Robin EY20, EY28 Service Manual

ROBIN

AMERICA, INC.

ROBIN

TO

WISCONSIN

ROBIN

ENGINE

MODEL

CROSS REFERENCE

LIST

ROBIN

EY08

EY15
EY 15V
EY20
EY2OV
EY23

EY28

EY3

5

EY40

-

EY45V
EY2

1

EY44
EY 18-3
EY25
EY27

EH11
EH12

EH15

EH17
EH21

EH25

EH30
EH30V
EH34
EH34V
EH43V

EC13V

DY23
DY27
DY30
DY3

5

DY4 1

WISCONSIN

ROBIN

SIDE

VALVE

W

1-080

W1-145
W1-145V
W1-185
W1-185V
W1-230
W 1-280

W

1-340
W 1-390
Wl-45OV
EY21W
EY44W
EY18-3W
EY25W
EY27W

OVERHEAD

VALVE

WO1-115
wo1-120
WO1-150
WO1-170
wo1-210
WOl-250
WO 1-300
WO1-300V
WO1-340

WO

1

-340V

WO 1-43 OV

TWO CYCLE

WT1-125V

DIESEL

WRD

1-230

WRD

1-270

-1-300
WRD1-350
WRD1-410

0

0

0

CONTENTS

Section

1

.

SPECIFICATIONS

2

.

PERFORMANCE

2-

1

Maximum Output

2-2

Continuous Rated Output

2-3

Maximum Torque

3 . FEATURES

4

.

GENERAL DESCRIPTION

Cylinder. Crankcase

4- 1

Main Bearing Cover

4-2

Crankshaft

4-3

Connecting Rod and Piston

4-4

Camshaft

4-5

Valve Arrangement

4-6
4-7

Cylinder Head
Governor

4-8

Cooling

4-9

Lubrication

4-10
4-1

1

Ignition

Carburetor

4-12

Air Cleaner

4-

13

4-14

Sectional View

Title

...............................................

............................................

............................................

..............................................

.............................................

Page

...........................................

1

...........................................

.......................................

.................................

.......................................

3

of

ENGINE CONSTRUCTION

...............

.....................................

......................................

...........................................

................................

......................................

.........................................

...........................................

...........................................

...........................................

of

Engine

..................................

4
4

4

5

5

6
6

7

7

8

8
8
9
9

10

5

.

DISASSEMBLY

5-1

Preparation and Suggestion

5-2

Special

5-3

Haw

5-4

How To Reassemble

6

.

MAGNETO

6-1

Magneto

6-2

Breaker Point Adjustment

6-3

Timing Adjustment for

6-4

Magneto Trouble Shooting

6-5

Solid

7 .

GOVERNOR ADJUSTMENT

8

.

CARBURETOR

8-

1

Operation and Construation

8-2

Disassembly and Reassembly

9 . BREAK-IN OPERATION

and

REASSEMBLY

Tools

..........................................

To

Disassemble

...............................................

.............................................

State

Ignition

............................................

...............................

.................................

.....................................

.....................................

.................................

EY15. EY20

.................................

......................................

...................................

................................

Of

REASSEMBLED ENGINE

Point Type Ignition System

........

...............................

................

18
18

18
20
27

37
37

37
38
39
39

40
42

42
43

45

Section

10

.

ROBIN SOLID STATE IGNITION ENGINE

Features

10-1
10-2

Basic Theory of T
Basic Theory of

10-3

11

.

TROUBLE SHOOTING

.

1

Starting Difficulties

11
11

-2

Engine Misfires

1

1 -3

Engine Stops

11

-4

Engine Overheats
Engine Knocks

11-5
11

-6

Engine Backfires through Carburetor

12

.

INSTALLATION

12-1

Installing

12-2

Ventilation
Exhaust Gas Discharge

12-3
12-4

Power Transmission to Driven Machines

12-5

Wiring

13

.

ELECTRIC STARTING MOTOR

13-

1

Specifications
Operation

13-2

Title

.............................................

.

I.C.

...................................

P

.

I.T.

...................................

.......................................

......................................

.........................................

..........................................

.......................................

.........................................

............................................

.............................................

...........................................

....................................

..............................................

.........................................

............................................

(Option)

(T.I.C. and P.I.T.)

............

..........................

........................

..........................

pese

46
46

46
46

47
47

48
48
48

49

49

50

50

50
50
50
51

53

53
53

14

.

RECOIL STARTER DISASSEMBLY

14-1

How

To Disassemble (Type D)

How

14-2
14-3
14-4

15

.

CHECKS

16

.

TABLE

17

.

MAINTENANCE

17-1

17-2

17-3
17-4
17-5
17-6

17- 7 Preparation for

To Reassemble (Type

Check Items after Reassembly

How

To Do in Such

and

CORRECTIONS

of

CORRECTION STANDARDS

and

STORING

Daily Checks and Maintenance
Every

20

Hours

Checks and Maintenance

Every

50

Hours Checks and Maintenance

Every

100

-

200

Every

500 - 600

Every

1000

Hours (Yearly) Checks and Maintenance

Long

and

REASSEMBLY

................

..............................

D)

...............................

...............................

Cases!

.................................

...................................

...........................

.................................

..............................

.......................

.......................

Hours (Monthly) Checks and Maintenance
Hours (Semiannual) Checks and Maintenance

................

Abeyance

..............................

...........

.........

54
54

55
57
57

58
59
65

65
65
65
65
66
66
66

.

2.

PERFORMANCE

2-1

MAXIMUM

OUTPUT

The maximum ouput of an engine is such standard power as developed by the engine, after its initial break in period
the

moving

the maximum output

2-2

The continuous rated output of
mum
tion. It
the continuous power requirement

23

These mean the maximum torque

parts properly

CONTINUOUS

speed,

and

most favorable from the viewpoint of engine life and fuel consumption ratio,

is

suggested, therefore, that when designing a

MAXIMUM

worn

in, when operating with a fully open throttle valve. Therefore, a new engine may not develop

in

the beginning because the moving

RATED

OUTPUT

an

engine

is

of

that mechanism be kept below

TORQUE

of

the output shaft and fuel consumption ratio at the maximum output of an engine.

4

parts

are not

sudrpower as developed

driving

PERFORMANCE

MODEL EY15D,

Ma;.

Torque

system

the

in

a

properly

by

that engine when

worn-in

running

condition.

continuously at

with

for

any mechanism, with this engine

continuous rated output specified.

CURVES

15B

(

1

for

B

type

~

0.7

the governor

as

prime mover,

kg-m

-

I

I

7

0.6

with

an

in

opera-

all

opti-

HP

I\ I

tii

2000

(1

000)

Revolution

3000

(1

500)

-2-

I

I

I

I

I

I

4000

r.p.m.

(20001

5

4

3

HP

L.

B

w

r

22

PERFORMANCE CURVES

MODEL EYZOD

Max.

Toraue

PERFORMANCE CURVES

MODEL

1

.o

EY28D,

288

I

)

for B tvm

1

2000

3.

FEATURES

1.

Compact, lightweight, durable, powerful 4-cycle air-cooled engine embodying ingenious design techques

3000

Revolution

4000

r.p.m.

2000

(1

000)

3000

(

15001

Revolution

r.p.rn.

and

workmanship.

2.

Simple construction, smart appearance, maximum easiness of start owing to automatic decompression device

3.

Pointless

4.

Reliable prime mover for variety of purposes with smooth speed control by a governor under varying load conditions.

5.

Economical because fuel consumption is very low.

6.

Great ve:satility in installation through a

Solid

State ignition system is newly adopted

for

preventing poor igniting as option.

360"

belt extension possibihty and a two-side

oil

fill

and drain arrangement.

4000

I20001

skilful

-3-

4.

GENERAL DESCRIPTION

4-1

CYLINDER, CRANKCASE

The cylinder and crankcase are single piece aluminum die
casting. The cyhder liner, made of special cast
into the alminum casting. The intake

located on one side

into the casting.

of

the cyhder,

and

exhaust

and

of

ENGINE CONSTRUCTION

iron,

is built

ports

are

are also inserted

The crankcase

the main bearing cover

(See Fig.

4-2

MAIN

The main
of

the engine can readily be checked by simply removing the cover. It

ing machmes, such as generators and pumps.

Two

oil

The

EY

(See

Fig.

is

separable on the output shaft side, where

is

attached to it.

1

.)

BEARING

bearing

gauges also serving as

15B engine has 2 chain guides and a built-in shelter plate to prevent

4.)

cover made

COVER

of

aluminum die casting is built

oil

filler caps can be mounted. (See Fig. 2 and Fig.

Ring

for

/

Centering

Fig.

onto

the output shaft side of the crankcase

is

provided with a flange

3.)

oil

from

being

1

and

boss

stirred

so

that the inside

for directly mount-

by

the governor gear

Oil

Gauge

Fig.

2

Oil

Gauge

-4-

I

Governor Gear

Fig.

3

Chain

Guide

-

Shelter

1

Fig.

4

(E

Y

15B)

Plate

4-3

CRANKSHAFT

The crankshaft
output end.

"he

EY

(See

15B

type has a built-in drive sprocket. (See Fig.

Induction Hardening
(Portion

is

forged of carbon steel, and the crankpin

Fig.

5.).

of

Crankpin)

Crank Gear

(Pressure-Fit)

Fig.

5

is

induction-hardened. It has a crank gear premred-fitted on the

6.)

Drive Sprocket

-

Fig.

6

(E

Y

158)

4-4

CONNECTING

ROD,

PISTON

and

PISTON

The connecting rod is forged of aluminum alloy, which it­self serves as bearings at both the large and

has

a

large end
cating

oil.

built-in

oil

scraper for splashing the lubri-

small

ends. The

The piston is cast of aluminum alloy, and has grooves for

rings

receiving two compression
(See

Fig.

7.)

PISTON RINGS

for

EY28 ENGINE

and one

This piston rings are made of special cast iron

shape

of

the top ring

taper under cut; and the

is

barrel face, that of second

oil

ring has cutter expander. These

rings are very much effective for decreasing engine

oil

ring.

and

ring

the

oil

consumption.

RING

is

1

Fig.

Connecting

Rod

Oil Scraper

7

Lock

Rod

Washer

-5-

4-5

CAMSHAFT

In

the D type, the camshaft

the camshaft has aluminum

In

the B type, the camshaft is made of carbon steel, and

9.)

(See Fig.
are used

The camshaft functions also as an output shaft, and is driven by

in

the output shaft side.

is

integrally built with a cam gear

plain

bearings attached to both ends.

of

(No

EYlSB

J

special cast iron, and has intake and exhaust cams. Also

ball bearing is used.) (See Fig.

8.)

type has a pressured-fitted cam gear and a driven sproket.

1/2

rotation

of

the crankshaft,

Ball

bearings

Driven Sprocket

(Pressure-Fit)

Cam

Gear

Fig.

8

4-6

VALVE ARRANGEMENT

The exhaust vahe is located upstream
the result that the exhaust valve
improved engine durability. The inner side

of

the coolingair with

is

intensiveiy cooled

of

the valve head

for

is reinforced with hard alloy fused to it for added durability.

(See Fig.

10.)

I

Fig.

9

Exhaust Valve

Fig.

(E

Y

70

156)

Direction

of

Cooling

Wind

-6-

4-7

CYLINDER

HEAD

The cylinder head

is

an aluminum die casting,

and

forms a

Ricardo type combustion.chamber with ample area for high

is

combustion effeciency. The spark plug
mounting
(See Fig.

4-8

of

the fuel tank.

11.1

GOVERNOR

tilted for easy

The governor is a centrifugal flyweight type which permits
constant operation at the selected speed against load varia­tions. Governor gear
out fail, and

Fig.

(See

it

12.)

is

installed on the bearing cover with-

engages with the cam gear afterreassembling.

Fig.

1

1

1

/

Main

Bearing Cover

Governor Gear

Fig.

Complete

12

Governor

Sleeve

-7-

4-9

COOLING

The cooling fan serving

also

as a flywheel

cools

head cover are provided for guiding the coohg

4-10

The

ing and splashing the
attached
(See Fjg.

LUBRICATION

rotating and sliding parts are being lubricated by

oil

in the crankcase with the

to

the connecting

13.)

rod.

the cyhder and cylinder head by forced air cooling. Cylinder baffles

air.

scoop-

oil

scraper

and

4-1

1

IGNITION

The ignition system is a flywheel magneto type with ignition timing set at

flywheel and ignition

the crankcase.

(For

(BREAKER

coil.

The flywheel serving also as a fan is mounted directly

further detds, refer to Section on the Magneto.) (See Fig.

POINT IGNTION TYPE)

23"

before

(SOLID

Fig.

13

TDC.

The magneto

on

the crankshaft, and the ignition

14

and Fig.

STATE IGNITION TYPE)

Ignition

15.)

Coil

is

composed

Ea\?

of

coil

a

in

Fig.

14

-8-

Fig.

15

D

4-12

A

CARBURETOR

horizontal draft carburetor is employed. It
fully set after thorough tests to assure satisfactory start up,
acceleration, fuel consumption, output performance etc.
For construction and order details, refer to the Section on
Carburetor Construction, Disassembly
(See

Fig.

i6.)

has

and

Reassembly.

been care-

Fig.

16

m

4-13

The air cleaner
type using a sponge element.
double element air cleaner is optionally available.)

(See

AIR

Fig.

CLEANER

of

17.)

the standard type engine is an oblong

(A

cyclone type semi-wet

Air

Cleaner for

Standard Type

Cyclone Type

(Option)

Mushroom Cyclone Type
(Option)

Fig.

17

-9-

4-14

SECTIONAL

VIEW

OF

ENGINE

4-14-1

Blower

MODEL

Cylinder

Ignition

Head

Housing

Coil

Piston

Flywheel

(Cooling Fan)

EY15D

Pin

Starting

Recoil

Pulley

Starter

MODEL

(BREAKER POINT IGNITION TYPE)

-

EY15D

10

-

Governor

\

I

i

/-Speed Control Lever

Piston

Stop Button

Connecting

Rod

Air Cleaner

'Carburetor

.Muffler

.Intake and

Exhaust Valve

Tappet

Oil

Scraper-

MODEL

-

11

EY15D

-

1

Camshaft

4-14-2

MODEL

EY15B

Cvlinder Head

Blower Housing

Ignition

(Cooling Fan)

Coil

Piston Pin

Flywheel

Spark Plug Cap

Spark Plug

Piston Ring

Crankcase

Chain Guide

Crankshaft

Main Bearing Cover

Starting Pulley

Recoil

Starter

--/

MODEL

(SOLID STATE

EY15B

IGNITION

-

12

-

TYPE)

L

Governor

Fuel

Tank

I

1

Piston

Stop Button

Connecting Rod

\r

Speed Control Lever

Air Cleaner

Carburetor

Muff

I

er

Intake and
Exhaust Valve

Tappet

Oil

Scraper

MODEL

EY15B

-

13

Chain

-

4-14-3

MODEL

EY20D

Recoil

Starter

(BREAKER

MODEL EYPOD

POINT IGNITION

-

14

-

Cover

Governor

TYPE)

Speed Control

Lever

Piston

Stop Button

Connecting

Oil Scraper

Air Cleaner

Rod

Carburetor

.Muffler

Camshaft

1

MODEL

-

EY20D

15

-

\-

\“Tappet

Intake and

Exhaust Valve

4-14-4

MODEL

EY28

,Spark

Spark

Plug

Plug

Cap

Flywhe

Piston

Crankcase

-Governor

Ring

lg

Cover

(SOLID

MODEL

EY28

STATE IGNITION TYPE)

-

16

-

Fuel Tank

-0

I

MODEL

-

17

EY28

-

Intake and

Exhaust

Tappet

Valve

PREPARATIONS

and

SUGGESTIONS

When disassembling the engine, remember well the
correctly.

Have boxes ready

To

If

you are uncertain

to

keep disassembled parts by group.

of

identifying some parts, it is suggested that tags be attached

prevent missing and misplacing, temporarily assemble each

locations

Carefully handle disassembled parts, and clean them with washing oil.
Use the correct

SPECIAL

For

your reference, the following shows special tools

Part

No.

2099500407

tools

in the correct way.

TOOLS

Tool

Flywheel Puller

bolt)

(with

Use

For pulling
Flywheel

of

off

Robin Enpne

Applicable

E

YO8
EY10,13,14
EY 15,18,20
EY23,25,27
EY28,33,35
EY40,44

group

Model

of

individual parts

of

disassembled parts.

for

Disassembiy, Measuring and Inspection Instruments.

so

that they can

to

Shape

them.

be

reassembled

23095001

227 95003

230

95002

205 95001

07

07

07

07

Valve

Spring

Retainer

Valve

Guide

Puller

For mounting and
dismounting Valve
Spring Retainer
and Retainer

For pulling

Valve

guide

Lock

off

EC05.07,lO

EC17,25,37

€YO8

EY10,13,14
EY 15,18,20
EY23,25,27
EY28,33,35
EY40,44

EY08

EYlO

EY13, 14

-

18-

Part

No.

2069500107

Tool

Use

Applicable

Model

I

EY

18,23

2279500107

2349500107

2079500107

226

9500

1

07

Valve Guide
Puller

Guide
(Chain Guide)

For

pulling

Valve guide

For mounting

chain guide

off

EY

1

5,20

EY28

EY25,27

EY15B

“20248

Timing Tester

For

qdjusting

timing

EY10,13,14

EY 15,18,20
EY25,27
EY33,35,40

EY44

EC03,04,05
EC07,10,17
EC25,37

-

19

-

5-3

HOW

TO

DISASSEMBLE

I

Order

I:

1

Item

Drain plug

Recoil starter

*Length

(1)

(1)

of

the bolt indicates the length from the bolt head bottom surface

Procedures

Drain engine oil.

8

mm

on

Flange

Drain plugs

crankcase.

Remove the recoil starter.

6@

x

both sides of

bolt: 4 pcs.

the

Remarks

the gasket.

to

lose

to

the threaded end.

Tool

14

mm spanner Be careful not

10

mm box spanner

Gasket

-

20

-

Order

3

4

Item

~~

Blower housinl

Fuel tank and

head cover

Air cleaner

Muffler cover

Procedures

(1)

Remove the Blower housing from the
crankcase

EY15,20
EY28

(1)

Close the fuel cock.

(2)

From the carburetor disconnect the fuel

and

head cover.

...

64

6q5

......

6q5

x

12 mm bolt: 2 pcs.

x

14

mm bolt: 2 pcs.

x

12

mm

bolt:

4

pcs.

pipe between the fuel strainer and carbu­retor

on

the side

(3)

Remove the fuel tank from the cylinder

of

the fuel strainer.

head.

EY15,20
EY28

(4)

Remove the head cover from the cylinder

...

......

64

nut: 2 pcs.

84

nut: 4 pcs.

head.

(1)

Remove the air cleaner cover and element.

(2) Remove the air cleaner case from the car-

buretor.

6rp

nut: 2 pcs.

(3)

Disconnect the breather pipe.

(1)

From the muffler remove muffler cover.

EYl5,20
EY

28

...

.....

64

x

8

mm bolt: 3 pcs.

6q5

x

8

mm bolt: 4 pcs.

Remarks

Fastened together
with the fuel tank

Air cleaner is fasten­ed together with the
carburetor.

Tool

10

mm box spanner

10

mm spanner or

12 mm spanner

10

mm box spanner

10

mm box spanner

~

7

Muffler

(1)

Remove the muffler from the cylinder
portion of the crankcase.

8q5

nut: 2 pcs.

Brass nut

Muffler

Cover

6”.

12 mm spanner

/I

Mu’ffler

-

21

-

Order

8

9

I

Item

Governor lever
and the relative

parts

Carburetor

Procedunx

(1)

Remove the governor lever from the
governor lever shaft.

6$1

x

25

mm bolt: 1 pce.

(2)

Remove the governor

spring

from the carburetor.

(1)

Remove the carburetor from the cylinder

rod

and

rod

portion of the crankcase.

Remarks

Just

loosen the bolt,

unnecessary to take

out

the bolt.

10

or

mm

10

Tool

box

spanner

mm spanner

~ ~~

1

Lever

Fig.

-

22

18

-

Order

I

10 Starting pulley

11 Flywheel

12 Ignition coil

Spark

Item

"

(1)

Remove the starting pulley from the fly-

wheel.

64

x

Fit a box or socket wrench over the

flywheel nut, and strike it hard with

hammer to remove the nut

14

mrn,

"

"

-

Plug

washer.

(1) Remove the flywheel from

(1)

Remove the ignition plug cap from
ignition plug; and remove the iption
coil

64

x

Cap

Rocedu~s

12 mm bolt: 3 pcs.

EY28:

from the crankcase.

25 mm bolt: 2 pcs.

18

mm)

(EY

15,20:

and spring

the

crankshaft

a

the

I

Remarks

Be

careful not to

damage the blades

of

the

flywheel
a driver and a like.
Strike counterclock-

wise with

(See Fig.

Fit the flywheel pull­er

as

shown
turn the center bolt
clockwise and pull
out the flywheel.

Sems bolt

a

hammer.

19.)

in

Fig.20,

with

I

~

~

Tool

10

rnm

box

spanner

19

mm

box

spanner

24

mm box

or

spanner

Flywheel puller

I

1

10

mm box spanner

(Solid

State lgnitio

Flywheel Puller

Fig.

-

23

-

\

0

20

\

Flywheel

Order

13

14

Item

Spark plug

~~ ~~

Cylinder head

Procedures

(1)

Remove the spark plug from the
cylinder head.

(1)

Remove the 8 mm bolt and remove the

~~ ~~ ~

cylinder head from the crankcase.

89

x

40

mm bolt: 8 pcs.

(2)

Remove the cylinder head gasket
the crankcase.

from

Remarks

21

mm

12 mm

Tool

box

box

spanner

spanner

I

,”-.

15

Intake and

exhaust valve

16 Main bearing

cover

(1)

Remove the inner and outer tappet
covers from the crankcase.

69

x

I2

mm bolt: 2 pcs.

(2)

Pull out the intake and exhaust valve.

(3)

Remove the valve spring and the valve
retainer

(1)

From the crankcase remove the bolt

.

fastening the main bearing cover.

EY

15,20

EY28

(2)

Remove the cover,

.

. . .

. .

. .

.

6$

x

30

mm bolt: 8 pcs.

8$

x

28 mm bolt: 8 pcs.

lightly

tapping the

cover evenly with a plastic hammer.

Spark

Plug

Put the notch on the
outer circumference
of the

spring

retainer

on this side.

Hook

the medium

size

(-)

drive at the

dent (lower side)

of

the spring retainer
and pull out the
valves, while pulling
the spring retainer

toward

(See Fig. 2

you.

1

.)

Sems bolt

Be careful not
damage the

oil

to

seal.

(See Fig. 22.)

Cvlinder Head

10

mm

box

spanner

The front

is

this

side.

(-)

driver

10

mm box spanner

Crankcase

Cyclone

Cleaner

I

Drain

Plug

-

24

-

Oil

Seal

Guide

18

Tappet

J

Fig.

21

Procedules

(1)

Remove the camshaft from the crankcase.

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

(1)

Remove the tappets from the crankcase.

Main Bearing

L

F&.

22

Remarks

To

prevent the tap-

pets from falling

or

Tool

Cover

damaging, place the

~~ ~

crankcase
side. (See Fig.

on

the

23.)

Before removing put

a mark

of

intake

or

exhaust on each tap­pet.

In

the

EY

15B

type, remove the tap­pets after step

2

1.

Intake Valve,

9

!

GoGernor Gear

1-

I

Camshaft

Exhaust Valve

Valve Spring

Spring

Retainer

Tappet

-

25

-

I

Fig.

Tappet

23

Order

19

Item

I

Connecting rod
and piston

Procedures

I

(1)

Scrape off carbon and other foreign de­posits from the upper parts of the cylin-

der and piston, and then straighten out
the bent tabs of the lock washers
the connecting

rod,

and remove two

pieces of the bolt.

(2)

Remove the

oil

scraper, lock washer and

connecting rod cap from the crankshaft.

(3)

Turn the crankshaft until the piston

I

raised up

to

the highest position,
the connecting rod up, and remove the
piston out of the top of the cylinder.

on

is

push

Remarks

I

In

the

EYI

5B type,

rod to the position
shown in

Fig.

24.

Tool

i

10

mm box spanner

or

10

mm spanner move the connecting

20

22

Piston and
piston pin

(1

j

Remove the two clips, pull out the piston
pin, and take the piston off from the
small end of the connecting rod.

Be careful not
damage the inside

of

the small end of

the connecting rod.

(2)

Spread the open ends
and remove them frGm the piston.

of

the piston rings

Be careful not
break the rings

spreading too much.

(1)

I

Remove the woodruff
magneto).

(2)

Lightly hammer the magneto end

key

(for the Be careful not

damage the

of

oil

the crankshaft, and pull it out of the
crankcase.

(1)

Remove the woodruff key (for the Crankshaft

Camshaft Chain damage the oil seal.

(for

EY15B)

magneto).

(2)

Remove the crankshaft and the camshaft
at the same time from the crankcase,
tapping the crankshaft tip in the magneto
side.

Piston

Ring

Be careful not to

To

prevent the tappets

from

failing or

aging, place the crank-

on

case

the side.

Piston

to

to

by

to

seal.

dam-

Connecting

Rod

iston Pin

"

joodruff

\

Key

Crankshaft

Fig.

24

(E

Y

15B)

-

26

-

5-4

HOW

.Precaution

TO

REASSEMBLE

in

reassembling

Every and each part should be cleaned thoroughly. Especially, pay utmost care and attention to the cleanliness of the
piston, cylinder, crankshaft, connecting rod and bearings.
Scrape completely off carbons from the cylinder head and the upper part of the piston; especially the carbon adhered

in

the groove
Carefully check the lip portion of every
Apply enough
Replace

of

the piston ring should be carefully and completely taken out.

oil

to the lip portion of the oil seal when reassembling.

all

the gaskets with new ones.

oil

seal. If faulty one is found, replace it without any hesitation.

Replace the key, pin, bolt, nuts, etc. with new one, if necessary.
Whenever tightening torque is specified, conform to the specified figures.
Apply

oil

to the revolutionary parts and friction surfaces, when reassembling.

Check and adjust the clearances of various portions and then reassemble.

or

When some main portions are assembled in the course of reassembling, turn

move the gadgets by hand and pay at-

tention to the frictional noise and resistance.

*Sequence and precautions in reassembling

5-4-

1

CRANKSHAFT

1)

Fit the

oil

seal guide onto the end of the crankshaft,

and insert the crankshaft into the crankcase as shown

in

Fig.

25.

NOTE:

2)

Put woodruff key (for magneto)

In case

ful

not

of

not

using the oil seal guide, be care-

to

damage

the

oil

seal

in

place.

lip.

I.

Fig.

25

-

27

-

3)

DIMENSIONS

D

(Crankshaft pin

PISTON RING GAP

of

CRANKSHAFT PIN

Dia.)

PISTON RING
CLEARANCE

CONNECTING
CRANK PIN

CONNECTING
PISTON

54-2

CRANKSHAFT, CAMSHAFT, CHAIN
TAPPET

1)

Set
the chamshaft, as

NOTE:

2)

Put

crankshaft and the camshaft parallel. Then mount
them

SIDE

IN

GROOVES

ROD

ROD

PIN

TO PISTON

(for

the

chain

Set

matches
shaft

the tappets

onto

the

TO

TO PISTON PIN

EYISB)

in

the sprockets

shown

in

the chain

and

crankcase.

so

to

the timing marks

the

camshaft.

in

the crankcase, and then set the

OIL

RING

DIA.

SI

DE

of

the crankshaft and

Fig.

27.

that the white

and

link

of

the crank-

0.090L - 0.135L 0.050L

OL

-

0.065L

Table

1

plate

-

0.063L

0.1

0.01OL - 0.029L

0.009T

&A

-

0.095L 0.050L

-

0.065L 0.01

L - 0.3L

-

0.01

OL

-

0.09OL

0.01OL - 0.065L 0.01OL

0.020L - 0.046L 0.037L

L: LOOSE

T: TIGHT

Ling Plate (White)

V

Timing Mark

,”--

Fig.

27

(EY

15s)

-

28

-

54-3

1)

PISTON and

If

no

ring expander

spreading

NOTE:

PISTON

the

rings only far enough to

Pay attention not to break the rings

top ring. Meantime, the surfaces

RING

is

available,

install

the

slip

them

of

rings

by

placing

over

the

by

twisting. Install the oil ring

the second ring and the top ring with carved marks

the

open

ring

correct kg grooves.

ends over

first

followed

the

first land

by

of

the

piston

the

second ring and then

are

to

be

faced

and

up.

I

Top Ring

Second Ring

Oil Ring

Piston Ring

Fig.

28

I

I

Taper Barrel Face

Cutter Ring

(without expander) (with expander)

Fig.

29

I

EY15,20

I

I

Taper Under Cut

EY28

I

.

-

.

..

J

2)

Reassemble

NOTE:

the

piston and connection

Apply enough oil to the small top end

Be

sure

to

place the clips on

rod

both

by means

ends

of

the

piston

of

the connecting rod.

of

the

piston pin.

-

29

-

pin.

3)

When installing the connecting rod into place, hold
piston rings with the
(if

no

ring guide is available, keep pressing the piston

rings with finger tips and gently strike the top
piston with a wooden piece

and check that the symbol

necting rod is in the direction

NOTE:

NOTE:

NOTE:

Apply enough oil

ing

rod

reassembling.
The open ends
apart from one another
ery

.

The clearance between the piston and cylinder must be measured

ring

guide

as

shown in Fig.

or

the like

@or

mark

MA

of

the flywheel magneto.

to

the piston rings, connect-

plain bearings and cylinder wall before

of

the piston rings must be

on

the piston periph-

of

to

push

it in),

on the con-

30

the

90"

I

Piston

Fig.

30

at

the piston skirt thrust surface.

Ring Guide

544

CONNECTING

1)

Turn

the crankshaft to the bottom dead center, light-

ly

hammer the piston head

contacts the crankpin, and assemble.

2)

When reassembhg the connecting

alignment projection mark on the

3)

Oil scraper

Fig.

31

.)

NOTE:

NOTE:

NOTE:

NOTE:

Use new lock washers, and bend the tabs se­curely.
After reassembly, confirm that the connecting
rod moves lightly.

Connection rod cap tightening torque:

EY15

EY20

EY28

For the piston, piston ring and rod clearance, see Fig.

ROD

is

to be set on the side

.

,

. . . . . . . .

. .

. . .

+-

until

.

. . .

the

connecting

rod

cap, match the

rod.

of

magneto. (See

90-

115

170

-

200

kg-cm

kg-cm

rod

I

26.

Alignment

Mark

Fig.

31

Oil

Scraper

-

30

-

5-4-5

Insert

the

camshaft.

NOTE:

NOT€:

TAPPET and CAMSHAFT

the

tappets back into their holes first,

Align the timing mark
cam gear with the one on the crank gear.

is

timing

or

In the EY158,

sprocket’s timing mark.

If the intake tappet and exhaust tappet were
assembled contrarily each other, the tappet clear­ance cannot be kept correctly.

wrong, the engine cannot operate properly

at

all.

(See

Fig.

at

the root of a tooth of the

32.)

set

the white link plate

(See

Fig.

and

27.)

then

If

thevalve

mount

at

the

Fig.

32

5-4-6

Install

NOTE:

NOTE:

NOTE:

MAIN

BEARING COVER

the

main

bearing cover
When the chain guide
the clearance between the chain and the chain guids

CHAIN GUIDE tightening torque

As

the governor gear

{See

side,

Fig.

ing cover

checking that

gear.
replaced, pressure-fit
the main bearing cover.

to

the

crankcase.

is

replaced in the EY158, use the guide (chain guide)

70

to

90

kgcm.

Chain Guide

n

Fig.

33

(E

Y

75B)

is

mounted on the main bear-

install the main bearing cover while

it

meshes with the teeth of the cam

35.) Meantime, if the oil

a

new

oil

n

seal

seal

before installing

need be

is

from 0 to 0.5mm.

I

\

(See

(See

Fig.

33.1,

or

set

the chain

Fig.

34.)

Fig.

34

(E

Y

156)

Pay attention

the governor gear and cam gear

to

the engagement

so

that

of

-

31

-

NOTE:

When installing main bearing cover, apply oil to the

bearing and oil
the crankshaft or camshaft to protect the oil
lip from damage. Then place the main bearing
cover on.
Check the crankshaft and camshaft their side clear-

ance are

the adjusting shims. (See Fig.

adjustment of the camshaft

0

seal

lip.

Fit

the oil

-

0.2

mm; and if not adjust them with

seal

36.)

is

not necessary)

guide over

seal

(In D type,

Fig.

36

NOTE:

NOTE:

Main bearing cover tightening torque:

EY15,

EY20.

EY28

Fig.

crankshaft and camshaft side clearance between the

machined face of the crankcase and adjusting collar.

As

the crankcase, adjust the clearance
thickness

. . . . . .

37

a

paper packing

. . . . .

shows one

of

0.22

.

80-

100

. . . . .

170 - 190

of

the methods measuring the

is

used on

mm into account.

the

kg-cm

kgcm

machined face

by

taking this

(See

Fig.

37.)

of

I

11

II

Y=II

Dial Indicator

Ground Surface of Crankcase

(The surface

1

1

put together with the
main bearing cover.)

of

the crankcase

is

surface of

to be

the

-32

-

5-4-7

Remove carbon

NOTE:
NOTE:

INTAKE and EXHAUST VALVES

and

If

the

valve face

If

there

is

placing,
new valve guide

gum deposite

is

dinted

an excessive clearance between the valve guide and valve stem, replace the valve guide

pull

out

the valve guide, using the valve guide pulling base and

into

or

place.

from

the valves, valve seats, intake

warped, replace the valves with new ones.

Valve Guide Puller

and

exhaust

bolts

ports

and

valve guides.

as

shown

in

with

a spare. For

Fig.

38,

and pressure-fit a

Valve Guide Puller

Crankcase

E

Valve Guide

re-

F&.

39

A-VALVE FACE ANGLE

B

-SEAT ANGLE

C-GUIDE INSIDE DIA.

D-VALVE STEM OUTSIDE

MAXIMUM ALLOWABLE
CLEARANCE BETWEEN C and D

€-VALVE STEM

TILT

DIA.

ANGLE

INTAKE

EXHAUST

INTAKE

EXHAUST

VALVE

EY15

Fig.

38

and

VALVE GUIDE CLEARANCE

EY20

45O

45O

dia.

dia.

dia.

+0.022

1::::;

1:::;

-

0.062L

-

0.looL

3"

6.5

6.5

6.5

0.025L

0.056L

53'

Nut

EY28

3"30"

L:

LOOSE

Table

-

33

2

-

5-4-8

Lower
the
NOTE: The correct tappet clearance for

TAPPET ADJUSTMENT

the

tappet

all

the

clearance.

is

cold.

(See

Fig.

way

40.)

down,

push

the

valve,

both

intake and exhaust

and

insert a feeler gauge between

valves

is

0.1

Intake, Exhaust Valve Valve Spring

Grinding Face

mm

*

the

0.02

valve

mm

and

tappet stem to

as

measured when

measure

the

engine

..

i

I

Fig.

40

NOTE:

NOTE: After the tappet clearance adjustment, install the

NOTE: INSTALLATION of SPRING RETAINERS

If

the clearance

trary, if the ciearance

a

obtain

tappet clearance once again if

Place the notch on the outer circumference of the
retainer toward this side and insert the retainer, like
pushing in, using
used for

insertion may be easier.

good fit. Then adjust the clearance.

EY18

is

smaller than specified, slightly grind the top

is

too large, replace the

it

a

special tool. (This special tool

and other models.)

(See

Fig.

-

Tappet

is

correct.

If

adriver isused,

42.)

valve

vT/

Spring Retainer

Fig.

41

of

the

valve

stem, and measure

with new one, and polish its contact surface with a compound to

valve

spring retainers, and turn the crankshaft, and measure the

is

it

again. On the con-

Front should be this side.

I

Fig.

-

34

-

Valve Spring Retainer

42

I

54-9

Remove carbon from the cylinder head, particularly

I

the head

NOTE:

NOTE:

CYLINDER HEAD

its

combustion chamber, and make clean the cooling

for

distortion.

Replace the cylinder head gasket with a new one.
DlSTlNGTlON between the GASKET of EY15, EY20and EY28
The pitch
for EY15 and EY20 are same. However, the inner dimensions are different each other. The gasket for EY15
red mark while the gasket for EY20 has a green mark.

of

the holes

for

the bolts fastening cylinder head and the outer circumference dimensions

fins.

of

Also

the

check

gasket

has

a

43.

is

15K. and

Red

mark

NOTE:

NOTE:

NOTE:

5-4-10

For EY28, refer to Fig.

Cylinder head tightening torque:

DISCRIMINATION of CYLINDER HEAD

As stated above, the pitch

head

is

common to both EY15 and EYZO. For en-

abling

to

discriminate the cylinder head
from that of EY20, an embossed mark 15
to the former, while no embossed mark

the

latter.

For EY28, an embossed mark "EY28"

the combustion chamber side of the cylinder head.

Meantime, embossed mark for­EY15 Kerosene engine
EY20 Kerosene engine is 20K.

SPARK PLUG

Tightening torque of the spark plug:

5-4-1

EYl5, EY20

EY28

1 IGNITION

...........

...............

COIL,

FLYWHEEL and STARTER PULLEY

Green

mark

190

-

230 kg-cm

of

the holes of cylinder

of

is

is

given on

120 - 150

230

-

250

kg-cm

kg-cm

EY15

is

given

given to

Fig.

43

Fig.

44

Embossed

EY28

-

mark

1)

Temporarily fasten the ignition
ened together with the flywheel.

NOTE:

NOTE:

Before installing, wipe out oil from the crankshaft and the tapered portion of the flywheel.
Flywheel tightening torque:

coil

to

the crankcase, and install the flywheel

600

-

650

kg-cm

-

35

-

to

the crankshaft. Starting pulley

is

fast-

2)

After measuring the

air

gap between the ignition coil

and flywheel, retighten the ignition coil. (See Fig.

Air gap:

0.5

mm

45.)

.

/"

\

45

54-12

To

the

54-13

When reassemblying, refer to the

5-4-14

CARBURETOR

the cylinder portion of the crankcase. install

air

cleaner and fasten with two

GOVERNOR LEVER

MUFFLER and MUFFLER COVER

pieces

7. GOVERNOR

in

the order of the gasket, insulator, gasket and carburetor, and then mount

of 6 mm nut.

ADJUSTMENT.

1

\

Fig.

With two pieces of the brass nut fasten the muffler to the crankcase and then install the muffler cover.

54-15

Install

NOTE:

54-16

With 4 pieces

NOTE:

HEAD COVER, FUEL TANKand FAN COVER

in

the order

If

these items are installed in the order of the head cover, fan cover and fuel tank, removal of the fan cover

be impossible.

RECOIL

It

is

of

69

feared

of

the

head cover, fuel tank

STARTER

x

8

mm bolt fasten the recoil starter.

that

the

bolt

longer

than

8

and

mm

fan

may

cover.

damage

the

blades.

I

,"-

would

-

36

-

6.

MAGNETO

6-1

MAGNETO

The spark for ignition is furnished by a magneto assembly. The magneto consists of a flywheel, ignition
breaker assembly (including condenser),

mounted in crankcase directly, The

ed in

6-5.

The

breaker points, whch are mounted in the crankcase in­side the flywheel should be checked twice a season or when­ever the ignition spark becomes weak.

of pitting

rected, and then it becomes necessary to readjust the gap to

its proper clearance.

The normal breaker point opening (point gap) is
at full separation. Since the spark timing of
by the point opening,
curate spark advance. (Refer to

or

pyramidding, the breaker points must be cor-

use

a timing light to obtain an ac-

EYl5B

If

'6

-3

of

which flywheel

type engine normally incorporates a solid state ignition system

there

is

an evidence

0.35

23"

is regulated

TIMING

ADJUST-

is

mounted on crankshaft and ignition coil contact breaker are

mm

MENT.")

coil

and contact

(T.1.C)

Contact

describ-

Breaker

Fig.

46

To

adjust breaker point opening, remove starting pulley, blower housing and flywheel from the engine and proceed

follows: (See Fig.

1)

Remove breaker cover from contact breaker.

2)

Turn crankshaft over until breaker arm comes in contact with the

opening of

3)

Loosen contact support plate lock screw just enough

4)

Insert a

CAUTION:

obtained due

5)

Apply a screw driver to adjusting tab and move the contact support plate just enough
sliding the feeler gauge from between the points.

6)

Tighten lock screw and recheck breaker point gap.

7)

Pull

a strip of

CAUTION:

8)

Mount flywheel, blower housing and starting pulley on engine after adjustment.

46.)

0.35

mm)

0.35

mm feeler gauge between the points.

Adjust breaker point gap without opening

to

the bending

8

-

10

mm wide white paper through the closed points to remove oil and dust

When inserting a sheet

of

contact

of

breaker arm.

paper, never open the breaker point gap more than 2 mm.

high

point of the breaker cam. (Maximum point

so

that bracket can be moved.

it

more than 2 mm, otherwise rated heel-pressing force may not

so

that a slight drag

on

the point surfaces.

is

felt while

as

be

.'

'

-

37

-

6-3

TIMING ADJUSTMENT

(See

Figs.

47,48

and

49)

The spark is timed to occur at

23”

before the piston reaches

TDC

on the compression stroke.

This

spark advance of

23”

is

controlled by the breaker point opening and tius advance is obtained when the breaker point opening is adjusted according

to

the

BREAKER

justed through the following procedures using a timing tester as

NOTE: Refer

6-3-1

ALIGNMENT

(See Fig.

For timing adjustment, the

marks are provided as shown

*

‘M”

*

‘P-

6-3-2

TIMING ADJUSTMENT

1)

Bsconnect the stop button lead wires

2)

Remove blower housing

3)

Connect the timing tester lead with red rubber cap

to

the crankcase. (See Fig.

While the points are open, the buzzer within tester remains ringing and when the

silent. (See Fig.

4)

Turn

POINT ADJUSTMENT

to

section

47.)

“4-1’1

MARK

IGNITION”

for TIMING ADJUSTMENT

to its proper point gpening. However, the advance timing is more accurately ad-

shown

in Fig.

48.

and

“13.

CHECKS

and

CORRECTIONS.”

1

following

in

Fig.

alignment

47.

mark and line on the crankcase

mark and line on fhe flywheel cooling fan

with

TIMING TESTER

and

the coil primary wire.

from

engine.

to

the coil primary wire and ground the lead with b!ack rubber cap

48.)

48.)

the flywheel slowly until alignment mark on the flywheel is in the line

Fig.

47

points

are closed, the tester remains

with

alignment mark on the carankcase.

/-

Fig.

48

Fig.

49

-

38

-

Remove the flywheel without turning crankshaft at all.
Loosen the lock screw of the breaker point support plate

so

that the breaker point can be rotated.
By rotating the support plate
ringmg from being silent. (See Figs.

Put the flywheel back and check by rotating flywheel slowly. If the buzzer in timing tester starts ringing when line

mark

on

the flywheel is in the line with line mark

is correct.

If the timing mark lines are not in alignmnent, then readjust the point opening according to the

ADJUSTMENT, by removing the flywheel and repeat the checking procedure
After completing the timing adjustment remount the blower housing and connect the coil primary lead to the stop
button.

of

the breaker point, fmd the exact point when the buzzer within timing tester starts

48

and

49.)

on

the crankcase. When the line marks are in alignment, the timing

BREAKER

3)

through

5).

MAGNETO TROUBLE SHOOTING

When the engine does not,start
they are caused by

1) Check igntion cable for possible corrosion, broken, worn insulator or loose connection.

2) Check the sparking as described later in this section.

3)

Check if the breaker points require cleaning, or adjusting
may have to be replaced too.
Refer to ‘BREAKER POINT ADJUSTMENT.”

4)

If no spark takes place, replace igntiion coil.

*SPARK

Remove spark plug from cylinder head and place it on blower housing, with the ignition cable connected to it.
Crank the engine several times by starting pulley and observe the spark
strong, the ignition system can be eliminated as the source

If the spark is weak or there is

The correct electrode gap is

a

defect

TESTING

or

starts with difficulty, or when its operation is unstable, the following tests will clarify if

in

the magneto.

no

0.6

or

not. If the points are badly corroded or pitted, condenser

in

the spark gap of spark plug. If the spark is

of

trouble.

spark at all, repeat the checks according to the procedures 1) through

-

0.7

mm. (Refer to section

“15.

CHECKS

and

CORRECTIONS.”)

3)

POINT

above.

6-5

SOLID

STATE

IGNITION (See Section

10

“ROBIN

SOLID

STATE

IGNITION ENGINE”

details.)

The following solid state ignition systems are available as optional or standard:

1) T.I.C. (TRANSISTOR IGNITION CIRCUIT)
On the outside
standard type engine, and the exciter coil (primary-excitation) is available as an optional part. (The flywheel is for
common use.) (See Fig.

2) P.

I.

T.

(PULSER IGNITION TRANSISTOR) (EY 15, EY20)

The ignition coil and lighting coil are installed inside the flywheeel. Thls built-in type ignition system is installed to

the engine in whch lighting coil is requested. (P.I.T. unit is installed on the outside of the flywheel,)

of

the flywheel, an igntiion coil is installed, which is so-called outer coil type. This is equipped to the

59.)

(EY15,

EY20, EY28)

-

39

-

for

7.

GOVERNE

Models

gear and the throttle valve

EY

15,

EY20

and

EY28

employ a centrifugal flyweight type governor. The governor

of

the carburetor

is

automatically regulated

by

order to maintain constant engine speed against load variations.

The adjustment procedure

1)

Connect the carburetor throt?le lever to the governor lever with the connecting link,

or

shaft.

2)

Install the speed control lever to the cylinder head.

3)

Connect the governor lever to the control lever with the governor spring.

of

the governor is as follows (See

Figs.

50

and

5

1.):

is

mounted on the governor

a

lever which is connected to the governor

and

mount them onto the govern

in

*The

For
hooked at
point

4)

Turn

firm

Control lever

Fig.

50

point

where the governor spring

EY15

and

EY28

the governor spring

the

point

1,

while

it

is

to

2

for

EY20.

rhe

control lever

towards

high

that the carburetor throttle valve

can

stay wherever it

is

is

to

be hooked

be

hooked at the

speed, and

is

fully

required.

is

to

be

con-

opened.

I'

An

example

Fig.

51

Governor Lever

of

the governor spring being hooked

Fig.

52

I

-40

-

5)

With a screwdriver in the groove
turn it 'clockwise"

longer moves, and then lock the governor lever to the
governor shaft with the governor lever tightening bolt.
(See Fig.

*Dimensions of the governor spring for the engine to be connected to the generator:

Both

EY

governor spring to be hooked are different each other according to the hertz. Meantime, the dimensions

or

spring

53.)

15

and EY20 engines can be connected to the generators

for the standard engine is same as those

fully

of

the governor shaft,

until the governor shaft no

of

the

spring

Governor Lever

Fig.

53

of

both

50Hz

and

60Hz;

and the'dimensions of the

for the engine to be connected to the

60Hz

of

the govern-

generator.

EY28 engine
to the right generator. Meantime, standard type engine is for

Discrimination according to the dimensions:

can

be connected

to

the generators

EY15/60Hz

EY20/60Hz

"

EY28/60Hz(

of

both

(Standard)

-I

--I

(Longer

(a)

(all"

Hook

(Longer Hook Side)

(Standard)

STD)

50

Side)

Hz

the

and

60

60

Hz;

Hz

generator.

-::-

but it is necessary to select the right engine

EY 15/50Hz

I4Al-l

(Longer

EY20/50Hz

"

(Longer Hook Side)

EY28/50Hz

Hook

(A)

Side)

*For EY15,

*Both ends

ed

to

contrary directions.

EY20

and

of

the spring for

Fig.

54

EY28

it is commonly said that the governor spring longer in the length of

EYI 5 are bended to the same direction, while both ends of

-41

-

the

spring for

(A)

is

for

EY20

50

Hz.

are bend-

8.

CARBURETOR

8-1

OPERATION

8-1

-1

FLOAT SYSTEM

The float chamber
level during engine operation.
The fuel
float rises; and when its buoyancy and fuel pressure are balanced, the needle valve close
keeping the fuel at the reference level.

flows

from the fuel tank into the

and

CONSTRUCTION

is

located just below the carburetor body and, with a float and a needle valve, maintains a constant fuel

float

r

By-Pass Choke

(See

Fig.

55

and

Fig.

56.)

chamber through the needle valve. When the fuel rises to a specific level, the

,-

Pilot Jet

to

the shut

n

off

the fuel, thereby

Throttle

Pilot Outlet

Valve

I

I

Fig.

55

.

Main

Main

Air

Body

Float

Main Jet

Nozzle

Jet

/-'-

Needle

Float

-

42

-

8-

1-2

PILOT SYSTEM

The pilot system feeds the fuel
The fuel is fed through the

The fuel-air mixture is fed to the engine through the pilot outlet and the by-pass.

During

8-1

The fuel is metered by the

The choke

8-2

engine

-3

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

through the bleed holes in the main nozzle, and the mixture
taken through the air cleaner into an optimum fuel-air mixture, which

8-

1-4

sure applied to the main nozzle increases

idling,

the fuel is mainly fed from the pilot outlet.

MAIN

SYSTEM

CHOKE

is

used for easy start in the cold season. When the recoil starter

DISASSEMBLY

Apart

from

mechanical failures, most

due to a clogged up air or fuel passage in jets, or fuel level variations.

buretor must be kept clean at all times. The carburetor

to

the engine during idling and low-speed operation.

main

jet to the pilot jet, where it is metered, and mixed

main

jet and fed to the main nozzle.

and

REASSEMBLY

The

is

atomized out of the main bore. It is mixed again with the

and

draws much fuel accordingly; thus easily start up the engine.

of

carburetor troubles are caused by

disassembly

with

air metered by the main

is

supplied to the engine.

is

pulled

with

an

incorrect mixing ratio, which may arise mainly

In

order to assure proper

reassembly procedures are

and

the air metered by.the pilot air jet.

air

jet is mixed

a

closed choke, the negative pres-

flow

of

air

as

follows:

with

the fuel

air

and fuel, the car-

(See

Figs.

57

and

58.)

7

8

-4gJ

29

"i

134

I

7

8*

12

Fig.

A

57

(EY

15,201

-43

l0e

l1

"---@

12

4

Fig.

58

(E

Y28)

-

8-2-1

THROTTLE SYSTEM

1)

Remove the Philips screw (27) and throttle valve (22), and

2)

The spring

(24)

can be taken out by removing the throttle stop screw

pull

out the throttle shaft (23).

(25).

*Exercise care not to damage throttle valve ends.

8-2-2

CHOKE

1)

Remove the Philips screw

2)

When reassembling the choke shaft, make sure that the cutout in the choke valve faces the main air jet.

SYSTEM

(14)

and choke valve

(1

9,

and pull

out

the choke shaft

(1

6).

Meantime, when reassembling the moderation regulating ball (20) and the spring (21), set these parts at the
positions with the rings

8-2-3

PILOT

1)

Remove the pilot jet (26),

2)

Reassembly

SYSTEM

(1

8)

and (19) and then reassemble.

using

correct tool to avoid damage to it.

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

8-2-4

MAIN

SYSTEM

1)

Remove the bolt

2)

Re-move the main jet (13) from the body

and then remove the pipe assy

3)

Reassembly

(1

2)

and take out float chamber body

(29)

(lo).

(6).

[In

case

of

EY28,

remove the main jet (13) from the pipe assy (29),

and the nozzle (28) from the carburetor body

(6).]

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

70

kg-cm.

right

8-2-5

FLOAT SYSTEM

I

j

Pull

out the float pin

it

with rubber needle.

CAUTION:

When cleaning the jets, use neither a drill

adversely affect fuel

2)

When removing the needle valve and floats, gently tap the reverse side using the
and remove because the float pin is calked

(9)

and remove the float

flow).

Be sure to use compressed air

(8)

and needle valve

nor

a wire (because of possible damage

to

blow them clean.

to

the carburetor body.

(1

7).

If

the needle valve need be replaced, replace

of

the orifice which will

rod

more slender than the float

pin

-

44

-

9.

BREAK-IN OPERATION

An

overhauled engine must be operated at low speed break-in the parts. A thorough break-in is indispensable particularly

when

the

cylinder, piston,:piston rings

The recommended break-in schedule is shown below.

or

of

REASSEMBLED ENGINE

valves are replaced with new ones.

I
I
I

EY15

HP

1.35

2.7 HP

1

I

LOAD

EY20 EY28

NO

LOAD 2,500 rpm

NO

LOAD

NO

LOAD

1.75 HP

3.5

HP

I

I

2.75 HP

5.5

HP

CRANKSHAFT REV.)

3,000

I

3,600 rpm

I

3,600 rpm

I

3,600 rpm,

SPEED

rpm

10

10

1

10

I

30 minutes

I

60

TIME

minutes
minutes

minutes

minutes

-45

-

10.

10-1

Model

breaker type ignition device, utilizing the power transistor as an element for controling eiectric current. There are two types
of this system, the one is outer coil type without pulser and is called
type has a built-in pulser coil and is called P.I.T. (Pulser transistor type). T.I.C. is a standard ignition system for

ROBIN

FEATURES

EYl5D

and

EY20D

SOLID

can employ as option a pointless ignition system, called Solid State Ignition, whch is the circuit

STATE

IGNITION

ENGINE

T.I.C.

(Transistor ignition circuit type) and the other

('F.I.C.

and

P.I.T.)

EY28D,

B.

r

Being different from the breaker point type ignition system, this brand-new system

startingup failure owing to dirty, burnt or oxidized point surface, lowering of ignition efficiency being caused by moisture,

rough

surface of breaker point and incorrect timing resultant from worn mechanical parts.

10-2

BASIC

T.I.C. (Transistor ignition type) consists ofthe flywheel and
ignition coil with built-in transistor; and its basic theory is as
follows:

Revolution
primary side of the ignition coil, and the electric cur­rent
the electric current
The flywheel goes round further, and at the time
ignition the electric current C runs, then the electric
current
electric current
tor,
electricity
ignition coil and it sparks at the plug.

THEORY

of

the flywheel generates electricity on the

A

runs. A makes the power transistor

D

runs

is

abruptly cut; and as a result, the

is

generated on the secondary side of the

of

T.I.C.

B

passes.

to

the signal transistor,

B,

passing through the power transis-

(See

Fig.

'ON"

by

which the

high

59.)

and

of

voltage

I

Resister

is

completely free from such troubles as

-

1

T

Ignition

11

.-

&

Coil

m

C

8

01

v)

I

X

I"

Fig.

59

10-3

BASIC

P.1.T

@her ignition transistor type) consists of the igni-

tion coil,

as

follows:

1) Revolution of the
primary side
rent

the electric current

2)

The flywheel goes round further, and at the time of
ignition, the pulser coil generates electricity, and the
electric current

Then, the electric current D runs, by which the elec­tric current

voltage electricity is generated on the secondary side

of

the ignition coil and it sparks at the plug.

THEORY

P.I.T.

unit and flywheel; and its basic theory is

of

the ignition coil, and the electric cur-

A

runs. A makes the power transistor

B

is cut abruptly, and as a result the high

of

P.I.T.

flywheelgenerateselectricity

B

passes.

C

runs;

and

(See

SCR

becomes

Fig.

"ON"

60.)

on the

and

"ON."

Fig.

60

-

46

-

11.

TRQU

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

1. The cylinder filled with a proper fuel-air mixture.

2.

An

appropriate compression in the cylinder.

3.

Good sparks at the correct time 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.
pipe, just to
The most common causes of engine troubles are given below:

11-1

g.,

a heavy load on the engine when it is about to start at low speed, and a

say

a few.

STARTING

DIFFICULTIES

high

back pressure due to a long exhaust

11-1-1

7)

11-1-2

If starting difficulties and loss of power are not due to the fuel system or ignition system, the following must be checked for
possible lack

1)

2)

3)

4)

FUEL SYSTEM

No

gasoline in th fuel tank;
The carburetor is not choked enough, particularly when the engine is cold.
Water, dust
Inferior grade gasoline or poor quality gasoline is not gasfied enough to produce the correct fuel-air mixture.
The carburetor needle valve is held open by dirt or gum.
carburetor when the engine is idling. (Overflow)

Th~s

of the like.
If the carburetor overflows, excessive fuel runs into the cyhder when starting the engine, making the fuel-air mixture
too rich to burn. If this happens, remove the spark plug, and turn the starting pulley a few turns in order to let the
rich fuel-air mixture out of the spark plug hole into the atmosphere. Keep the carburetor choke open during this
operation. Dry the spark plug well, screw
When the engine is cold, pull the carburetor knob to let the gasoline

COMPRESSION SYSTEM

Engine inside is completely dried up because of a long period
Loose or broken spark plug. This causes a hissing noise made by mixture gas running out
stroke during cranking.
Damaged head gasket
Incorrect Tappet Clearance
If the correct compression is not obtained even after remedying the above, disassemble the engine and check further

or

gum

in the gasoline block flow

trouble may be remedied, depending on cases, by lightly tapping the float chamber with the grip of a screwdriver

of

compression.

or

the fuel cock is closed.

of

the fuel to the carburetor.

This

trouble can be detected as the fuel flows out

it

into place, and try to start again.

flow

into the carburetor.

of

non-operation.

of

cylinder in compression

or

loose cylinder head. A similar hissing noise is produced during compression stroke.

of

the

as follows:

a) Valve stuck open due
b) If the piston rings are stuck on the piston, remove the piston and connecting rod from the engine, and clean, remedy

or replace the parts.

to

carbon

or

gum on the valve stem.

-

47

-

11-1-3

ELECTRICAL SYSTEM

Check the following for lack

1) Leads

2)

3)

4)

5)

6)

7)

8)

9)

10) Incorrect spark timing.

11-2

1)

2)

3)

4)

5)

6)

7) Insufficient compression.

of

the ignition coil, spark plug

Ignition coil damaged and shorted.
Spark plug cable wet or soaked with
Spark plug dirty or wet.

Spark plug electrode gap incorrect.
Spark plug electrodes in contact with each other.

Contact breaker points pitted or fused.

Breaker arm stuck.
Condenser leaking

ENGINE MISFIRES

Incorrect spark plug electrode gap. Adjust it to anywhere between
Ignition cable worn and leaking.
Sparks weak.
Ignition wire connections loose.
Pitted or
Water in gasoline.

worn

breaker points.

of

sparks.

or

grounded.

or

contact breaker disconnected.

oil.

0.6

and

0.7

mm.

11-3

ENGINE

1)

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

2)

Vapor lock,

3)

Vapor lock in the fuel lines or carburetor due to the use of too volatile winter gas

4)

Air

vent hole in the fuel tank cap plugged.

5)

Bearing parts seized due to lack

6)

Magneto

114

ENGINE OVERHEAT

Crankcase
Spark timing incorrect.

Low

grade gasoline is used, or engine
Cooling air circulation restricted.
Cooling

Cylinder head
Engine operated in
Exhaust gas discha'rge restricted,
Engine running on low-octane gasoline detonates due

STOPS

i.

e., gasoline evaporating

or

ignition coil faulty.

oil

level

low,

Add

oil

air

party misdirected causes loss of coohg efficiency.

cooling

fins

clogged up with dirt.

an

enclosed space without fresh supply of cooling air.

in

the fuel lines due to overheat around

of

oil.

immediately.

is

overloaded.

or

carbon deposits in the combustion chamber.

to

heavy load at low speed.

the

engine.

in

the hot season.

-

48

-

11-5

ENGINE

1)

Low-quahty gasoline.

2)

Engine operating under heavy load

3)

Carbon or lead deposits

4)

Spark timing incorrect.

5)

Loose connecting

6)

Loose piston

7)

Causes

KNOCKS

rod

pin

due to wear.

of

engine overheat.

at

low speed.

in

the cylinder head.

bearing due to wear.

11-6

ENGINE

1)

Water

2)

Intake valve stuck.

3)

Valves overheated,

4)

Engine cold.

BACKFIRES

or

dirt in gasoline,

through

or

low-grade gasoline.

or

red-hot carbon particles in the combustion chamber.

CARBURETOR

-49

-

12.

in whch the engine

INSTALLATION

Engine life, ease of maintenance and inspection, frequency of checks and repairs, and operating cost all depend on the way

is

installed. Carefully observe the following instructions for installing the engine.

12-1 INSTALLING

,-

When mouhting the engine, carefully examine its position, the method
and the method of supporting the engine.

When determining its mounting position, in particular, make sure that gasoline and oil can easily be supplied andchecked, the
spark plug and breaker can easily be checked, the

air

cleaner can easily be serviced, and that the oil can easily be discharged.

of

connecting it to a load (machine), the foundation,

12-2 VENT1 LATlON

Fresh

air

is necessary for coohg the engine and burning the fuel.

In cases where the engine is operated under a hood

lock,

oil

deterioration, increased
to operate the engme properly, It is necessary, therefore, to provide a duct
prevent recirculation

Take steps as necessary to keep the engine room temperature below

of

the hot air used for engme cooling, and temperature rise of the load (machme).

oil

consumption,lossaof power, piston seizure, shorter engine life, etc., making

or

in a small room, temperature rise

or

baffle to guide cooling

50°C

even in the hottest period

in

the engine room can cause vapor

it

impossible

air

to the engine to

of

the year.

12-3 EXHAUST GAS DISCHARGE

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

is

used in such a case, the internal resistance increases causing loss of engine power.

crease

in

proportion

Exhaust pipe:

to

exhaust pipe length.

Less

than 3 m long, pipe inside diameter

Less

than 5 m long, pipe inside diameter

25

rnm,

30 mm.

Thus

outdoors.

pipe inside diameter must in-

If

a long exhaust

12-4 POWER TRANSMISSION

12-4-1

Take the following notes into consideration.

If

12-4-2

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 couphg manufacturer.

BELT

DRIVE

*

V-belts are preferable to flat belts.

*

The driving shaft

*

The driving pulley of the engine must be in line with the driven pulley of the load.

*

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

*

If

possib!e, span the belt horizontally.

*

Disengage the load when starting the engine.

no clutch

is

used, use a belt tension pulley

FLEXIBLE

of

the engine must be parallel to the driven shaft

COUPLING

to

DRIVEN MACHINES

or

the like.

of

the load.

-

50

-

12-5

WIRING

RECOIL STARTER OPERATION

Wire as shown

ing

coil

for

Models

an

intermediate tap.

[BREAKER

POINT IGNITION TYPE]

in

the wiring diagram below. Normally, those indicated

EY15,.EY20 and EY28

Condenser

(an

optional, not standard accessory) permits installation

Ignition

Magneto

Fig.

61

by

dotted lines are not included in engine wiring. Light-

of

an

AC

buzzer with

Coil

2

m

3

-

n

?

m

P

v)

[SOLID

1.

T.

STATE IGNITION TYPE for

I.C.

(Standard)

MODELS

EY15

and

EY201

2.

P. I.T. (with lighting coil)'

BlacklYellow

Spark Plug

Buzzer Switch

Fig.

62

""

Fig.

63

-

51

-

[SOLID STATE IGNITION TYPE for MODEL EY28l

1.

T.

I.

C.

(Standard)

Ignition Coil Connecter

Spark

Plug

Exciter Coil
(Option)

Flywheel

Fig.

c

Stop Button

l-

Black

rrm

64

[ELECTRIC STARTER TYPE for MODEL EY281

Ignition

S

r-----

77h

I""

Battery

(12V

Coil

Unit

24AH)

Key Switch

Black

Starting Motor

/"-

Fig.

-

65

52

-

13.

ELECTRIC

SBA

TBNG

MOTOR

(OPVBO

for

EV28

ONLY)

13-1

SPECIFICATIONS

Part Name

Maker

Voltage

output

Weight

Starting Motor

Nihon Denso

12v

0.6

kW

3.0

kg

K.

K.

Bolt

Drive Lever

13-2

Connect the
ing motor magnet switch.
The state
ing figure:

When the key switch is put to

closed and the current flows
The magnet switch coil is excited, and the contact

UP.
Then the continuity

pinion gear
The pinion gear is engaged with the ring gear, and the
engine cranking is made.
This means that the lower current flows in the

and

OPERATION

(t)

of

starting motor

is

instantaneously pushed out

in

the

S-+

circuit larger starter current

side

of

battery to the

“ON”

to

is

made to the starting motor, and the

8$

terminal

is as shown in the follow-

“ON,”

the

M+

the arrowhead direction.

by

the drive lever.

flows.

of

circuit is

is

drawn

M+

circuit,

start-

Stop

Collar

Fig.

66

From Rectifier

Battery

Magnet Switch

Fig.

67

1

Key Switch

B

-

53

-

14.

RECOIL

STARTER DISASSEMBLY

and

REASSEMBLY

The recoil starter hardly

form disassembly and reassembly in the following procedures:

Tools to be used:

14-1

HOW

TO

Remove the recoil starter from the engine with a box
spanner.

Pull

the starting knob and pull out the starter rope

30

to

40

cm. Firmly press the reel with a thumb as
shown in
verse turn ai the place where the reel notch comes to
the outlet
the inside
utilize the reel notch, and rewind it until the rotation
stops in the arrowhead direction, braking the reel rota­tion with

Fig.

of

of

a

thumb.

has

a trouble in the normal use, however, in case

Box

spanner (spanner), Cutting pliers (pliers) and Screw driver

DISASSEMBLE

68

so

that the reel should not make re-

starter rope. Pull out the starter rope

recoil starter with a screwdriver. Then,

(D

Type)

for

to

it

has a trouble

Starter

or

at the time

Rope

Starter

Fig.

68

Notch

of

lubrication, per-

%

Knob

'4

3)

When removing, take out the parts in the order
numbering in Fig.

1.

U

2.

Thrust washer

3.

Friction spring cover

4.

Return spring

5.

Friction spring

6.

Ratchet

Meantime,

shaft with cutting pliers

69.

type snap ring

for

removing the U type snap ring, nip the

and

push it out.

of

the

2

@-"

353

Fig.

69

-54-

b

Take out the reel from the starter case as shown

4)

70:
In this case, slowly take out it turning the reel lightly
toward left and right

so

that the spring is removed
from the reel hook section.
If the reel is suddenly taken out, there is
spring jumps out in the form as it

so

very dangerous,

(If

the spring jumped out, house it in the starter

instructed in Fig.

be carefuly of it.

75.)

a

fear that the

is

hooked, whch is

Finally, release and take out the starter rope tied to
both the reel side and the starting knob side.
Thus, the disassembly work ends.

in

Fig.

case

as

I

Starter Case Spring

Fig.

70

14-2

1)

HOW

TO

REASSEMBLE

(Type

D)

First, have the starter rope pass through the starting
knob, and tie the rope as shown in Fig.
Then, have the opposite side

of

71

No.1.

the rope pass through
the starter case and the reel, and tie it as shown in
Fig.

71

No.2.

(In

the Fig.

you see

Then surely house the end

71

both the ropes

in

figures

No.

1

and

are

tied quite lightly, as

No.2.

in

Please note this is

just for the purpose of easy understanding. Therefore,

when actually tying, tie the rope as tighteiy as possible.

2)

Confirm that the spring
housing section, and have the spring to form
inner edge will be about
and that it

hooks

surely the reel hook.

is

surely set in the starter case

so

1

mm from the starter shaft

Meantime, with the pliers about 10 cm long spring
the inner edge can easily be formed.

the reel.

that its

from

No.2

Outer

Edge

Fig.

of

Spring

71

Good

No.1

/

Reel

Hook

-

55

Starter Shaft

-

4cm

\

Inner Edge

Fig.

72

of

Spring

3)

Before putting the reel in the starter case, wind the

starter rope in the arrowhead direction as shown

73,

and at

2.5

windings take out the rope from the reel

hook

notch. Set the reel

to the inner end of the spring,

in

and put the reel in the starter case.
(At this time, confirm that the reel hook is duly set

the spring.)

in

Fig.

Then, hold the starter rope as shown

4

turn the reel

times in the arrowhead direction, When

wound up, firmly press the reel not

to

73,

allow reverse

turn, and pull the starting knob. Then, pull out from

the starter case the starter rope utilized for winding,
and slowly return khe starting

4)

When reassembling the parts, follow up in the reverse
order

to

Fig.

69.

knob.

When putting the friction plate in the hole for it, set
the return spring

a

little upward as shown in

Fig.

74

that the friction plate can easily be put in the hole for
it.
Next, turn the friction plate in the arrowhead direction

till the position where its notch matches with the ratch­et. Push firmly the friction plate to the reel side, and

a

U

put the thrust washer and then clamp it with

shape

snap ring.

U

(Clamp the

shape snap ring with cutting pliers.)

Fig.

to

and

so

Fig.

73

t

With the above, the disassembly and reassembly

assembled. Therefore, for caution's sake check the function

in

described

the next page.

works

end, however, there

-

56

Fig.

74

is a case that the parts are

of

the recoil starter following the confirmation items

-

not

properly re-

14-3

CONFIRMATION ITEMS AFTER REASSEMBLY (Type

1)

Pull

the starting knob

i)

If

the starting knob is felt heavy to pull and cannot be pulled, check whether the parts were reassembled correctly

2

or

3

times, and pull out the starter rope a little.

as instructed.

n)

If the ratchet does not function, check whether the spring is hooked properly.

2)

Pull the starting knob, and pull out the starter rope all the way long.

i)

If

the starter rope remains left in the reel or the starter rope does not return at all, immoderate strain is imposed on

the spring.

ii)

If the return power of the starter rope is weak
mobile
tions explained in the paragraph

iii)

If the sound is heard that the spring is falling off, and the starter rope cannot.be wound in relay, reassemble once

So

rewind the starter rope

oil

in the frictional portions. If it does not revive yet, wind it

1

or

i)

above and

2

times as per instruction in Fig.

or

the starting knob is drooped

confirm

again from the biginning.

D)

68.

on

the way, inject a few drops

1

or

2

times.

(In

this case, refer to the instruc-

whether or not immoderate strain is imposed

on

the spring.)

of

14-4

HOW

TO

DO

IN

SUCH

1)

In case the spring jumps out when disassembling

CASES!

With thin wire make a ring smaller than the case for
spring, and hook the outer edge of spring on the part
of the ring

as

shown

in

Fig. 75. House it in the spring

housing section of the reel, and calmly remove the

ring, pressing the spring with fingers

so

as not
out.
The ring can easily be removed by gouging it with the
tip of the screwdriver or the like.
Meantime, refer to Fig.

72

for

not

to mistake the hous-

ing direction of the spring.

2)

In

case of lubricating

Lubricate the rotating parts, frictional parts and spring
with heat resistant grease, if possible,
the time of disassembly

3)

In

case the direction of rotation

or

at the end

or

mobile oil at

of

season for use.

is

reverse (Type

to

come

B)

Fig.

75

As

this manual is

for

right rotation

recoil

starter, perform reverse

work

for

left rotation recoil starter.

-

57

-

15.

After disassembling and cleaning the engine, check and repair, if necessary, according to the correction table. The correction
table applies whenever the engines are repaired.
table. Correct maintenance
The meanings of the terms

CHECKS

Correction

Repair, adjustment
Correction Limit
The limit on wear, damage or functional deterioration of engine parts beyond which normal engine performance can­not be expected without repairing such parts.
Use Limit

The limit beyond which parts can
Standard Dimensions

The design dimensions

Correction Tolerance

Tolerance on the dimensions

and

CORRECTIONS

It

is important for the servicemen to be familiar with the contents of this

is

recommended by observing the correction standards specified.

used

in the correction table

or

replacement

of

new parts minus tolerance.

of

any engine parts.

no

longer be used in respect of performance

of

engine parts refinished or adjusted.

are

as follows:

or

strength.

P

-

58

-

16.

TABLES

OF

CORRECTION STANDARDS

ITEM

Flatness of cylinder

head

Bore

Roundness 0.01

Cylindricity

Valve seat contact
width

at skirt,

0.25

I.D.

in

Valveguide

O.D.

thrust direction

(incl. over size)

0

C 0.5

ENGINE

I

MODEL

I

EY20
EY28

EY 15

EY

20

EY28
EYl5

EY 20
EY

EY15
EY20
EY 28

EY 15

EY15

I

EY20
EY 28

EY15

EY28

1

1

28

1

1

S.T.D.62.98 dia.

B

S.T.D.66.98dia.

S.T.D.

B
C

STANDARD

SiZE

Less

than 0.1

S.T.D. 63 dia.

67 dia. rnax.

S.T.D.

75

dia.

6.5@

63.23 dia.

67.23 dia.

74.98 dia.

75.23 dia.

75.48 dia.

.

-

+0.019

I

Dif.

0.01

1.2

+0.022

-

between

&

rnin.

5

-1.5

0

0.02

0

1

0.15

0.1

5

2.5

0.1

5

-0.1

USE

LIMIT

0.65

0.1

-0.1

REMARKS

7

I

5

At middle
portion

1

plate,

Cylinder
gauge

Micro­meter

TOOL

CORRECTION

METHOD

Correct

Boring

Correct

Replace

Replace

EY15

I

EY2O

Width

of

ring

groove

1

Piston

pin

hole

EY15

Clearance between

piston

and

cylinder

Clearance between
pisition ring and
ring groove To

EY20

EY

EY 20 0.010-0.055

28

I

I

I

Oil

Top 1.5

Oil

"*

14 dia.

16

30

dia.

P

I

+0.060

t0.040

+0.002

I

-0.009

+0.002

-

0.009

0.020-0.059

0.040-0.079

0.090-0.135

0.060-0.1

0.010-0.065

0.050-0.095

0.010-0.065

-

59

05

-

I

0.035

-

0.025

0.1 5

Replace

0.035

Max. cylin-

thrust direc­tion

5

0.1

5

Micro­meter

Replace

Replace 0.1

Clearance between
pirition ring and

ring groove

Fit between piston
and piston

Ring

Ring width 2nd

pin

gap

ENGINE STANDARD CORRECTI,

MODEL TOLERANCE

EY28 0.01 0-0.065

EY15

1

EY20

1

EY

28

EYZO

I

EY28

TEY15

1

1

Oil

2nd

2;

Oil 2.8 -0.010--0.030

TOP

2.0

2.0

011

2.8

Top

1.5

2nd 1.5 4.010-

Oil

3.0

0.050-0.090

0.01 0-0.065

-0.009-0.010

0.20

0.05

0.1

~~~

-0.090--0.110

-0.060--0.080

T

-0.050--0.070

-0.010--0.030

-0.010--0.030

-

-

-

0.40

0.25

0.3

0.030

Y

LIMIT

0.1

5

0.06L

1.5

-0.1

I

USE

LIMIT

0.1

0.06L

1.5

-0.1

5

REMARKS

I

1

TOOL

Feeler

gauge.
Micro­meter

Feeler

CORRECTION

METHOD

Replace

Replace

Replace

0

-

I

I

end

Large

Clearance between EY20
rad large end
and crankpin EY28 0.020-0.046

Small end I.D. 0.010-0.021

Clearance between

small

and pinston pin

Large

clearance

Parallelism between
large end and

small

I.D.

end I.D.

end

side

end bores

I.D.

1

1

EY28

EY15 24 dia.

EY

20 26 die.

EY

28

EY15

EY

28

Ey15

EY20 0.010-0.029

EY28

EY15

EY

15

EY28

EY20

14 dia.
16 dia.

I I

28

dia.

14 dia.

16

dia.

1

I

I

-0.008

+0.013

0.037-0.063

0.1

-

0.3

0.05

-

0.04

0.1

0.2

0.08

0.1 2

1

0.1

.o

-0.04

0.1

0.2

0.08

0.1

2

1

.o

0.1

Micro­meter

Cylinder

Cylinder

gauge,

Micro­meter

Cylinder
gauge

Cylinder
gauge.
Micro-

meter

Feeler

gauge

Test

bar

and Dial

Replace

Replace

Replace

Replace

Replace

Rernachine

or Replace

Re-machine
or Replace

Distance between
large

end

small

and

end bores

EY

28

100

0.15

-

60

-

ITEM

Crankpin

roundness

0.D

AODEL

EY28

EYt5
EY20

EY 28

24

1

28

1

die.

dia.

l-

CORRECT1

TOLERANCE

-0.037

-0.050

-0.020

-0.033

Less

than 0.005

N

LIMIT

0.1 5

TOOL

0.5 Crankpin O.D.

Micro­meter

Micro.
meter

CORRECTION

METHOD

Re-machine

or

Replace

Crankpin O.D.
cylindricity

Crankpin O.D.
parallelism

Crankshaft

journal

O.D.

lobe

Cam

Journal

height

O.D.

EY15

EY 20

EY28

EY20

EY15

EY 158

EY 28D

Drive

Mag.

8.

Drive

Mag.

s.

Drive

Mag.

s.

Drive

s.

Mag.

t-

Drive

Mag.

s.

Drives. 15dia.

s.

Mag.

s.

25

25

s.

25 die.

25

s.

30 dia.

30 dia.

s.

15

15

s.

25 dia.

15 die.

25

die.

dia.

die.

dia.

dia.

dia

Less

than 0.005

Less

than

0.008

-

O.OO3

-

0.01

2

io.1

-0.01

6--0.027

-0.003--0.012

-0.016--0.027

-0.016--0.027

-0.020--0,033

-

0.05

-

0.25

-0.05

Micro­meter

Dial

wuge

-

0.05

-

0.25

I-

-0.05

Micro­meter

Micro-

meter

Micro­meter

Replace

Replace

Replace

length

Free

Squareness

EY28B

EY15
EY 20
EY 28

EY15
EY 20
EY 28

Drive

Mag.

s.

30 dia.

s.

37

25 dia.

-0.003--0.012

-0.020--0.033

-61

-1.5

,

,o

1

For total
length

Vernier

calipers

Square

Replace

Replace

-

ITEM

ENGINE STANDARD CORRECT1

1

MODEL

I

SIZE TOLERANCE

N

LIMIT

USE

LIMIT

REMARKS

CORRECTION

I

METHOD

Clearance between

stem and guide

Clearance between
groove and retainer

Stem

end length

EY15

EYrn Intake
EY 28 Exhaust

EY15

Intake 0.025
Exhaust

I I

I

EY,5

I

Intake Exhaust 5.9

I

EY2O

I

Intake

Exhaust

Tntake
Exhaust

I

EY15

I

EY28

35.6

43.7

5.9

6'2

6.4

4.45

0.056

0.025

0.056

1

I

I

When

0.10

0.1

-

0.062

0.1

-

0.062

-

0.100

cold

*0.02

-

0.3

00

-0.15

"

0.3

blow

0.05

abow

0.25

0.5

-1

.o

-

0.5

0.3

0.5

-1

-

0.5

.o

At middle

Micro-

meter

Cylinder
gauge

Feeler

gauge

Feeler

gauge

Vernier
calipers

Vernier
calipers

Replace

Replace

Correct

Replace

Replace

Replace

stem and guide

Spark plug

Spark gap

Spark timing

Point opening

EY28

1

I

EY28

EY15

I

:;:

EY15
EY 28

I

EY20

I

NGKBBHS

I

NGK

I

23'before

I

BPBHS

T.D.C.

1

0.013

0.013-0.043

1

I

0.6

f

-

-

0.05

0.037

0.7

0.2

t

f

1

5"

0.1

0.2

Feeler

Timing
tester

breaker Adjust
spanner

I

1

Adjust
replace

Adjust

or

-

62

-

tTEM

MODEL

HP/rpm

CORRECTION

LIMIT

REMARKS

Max.

output

Continuous

Output

ITEM

Fuel

Consumption

ITEM

Lubricant

Consumption

Rated

EYISD
EYl5B
EY2OD

EY28D
EY 288

EY15D

EYl58
EY2OD
EY 28D
EY28B

EY15

EY20
EY28

MODEL

EY15

EY20
EY28

3.514000

3.512000

5.0/4000

7.514000

7.512000

2.713600

800

2.711

3.513600

5.513600

800

5.511

liter/hr MODEL

1.1

1.2

2.7

cc/hr

10

15

Below

110%

of

rated

output

CORRECTION PRECISENESS

135%

of

the

standard value

LIMIT

50

60

cc/hr

and

up

CORRECTION PROCEDURE

3600

rPm at cOnthuOuS rated

REMARKS USE

Output

c

*Use the

ITEM

Fixed quantity

of

Lubricant

SC

ITEM

Specified Lubricant
Qualiw

MODEL

EY15
EY20

EY28

or higher grade engine oil.

MODEL

EY15

EY20
EY28

Q

0.6

0.85

Comparison between oil viscosity and temparature

r

Single
grade

Multi­grade

-20

?,I,

I

I

I

-10

1OW-30

I

0

10

I

I

!,

#30

1

#40.

1

I

30 4OoC

I

20

I

I

REMARKS

I

When the peripheral temparature

below -2OoC, use the oil

and

quality fitted to the local conditions.

When the peripheral temparature

I

than 4OoC. use the oil

I

quality fitied to

The oil consumption
when

used

rature,

day.

REMARKS

the

local conditibns.

under high peripheral tempa-

so

it

is

necessary to check every

of

viscosity

of

vismsitv and

is

apt to increase,

is

is

more

I

I

I

~~.

1

If

quality and quantity

of

the engine oil become lower or less, burning might be caused

-

63

-

ITEM FREOUEMCYOFOILCHANGE

Oil Chaw

ITEM

Cylinder prowre

ITEM

Mn. acderating
molution

ITEM

Cylinder haad EY

bolts

EY15
EY 20
EY

28

MODEL

EY15

EY2O

28

EY

MODEL

EY 15D
EY

15B

EYZOD
EY28D
EY28B

I

MODEL

20

EY28 220

kglcm'lrpm

00

514

61400

rpm

1200

600

1200

1200

600

I

kgem

190

-

-

First time: Change

Second Time and Thereafter: Change

CORRECTION LIMIT

70%

of

and down

TOOL

I

I

ft-lb

230

260

oil

after

normal value

I

TOOL

20

houn operation.

oil

every

50

hours operation.

TOOL

Pressure gauge

REMARKS

I

I

REMARKS

Torque wrench

REMARKS

Reference value
Crankshaft

Rev.

-_

Connectin0

twin

Magneto clamp
nuts

..

WlfS

Smrk

rod

Plug

EY15

EY 28
EY15

I

Ff;:

I

EY28

EY28

SO-

-

170

1

600-

1

170-

120

-

230

-

115

200

650

190

150

270

I

1

Torque wrench

Toraue wrench

Torque wrench

-64-

&

-

17.

me following maintenance jobs apply when the engine
tenance intervals are by no means guarantees for maintenance free operations during these intervals.

17-1 DAILY CHECKS and MAINTENANCE

MAINTENANCE

For

example,

every

50

if

hours.

the engine is operated

and

STORING

is

operated correctly under normal conditions. The indicated main-

in

extremely dusty conditions, the

air

cleaner should be cleaned every day instead

of

I

Remove dust from whatever parts which

accumulated dust.

I

Check external fuel leakage. If any, retighten
replace.

I

Check screw tightening. If
re-tighten.
Check

17-2 EVERY

I

Change crankcase

Checks and maintenance

any

loose one

oil

level in crankcase and add up as necessary.

20

HOURS CHECKS

Checks and maintenance

oil.

is

found,

and

MAINTENANCE

I

The governor linkage

Not

or

only

Loose

accidents.

If

the engine

I

To

remove run-in wear particles

Reasons for requiring them

is

especially susceptible to dust.

wasteful but also dangerous

screws and nuts

is

operated without sufficient

Reasons for requiring them

will

result

in

vibration

oil,

it

will

1

17-3 EVERY

Change crankcase
Clean

air

Check spark plug.
gasoline

17-4 EVERY 100

or

I

I

Clean fuel filter and fuel tank.
Clean contact breaker points.

50

HOURS (10 DAYS) CHECK and MAINTENANCE

Checks and maintenance

cleaner.

polish

-

Checks

oil.

If

contaminated, wash in

with

emery paper.

200

HOURS (MONTHLY) CHECKS

and

maintenance

Contaminated

Clogged

Output power is reduced and starting

is

air

made difficult.

and

~~ ~ ~~~

I
1

The engine

I

The engine output drops.

-

65

-

Reasons for requiring them

oil

accelerates wear.

cleaner harms engine operation.

MAINTENANCE

Reasons for requiring them

will

be out

of

order.

17-5 EVERY

500-

600

HOURS (SEMIANNUAL) CHECKS

and

MAINTENANCE

Checks

Remove cylinder head and remove carbon
deposit.

Disassemble and clean carburetor.

77-6

EVERY 1000 HOURS (YEARLY) CHECKS

Checks and maintenance

Perform overhauls, clean, correct

parts.

Change piston

Replace fuel

rings.

pipe

17-7 PREPARATION

1)

Perform the above

2)

Drain

fuel from the fuel tank and carburetor

3)

To

prevent rust in the cylinder bore, apply oil through the spark plug hole and turn the crankshaft several turns by

hd. Reinstall the plug.

4)

Turn the starting pulley by

5)

Clean the engine outside

6)

Put a vinyl

or

17-1

other cover

and

maintenance

The engine

and

MAINTENANCE

or

replace

once a year. To prevent

for

and

with

over

LONG

17-2

hand

ABEYANCE

maintenance

and leave

oiled cloth.

the engine and store the engine

jobs.

float

chamber.

it

where the resistance

The engine output drops and become out

is

the heaviest.

in

dry place.

Reasons for requiring them

will

be out of order.

for

Reasons

from

danger caused by the fuel leakage.

requiring them

of

order.

1

-

66

-

Industrial

Engines