Robin EH18V Service Manual

SERVICE

MANUAL

IVIodel

EH18V OHV

396S322

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

Title

Page

1

. SpEClF[CATlONS

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

1

2.

PERFORMANCE ............................................................................................

2

2-1 Maximum Output

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

2-2

Maximum Torque

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

2

2

2-3 Performance Curves

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

2
3

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

3

3

. FEATURES

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

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

5

. DISASSEMBLY AND REASSEMBLY

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

11

.

11
11
12
27

5-5

Break-in Operation

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

40
41

6-1 Flywheel Magneto

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

41
41

5-1 Preparations and Suggestions

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

5-2 Special

Tools

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

5-3

Disassembly Procedures

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

5-4 Reassembly Procedures

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

6 . MAGNETO

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

6-2 Basic The0

ry

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

6-3

Wiring Diagram

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

42

7.AUTOMATlC DECOMPRESSlON SYSTEM

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

43

8.CARBURETOR

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

44

.

8-1 Operation and Construction

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

44
45

47

47

8-2

Disassembly and Reassembly

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

9 . STARTING SYSTEM

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

9-1 Recoil Starter

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

Section

10.

TROUBLESHOOTlNG

10-1 Starting Difficulties
10-2 Engine Misfires
10-3 Engine Stops
10-4 Engine Overheats
10-5 Engine Knocks

10-6

Engine BacMires Through Carburetor

11

.

lNSTALMTlON

11-1 Installing
11-2 Ventilation
11-3 Exhaust Gas Discharge

12

. SERVICE DATA

12-1 Clearance Data and Limits
12-2 Torque Specifications
12-3 Oil Grade Chart

13.

MAINTENANCE AND

13-1 Daily Maintenance (Every
13-2 Initial
13-3

Every

13-4 Every 100-200 Hours (Monthly) Maintenance
13-5 Every
13-6 Every
13-7 Engine Storage

Title

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

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

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

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

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

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

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

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

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

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

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

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

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

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

STORAGE

8

Hours)

20

Hours Maintenance

50

Hours (10 Days) Maintenance

500-600

1

000

Hours Maintenance

Hours (Yearly) Maintenance

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

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

Page

51

51
52
52

52

53

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

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

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

53

54

54

54

54

55
55

61

61
62

62

62

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

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

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

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

62

63
63

63

63

..

1.

SPECIFICATIONS

Model

TY

Pe

Bore

X

Stroke

Piston Displacement

Maximum Horsepower

Maximum Torque

~ ~ ~~~~

Rotation

Cooling

~

Lubrication

EH18V

Air-Cooled, 4-Cycle, Vertical Shaft, Overhead Valve, Gasoline Engine

(2.64

4.4 /3600
(6/3600

1.29 / 2700

(9.3/2700

Counterclockwise

'

'

Forced Air Cooling

67 X 52

(1 1.1 6

As

Oil Pump Type

mm

X

2.05

in.)

183

cc

c,u.in.)

KW/

rpm

HP/rpm)

kg-m / rpm

ft. Ibs/rpm)

Viewd From PTO Shaft Side

Lubricant

Carburetor
Fuel

Fuel Feed

~ ~~ ~ ~~

Governor System
Ignition System
Spark Plug

Starting System
Dry Weight

Dimensions Without

P.T.0

Shaft

LXWXH

I

Oil

SAE

Automobile

Horizontal Draft Type

Automobile Gasoline

Gravity Type

Centrifugal Flyweight Type

Flywheel Magneto (Solid State)

CHAMPION

Recoil

17

409 X 372

Specifications and dimensions are subject to change without notice.

x

31 1 mm

#20, #30 or 1OW-30

L86C

Starter

kg

(37.5

Ibs.)

(16.10 X 14.65 x 12.24

in.)

-1-

2.

PERFORMANCE

2-1

MAXIMUM OUTPUT

The maximum output
valve fully opened after its initial break-in period when all the moving parts are properly worn in.

Therefore, a new engine may not produce the maximum output in the beginning because the moving

parts are not in a properly worn-in condition.

2-2

MAXIMUM TORQUE

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

output.

2-3

PERFORMANCE CURVES

EH18V

of

an engine

5.2;

(7.

0

Tn"--r

4.41

(6.0

is

such a standard power

""_~_

as

produced by the engine with

"""

"""_

"""

its

throttle

7.4!

(2.

0

2000 2400 2800 3200

REVOLUTlON

-

3600

r.p.m

"i

-2-

3.

FEATURES

1.

The overhead valve design offers compactness, light weight and ideal combustion characteristics
resulting in more power

2.

The parts

3.

The automatic decompression system offers easy and sure starting.

4.

The muffler and carburetor are located

flow

5.

The oil pump and oil filter provide excellent lubrication regardless of engine posture during
operation.

6.

This engine

7.

The Pro-Poly version engine is covered with a stylishly designed
fuel tank incoroprated into it.

'8.

The Classic Steel version does not have the shroud or combined fuel tank.

4.

GENERAL DESCRIPTION

4-1

CYLINDER AND CRANKCASE

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
output shaft side, where the main bearing cover is
attached. (See Fig.

such

as a large capacity muffler, dual element air cleaner reduce noise

much easier in the design of power equipment.

is

offered in two stylish versions.

4-1.)

from

less fuel and prolonged engine life.

on

opposite sides, making the arrangements

OF

on

ENGINE COMPONENTS

the

shroud

with the

to

a minimum level.

for

cooling air

4-2

MAIN BEARING

The main bearing cover is an aluminum
diecasting, which is mounted
side of the crankcase. Remove the main bearing
cover

to

inspect inside
The main bearing cover also functions as an oil
pan, with,a trochoid

(See Fig.

4-2.)

COVER

of

the engine.

oil

pump and

..

on

the output shaft

oil

filler.

-3-

Fig.

Fig.

4-1

4-2

4-3

CRANKSHAFT

The crankshaft is a forged carbon steel, and the
crank pin

is

induction-hardened. The PTO end
the shaft has a crankshaft gear which is pressed
into position. (See

44

CONNECTING

Fig.

ROD

4-3.)

AND PISTON

of

Fig.

CRANKSHAFT

4-3

r,

GEAR

The connecting rod

is

a forged aluminum alloy,
and its large and small ends function as bearings.
The piston

4-5

CAMSHAFT

The camshaft is a hollow shaped

is

an aluminum alloy casting, and

and

made of
special cast iron with the camshaft gear casted
together.

A

centrifugal decompression lever is assembled
the camshaft. The lubrication oil
by the groove
(See Fig.

4-5.)

on

the end of the camshaft.

pump

is driven

on

Fig.

4-4

-4-

Fig.

4-5

4-6

VALVE ARRANGEMENT

The intake valve is located at flywheel side

'

cylinder head.

of

the

Hard alloy valve seats are 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.

(See

Fig.

4-6.)

4-7

CYLINDER HEAD

The cylinder head ,is an aluminum die casting,.
which utilizes wedge type combustion chamber for
the highest combustion efficiency.
(See Fig.

4-7.)

EXHAUST

Vi

Fig.

II

4-6

n

4-8

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 bearing cover and driven
camshaft gear. (See Fig.

4-8.)

by'

the

-5-

Fig.

Fig.

4-7

4-8

4-9

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

0

LUBRICATION

EH18V
EH18V

has a trochoid pump outside the main bearing cover that is driven by the camshaft.

uses

forced

splash

type lubrication.

(See

Fig.

4-9.)

/

M6

FLANGE BOLT

OIL

SHELTER

...

PLATE

1

pce.

CAMSHAFT

M,

AIN BEARING

COVER

OIL PUMP

COVER

Fig.

4-9

-6-

&-

M6

FLANGE

BOLT

...

4pcs.

4-1

1

IGNITION

The

ignition system

magneto ignition system which consists of a

SYSTEM

is

a transistor controlled

fly-

wheel and an ignition coil with a built in transistor

mounted on the crankcase.
This system has an automatic ignition timing
advancing for easier starting. (See Fig.
For details, refer to page

39,

section

4-10.)

6.

4-12

CARBURETOR

The engines are equipped with a horizontal draft
carburetor

that

has a float controlled
and a fixed main jet.
The carburetors are calibrated carefully for the
sure starting,

good

acceleration, low fuel con­sumption and sufficient output.
For the- datails, refer

CARBURETOR”.

4-13

AIR

The air-cleaner

.

element system. (See

(See

CLEANER

is

to

page 42, section

Fig.

4-11.)

a heavy-duty type with a dual

Fig.

4-12.)

fuel

system

“8

WING

BOLT

GROMMET

I;’

eo

.

Fig.

4-1

1

<

#(URETHANE FOAM)

:’

.

.’

J

CLEANER COVER

PRIMARY ELEMENT

-7-

Fig.

SECONDARY ELEMENT

SECONDARY ELEMENT

PAPER ELEMENT)

(PAPER ELEMENT)

4-12

4-14

DECOMPRESSION

An

automatic decompression mechanism which
opens exhaust valve
compression top is assembled
easy starting. (See
For details, refer

to

Fig.

page

SYSTEM

before

4-13)

41,

the piston reaches

on

section

the camshaft for

7.

[

AUTOMATIC DECOMPRESSION

RETURN SPRING

&$

SYSTEM

n

-a-

4-15

SECTIONAL

VIEW

OF

ENGINE

RECOIL

STARTER

\

BLOWER

I

HOUSING

MAIN

BEARING COVER

-9-

CRANKSHAFT

SPARK

PLUG

MUFFLER

CONNECTING

-

10

-

ROD

5.

DISASSEMBLY

5-1

PREPARATIONS AND SUGGESTIONS

AND

REASSEMBLY

When disassembling the engine, remember the locations

1)

reassembled correctly. If you are uncertain of identifying some parts,
attached to them.
Have boxes ready to keep disassembled parts

To

prevent missing and misplacing, temporarily assemble each group

Carefully handle disassembled parts, and clean them with

in

Use the correct tools

5-2

SPECIAL

I

I

228-

I

Market

TOOLS

Tool No.

95003-07

parts

PISTON

the correct way.

I

I

Piston ring compressor

I

Flywheel puller

RING

COMPRESSOR

Tool

by

group.

of

the individual parts

oil

if

necessary.

I

I

For placing piston ring

1

For

/

/

of

pulling

so

that they can be

it

is suggested that tags

disassembled parts.

Use

off

the flywheel

be

I

I

I

-

11

Fig.

-

FLYWHEEL PULLER

5-1

5-3

DISASSEMBLY PROCEDURES (CLASSIC STEEL) / (PRO POLY)

~~

Step

I

Part

to remove

Spark

plug

I

Remove spark plug cap and spark plug.

Procedures

'I

Oil

drain,

oil

(1)

filter

and

Remove

(2)

Remove

(3)

Remove oil filter. bracket

(4)

Remove

M6X

oil

gauge.

oil

drain

oil

filter bracket.

12mm

bolt

plug

....

and

2pcs.

drain

oil.

II

I

~~

Remarks

I

19mm

14mm box wrench

lOmm

Tool

plug wrench

box

wrench

OILGAUGE

y

T

OILGAUGE

p

T

SPARK PLUG LTER

OIL FILTER BRACKET

OIL DRAIN PLUG

'

M6

BOLT

'..

2pC~.

-

mm

SPARK PLUG

,

'

OIL FILTER BRACKET

Fig.

5-2

-

LTER

'

12-

OIL

~AC

clni

DRAIN

r

...

PLUG

gnrc

5-3

DISASSEMBLY PROCEDURES (CLASSIC STEEL) -CONTINUED

Part

to

remove

Procedures

Recoil starter

Fuel tank

M6

FL

Remove recoil starter from the engine.

M6X8mm

bolt

-0..

4pcs.

(1) Remove fuel tank.

M6X 12mm

bolt

.-**

2pcs.

(2) Remove fuel pipe from the fuel tank.

(3)

Remove side guard.

M6

X

12mm

bolt

*

-

Zpcs.

(4)

Remove bracket (fuel tank)

....

(stop

lpce.

switch).

RECOIL

STARTER

M6X 14mm bolt

(5)

Remove cover

ASS’Y

lOmm box wrench

M6

FLANGE

BOLT

-8-

GPCS.

COVER

(stop switch)

HOSE

CLAMP

-

Fig.

13’

I.

5-3

-’

M6

SIDE

GUARD

FLANGE

BOLT

. .

.

1

pce.

5-3

DISASSEMBLY PROCEDURES (CLASSIC STEEL) -CONTINUED

-

Part to remove

Step

Procedures

-

5

Air cleaner

(1) Remove air cleaner cover and air cleaner

element
M6 wing bolt

(2) Remove breather hose from cleaner

and crankcase.

(3)

Remove air cleaner base from air cleaner
bracket.
M6X12mm bolt

(4) Remove cleaner base and gasket (air

cleaner) from carburetor.
M6

nut

(5)

Remove bracket
M6X 12mm bolt

(6)

Remove bracket

M6

X

14mm bolt

M6x 14mm tapping

....

**--

.--.

2pcs.

(A/C)

....

(NC

lpce.

Ipce.

from the engine.

lpce.

cover)

-

1 pce.

bolt

....

lpce.

base

-

PROCEED TO STEP

7

OF DISASSEMBLY PROCEDURES

M6

X

14mm

BOLT

...

lpce.

M6

Remarks

WING BOLT

...

Ipce.

Tool

lOmm box wrench

lOmm

box wrench

lOmm box wrench
lOmm box wrench

M6 x 14mm

AIR

CLEANER

COVER

AIR CLEANER

AIR CLEANER BASE

HOSE

Fig.

5-4

-

14-

CLAMP

M6

NUT

...

~PCS.

BREATHER HOSE

5-3

DISASSEMBLY PROCEDURES (PRO POLY) -CONTINUED

Part

to

Step

3

4

5

remove

Top cover

Recoil starter

Air

cleaner
cover and
engine shroud
(with fuel

tank)

L

TOP

Procedures

Remove top cover from the engine.
MSX 16mm tapping screw

Remove recoil starter from the engine.

M6

X

12mm bolt

(1)

Remove air cleaner cover and element
M6 wing bolt

(2) Remove fuel pipe

(engine shroud).

(3)

Remove engine shroud.
M6X 12mm

(4)

Remove bracket
M6X14mm bolt
M6X 14mm tapping bolt lpce.

COVER TAPPING SCREW

.

- -

90.-

bolt

-

-

4pcs.

1

pce.

from

....

lpce.

(NC

....

lpce.

. .

2pcs.

the

cover)

fuel

tank

Remarks

I

RECOIL STARTER

...

~PCS.

Tool

(+)

driver

lOmm box wrench

lOmm

box wrench

lOmm box wrench

M6

X

14mm BOLT

...

lpce.

X

12mm BOLT

AIR

CLEANER COVER

-

BRACKET (A/C

m TAPPING BOLT

...

.

.

4pcs.

.

1

pce.

cover)

-

15-

5-3

DISASSEMBLY

-

Step

Part to remove

-

6

Air

cleaner

PROCEDURES (PRO POLY) -CONTINUED

Procedures

(1)

Remove air cleaner element

bolt

....

M6 wing

(2)

Remove breather hose from cleaner base
and crankcase.

(3)

Remove air cleaner base from air-cleaner
bracket.
M6X12mm

(4)

Remove cleaner base and gasket
cleaner) from carburetor.
M6

nut

- -

(5)

Remove bracket
M6X12mm

lpce.

bolt

----

2pcs.

(AK)

bolt

....

lpce.

from

lpce.

the

(air

engine.

AIR

CLEANER ELEMENT

Remarks

M6

WING

BOLT

\

Tool

lOmm

box

wrench

lOmm

box

wrench

lOmm box wrench

'1.

1

pce.

r:

Fig.

5-4

-

16-

5-3

DISASSEMBLY PROCEDURES (CLASSIC STEEL) / (PRO POLY)

Step

r

'art

7

Speed control

Governor

8

lever

to

remove

Procedures

(1)

Remove speed control assembly from the
crank case, then remove governor spring

from the governor lever.

M6X

12mm bolt

(2)

Remove choke rod from speed control
assembly, then remove choke rod from

choke

shaft

(1)

Remove governor lever from the governor
shaft.

M6

X

25mm

(2)

Remove rod spring and governor
governor lever, then remove rod spring
and governor rod from throttle shaft of the
carburetor.

.-..

2pcs.

of

the carburetor.

bolt

and

washer

assy

- - -

rod

Remarks

1

pce.

from

SPEED CONTROL LEVER

Tool

lOmm box wrench

box

lOmm

wrench

W

Fig.

\

5-6

-

Fig.

17-

5-5

'

Dart

to

remove

Procedures

Remarks

Tool

Carburetor

Muffler

M5 x 10mm

\

TAPPING

MUFFLER

(1)

Remove carburetor from

(2)

Remove gasket and insulator from stud

bolts.

(I)

Remove muffler cover from muffler.

M5X

lOmm

tapping screw

(2)

Remove muffler

M8

X70rnm

and

bolt and washer

stud

....

gasket.

bolts.

3pcs.

(muffler)

assy

-*..

M8

X

16mm

bolt and washer

assy

.*.-

SCREW

I

...

3pcs.

COVER

M8

x

16mm

Zpcs.

lpce.

BOLT AND

(+)

driver

12mm

box

wrench

Fig.

5-7

-

CARBURETOR

18-

-

Step

Part

to

remove

Remarks Procedures

Tool

I

-

11

12

13

Oil

filler

Blower
hausing

Ignition coil

Remove the clamp from oil filler, and remove
oil filler bracket.

M6X

12mm

bolt

-

-

Ipce.

Remove the blower housing from the
crankcase.

M6x

12mm bolt

M6X

14mm bolt

(1)

Disconnect stop switch wire from
switch.

(2) Remove ignition coil

M6

X

30mm bolt

....

....

2pcs.

lpce.

-

-

-e

from

2pcs.

stop

crankcase.

I

Omm

box

lOmm

box

box

lOmm

wrench

wrench

wrench

-

19-

Part

to

remove

Flywheel

I

(1)

Remove starter pully from flywheel

MI4

(2)

Remove flywheel from crankshaft.
(See

Fig.

(3)

Remove key from crankshaft.

nut

5-1

Procedures

Ipce.

1.)

I

Remarks

I

I

18mm

(-)

Tool

box

driver

I

wrench

STARTER

Fl

PULLEY

e

M14

&

NUT

'..

lpce.

KEY

\

Fig.

5-1

0

Fig.

5-9

-20-

Fig.

5-12

Step

Part

to remove

Procedures

Remarks

Too

I

15

Brake

assy

(1)

Remove

M6

BRAKE

X

12mm

ASSY

\

brake

bolt

assy.

-

-

4pcs.

M6

x

12mm

lOmm

BOLT

...

box

4pcs.

wrench

-21

Fig.

-

5-13

Step

Part

to remove

Procedures

Remarks

Tool

-

16

17

Cylinder

Cylinder
head

(1)

Remove cylinder baffle.

*.--

M6X8mm bolt

(1)

Remove rocker cover and guide plate

lpce.

from cylinder head.
M6

X

12mm bolt 4pcs.

(2)

Loosen lock nut for rocker arm adjusting
screw.
M8 lock nut

(3)

Slide

off

-

2pcs.

rocker arm shaft from the holder
to the flywheel side, remove rocker arms.
(See

Fig.

5-1

5.)

(4)

Remove push rods.

(5)

Remove cylinder head and gasket.
M8X65rnm
M8X40mm
M8 flangenut

bolt
bolt

2pcs.

.---

-....

lpce.

1

pce.

1 Omm box wrench

lOmm box wrench
12mm box wrench

12mm box wrench

Fig.

5-14

-22-

Fig.

5-15

-

Step

'art to remove

-

18

Intake and

exhaust valve

19

Breather

-

INTAKE VALVE

EXHAUST VALVE

Procedures

(1)

Press down spring retainer and

slide

release from the groove of valve stem,
then remove spring retainer and valve
spring. (See Fig.

5-16.)

(2) Remove intake and exhaust valves

cylinder head.

(1)

Remove breather cover.

M6

X

12mm

bolt

.

2pcs.
Remove gasket (tappet cover), breather
plate and gasket (breather plate).

it

to

from

Remarks

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

valve seats and guides.

Tool

lOmm box wrench

\\

COLLET

I

I

VALVE

RETAINER

SPRING

-23

Fig.

-

5-1

M6

x

12mm

BOLT

...

7

Fig.

5-1

6

2pcs.

/

Part

to

remove Procedures

Remarks

Tool

Main bearing
cover (See

Oil

pump

(1)

Remove main bearing cover.

Fig.

5-18.)

M6X30mm bolt and washer

(1)

Remove

oil

pump cover from main bearing

cover.

M6

X

12mm bolt - 4pcs.

(2)

Remove

oil

pump (Inner) and

(Outer).

assy

*e*. 8~~s.

oil

pump

Do

not

lose

crankshaft.

spacer

for

lOmm box wrench

lOmm box wrench

OIL

PUMP

M6

COVER

x

12mm

I

BOLT

'.'

fi

4pcs.

Fig.

5-1

9

-24

-

-

Step

22

-

Part

to

remove

Camshaft and
tappets

1

(1)

Remove camshaft from crankcase.
(See Fig.

(2)

Remove tappets from crankcase.

Procedures

5-20.)

Remarks

To

prevent the tappets

from

getting damages, put

the crankcase cylinder

down.

side

(See Fig.

Tappet

in

Mark tappets prior
moval to prevent error.

5-20.)

must

be

installed

their original position.

to

/,

/,

,/'

Tool

re-

I

f

I

TAPPET

CAMSHAFT

I

/'

B

I

I

Fig.

5-20

-25-

Step

I

Part

to

23

I

remove

Connecting
rod and
piston

(1)

Remove connecting rod bolts and
connecting rod cap.
Connecting

(2) Turn crankshaft until piston

center,
assembly through

(3)

Remove
connecting

(4)Remove piston rings from piston.

Procedures

rod

bolt 2pcs.

push

out connecting

clips

and piston pin

rod

from piston.

L

24

I

(l).Tap

Crankshaft

lightly

on

flywheel end of crankshaft

to

remove from crankcase. (See Fig.5-22.)

top

of cylinder.

is

at top dead

rod

and piston

to

remove

I

I

Scrape off all carbon
deposits that might

interfere

piston

from

cylinder.

Remarks

with

removal

upper end

I

lOmm box wrench

of

of

Ring expander

Tool

Fig.

W

5-22

Fig.

5-23

-26-

M

0-

\

CONNECTING

SPACER

ROD

CAP

f-

5-4

REASSEMBLY PROCEDURES

0

PRECAUTIONS

1)

Clean parts thoroughly’before reassembly.

.FOR

REASSEMBLY

Pay utmost attention to cleanliness of piston, cylinder, crankshaft, connecting rod and bearings.

2)

Scrape off all carbon deposits

3)

Check lip of oil seals. Replace oil seal if the lip
Apply

4)

Replace all the gaskets with new ones.

5)

Replace keys, pins, bolts, nuts, etc.,

6)

Torque bolts and nuts to specification referring to page

7)

Apply oil to rotating and sliding portions.

8)

Check and adjust clearances and end plays where specified in this manual.

oil

to the lip before reassembly.

from

cylinder head, piston top and piston ring grooves.

is

damaged.

if

necessary.

59

“12-2

TORQUE SPECIFICATIONS”

5-4-1

(1)

CRANKSHAFT

Install crankshaft on crankcase using an oil
seal guide to avoid damage to crankshaft
seal. (See

Fig.

5-24.)

oil

Fig.

5-24

-27

-

5-4-2

(1)

PISTON AND PISTON RINGS

Install oil ring first, then second ring and top
ring. Spread ring only far enough

to

slip over
piston and into correct groove. Use care not to
distort ring. (See Fig.

5-26.)

Fig.

5-25

5-4-3

PISTON AND CONNECTING ROD

Install piston on connection rod.
Oil the small end of connecting rod before instal-

ling piston and piston pin.

Use

clips

on

both

side

of

the piston pin to secure

piston pin in position.

EN

ENDS

OF

PI

Fig.

Fig.

5-26

5-27

-28-

5-4-4

(1)

CONNECTING

ROD

Before installing the piston and connecting rod

in

the cylinder, oil the piston, piston rings and

cylinder wall.

(2)

Stagger the piston ring gaps

the piston. (See Fig.

5-28.)

90”

apart around

Use a piston ring compressor when installing
piston.

Install piston and rod with the
flywheel side
(See

Fig.

(3)

Turn crankshaft

29.)

of

the crankcase.

to

bottom dead center, then tap

“MA”

marks

lightly top of the piston until large end
connecting

rod

meets crank

pin.

of

on

the

Fig.

5-28

(4)

Install connecting rod cap with the match mark

on

the main bearing cover side. (Match this

mark with the one

on

the left side

of

necting rod’s large end viewed from main

2

30)

pcs.

bearing cover side.) (See Fig.

Connecting rod bolt

-0.-

con-

PISTON

CONNECTING

CRANKCASE

RING

COMPRESSOR

ROD

Fig.

5-29

Tightening torque

17-20

170-200

12.2-14.5

Check for free movemont of connecting rod by

turning crankshaft

slowly.

N*m

kg-cm

ft4b

-29

-

Fig.

5-30

5-4-5

(1)

(2)

TAPPET

AND

CAMSHAFT

Oil tappets and install in their original position.

in

Push

Lubricate bearing surfaces
Align timing mark
crankcase. (See

fully to avoid damage during camshaft installation.

of

camshaft.

on

crankshaft gear with timing mark

Fig.

5-31.)

on

camshaft and install camshaft

in

the

r'

Incorrect

valve

timing will cause engine's malfunction.

CAMSHAFT

Fig.

5-3

CRANKSHAFT

1

-

30

-

5-4-6

(1)

ADJUST CRANKSHAFT END

PLAY

Adjust end play to the,specified values using the proper spacer.
The proper spacer. may be determined

R1

”7-

by

the following manner.

MAIN BEARING COVER

I,

I

Fig.

5-32

0

CRANKSHAFT END

(1)

Measure the depth “Al” (From the mating surface to the inner race

(2)

Measure the height

(A1+0.3)

-

Bl=SIDE CLEARANCE (mm)
(SIDE CLEARANCE)
(A+0.012)

-

Bl=SIDE

SIDE CLEARANCE

PLAY

“Bl”

(From the mating

-

0.2=THICKNESS OF CRANKSHAFT SHIM (mm)

to

the crank gear.)

CLEARANCE(in)

-

0.008=THICKNESS

OF

CRANKSHAFT

Following are available spacer shims.

1

SPACER

SHIMS

CRANKSHAFT

.

T=0.6

T=0.8

T=l

.O

mm

(0.024”)

mrn

(0.031”)

mrn

(0.039”)

~~ ~~

of

the ball bearing.)

SHIM

(in)

-

31

-

5-4-7

(1)

MAIN

Install oil pump

M6

X

BEARING

to

the main bearing cover.

12mm bolt

8-9.5 N*m

80-1

00

6-7

COVER

....

4

pcs.

kgcm

ft*lb

CRANKCASE KEY

Lubricate the
faces. Add a light film of
bearing cover face

oil

seal and bearing sur-

to

hold the gasket in

oil

on the main

place.
Place spacers chosen at procedure 5-4-6
on crankshaft.
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.

M6

X

30

mm

bolt and washer

Tightening

8-9.5

80-1

00

6-7

torque

Nom

kgocm

ft*lb

-.-.

8

pcs.

CRANKSHAFT

OIL

0

RING

OIL

-32

PUMP

PUMP

-

(INNER)

COVER

M6

BOLT

".

~PCS.

Fig.

5-33

M6

BOLT

AND WASHER

ASS'Y

...

~Pcs.

5-4-8

BREATHER VALVE

Attach breather plate (breather valve) and breather

cover
(See Fig.
Replace gaskets with new ones if they are torn

to

crankcase

5-34.)

using

proper gaskets.

or

damaged.
Replace breather hose at least once a year or when
ever

a

crack was found.

Fig.

5-34

5-4-9

(1)

CYLINDER HEAD

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

the

valve seats and valve guides.

(2)

Replace valves that are badly burned, pitted
warped.

(3)

When installing the valves
oil the valve stems and insert them

in

the cylinder head,

into

valve guide. Then place the cylinder head on a
flat table, install the washer, valve spring and
spring retainer. (See Fig.

(4)

Valve guides should be replaced when the

5-35.)

valve stem clearance exceeds specifications

“SERVICE DATA’

(See

page

57)

Draw the valve guides out and press the new

guides

Refer

in.

to

“SERVICE DATA”

for clearance spec­ifications.
After replacing the valves and guides, lap

in

valves
around the face

place until a uniform ring

of

the valve. Clean valves and

wash cylinder head thoroughly.

(5)

Install cylinder head to cylinder with new head
gasket.

valves,

or

the

shows

INTAKE

VALVE

Fig.

5-35

r

When installing head gasket, show Fig.

Tighten three flange bolts and

in

evenly

three steps

by

the following tight-

5-36.

a

ening torque:

M8

X

65

Cylinder head

1

st

step

50

kgocrn

3.6

ft*lb

M8

X

40

M8

flange nut

Tightening

2nd

step

10

100

7.2

mm bolt
mm bolt

torque

N-m

kgocrn

ft-lb

...-

-.*-

. e.. .. ..

final

23-26

230-270

17-30

flange nut

2

pcs.

1

pce.

1

pce.

step

Nom

kgmn

ft*lb

-33-

5-4-10

(1)

(2)

5-4-1 1 VALVE CLEARANCE ADJUSTMENT

(1)

(2)

ROCKER

ARMS AND PUSH RODS

Insert push rods into crankcase.

of

Put push rod tip in the hollow
Apply

oil

to

the

rocker arms and assemble them to the cylinder head using the rocker shaft and spacer.

tappet top.

Position the piston at the top dead center
obtained by placing the key

Loosen

the lock nut

on

slot

on

the power take off shaft

the rocker arm and turn
the rocker arm and the valve stem end. (See Fig.
Tighten the lock nut.

of

the compression stroke. The top dead center may

to

45"

Fig.

from the center

5-37

the

adjusting screw to adjust the clearance between

of

cylinder.

5-38.)

be

\

,'

0.085-0.1 15

-

[NOTE)

Check and adjust valve clearance with engine cold.
Check operation
Remeasure valve clearance.

(3)

Install guide plate and rocker cover using a gasket.

M6

X

12

mm bolt

of

valves

mm

by

turning crankshaft.

4

pcs.

-34-

54-12

Install brake assy

M6

BRAKE

X

12

mm

ASSEMBLY

to

the engine.

bolt

.

4

80-

1

00

pcs.

kg-cm

Never apply

5-4-13

(1)

(2)

(31

FLYWHEEL

Put the woodruff key in the key way
shaft.
Wipe

off
tapered portion of the crankshaft and the fly­wheel center hole.
Pull the brake lever.
Install the flywheel to crankshaft.

Tighten the flywheel nut with the starter

pulley. (See Fig.

I

oil

or (grease) on the internal

MAGNETO

oil and de-grease thoroughly from the

5-39.)

Tightening torque

59-63

600-650

43-47

Nom

kgocrn

ft'lb

of

crank-

I-

of

flywheel and brake.

Fig.

RANKSHAFT

5-39

5-4-14

Install the ignition coil to the crankcase.

Adjust the air gap between the ignition coil and
the flywheel using a thickness gauge (filler gauge)
and tighten the bolts. (See Fig.

M6

IGNITION

X

30

mm

I

I

0.01

COIL

bolt

-

Air

gap

0.3-0.5

2-0.020

-

mm

2

in.

pcs.

5-40.)

I

I

-.35

-

Fig.

5-40

5-4-15

BLOWER

HOUSING

AND

BRACKETS

Install blower hosing, oil filler bracket (fuel tank)
and air cleaner bracket.

M6

BOLT

x

12mm

...

lpce.

BLOWER
HOUSING

\

M6

x

BOLT

14mm

'.'

3PcS.

Classic

M6
M6

Pro

M6
M6 X 14

5-4-16

Steel

X

12

mm

X

14

mm

Poly

X

12

mm
mm

CYLINDER

bolt
bolt

bolt
bolt

-.

-

1

pce.

....

3

pcs.

-

2

pcs.

--e.

2 pcs.

BAFFLE

Install cylinder baffle.

M6

X

8

mm

54-17

OIL

FILLER

Install oil filler

M6

X

12

mm

5-4-18

CARBURETOR

bolt

to

the engine.

bolt

1

....

pce.

1

pce.

Install the gaskets, insulator and carburetor.

I

~~~

M6

BOLT

M6

x

x

12mm BOLT

14mm

...

2pCS.

TAPPING BOLT

Fig.

54 1 (Classic

...

2pcs.

\v

...

1

Dce

Steel)

M6

x

BOLT

J

14mm

...

2pcs.

ENGINE

SIDE.

GASKET 2 (INSULATOR)

CABURETOR

Fig.

542

I

-36-

\-

TAPPING BOLT

Fig.

5-41

(Pro

...

lorn.

Poly)

5-4-19

(1)

.I

Attach the air cleaner gasket to the carburetor
flange when installing air cleaner base
engine. (See Fig.

(2)

(3)

AIR CLEANER

Install cleaner base

Tighten the clamp.for stop switch wire together w

M6

Nut

**..

Tightening torque

[NOTE]

Install cover and element to the air cleaner base.

M6

wing bolt lpce.

~PCS.

8-9.5

80-1

5-43.)

on

studs, install bracket, cleaner

N*m

00

kgcm

on

the

ith cleaner bracket

I

Connect a breather pipe between breather and air cleaner.

SLOW

MAIN

AIR

AIR

BLEED

BLEED

on

crankcase side.

JET

JET

Fig.

5-43

AIR

VENT

HOLE

5-4-20

GOVERNOR

ADJUSTMENT

For correct Carburetor throttle opening and gov-

ernor regulation, the governor lever must be pro­perly adjusted.

(1)

Install throttle lever ,control linkage on gov­ernor lever and choke shaft control rod in
choke lever.

(2)

Hook

hole
Install bracket assembly

(3)

Install governor lever

spring from control lever hole

(B)

in governor lever as shown in Fig.

on

crankcase.

on

governor shaft but do

(A)

to the

5-44.

not tighten clamp screw.

(4)

Turn governor lever clockwise until throttle
valve.
in this position. (See Fig.

Check that governor lever clamp screw is loose

so

(5)

Insert a screwdriver in slot at end

in

carburetor

governor shaft

is

opened

fully.

5-45.)

can

be turned independently

Hold lever

of

governor
shaft. Turn clockwise as far as shaft can be
turned. Tighten governor lever clamp screw.

of

Fig.

5-44

-37-

Fig.

5-45

5-4-21

(1)

MUFFLER AND MUFFLER COVER

Install muffler and muffler gasket.

M8

X

70

mm

bolt and washer assy

M8 X 16

mm

bolt and washer

Tightening torque

22.5-26.5

Nom

assy

.-..

2pcs.

..

..

lpce.

230-270

16.6-1 9.5

(2)

Install muffler cover

M5

X

10

mm

Tapping screw

5-4-22 FUEL

(1)

Install fuel tank bracket.

M6

(2)

Install fuel tank.

M6

(3)

Install side guard.

M6

X

X

X

12

12

12

TANK

mm

bolt

mm

bolt

mm

bolt

kgecrn

ft*lb

to

the muffler.

(if

applicable)

-.

- -

2pcs.

....

2pcs.

.

2pcs.

- -

3

pcs.

(4) Install cover (stop switch).

5-4-23

(1)

(2)

5-4-24

(1)

RECOIL

STARTER

AND

ENGINE

SHROUD

Install recoil starter and engine shroud.

M6

X

8

mm

bolt

--.e

4pcs.

Connect fueI pipe between fuel cock and carburetor.

OIL

FILTER BRACKET AND

OIL

FILTER

Install oil filter bracket

M6

X

12 mm bolt

-...

2pcs.

I

(2)

Tighten filter using a proper tool about 3/4 turn

Tightening torque

8-9.5

80-1

6-7

00

I

Nom

kgwn

ft*lb

after gasket contacts mounting surface

engine.

Check for leaks at test running after engine

is

assembly

completed.

of

-38-

OIL

FILTER

/

BRACKET OIL FILTER

Fig.

5-46

\

5-4-25

(1)

SPARK

Install spark plug

Spark plug

PLUG

to

the cylinder head.

:

CHAMPION L86C

I

I

L

(2)

________~~~

New spark plug

1

1.8-1

4.7

120-1

8.7-1

0.9

Connect spark plug cap to the spark plug.

5-4-26 ENGINE

50

N-m
kgocm

ft*lb

Tightening

~~~

OIL

torque

Retightening

22.6-26.5 N*m

I

230-270

16.6-1

9.5

kg-cm

fblb

1

I

After complete reassembly, turn the engine over and pull the recoil starter
conditions or loose fitting parts.
Review and check wiring.
Fill crankcase with correct grade of oil. (See page

Crankcase oil capacity

5-4-27

(1)
(2)

CHOKE

AND

Start the engine. (Operate the engine without load.)
In order to fix the position

:

500cc

SPEED ADJUSTMENT

of

the speed control lever, insert a philips screw driver into the hole (A)

59,

"OIL

GRADE CHART

the speed control lever through the hole of the speed control bracket.

(3)

Loosen the adjusting screw on the speed control lever.

(4)

Check the engine speed by a tachometer or a revolution counter.

is

3350

Correct engine speed

(5)

Loosen the bolts
become

3350

r.p.m.

(B)

and (C), Move the speed control bracket to the position where the engine speed

r.p.m.

In order to reduce the engine speed move the speed control bracket -to the left.

(6)

After adjusting the engine speed, re-tighten the two bolts

(7)

Tighten the adjusting screw until it contacts the choke lever.

(B)

and

(C)

to

check for any abnormal

")

to

fix the bracket.

of

ROD

SPRING

B

CHOKE

\

\

LEVER

\

-39

A

SPEED
SCREW

n"L

When speed control bracket

in

the direction

Fig.

5-47

-

of

CONTROL

(PAN

the

arrow,.

LEVER

HEAD)

LOW

SPEED

is

moved

engine speed

is

reduced.

5-5

BREAK-IN OPERATION

An

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

connecting rod should be thoroughly

RUN-

IN

before being put back into service.
Good bearing surfaces and running clearances between the various parts can only be established
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.

by

I

Steps

Step
Step
Step
Step

1

2

3

4

Load Engine speed Time

No
No

2.0

4.0

load

load

HP

HP

2500
3000
3000
3000

rpm
rpm
rpm
rpm

10
10

30
60

min
min
rnin
min

-

40-

0

MAGNETO

6.

6-1

FLYWHEEL

".

MAGNETO

The ignition system of the
characteristic.
Being different from the breaker point type ignition system, this- system
troubles as starting-up failure due to dirty, burnt or corroded point surface. The electronic automatic
advancing ensures extremely easy starts and stable high performance at operating speed
ignition timing to the most suitable point.

6-2

BASIC

.

To

ensure the easy startability of the engine, the step advancing ignition timing system
the ignition coil. This system enables the engine to have basically two different ignition timings
according

1)At lower speed of the engine
Rotation of the flywheel induces current

transistor, it

As

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

is

activated and lets the current b flow through

This generates the collector current

IZ

because the power transistor is turned off.
This sudden current change generates a big voltage on the secondary side
sparks the spark plug.

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

power transistor, it is activated and the current

As

the

speed
collector current
transistor
This sudden current change generates a big voltage
sparks
The ignition timing control circuit for the higher engine speed is activated sooner than the control
circuit for the lower speed and not activated when the engine speed is in a lower range.

THEORY

to

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

is

activated and the current

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

is

activated and provides the base current

16

and will bypass the current

is

turned

at

the spark plug.

off.

EH18V

is a pointless flywheel magneto .with an autcmatic advancing

is

completely free from such

by

is

incorporated in

I,,

as this current flows through the base terminal

LZ

starts flowing.

for

the lower engine speed

the

base terminal of the power transistor.

L

which will bypass the current

11

as this current flows through the base terminal

12

starts flowing.

Is

to the power transistor. This current induces the

IL

to shut down

on

the secondary side of the ignition coil causing

the

11

and abruptly shut off the current

of

the ignition coil and which

current

IZ

abruptly because the power

advancing the

of

the power

of

the

-41

-

(B.T.D.C.)

.

23"

4

I

F

ELECTRONIC ADVANCING FLYWHEEL

MAGNETO SYSTEM

1

STEP

ADVANCING

6-3

WIRING DIAGRAM

STANDARD

15.1

,

500

,

1000

ENGINE REVOLUTION

Fig.

,

2000

6-2

I

3000

(r.p.m.)

Stop

switch

Flywheel

Fig.

6-3

-42

-

7.

AUTOMATIC

DECOMPRESSION

SYSTEM

The decompression system operates to release compression
The release lever mounted on the camshaft has a flyweight at one end and a crescent cam at the other
end. When starting the engine, the crescent cam juts out from the exhaust cam.
The exhaust tappet rides over the crescent cam opening the exhaust valve

CRESCENT CAM

EXHAUST CAM

Fig.

7-1

by

lifting

up

the exhaust valve at starting.

to

release compression.

LEVER

a

When the crank speed reaches a certain revolution, the flyweight
the centrifugal force turning the release lever to retract below the crescent cam. Thus the exhaust valve
closes allowing a sufficient compression for the engine to start

FLYWEIGHT

CRESCENT

CAM

Fig. 7-2

up.

of

the release lever moves outward

LEVER

by

-43-

8.

CARBURETOR

8-1 OPERATION AND CONSTRUCTION

(See

Fig.

7-2.

and

SI.)

8-1 -1 FLOAT SYSTEM

The float chamber is located just below the carbu­retor body .and, with a float and a needle valve,
maintains a constant fuel level during engine opera­tion.
The fuel flows from
chamber through needle valve. When the fuel rises

to a specific level, the float rises
buoyancy and fuel pressure are balanced, the needle
valve closes
fuel at the predetermined level.

to

shut off the fuel, thereby keeping the

the

fuel tank into the float

;

and when its

FLOAT

PILOT OUTLET

u

'\

Fig.

8-1

'

PILOT JET

Fig.

8-2

-44-

8-1-2 PILOT SYSTEM

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

to

The fuel is fed through the main jet

by

the pilot air jet.
The fuel-air mixture is fed to the engine through the pilot outlet and the bypass.
At idling speed, the fuel is mainly fed from the pilot outlet.

8-1-3 MAIN SYSTEM

The main system feeds the fuel to the engine at medium- and high-speed operation.
The fuel
mixed with the fuel through the bleed holes in the main nozzle, and the mixture is atomized out

main bore. It
mixture, which

8-1

The

the negative pressure applied to the main nozzle increases and draws much fuel according1y;thus easily
start

8-2 DISASSEMBLY AND REASSEMBLY

Apart from mechanical failures, most of carburetor troubles are caused by an incorrect mixing ratio,
which may arise mainly due to a clogged up air or fuel passage in jets, or fuel level variations. In order
to assure proper flow
disassembly and reassembly procedures are as follows

is

metered by the main jet and fed to the main nozzle. The air metered by the main air jet is

is

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

is

supplied to the engine.

-4

CHOKE

choke is used for easy start when engine is cold. When the starter is operated with a closed choke,

up

the engine.

of

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

the pilot jet, where it is metered, and mixed with the air metered

of

the

:

(See Fig.

8-2.)

8-2-1 THROTTLE SYSTEM

(1)

Remove the philips screw

(14),

and pull out the throttle shaft(l3).

(2)

The spring
throttle stop screw

*

Exercise care not

8-2-2

(1)

(2)

8-2-3 PILOT SYSTEM

(1)

(2)

CHOKE SYSTEM

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

Remove the pilot jet
avoid damage to it.

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

(19)

can be taken out

(20).

to

(23)

(15)

and throttle valve

by

removing the

damage throttle valve ends.

and choke valve

(16).

(18),

using correct tool to

(17),

and

13

24

-

@-"--11

10

-

45

-

Fig.

8-3

8-24

(1)

(2)

(3)

MAIN

Remove the bolt

From the body

Reassembly

a)Fasten the main jet securely

engine malfunction.

b) The bolt tightening torque

SYSTEM

(11)

(3)

remove the main jet

and take out float chamber body

is

(5).

(9).

to

the body. Otherwise, the fuel may become too rich and cause

80

kg-cm.

8-2-5

(1)

When cIeaning the jets, use neither a drill nor a wire (because of possible damage to the
orifice which will adversely affect fuel flow). Be sure to use compressed air

(2)

FLOAT

Pull out the float pin

When removing the needle valve and floats, gently tap the reverse side using the rod more slender

than the float pin and remove, since the float pin is calked

SYSTEM

(8)

and remove the float

(7)

and needle valve

to

(6).

to blow them clean.

the carburetor body.

-

-46

n

-

9.

STARTING

9-1

RECOIL

STARTER

SYSTEM

When repairing recoil starter, disassemble and re­assemble in the following procedures.
Tools: Socket wrench, Needle nose pliers, Screw driver

9-1-1

HOW

(1)

Remove recoil starter from engine.

(2)

Pull starter knob and pull out starter rope for

30-40cm

TO

DISASSEMBLY

to line up notch

on

reel with outlet
hole for starter rope.
Hold reel with thumb and pull starter rope

inside the starter case with screw driver.

(See Fig.

9-1

or

9-2.)

Rewind reel clockwise until the rotation stops.
When rewinding the reel, control the rotation

by

holding starter rope

using

the notch

on

the

reel and pressing the reel with thumb.

(3)

Remove parts in the following order.

1.

Return spring

2.

Rachet

3.

Friction spring

4.

Rachet guide

5.

Set screw

Fig.

9-1

0-3

(Classic

Steel)

-47-

STARTER

ROPE

Fig.

-3

&--"

9-2 (Pro

4

Poly)

(4)

Remove the reel from the starter case as shown

Fig.

in

9-3.

Take out the reel slowly turning it lightly

to

towards the left and right
from the hook.

Do

not remove the reel quickly

remove spring

or the spring may escape from the starter case.
Untie the starter rope from the knob and remove.

STARTER CASE

9-1-2

(1)

HOW

Put

and tie it

TO

REASSEMBLE

the starter rope through the starter knob

as

shown in Fig.
tightly for the safety sake.)
Put the opposite side

of

starter case and reel. Tie
the starter knob end and put the
completely.

9-4.

(Tie the rope

the rope through the

it

in the same way

knot

in the reel

as

L

Pro

Poly

STARTERCASE

Fig.

9-3

Fig.

9-4

(2)

Check that the spring is securely set in the reel.

Adjust

so

the position

of

inner end

of

the spring

it hooks on hook in the starter case securely.
The shape of starter spring inner end may be
adjusted with

a

plier

if

necessary.

I

I

INNER

-48-

END

OF SPRING

OUTER END

/

'

Fig.

9-5

SPRING KEEPER

BEARING

OF

REEL

SPRING

(3)

Prior to installing the reel in the starter case,

wind

the starter rope in the reel for

2.5

the arrowhead direction as shown in Fig.

Then let the rope out

of

the reel from the reel
notch. Line, up the reel hook with the inner end
of the spring and install the reel in the starter
case.

is

Check that the inner end of spring

securely

hooked onto the hook.

turns in

9-6.

Fig.

9-6

(4)

Reassemble the parts in reverse order of disas­sembly.

I

Check that the ratchets are pushed
ratchet springs toward the center

of

the recoil.
Install the friction plate with its two bosses set
inside of the bent portion

Apply small amount of lock-tight

of

ratchets.

to

the center

screw and torque it.

Thightening

3.9

4.0

2.9

(5)

Hold starter rope as shown
turn reel

4

torque

Nom

kg*crn

ft4b

times

in

in

Fig.

the

arrowhead direction.

9-8

Firmly press the reel not to allow reverse turn
and pull starting knob to

let

starter rope out
starter case.
Return knob slowly to let starter rope rewind

in

reel.

by

the

and

of

I

Classic

C~-FRICTION

&-SET

Steel

-RATCHET GUIOE

SPRING

SCREW

Fig.

9-7

Pro

Poly

0-FRICTION

“RATCHET GUIDE

Pro

SPRING

SET

SCREW

Poly

-49-

Fig.

9-8

(6)

Test the operation

project and retract properly. Mount the recoil starter

(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 and spring with heat resistant grease or mobile oil when

of

the recoil starter to see if the rope recoils satisfactorily and the ratchets

to

the engine.

of

the reel and rewind the spring into the housing.

reassembling the recoil and prior to long term storage.

-50-

a

IO.

TROUBLESHOOTING

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

1.

The cylinder filled with a proper fuel-air mixture.

2.

Good compression in the cylinder.

3.

Good spark, properly timed, to ignite the mixture.

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

make engine start difficult,
a high back pressure due to a long exhaust pipe.

The most common causes of engine troubles are given below:

10-1

STARTING DIFFICULTIES

e.

g.,

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

are

also other factors which

10-1-1

(1)

(2)

(3)

(4)

(5)

(6)

10-1-2

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 of compression.

(1)

(2)

(3)

(4)

FUEL

No

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

The carburetor

Water, dust or gum in the gasoline interfering the fuel flow to the Carburetor.

Inferior grade gasoline or poor quality gasoline is not vaporized enough to produce the correct
fuel-air mixture.
The carburetor needle valve is held open by dirt

flows out
This trouble may be remedied, depending
grip of a screwdriver or the like.

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

the fuel-air mixture too rich
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

it into place, and try to start again.

COMPRESSION SYSTEM

Engine inside is completely dried up because

Loose or broken spark plug. This causes a hissing noise made by mixture gas running out
cylinder in compression stroke during cranking.
Damaged head gasket or loose cylinder head. A similar hissing noise
sion stroke.
Incorrect valve clearance
If the correct compression is not obtained even after remedying the above, disassemble the engine
and check further as follows:
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.

SYSTEM

is

not choked sufficiently, especially when the engine is cold.

of

the carburetor when the engine

to

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

or

gum. This trouble can

is

idling. (Overflow)

on

cases, by lightly tapping

of

a

long period

of

storage.

is

be

detected as the fuel

the

float chamber with the

produced during compres-

of

-51

-

10-1-3

Check the followings for lack of spark

(1)
(2)

(3)

(4)

(5)

(6)

(7)

10-2

(1)

(2)

(3)

(4)

(5)

(6)

10-3

(1)

(2)

(3)

(4)

(5)

(6)

IGNITION SYSTEM

.

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

Spark

Spark plug electrodes are connected or bridged.
Incorrect spark timing.

Incorrect spark plug electrode gap. Adjust it

Ignition cable worn and leaking.
Sparks weak.
Ignition wire connections loose.
Water in gasoline.
Insufficient compression.

Fuel tank empty. Water, dirt, gum, etc. in gasoline.
Vapor lock,
Vapor lock in the fuel lines or carburetor due to the use
Air vent hole in the fuel tank cap plugged.
Bearing parts seized due to lack of oil.
Magneto or ignition coil faulty.

of

the ignition coil or spark plug.

plug electrode gap incorrect.

ENGINE MISFIRES

ENGINE

STOPS

i.

e., gasoline evaporating

to

anywhere between

in

the fuel lines due to overheat around the engine.

0.7

and 0.8mm.

of

too volatile winter gas in the hot season.

10-4

ENGINE OVERHEATS

(1)

Crankcase oil level low. Add oil immediately.

(2)

Spark timing incorrect.

(3)

Low

grade gasoline is used, or engine

(4)

Cooling air circulation restricted.

(5)

Cooling air path misdirected causes loss

(6)

Cylinder head cooling fins clogged up with dirt.

(7)

Engine operated

(8)

Exhaust gas discharge restricted, or carbon deposits in the combustion chamber.

(9)

Engine running

in

an enclosed space without sufficient cooling air.

on

low- octane gasoline detonates due to heavy load

is

overloaded.

of

cooling efficiency.

at

low speed.

-

52

-

10-5

(1)

(2)

(3)

(4)

(5)

(6)

(7)

10-6

(1)

(2)

(3)

(4)

ENGINE KNOCKS

Poor quality gasoline.
Engine operating under heavy load
Carbon or lead deposits

in

the cylinder head.

at

low speed.

I.

Spark timing incorrect.
Loose connecting rod bearing due to wear.

Loose

piston pin due to wear.

Engine overheated.,

ENGINE BACKFIRES THROUGH CARBURETOR

Water

or

dirt in gasoline,

or

low-grade gasoline.
Intake valve stuck.
Valves overheated, or hot carbon particles in the combustion chamber.
Engine cold.

-

53

-

11.

INSTALLATION

Engine life, ease of maintenance and inspection, frequency

is

all depend on the way in which the engine

installing the engine.

11

-1

INSTALLING

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

11-2

VENTILATION

Fresh air is necessary for cooling the engine and burning the fuel.

the

a

engine

duct

In the case
can cause vapor lock, oil deterioration, increased oil consumption,
shorter engine life, etc., making it impossible to operate the engine properly.
to provide

for engine cooling, and temperature rise

Keep the engine room temperature below

or

is

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

baffle

to

guide cooling air to the engine to prevent recirculation of the hot air used

installed. Carefully observe the following instructions for

of

the machine.

50°C

even in the hottest period of the year.

of

checks and repairs, and operating cost

loss

of

power, piston seizure,

It

is necessary, therefore,

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

3m

Exhaust pipe: Less than

Less than

long, pipe inside diameter

5m

long, pipe inside diameter

25

30

mm,
mm.

of

-54-

12.

SERVICE

DATA

“STD”

Whereas, “Limit” shows the maximum allowance

If

12-1

in the following table is the parts dimension from the brand new engine

for

the parts

the measurement exceeds beyond the “Limit”, the part needs

CLEARANCE

‘DATA

AND

LIMITS

ITEM

CYLINDER

0

Valve

HEAD

seat contact width

IN. EX.

or

the spare parts.

to

be used

to

be replaced and/or repaired.

on

the engine.

STD

LESS

THAN

0.05

(0.002)

0.7

-

1

.O

(0.028 - 0.039)

Unit : rnm

Limit

0.1

(0.004)

2.0

(0.079)

(in)

Valve

guide inside dia.

5.500 - 5.51

(0.21 65 - 0.21 72)

8

5.65

(0.2224)

-55-

Unit

:

mm

(ir

CYLINDER

0

Inside dia.

0

Roundiness after reboring

ITEM

STD

1

st

reboring

2nd

reboring

T

STD

67.000 - 67.01 9

(2.6378

67.250

(2.6476

67.500

(2.6575

LESS

0.01

(0.004)

-

2.6385)

-

67.269

-

2.6484)

-

67.51 9

-

2.6582)

THAN

Lmit

To

be rebored when the

difference between max. and

min.

of

diameter reached to 0.1

(0.004).

Ditto

0

Cylindricity after reboring.

PISTON

0

Piston size (At skirt in thrust
direction)

STD

1

St

2nd

Q/S

01s

LESS

0.015

(0.0006)

66.96

(2.6362

67.21

(2.6461

67.46

(2.6559

THAN

-

66.98

-

2.6370)

-

67.23

-

2.6469)

-

67.48

-

2.6567)

66.87

(2.6327)

67.1 2

(2.6425)

67.37

(2.6524)

-56

-

Uni

:

mm

(in)

ITEM

0

Ring groove side clearance

0

Piston pin

0

Piston pin outside dia.

hole

I

t

TOP

2nd

Oil ring

T

I

"

"

"

STD

0.050

-

0.095

(0.001 9

(0.001 6

(0.5508

(0.5508

-

0.0037)

-

0.040

13.991

13.992 - 14.000

0.085

-

0.0030)

0

-

0.035

(0

-

0.001 4)

-

14.002

-

0.551

-

0.551 2)

3)

Limit

(0.006)

(0.006)

2

0.1

(0.006)

14.035

(0.631

3)

13.960

(0.6284)

Clearance between piston and
cylinder at skirt area.

0

Piston ring end gap

TOP

2nd

oil ring

'

(0.0008

(0.01 18

0.020

-

-

0.05

-

(0.0020

0.3

-

-

0.059

0.0023)

0.25

-

0.098)

0.9

0.0354)

0.23

(0.01

0)

1.3

(0.0091)

2.1

(0.0591)

-

57-

Unit

:

rnm

(in)

CONNECTING

0

Big end inside dia.

0

Clearance between big end
and crankpin

0

Small

end inside dia.

0

Clearance between small end
and piston pin

ROD

ITEM

STD

26.000 - 26.01 3

(1.0236

(0.001

14.01

(0.551 6

0.037

-

-

5

-

0

-

-

1.0241)

0.063

0.0024)

14.021

0.5520)

Limit

26.1

(1.1 850)

0.2

(0.008)

14.08

(06331)

0

Big end side clearance

CRANKSHAFT

0

Journal dia.

0.01

0

-

0.029

(0.0004 - 0.001

-

0.3

0.1

-

(0.0039

25.950

(1.0217

24.988

(0.9838

0.01

-

25.963

-

1.0221)

Dl, D2

-

24.997

-

0.9841)

1)

18)

0.1 2

(0.0047)

0.5

(0.040)

25.84

(1.1 752)

-58-

Unit:

mm

~

(ir

CAMSHAFT

0

Cam height

0

Journal
"D"

outside dia.

type

VALVE

0

Valve stem outside dia.

ITEM

~

IN.EX.

CAMS

Dl

D2

IN.

STD

-

29.8

29.6

(1.165-1.173)

-

16.973

(0.6682

14.973

(0.5895

5.440

(0.21 42 - 0.21 48)

16.984

-

0.6687)

-

14.984.

-

0.5899)

-

5.455

Limit

29.45

(1.159)

16.95

(0.6673)

14.95

(0.5886)

5.35

(0.21 06)

0

Clearance between valve stem dia.

and valve guide

0

Valve clearance

EX.

IN.

EX.

IN./EX.

(cold)

5.426

(0.21 36

0.045

(0.0018

0.056

(0.0022

0.085

(0.0033

-

5.444

-

0.21 43)

-

0.078

-

0.0031)

-

0.092

-

0.0036)

-

0.1 15

-

0.0045)

5.35

(0.21 06)

0.3

(0.01 2)

0.3

(0.01 2)

-59-

Unit

:

mm

~~

(in).

TAPPET

0

Stem outside dia.

Guide inside dia.

0

Tappet guide clearance

ITEM

8

STD

7.960 - 7.975

(0.31 34

(0.31

(0.001

-

0.3140)

8.000

-

8.01

50

-

0.31

0.025 - 0.055

0

-

0.0022)

Limit

5

56)

ROCKER

0

Rocker shaft outside dia.

0

Rocker

VALVE SPRING FREE LENGTH

ARM

arm

shaft clearance

11.995 - 12.000

(0.4722

12.01

(0.4731

(0.0006

6 - 12.034

6 - 0.039

0.01

-

0.4724)

-

0.4738)

-

0.001

5)

11.92

(0.4693)

0

-60-

Unit

:

mm

(in)

0

Valve cutter angle(a)

0

Valve contact width(b)

12-2

TORQUE SPECIFICATIONS

DESCRIPTION

Cylinder head bolts
Connecting rod cap bolts

ITEM

STD

a:

90"

:

0.7

-

1

b

a

kg

cm

,

170

-200

.O

(0.028

-

0.039)

TIGHTENING TORQUE

N*m

-

19.6

Limit

2.0
(0.079)

16.6

12.2

ft=

Ib

-

19.5 22.5 - 26.5 230 - 270

-.

14.4 16.6
Flywheel nut
Main bearing cover bolts

Spark plug

12-3

OIL

GRADE CHART

Single

Lubricant

Quality

grade

New

spark plug

Retightening

I

58.8

-

63.7 600 - 650

-

100

120- 150

Recommended oil viscosity for the embient temparature

I

5w

-

20

-4

I

1

I

T

10

w

20

w

##

20

low-30

I

-

10

14

0

32

10

50

I

I

I

I

I

20
68

#

30

I

30
86

1

I

43 - 47

5.7

-

8.7

-

-

16.6

I

I

I

I

40

104

7.2 7.8 - 9.8 80

10.9 11.8-14.7

19.5 22.6 - 26.5 230 - 270

1

"C

"F

1

1

Use

oil

classified

Multi-grade oil tends to increase its consumption at

as

SC

or

higher.

-

61

high

-

ambient temperature.

13.

MAINTENANCE AND STORAGE

The following maintenance jobs apply when the engine is operated correctly under normal conditions.
The indicated maintenance intervals are by no means guarantee maintenance free operations during

these intervals.
For example, if the engine is operated in extremely dusty conditions, the air cleaner should be cleaned
every day instead

13-1

DAILY MAINTENANCE (EVERY

of

every

50

hours.

8

HRS.)

MAINTENANCE

1)Clean away dust and chaff from engine.

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

3)

Inspect for loose hardware and

retighten if necessary.

4)

Check oil level and add to full mark.

13-2 INITIAL

I

1)Change crankcase oil.

20

HOURS.

MAINTENANCE

MAINTENANCE

REMARKS

Governor linkage is especially sensitive Read instruction for

to dust.

If

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

off

I

and

I

To

remove sludge from run-in operation.

REFER

use.

Read instruction for
use.

Read instruction for
use.

Read instruction for
use.

REFER REMARKS

Read instruction for

I

13-3 EVERY

1)Change crankcase oil.

2) Clean air cleaner.

50

HOURS.

MAINTENANCE

I

3)Check and clean spark plug.

4)

Clean cooling system.

(10 DAYS) MAINTENANCE

Contaminated oil quickens wear.

If dirty, wash in gasoline or polish with
emery paper.

-

62

-

REFER REMARKS

Read instruction for
use.

Read instruction for

1

use.
Read instruction for

1

use.
Read instruction for

use.

13-4

EVERY

100-200

HOURS. (MONTHLY) MAINTENANCE

MAINTENANCE

REFER

REMARKS

1)

Inspect cooling system and remove dirt

Consult

your nearest

Remove blower housing and clean up

and chaff.

Robin

dearer.

between fins and housing.

I

2)Clean and adjust spark plug gap.

Read instruction for

I

use.

3)

Change,

oil

filter.

Read

instruction

for

use.

13-5 EVERY 500-600 HOURS. MAINTENANCE

MAINTENANCE

I

REMARKS

I

REFER

I

1)

Remove carbon from cylinder head.

Carbon deposits

in

combustion chamber

Consult your nearest

causes lack of power.

Robin dearer.

2)

Disassemble and clean carburetor.

Consult

your nearest

Robin dearer.

I

3)

Clean fuel tank.

Consult your nearest

Robin dearer.

I

4)Adjust valve clearance.

I

Consult your nearest

Robin

dearer.

I

5)

Replace spark plug.

Consult

your

nearest

Robin

dearer.

6)Overhaul engine

Consult your nearest

Robin dearer.

I

13-6 EVERY

1000

HOURS.

(YEARLY) MAINTENANCE

MAINTENANCE

REFER

REMARKS

1)

Replace fuel lines once a year.

,

Robin

dearer.

Avoid hazards caused by fuel leakage.

Consult

your

nearest

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 spark 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.

several turns by hand. Reinstall the plug.

.

-

63

-

Industrial

Engines