing ignition timing system is incorporated in

the ignition coil. This system enables the engine

to

have basically two different ignition timings

according to the engine speed. Following are the explanation how the system works.

1)

At lower speed

of

the engine

Rotation

of

the flywheel induces current

I,,

as this current flows through the base terminal

of

the

power transister,

it

is activated

and

the current

IZ

starts flowing.

As

the engine reaches the ignition timing, the ignition timing control circuit for the lower engine speed

is activated and lets the current

L

flow through the base terminal of the power transistor.

This generates the collector current

L

which will bypass the current

11

and abruptly shut

off

the current

IZ

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.

-

43

-

2)

At the higher engine speed
Rotation
power transistor,

As

speed

collector current
power transistor is turned
This sudden current change generates a big voltage
which

of

the flywheel generates the current

it

is activated and the current

I1

as this current

IZ

starts

of

flow.

flows

the engine reaches the ignition timing, the ignition timing control circuit

is

activated and provides the base current

It,

and will bypass the current

Is

to

the power transistor. This current induces the

I,

to shut down the current

off.

on

the secondary side

will

spark the spark plug.

through the base terminal

for

the higher engine

IZ

abruptly because the

of

the ignition coil and

The ignition timing control circuit for the higher engine speed is activated sooner than the controI
circuit for the lower speed and not activated when the engine speed

is

in a lower range.

of

7

the

cn

3

h

(B.T.D.C.)

15”k

-

44

ELECTRONIC ADVANCING

MAGNETO

I

500

,

1000

ENGINE

-

SYSTEM

REVOLUTION

Fig.

6-2

FLYWHEEL

,

2000

(b)

3000(r.p.m.)

6-3

WIRING

DIAGRAM

STANDARD

Stop

switch

Connector

Black

Black

>

Spark

Plug

Ignition

Coil

Flywheel

ElNGlNE WITH ELECTRIC STARTER

DIODE

RECTIFIER

I

""""_""""

I

L

12VOLT

BATTERY

MtNIMUM

24

AMP.HR.

Fig.

6-3

-

45

-

7.

AUTOMATIC

DECOMPRESSION

SYSTEM

EH12-2, 17-2, 25-2 engines are employing the automatic decompression system
This enables easy and light start of the engine.
The automatic decompression system releases the compression
valve at the cranking. Following are the explanation using

of

works. The components
principle

At the end
exhaust valve slightly
end
When the engine is cranked, the crescent cam projects the camshaft cam profile and lifts up the tappet
because the gravity force on the weight is larger than the centrifugal force

of

the lever

of

the function

of

the compression process, the release lever lifts

is

a

crescent

CRESCENT

the systems are different for the type

is

same.

to

release the compression. The release lever has a flyweight

cam.

i

TAPPET,

I

type

of

the engine by lifting up the exhaust

“D”

engine

“D”

and type

up

the tappet which in turns opens up the

as

a standard feature.

as

a sample how the system

“B”

engines, however, the

on

its end and another

on

the weight.

LEVER

EXHAUST

Fig.

7-1

When the crank speed reaches up to a certain revolution, the crescent cam

cam profile because the centrifugal force applied onto the flyweight becomes larger than the gravity force
and the weight.and

CRESCENT

EXHAUST

is

shifted

CAM

CAM

to

the position shown in the illustration.

FLYWEIGHT

EXHAUST

-Y-T3

CAM

is

retracted into the camshaft

LEVER

,”-

Fig.

-

46

CAMSHAFT

7-2

-

8.

CARBURETOR

B

8-1

OPERATION

8-1

-1

FLOAT

AND

SYSTEM

CONSTRUCTION

The float chamber is located below the carburetor body
and, with a float and a needle valve, maintains a
constant fuel level during the engine operation.

The fuel flows from the fuel tank into the float chamber
through the needle valve. When the fuel rises to
specific level, the float rises, and when

its

buoyancy

a

and fuel pressure are balanced, the needle valve shuts
off the fuel, thereby keeping the fuel at the predeter­mined level.

PILOT

OUTLET

\

BY-PASS,"""

,

[""

I

I

PILOT

I 1 MAIN

\

k"""

'""""i=r""J'

"-""

AIR

AIR

+=""~Z

JET

JET

Fig.

8-2

FI

II

Fig.

-\

8-1

MAIN

AT

JET

-

47

-

8-1-2 PILOT SYSTEM

The pilot system feeds the fuel to the engine during idling and low-speed operation.
The .fuel

is

fed through the main jet

to

the pilot jet, where it

is

metered, and mixed with the air metered
by the pilot air jet.
The fuel-air mixture is fed to the engine through the pilot outlet and the by-pass.

At

the idling speed, the fuel

is

mainly fed from the pilot outlet.

/"l

8-1-3

MAIN

SYSTEM

The main system feeds the fuel to the engine at medium-and high-speed operation.
The fuel

is

metered by the main jet and fed to the main nozzle. The air metered by the main air jet is
mixed with the fuel through the bleed holes in the main nozzle, and the mixture is atomized out of the
main bore. It

which

8-14

is

CHOKE

The choke may be used for easy start when engine

is

mixed again with the air taken through the air cleaner into an optimum fuel-air mixture,

supplied to the engine.

is

cold. When the engine is cranked with a closed
choke, the negative pressure applied to the main nozzle increases and draws more fuel accordingly this
starting up the engine more easily.

8-2

DISASSEMBLY AND REASSEMBLY

Apart from mechanical failures, most
which may arise mainly due to

of

assure proper flow

air and fuel, the carburetor must be kept clean at a11 times. The carburetor

a

clogged up air or fuel passage in jets,

of

carburetor troubles are caused by an incorrect mixing ratio,

or

fuel level variations.

In

order to

disassembly and reassembly procedures are as follows.

8-2-1 THROITLE SYSTEM

(1)

Remove the philips screw
and pull

(2)

The spring
throttle stop screw

*

Be

careful not

out

the throttle shaft

(4)

can be taken out by removing the

(5).

to

damage the throttle valve rim.

(1)

and throttle valve

(3).

(2),

123

It

u

7%

\

8-2-2

(1)

(2)

CHOKE

Remove the philips screw

and pull out the choke shaft

SYSTEM

(6)

and choke valve

(8).

When reassembling the choke shaft, make sure that

the cutout in the choke valve faces the main air jet.
Meanwhile, when reassembling set the rings

(10)

at the right position.

8-2-3

(1)

(2)

PI

LOT SYSTEM

Remove

the

pilot jet
avoid damage to
Reassembly

it.

(ll),

using proper tools to

(9)

Tighten the pilot jet securely. Otherwise, the fuel
may leak, causing engine malfunction.

-

(7),

and

48

21

-@

13*
18

12

"----&

-

0

Fig.

8-3

B

8-2-4

(1)

(2) From the body

(3)

MAIN

Remove the bolt(l2)and take out float chamber body(l3).

(17) from the main nozzle
Reassembly

a)Fasten the main jet securely to the body. Otherwise, the fuel may become too rich and cause engine

malfunction.

b)The bolt tightening torque is 70kg-cm. Be sure to set the gasket

(13).

SYSTEM

(14)

remove the main nozzle

(15).

(15),

and then remove the main jet

(19)

and washer

(16)

and guide holder

(18)

for chamber

8-2-5

(1)

When cleaning the jets, be sure
Never use a drill or a wire because of possible damage of the orifice which will considerably affect
fuel

(2) When removing the needle valve and float, gently tap the reverse side using the rod more slender

FLOAT

Pull out the float pin (20) and remove the float
(23).

If the needle valve needs to be replaced, replace it with rubber needle.

flow.

than the

SYSTEM

float

pin

to

use

compressed air to blow them clean.

and

remove, since the float pin

(21)

and then remove the clip

is

calked

to

the carburetor body.

(22)

and needle valve

-

49

-

9.

STARTING

9-1

RECOIL

Equipments to be prepared : Driver, Pinchers (Pliers) and Protective Glasses

WARNING

STARTER

SYSTEM

starting the disassembly;

9-1-1

(1)

Disassembly

Setting off the spring power

-1

:

Hold

rope.

-2

:

-3

:Push

wound back.

-4:

-5

:

the starter knob and extract the starter

Extract the rope fully and hold the rope
that the knob
dicrect line with the rope guide.

and hold the reel with the thumbs of

both hands firmly

Pull off the knot of the rope out
unfasten the knot and pull it off to the direc-

tion

of

the starter knob.

By

controling the reel with the thumbs
hands, unwind the rope gently until the rota­tion

of

the

(Fig.

reel

Steps

of

stoos.

the rope in the reel makes a

so

9-1)

make

sure to wear

that

the

rope will not be

(2

persons required)

of

the reel,

of

the

so

both

protective glasses.

I

1

I

Fig.

9-1

r

The spring power is at its most when the rope is fully extracted. Therefore, do not abruptly put

hand nor loosen the pressure of your finger unintentionally.

off

/

your

(2)

Setting

-

1 : Fix

-

2

(3)

Setting the reel off (Fig.

-

1

-

2

-

-

WARNING

Do

not drop or shake the reel and put

because there

Disassembly is complete.

the

attachments

the case and loosen the set-screw.

:

Put off the set-screw, the latchet guide, the

friction

order from above.

:Push

up. Move the reel clockwise and counter-

clockwise about a quarter circle for several
times until it moves smoothly.

:

Pull up the reel gradually and slowly and put
it off from the case.

3

:

In

up,

spring and the latchet in the same

the reel lightly

case the spring

redo the steps

is

a spring set in the disassembled reel.

off

in

of

9-2)

(3)-1

(Fig.

9-2)

so

that it

the reel is close

and

will

(3)-2

it

on

a level table

not float

to

pop

again.

-

50

e-

Fig.

9-2

SET

RATCHET

FRICTION

RATCHET

'

SCREW

GUIDE

SPRING

REEL

WARNING

Before starting the assembly, make sure to wear the protective glasses.

9-1-2

(1)

Assembly

Steps

Setting the reel into the case.

-1

:Paste grease on the case. (Fig.

-2

:

Adjust the position

of

spring, which is set in the reel. (Fig.

-3

:Hold

the inner end

the reel

so

that the shafthook part and

of

the spring are hooked to-

gether. Drop the reel gently from above into

the case.

-4

:

Move the reel slightly counter-clockwise and
make sure the spring

(2)

Setting

-1

the

attachments

:

Set the latchet into the reel. (Fig.

9-3)

the inner end

is

hooked.

of

9-5)

the

9-4)

THE

RIB

THE

OF

THE BEARING

Fig.

9-4

END

GREASE PASTING

Fig.

TOUCHES

9-3

-2

:

Holding the latchet, set the
sub-assembly. (Fig.

9-6)

latchet-guide

-

51

-

THE LATCHET

I

cb-'

LATCHET

IS

KEPT AT CLOSE-POSITION

Fig.

9-5

SET

SCREW

RATCH ET
GUIDE

/

FRICTION
SPRING

GUIDE

SUB-ASSEMBLY

Fig.

9-6

(3)

Tightening

-1

i

Push the latchet-guide lightly by hand

the set-screw.

the latchet guide won’t move and tighten the
set-screw.

(4)

Storing the spring-power.

-1

:Hold the case tight and using both hands,

wind

up

the reel counter-clockwise 6 times.

-2:

Set

the ree to keep the position, whereby the

rope hole

a

direct line. (Fig.

WARNING

of

the reel and the rope guide make

9-7)

so

that

Fig.

9-7

The spring power

hand

nor

loosen

(5)

Setting the rope.

-1

:

Set the end

20

cm out

-2

:

Fasten the end

-3

:

Put the rope into the reel, whereby make sure

that the rope will not float up.

-4:

Hold the rope firmly with one hand at the
position about
keep the rope slightly pulled
will not be wound

-5

:Put the hand

rope back slowly obeying the winding power

of

the spring until the knob reaches the rope

guide.

is

at

its most when the

the

pressure

(2

persons required)

of

the rope through the

of

the reel. (Fig.

of

50

of

the rope.

cm

from the rope guide

in.

off

the reel gently and put the

reel

is

being wound. Therefore,

your finger unintentionally.

rope

guide and the rope hole

9-7)

(Fig.

9-9)

and

so

that the rope

do

not abruptly put

of

the reel and pull the end about

F;g.

9-8

ABOUT

20mm

off

your

Assembly is complete.

Fig.

9-9

-

52

-

(6)

Test the operation of
and retract properly. Mount the recoil starter to the engine.

(7)

If the spring escapes from the reel when disassembling the recoil, hook the outer end of the spring
onto the notch

(8)

Lubricate the rotating parts, sliding parts

reassembling the recoil and prior

of

the

recoil starter to see

the reel and rewind the spring into the housing.

to

long term storage.

if

the rope recoils satisfactorily and the ratchets project

and

spring with heat resistant grease or mobile oil when

-

53

-

IO.

TROUBLESHOOTING

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

1.

The cylinder filled with a proper fuel-air mixture.

2.

Good compression in the cylinder.

3.

Good spark, properly timed, to ignite the mixture.
The engine cannot be started unless these three conditions are met. There are also other factors which
make engine start difficult, e..

high back pressure due to

The most common causes of engine troubles are given below

g.,

a heavy load on the engine when it is about

a

long exhaust pipe.

to

start at low speed, and a

:

10-1

10-1-1

(1)

(2)

(3)

(4)

STARTING

FUEL

No

gasoline in the fuel tank ; or the fuel cock closed.

The carburetor

Water, dust

DIFFICULTIES

SYSTEM

is

not choked sufficiently especially when the engine

or

gum in the gasoline iterfering the fuel flow to the carburetor.

is

cold.

Inferior grade gasoline or poor quality gasoline not vaporized enough to produce the correct fuel-air

mixture.

(5)

The carburetor needle valve is held open by dirt or gum. This trouble can be detected as the fuel

flows out of the carburetor when the engine is idling. (Overflow)

This trouble may be remedied by lightly tapping the float chamber with the grip of a screwdriver or

the like.

(6)

If the carburetor overflows, excessive fuel runs into the cylinder when starting the engine, making the

fuel-air mixture too rich

few turns in order

to

to

burn. If this happens, remove the spark plug, and turn the starting pulley a

let the rich fuel-air mixture

out

of the spark

plug

hole into the atmosphere. Keep

the choke valve open during this operation. Dry the spark plug well, screw it into place, and try

start again.

10-1

-2

COMPRESSION SYSTEM

If starting difficultes and loss
must be checked for possible lack

Engine inside is completely dried up because of a long period

of

power are not due to the fuel system or ignition system, the followings

of

compression.

of

storage.
Loose or broken spark plug. This causes a hissing noise made by mixture gas running out of cylinder
in compression stroke during cranking.
Damaged head gasket or loose cylinder head.

A

similar hissing noise is produced during compression
stroke.
Incorrect Valve clearance

is

If the correct compression
check further as follows

not obtained even after remedying the above, disassemble the engine and

:

a) Valve stuck open due to carbon or gum on the valve stem.

b)If the piston rings are stuck on the piston, remove the piston and connecting rod from the engine.

Clean or replace the parts.

/"-

to

-

54

-

10-1-3

IGNITION SYSTEM

Check the followings for lack

of

sparks.

(1)

Wires

of

the ignition coil, spark plug

or

contact breaker disconnected.

(2)

Ignition coil damaged and shorted.

(3)

Spark plug cable wet or soaked with oil.

(4)

Spark plug dirty or wet.

(5)

Spark plug electrode gap incorrect.

(6)

Spark plug electrodes are connected or bridged.

(7)

Incorrect spark timing.

10-2

ENGINGE MISFIRES

Incorrect spark plug electrodge gap. Adjust it to anywhere between

0.6

and

0.7mm.
Ignition cable worn and leaking.
Sparks weak.

j.lj

Ignition wire connections loose.

(5)

Water in gasoline.

(6)

Insufficient compression.

10-3

ENGINE

STOPS

(1)

Fuel tank empty. Water, dirt, gum, etc. in gasoline.

(2)

Vapor lock,

i.

e., gasoline evaporating in the fuel lines due to overheat around the engine.

(3)

Vapor lock

in

the fuel lines

or

carburetor due to the use of too volatile winter gas in the hot season.

(4)

Air

vent hole

in

the fuel tank cap plugged.

(5)

Bearing parts seized due to lack

of

oil.

(6)

Magneto or ignition coil faulty.

,

104

ENGINE OVERHEATS

(1)

Crankcase oil level low. Add oil immediately.

(2)

Spark timing incorrect.

(3)

Low grade gasoline is used, or engine is overloaded.

(4)

Cooling air circulation restricted.

’

(5)

Cooling air path misdirected causes loss

of

cooling efficiency.

(6)

Cylinder head cooling fins clogged up with dirt.

(7)

Engine operated in an enclosed space without sufficient cooling air

(8) Exhaust gas discharge restricted,-or carbon deposits in the combustion chamber.

(9)

Engine running on low-octane gaoline detonates due

to

heavy load at low speed.

-

55

-

10-5

(1)
(2)

(3) Carbon

(4)

(5)

(6)

(7)

ENGINE

KNOCKS

Poor quality gasoline.

Engine operating under heavy load

or

lead deposits in the cylinder head.

Spark timing incorrect.

Loose

Loose piston pin due
Cuases

connecting rod bearing due

to

wear.

of

engine

overheat.

at

to

low

wear.

speed.

10-6

(1)
(2)

(3)

(4)

ENGINE

Water or dirt
Intake valve stuck.
Valves overheated,
Engine cold.

BACKFIRES

in

gasoline,

or

hot

THROUGH CARBURETOR

or

low-grade gasoline.

carbon particles in the combustion chamber

-

56

-

11.

INSTALLATION

Engine life, ease

of

maintenance and inspection, frequency of checks and repairs, and operating

cost

all

depend on the way in which the engine

is

installed. Review the following instructions carefully for

installing the engine.

11-1 INSTALLING

When mounting the engine, carefully examine

its

position, the method

of

connecting

it

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

oil

can easily be discharged.

11

-2

VENTILATION

Fresh air

is

necessary for cooling the engine and burning the fuel.

In the case the engine

is

operated under a hood or in a small room, temperature rise in the engine room

can cause vapor lock, oil deterioration, increased

oil

consumption, loss of power, piston seizure, shorter
engine life, etc., making it impossible to operate the engine properly. It is necessary, therefore, to provide
a duct or baffle

to

guide cooling air to the engine to prevent recirculation

of

he hot air used for engine
cooling, and temperature rise of the machine.
Keep the engine room temperature below

50°C

even in the hottest period

of

the year.

11-3 EXHAUST GAS DISCHARGE

Exhaust gas

is

noxious. When operating the engine indoors, be sure to discharge the exhaust gas

outdoors.

If

a long exhaust pipe is used in such a case, the internal resistance increases causing

loss

of

engine power. Thus pipe inside diameter must be increased in proportion to exhaust pipe length.

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

Less than 5m

long,

pipe inside diameter 33mm.

11-4 POWER TRANSMISSION

TO

DRIVEN MACHINES

11 -4-1 BELT

DRIVE

Take the following notes into consideration.

*

V-belts are preferable to flat belts.

*

The driving shaft of the engine must be parallel to the driven shaft

of

the machine.

*

The driving pulley

of

the engine must be in line with the driven pulley of the machine.

*

Install the engine pulley as close to the engine as possible.

*

If

possible, span the belt horizontally.

*

Disengage the load when starting the engine.

If no clutch is used, use a belt tension pulley or the like.

11-4-2 FLEXIBLE COUPLING

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

-

57

-

12.

SERVICE

DATA

“STD”
Whereas, “Limit”

If

12-

r

1

in

the

following

shows

the measurement exceeds

1

CLEARANCE DATA AND LIMITS

Flatness

Valve seat contact

width

table

is

the parts dimension from the brand new engine or the spare parts.

the maximum allowance for the parts to

beyond

the “Limit”, the part needs to be replaced and/or repaired.

r

IN.

EX.

be

used

STD

LESS

0.05

(0.002)

0.7

(0.028

on

the engine.

EH

12-2 / 17-2 / 25-2

THAN

-

1

.O

-

0.039)

Unit

Limit

0.1

(0.004)

2.0

(0.079)

:

mrn

(in)

I

Valve

guide inside dia.

EH 1 2-2
EH17-2

EH25-2

5.500

-

5.51

(0.21

65

-

0.21

6.035 - 6.053

(0.2376

-

0.2383)

8

72)

5.65

(0.2224)

6.1

5

(0.2421)

-

58

-

Unit:

mm

(in)

EH

1

2-2

EH

1 7-2

I

ITEM

Lmit

STD

STD

Lm

it

To

be rebored
when the
lifference
letween

ma.

snd min.

of

jiameter

.cached

to 0.1

:0.004).

-0

be rebored
vhen the
lifference
letween

ma.

nd rnin.

of

jiameter

eached to 0.1

0.004).

CYLINDER

Inside dia.

57.000

-

67.01

9

2.6378 - 2.6385)

60.000

-

60.01

9

(2.3622 - 2.3630)

STD

60.250

-

60.269

(2.3720

-

2.3728)

67.250

-

67.269

2.6476

-

2.6484)

1

st

reboring

2nd

reboring

Ditto

Ditto

60.500

-

60.51 9

(2.381

9

-

2.3826)

67.500

-

67.51

9

2.6575 - 2.6582)

0

Roundiness after reboring.

0

Cylindricity after reboring.

LESS

THAN

0.01

(0.004)

LESS

THAN

0.01

(0.004)

LESS

THAN

0.01

5

(0.0006)

LESS

THAN

0.01

5

(0.0006)

PISTON

0

Piston size

(At

skirt in thrust

direction)

59.96

-

59.98

(2.3606

-

2.3614:

59.87

(2.3571)

66.98

-

67.00

12.6370

-

2.6378)

66.89

(2.6335)

'STD

60.1

2

(2.3669)

67.23

-,

67.25

:2.6469

-

2.6476:

67.1

4

(2.6433)

60.21

-

60.23

(2.3705

-

2.371 3

1

st

01s

60.37

(2.3768)

67.48

-

67.50

(2.6567

-

2.6575:

67.39

(2.6531)

60.46

-

60.48

(2.3803

-

2.381

1

2nd

01s

I

-

59

-

Unit:

mm

(in)

2Y

LIN

DER

inside dia.

B

Roundiness

after

ITEM

reboring.

STD

1

st

reboring

2nd

reboring

r

75.000

2.9528

75.250

2.9626

75.500

2.9724

LESS

STD

-

75.01

-

2.9535)

-

75.269

-

2.9633)

-

75.51 9

-

2.9732)

THAN

0.01

(0.004)

EH25-2

-0

/hen

ifference

9

letween
md
liameter
eached to

0.004).

Lmit

be rebored

the

ma.

min.

of

0.1

Ditto

Cyiindricity after reboring.

PI

STON

0

Piston size (At
direction)

skirt

in

thrust

STD

1

st

2nd

01s

OJS

LESS

THAN

0.01

5

(0.0006)

74.98 - 75.00

(2.9520

(2.961

(2.9717

75.23

8

75.48

-

2.9528:

-

75.25

-

2.9626

-

75.50

-

2.9724

74.89

(2.9484)

75.1

4

(2.9583)

75.39

(2.9681)

-

60

-

Uni

:

rnm

(in)

ITEM

0

Ring groove side clearance

Piston pin hole

m

0

Piston pin outside dia.

t

2nd

Oil ring

T

STD

0.030 - 0.075

(0.001 2

(0.001 2 - 0.0030)

(0.0008 - 0.0030)

12.991 - 13.002

(0.51 15

-

0.0030)

-

0.030

0.020 - 0.075

0.075

-

0.51

19)

Limit

0.1

5

(0.006)

5

0.1

(0.006)

0.1

5

(0.006)

13.035

(0.51

32)

EH17-2

STD

0.035 - 0.080

:0.0014

(0.0010

(0.0004 - 0.0026)

(0.6296

0.025

0.01 0

15.991

-

0.0031)

-

0.070

-

0.0028)

-

0.065

-

16.002

-

0.6300)

Limit

0.15

(0.006)

0.1

5

(0.006)

0.1

5

(0.006)

16.035

(0.631

3)

Clearance between piston and
cylinder at skirt area.

Piston ring end gap

TOP

2nd

12.992 - 13.000

(0.51

15

-

0.51

18)

0.01

5

-

0.074

(0.0006

-

0.0029)

-

0.4

0.2

(0.008 - 0.01

6)

12.960

(0.51

02)

0.25

(0.01

0)

1.5

(0.0591

15.992 - 16.000

(0.6296

0.015 - 0.074

(0.0006

)

(0.008 - 0.01

0.2

-

0.6299)

-

0.0029)

-

0.4

6)

15.960

(0.6284)

0.25

(0.01

0)

1.5

(0.0091)

oil ring

0.2

-

(0.008

-

-

61

0.4

0.01

-

6)

1.5

(0.0591

)

0.05

-

(0.0002

0.25

-

0.01

0)

1.5

(0.0591)

STD

EH25-2

Unit:

mrn

Limit

(in)

1

Ring groove

Piston pin hole

side

clearance

Oil

2nd

ring

0.050

-

0.090

1.0020 - 0.0035)

~ ~ ~ ~~~~~

0.030 - 0.070

).0012 - 0.0028)

0.010

-

0.065

1.0004

-

0.0026)

0.1 5

(0.006)

0.1

(0.006)

(0.006)

I

17.991

1.7083

-

18.002

-

0.7087)

7

(0.71

~rn

Piston pin outside

dia.

17.992

3.7084

-

18.000

-

0.7087)

17.960

(0.7071

5

0.1

5

8.035

00)

)

Clearance between
cylinder at skirt area.

Piston ring

end

I

gap

piston

and

TOP

2nd

oil

ring

0.025

0.0001

0.1

(0.004

0.1 - 0.3

(0.004

-

0.064

-

0.0025)

-0.3

-

0.01

-

0.01

2)

2)

0.25

(0.01

0)

1.5

(0.0591)

1.5

(0.0591)

-

62

-

Unit:

mm

(in)

ITEM

EH

1

2-2

STD

Limit

ZONNECTING

ROD

D

Big end inside dia.

26.000 - 26.01

3

(1

-0236 - 1.0241)

26.1

(1.0276)

Clearance between big end
and crankpin

0.020 - 0.046

(0.0008

-

0.001

8)

0.2

(0.008)

I

0

Small end inside dia.

13.08

(0.51

50)

13.01

0

-

13.021

(0.51 22

-

0.51 26)

0

Clearance between small end
and

piston

pin

0

Big

end side clearance

0.01

0 - 0.029

(0.0004

-

0.001

1)

0.1

2

(0.0047)

0.1

-

0.7

(0.004

-

0.028)

1

.o

(0.040)

I

CRANKSHAR

0

Crankpin outside dia.

25.967 - 25.980

(1.0223

-

1.0228)

25.85

(1.01

77)

0

Journal dia.

Dl,

D2

24.988

-

24.997

(0.9839

-

0.9841)

1

-

63

-

m-

CONNECTING

0

Big

end

inside dia.

ROD

ITEM

-

EH

STD

30.000 - 30.01

(1.1811 -1.1817)

6

1

7-2

Unit:

Limit

30.1

(1.1850)

mm

(in)

Clearance between

Clearance between
and crankpin

and crankpin

Small end inside dia.

Small end inside dia.

0

Clearance between
and piston pin

Big

end side clearance

big

big

small

end

end

end

0,020

(0.0008

16.01

0

(0.6303

0.01

0

(0.0004

0.1

(0.004

-

0.049

-

0.001

9)

-

16.021

-

0.6308)

-

0.029

-

0.001 1)

-

0.7

-

0.028)

0.2

(0.008)

16.08

(06331

)

0.1 2

(0.0047)

1

.o

(0.040)

CRANKSHAFT

0

Journal

dia.

I

29.967 - 29.980

(1.1798

24.988

(0.9838

-

64

-

-

Dl,

D2

-

-

1.1803)

24.997

0.9841)

29.85

(1.1752)

lTEM

F

EH25-2

~

STD

0

Clearance between

big

end

and crankpin

0

Small end inside dia.

t

I

0

Clearance between small end
and piston pin

0

Big end side clearance

I

CRANKSHAFT

0

Journal dia.

-

I

34.000 - 34.01

6

(1.3386 - 1.3392)

0.025

-

0.057

(0.0010

-

0.0022)

18.01

0

-

18.021

(0.7091

-

0.7095)

0.01

0

-

0.029

(0.0004

-

0.001

1)

0.1 - 0.7

(0.004

-

0.028)

33.959

-

33.975

(1.3370

-

1.3376)

Dl

D2

1

TYPE

Z9.991 -30.000/29.988-29.99;
:1.1807

/

(1.1

806

-1.1

81 1) ;-1.1810)

3

TYPE

:1.1807

27.991 -30.0001

(1

o,

-1.1811)

'27.988-27.99
:-1.1022)

..

Limit

34.1

0

(1

.3425)

0.2

(0.008)

Unit:

mm

(in)

w

-

-

-

18.08

(0.71 18)

0.1

2

(0.0047)

1

.o

(0.040)

33.85

(1.3327)

-

65

-

Unit

:

mrn

(in)

CAMSHAFT

0

Cam

height

Journal outside dia.

"D"

I

type

Dl

ITEM

IN.=.

CAMS

Dl

D2

EH12-2

STD

29.6 - 29.8

(1.165

-

1.173)

16.973 - 16.984

(0.6682

14.973 - 14.984

(0.5895

-

0.6687)

-

0.5899)

/

EH17-2

Limit

29.45

(1.1 59)

16.95

(0.6673)

14.95

(0.5886)

VALVE

Valve stem outside dia.

0

Clearance between valve

valve guide

Valve clearance

stem

dia. and

IN.

EX.

IN.

Ex.

5.440 - 5.455

(0.21

42

-

0.21

48)

5.426 - 5.444

(0.21 36 - 0.21 43)

0.045

-

0.078

(0.001 8 - 0.0031)

0.056 - 0.092

(0.0022

-

0.0036)

5.35

(0.21

06)

5.35

(0.21 06)

0.3

(0.01

2)

0.3

(0.01

2)

IN

./EX.

(cold)

-

66

0.08 - 0.1

(0.0031 - 0.0047)

-

2

Unit:

mm

(in)

ZAMSHAFT

Cam height

a

Journal outside dia.

'D"

type

ITEM

IN.=.

CAMS

Dl

VALVE

Valve stem outside dia.

Clearance between valve stem dia. and
valve guide

"P

1

.. .. ..

..

..

..

..

..

Valve clearance

D2

IN.

Ex.

IN.

EX.

IN

./EX.

(cold)

EH25-2

I

Limit

30.6 - 30.8

(1.205

-

1.213)

30.45

(1.199)

24.967

-

24.980
(0.9823)

(0.9830

-

0.9835)

24.95

14.973

-

14.984
(0.5886)

(0.5895

-

0.5899)

14.95

5.975

-

5.990

(0.2303)

(0.2352

-

0.2358)

5.85

5.960 - 5.975
(0.2303)

(0.2346

-

0.2352)

5.85

0.045

-

0.078

(0.01

2)

(0.001 8 - 0.0031)

0.3

0.060

-

0.093

(0.01

2)

(0.0024 - 0.0037)

0.3

0.08 - 0.1

2

(0.0031

-

0.0047)

-

67

-

Unit:

rnrn

(in)

1

TAPPET

0

Stem outside dia.

0

Guide inside

0

Tappet

guide clearance

dia.

ITEM

STD

7.960 - 7.975

(0.31

34 - 0.31

8.000

-

8.01

(0.31

50

-

0.31

0.025

-

0.055

(0.001

0

-

0.0022)

Limit

40)

5

56)

VALVE

SPRING

FREE

LENGTH

-

68

-

Unit: mrn

(in)

ITEM

TAPPET

Stem outside dia.

Guide inside dia.

8

0

Tappet guide clearance

VALVE

SPRING

FREE

LENGTH

~~ ~ ~~~

I

ITEM

VALVE SEAT ANGLE(IN. EX.)

0

Valve cutter angle(a)

0

Valve contact width(b)

a

EH25-2

STD

Limit

7.960

-

7.975

(0.31 34 - 0.31

40)

8.000

-

8.01

5

(0.31

50 - 0.31

56)

0.025

-

0.055

(0.001

0

-

0.0022)

35.5
(1.4)

1

~

Unit: rnm

(in

EH12-2

11

7-2 125-2

STD

limit

a:

90"

b

:

0.7

-

1

.O

(0.028 - 0.039)

2.0

(0.079)

-

69

-

12-2 TORQUE SPECIFICATIONS

/

17-2

EH12-2

Cylinder head bolts

type

DESCRIPTION

N*m

-

26.5

TIGHTENING TORQUE

cm

kg

230 - 270 22.5

16.6

ft-

-

Ib

19.5

Connecting rod cap

Flywheel nut

Main bearing cover bolts

Spark plug

EH25-2

type

DESCRIPTION

Cylinder head

Flywheel nut

Main bearing cover

bolts

rod

bolts

New spark plug

Retightening

cap bolts

bolts

EH12-2

1

.16.6-19.6 8.8-11.2

58.8

-

63.7

-

9.8

7.8

11.8-14.7

-

26.5

22.6

Nom

-

41.2

-

26.9 Connecting

-

63.7

58.8

16.7-18.6

EH17-2 EH12-2 EH17-2

600 - 650

-

150

120

230 - 270

TIGHTENING TORQUE

kg

cm

-

420 33.3

340

225

-

275 21.3

-

650

600

I

170

-

190

EH12-2

6.5-8.3 170-200 90-115

5.7

8.7

16.6

24.6

16.3

I

12.3- 13.7

12.2-14.4

43

-

47

-

7.2 80 - 100

-

10.9

-

19.5

ft-lb

-

30.3

-

19.8

43 - 47

EH17-2

I

New spark

I

Retightening

plug

I
I

11.8

-

14.7

22.6 - 26.5

-

70

-

I
I

120

-

150

230 - 270

I

I

8.7

-

10.9

16.6 - 19.5

12-3

OIL

GRADE

CHART

Specified

Lubrican

Quality

T-

Single

grade

Multi-

grade

Comparison between oil viscosity and temparature

I

I

I

I

I

1

I I

I

-

20

-

10

0

10

20

30

40

"C

-4 14

32 50

68

86

104

"F

Use

oil classified

as

SE

or higher.

Multi-grade oil tends

to

increase its consumption at high ambient temperature.

-

71

-

13.

MAINTENANCE AND STORAGE

The following maintenance

jobs

apply when the engine
The indicated maintenance intervals are
these intervals.
For example,
every day instead

13-1

DAILY MAINTENANCE

1)

Clean away dust and chaff from engine.

2)

Check fuel leakage from fuel system. If any,
retighten fasteners
parts.

3)

Inspect for loose hardwares and retighten if
necessary.

4)

Check

if

the engine

of

every

MAINTENANCE

oil

level and add

is

operated in extremely dusty conditions, the air cleaner should be cleaned

50

hours.

or

replace necessary

to

full

mark.

is

operated correctly under normal conditions.

by

no means guarantees

Governor linkage is especially sensitive to dust.

~~ ~ ~~ ~~

Loose
parts.

bolts

and

nuts

may come

for

maintenance free operations during

REMARKS

~~

off

and result

in

breakage of other

13-2

INITIAL

I

1)

Change crankcase oil.

13-3

EVERY

I

1)

Change crankcase oil. Contaminated

2)

Clean

3)

Check and clean spark plug. If dirty, wash in gasoline

20

HRS.

MAINTENANCE

50

HRS.

MAINTENANCE

air

cleaner.

MAINTENANCE

(10

DAYS)

MAINTENANCE

L

To

remove

sludge

oil

from

run

quickens

or

REMARKS

-

in

operation.

REMARKS

wear.

polish with emery paper.

I

I

-

72

-

13-4

EVERY

100-200

HRS. (MONTHLY) MAINTENANCE

I

MAINTENANCE

I

REMARKS

I

~

1)

Clean fuel filter and fuel

tank.

2)

Inspect cooling system and remove

dirt

and

Remove blower housing and clean

up

between fins and housing.

chaff.

13-5

EVERY

500-600

HRS. MAINTENANCE

I

MAINTENANCE

I

REMARKS

I

I

1)

Remove carbon from cylinder head.

~ ~~~

I

Carbon deposits

in

combustion chamber causes lack

of

power.

I

2)

Disassemble and clean carburetor.

I

I

13-6

EVERY

1000

HRS. (YEARLY) MAINTENANCE

MAINTENANCE REMARKS

1)

Overhaul engine.

Clean and correct parts.
Replace piston rings and other necessary parts.

2)

Replace fuel lines once a

year.

Avoid hazards caused

by

fuel leakage.

13-7

ENGINE STORAGE

(1)

Perform the above

13-1

and

13-2

maintenance

jobs.

(2)

Drain fuel from the fuel tank and carburetor float chamber.

(3)

To

prevent rust in the cylinder bore,

apply

oil

through the sp

several turns by hand. Reinstall the plug.

ark plug hole and turn the crankshaft

(4)

Turn the starting pulley

by

hand

and

leave it where the

resistance

is

the heaviest.

(5)

Clean outside

of

the engine with

oiled

cloth.

(6)

Put a plastic cover

or

the like over the engine and store the engine in dry place.

-

73

-

SU6ARU

~bin America, Inc.

940 Lively Blvd. l Wood Dale, IL 60191 l Phone: 630-350~8200 l Fax: [phone]
e-mail: [e-mail] l www.robinamerica.com

PRINTED IN THE USA

I