Yamaha 1978 SS338, 1976 SS433, 1977 SS433, 1977 SS338, 1978 SS433 Condensed Service Data

Yamaha

ENGINES

YAMAHA

1976

AND

LATER

E338, SS338 AN D SS433 TWO

CYLINDER MODELS

CONDENSED SERVICE DATA

Engine

Model

E338

88338 88433

Bore-(mm). .

..

. .

...

. . . ... . .

....

60

60 68

Inches

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

2.362

2.362 2.677

Str

oke-(mm)

.... . ..

...

..

. .

...

. .

59.6

59.6

59.6

Inches

..

........

... .

....

....

2.346

2.340 2.346

No. of Cylinders

..

. .

...

.... . ....

2

2

2

Displacement-co . . ... . . . . ... . . . .

338 338 433

Cubic Inches

.........

...

.... .

20

I).

20.63 26.4

CoolingType .

..........

........

Free Air" Free Air Free Air"

Carburetor Model

....

. .

.. . ..

.

Mikuni (B) Keihin (PW) Keihin

(PW)"

Number Used

.... ..... , ...... 1 1 1

Ignition:

Type

.. ... ..

, .... ....

cm cm cm

Timing BT,_('

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

1.5-1.7 mm

1.6mm 1.6mm

Spark P'

,

Li

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

BR9EV""

BR9EV

BR9EV""

·1·

Electrode Gap(mm) .

.......

. 0.5-0.6t 0.5-0.6 0.5-0.6

Inch . . . . .

....

. . .

..

.. . ..

.

0.020-0.024t 0.020-0.024

0.020-0.024

Fuel/OilRatio

....

...

.....

. .

..

. . Autolube Autolube Autolube

"Models prior to 1980 use Free Air cooling. All 198

0-1981

models are equipped with

Axial Fan .

""Engine models prior to 1978 use Keihin (PW) model carburetors. All 1978-1981

models use Keihin (BD) model carburetors.

"""Models prior to 1980 use BR9EV. All 1980-1981 models use BR9ES.

tModels prior to 1979 use 0.5-0.6 mm (0.020-0.024 inch) electrode gap. All

1979-1981 models use 0.7-0.8 mm (0.028-0.031 inch) electrode gap.

on E338 models, 2,000 rpm on S8338

Model

Number

MAINTENANCE

models and 1,500 rpm on 88433 models.
Initial fuel/air mixture setting is as

1976

8PARK

PLUG. Selection of spark

follows:

SS338

155

plug will depend upon type of service

SS433

155

and ambient temperature . Standard

Model

Turns Out

plug is given in Condensed Service Data

1977

table. Excessively cold weather and/or

1976-1977

8S338

150

light load conditions may require spark

88338

1

8S433

150

plugs of warmer heat range. Hard

88433

P/4

usage, heavy loads and warm weather

1978

may require spark plugs of colder heat

1978

S8338 140

range.

SS338

P/8

8S433 152

8S433

P/

2

E338

220

CARBURETOR. A Keihin (PW) type

carburetor is used on S8 models prior to

1979-1981

1979-1981

1978 and a Keihin (BD) type carburetor

88433

1

6

/8

8S433

145

is used on 1978-1981 SS models. A

E338

240

Mikuni (B) type carburetor is used on

1978-1981

E338 models. Carburetor is installed on

E338 1

If

carburetor is removed for

overhaul

,

a "Y" type intake manifold and provides

refer to LUBRICATION section for

syn

-

the fuel/air mixture to both cylinders.

Standard carburetor main

jet

is as

chronizing Autolube pump to throttle

Standard idle speed setting is 1,700 rpm

follows:

opening.

294

I

Yamaha

ENGINES

'

YAMAHA

1975

AND

EARLIER

338,396

AND

433cc

TWO CYLINDER MODELS

CONDENSED

SERVICE DATA

338, 396,

433

Engine

Model

810

811,81

3 818

8ore-{mm

) .

60 65 68

Inches .

2.36 2.56 2.68

Stroke

-{mm

) .

59.6

59.6 59.6

Inches .

2.35 2.35

2.35

No.ofCylinders .

2

2 2

Displacem

ent-{

cc) .

338

396

433

CubicInches .

20.6 24.1 26.4

Horsepower

@ RPM:

SL,SW,EW ..

24@5500 28@5500 30@5500

SS

,GP

..

32

@650

0 36@6000 40@6500

CoolingType . Cent. Fan Cent. Fan Cent. Fan
Carburetor Model . Keihin Keihin or Mikuni

Diaphragm Diaphragm

Number Used .

lor

2

lor

2 • v. 2

Ignition:

Type .

Energy

Transter

agneto

Point Gap .

See1'ex

t.

ext SeeText

Timing Advance? .

No No

No

Timing 8TDC .

Sf-

~

.\

t

See

Text

SeeText

,,

't

Spark Plug:'

SL,SW,EW . .

NGK NGK NGK

87HZ 87HZ 87HZ

\ .

SS,GP

NGK NGK Champion

, .

89H 87HZ N2G

F, . I rude Gap (mm) . .

0.5-0.6 0.5-0.6 0.5-0.6

'nch .

0.020-0.024 0.020-0.024 0.020-0.024

.. ,lV"Oil Ratio . 20 :1* 20:1*

Autolube

*

If,

not equipped with "Autolube".

MAINTENANCE

Data

for

recommended

plug

for

normal

SPARK

PLUGS.

Selection of

spark

use. Excessively cold

weather

and/or

plugs

will

depend

upon

type

of service,

light

load conditions

may

require

spark

ambient

temperature

and

horsepower

plugs

of

warmer

heat

range.

Hard

of

engine.

Refer to '

Conden

sed

Service

us

age,

heavy

loads,

warm

weather

and

higher

horsepower

may

require

spark

plugs

of colder he

at

range

:

CARBURETORS.

Various

carbure-

tors

have

been

used. Refer to

the

appro-

pri

ate

carburetor

paragr

aphs

in

FUN-

DAMENTALS

section

for

carburetor

service.

For

adju

stment

of

carburetors

and

"Autolube"

refer

to

the

appropriate

following

paragraphs

.

ONE

(KEIHIN

OR

MIKUNI

DIA-

PHRAGM

) CARBURETOR.

The

car-

buretor

is

installed

on a "Y"

type

inlet

manifold

and

provides

the

fuel-air

mix

-

ture

to

both

cylinders. Initial

fuel-air

mixture

setting

is as follows:

SL338 (Keihin)-

Idle

mixture

needle . . . 1

Va

turns

out

High

speed

mixture

needle

.. ..

. 1V4

turns

out

Fuel

level (F- Fig. 1A) .

..

..

39 mm

Inlet

lever

height

(H-Fig

. 1A) 5.7 mm

C. Cle

arance

N.

Nul

a

M.

Mark

T. Throttle shan

288

Fig. 1-Vlew showing checking and adJuslmenl
polnls fOI synchlon /z;ng carburelor opening 10
" Aulolube"

011

InJecl/on. Pump Is I//Ied from

nOlmal position

to better show the mark . Refer

to text for

ltie

Iwo

melhods

of checkIng

adJuslment. .

SW396 (Mikuni l-c-

Idle

mixture

needle ... 114

turns out

High

speed

mixture

needle

. . . . . 1%

turns out

SW433, RW 433 (Mikuni)-

Idt uu xture

needle

. . . 1Vaturnsou

t

I igh speed

mixture

needle . ..

. . 1

V2

turns out

On all models

with

one carburetor.

linkage

adjustment

is

limited

to

syn-

chronizing

the

"Autolube

" oil injection

to

the

carburetor

throttle.

With

t~

carburetor

throttle

completely

ope

n

(maximum

speed)

and

the

pump

con-

trol rod

pulled

to

maximum

position.

clearance

(C- Fig. 1) should be

1-1.5

mrn (0

.04-0

.06

inch).

Clearance

is

measured

between

lower adj

usting

nut

and

lever

on

carburetor.

Adjustment is

accomplished by

turning

nuts

to obta

in

correct

clearance.The

top

nut

locks

the

position

onower

nut.

Another

method

is to open throttle

completely

and

check to see

ifoil

pump

end

of rod is

aligned

with

mark (M).

If

not

relocate

nuts

(N).

It

will usually

be

~

'f

fl

// 111

0"

~

Fig. 1A - Dlew/ng

of

Kelhln d/ephlllgm c"butt

tOI.

Refel to text fOI distance (F) between c.nl.

of

clllbuletol

bOil

and fuel

Ilne/

. Height

(HI

01

fuel Inlet needle Is

listed

In text. Refe' to

FU,.

DAMENTALS section fOI method of

adJustmtllt

ERTER

st be

remembered

that

the

lit is

centrifug

ally

controlled

Iriven

unit

responds, therefore

.ion

and

belt

face

width

have

a

.aring on

alignment

of

sheave

re. Two

sheaves

which

are

in

alig n men t

with

correct

belt

will move

out

of

alignment

if

omes too

tight

or too loose.

Belt

ar or a

belt

of

incorrect

width

) change

alignment

and

tension

ough

shaft

center

distance

and
re as specified.
lost models,

the

drive

belt

can

be

ed

with a minimum

of

disas-

by

pulling

the

belt

into

bottom

ve of

driven

pulley

then

slipping

ff

drive

pulley.

Installation

is

~

of

rein

oval

procedure.

-n b

elt

is

removed

and/or

unit

is

' ~mb led

,

inspect

all

components

SPEED

TUNING

GENERAL

, torque

converter

unit

is involved

.Y

speed

tuning

decision for two

ns; re

sults

and

safety.

ere is

little point

in

spending

time

noney modifying

and

fine-tuning

ngine

unless the

drive

trai

n is

)!e of ma king the best us e of i,h e

'power

gained.

The

degree

of mod-

lion

of

the

converter

drive

and

.n

units

is so

inter-related

that

an

.t

procedure

cannot

be

outlined.

, section ,

therefore

, will

attempt

to

mly

the

principles

which

apply

and

precautions to be observed.
he

high

engine

speeds

associated

h

performance

tuning

makes

it

-era tive

that

care

be used in

main-

ling the

balance

and

trueness

of

lch

components. Racing

drive

ches

should

be

equipped

with

a

tter

sh

ield.

;peed

tuning

the

converter

unit

gen-

l

ly involves

raising

the

eng

agement

-ed, extra

attention

to

dynamic

bal-

ce of

the

total

unit,

careful

belt

selec-

n,

and

combating

down-shift

lag

of

iv en

member. The

final

step

in con-

rt

er

tuning

is

mating

the

drive

unit,

It and

driven

unit

into a carefully

.lanced

package

which will

transmit

Igine

power

to

the

track

in

its

most

fect ive form .

Although

the

principles

of

perform-

nee t uning

can

be

documented,

so

'an y

variables

are

involved

that

the

d ual

practice

depends

on

experimen-

ation,

experience

and

a feeling for

the

ib (coupled

with a fair

amount

ofluck)

h

at

only

the

outlines

of procedure

can

ie given .

DRIVE CLUTCH

Speed

tuning

an

engine

usually

sac-

carefully

for

wear

or

other

damage. If

wear

is

abnormal,

attempt

to discover

the

cause

before

completing

the

repairs

and

returning

the

vehicle to service.

Excessive or

uneven

wear

on sides of

vee

belt

may

indicate

pulley

misalign-

ment,

bent

pulley

half

or

improperly

adjusted

idle

speed. Examine

pulley

faces for

wear

patterns

or

heat

discolor-

ation.

Determine

and

correct

the

cause

of

trouble

rather

than

just

renew

the

belt. Sheave

parts

should

fit

with

a

minimum

of

clearance

without

binding

. Apply a

light

coating

of oil or

low

temperature

grease

to

sliding

parts,

but

make

sure

that

no excess

lubricant

will be

thrown

on

belt

or

sheave faces

when

unit

is

in

operation.

Check

for specific

overhaul

informa-

tion

and

disassembly

notes

in

the

unit

sections or

illustration

s.

rifices

torque

at

the

low

end

to

obtain

a

power

peak

in

the

performance

range.

The

degree

of

"peakiness"

depends

on

the

type

of

competition

involved

and

determines

the

tuning

of

the

drive

clutch

.

In a

family

machine,

the

drive

clutch

should engage

smoothly

at

a r

elatively

low

engine speed

and upshi

ft

smoothly

through

the

power

range

under

all

combinations

of

throttle

setting

and

load. The

converter

package

should

automatically

shift

down as

necessary

to

keep

from

lugging

the

engine.

With a "peaky"

competition engine,

engagement

speed

must

be

raised

above

the

stall-out

point

of

engine

tuning

and

total

balance

of

machine,

track

surface

and

converter

should

permit

almost

instantaneous

accelera-

tion

to

peak

horsepower

range.

As

previously

stated,

clutch

engage-

ment

speed

can

be

raised

by

lightening

the centrifugal

weights

or by

strength-

ening

the

reaction

spring.

Clutch

and

machine

manufacturers;

and

some

per

-

Fig. 8-Cross

sectional

view

of

governor

centrifugal

weights

showing:

M-Face

movement

and;

Dotted

IInes-welght

movement;

to

high

speed

'pos/llon. Kidney

type

weight

Is

shown

at

right

while

left-hand

view

\\

shows

curved

cam-arm

type

In

which

pivot

(P)

moves

and

fulcrum

(F) Is

fixed.

Removing

material

In

shaded

area

(E)

will

have

greater

effect

on

engage

-

ment

speed;

at

shaded

area

(X)

will

have

greater

effect

on

shift

pattern.

C.

Gravit

y cente rline

F.

Fulcrum point

M. Advan ce movem

ent

P. Cen

trif

ugal pivot

Speed

Tuning

formance

specialists,

make

heavier

springs

available. But

sometimes

the

'

spring

is

not

the

whole

answer.

Centri-

fugal force

increases

geometrically

as

speed

increases

and any

inherent

im-

balance

is

correspondingly

multiplied.

Also ,

heavy

centrifugal

weights

plus

high

speed

plus a correspondingly

strong

balance

spring

in

driven

unit

exert

heavy

side

pressure

on

drive

belt,

resulting

in

increased

belt

wear

and

frictional

loss of

power. For

these

rea-

sons,

weight

modification (or selection)

is also a widely

used

modification

tech

-

nique

.

A

new

compensating

spring

for a

competition

clutch

should

be

com-

pressed

in a vise

overnight

to

pre-set

the

spring

before

installation. Weights,

weight

pins, rollers

and

similar

parts

should

be

installed

only in

sets

and

carefully

weighed

and

balanced

(using

druggists

scales

or

equivalent)

before

installation

. :r

weights

are

altered

by

trimming,

balance

must

be

maintained

both

as to

total

weight

and

configura-

tion. Dynamic

balance

and

centrifugal

action

are

both

affected by

selection

of

trim

point. Refer

to

Fig

. 8. As a

general

rule,

removing

weight

farthe

st

from

pivot

point

(P ),

from

hea

.v.y

side

of

gravity

centerline

(C),

or

nearest

pulley

outer

rim

will

have

the

greater

centrif

ugal

effect.

And

material

nearer

pulley rim

will "weigh

mor

e", "'.'n a

dynamic

balance' standpoiu t th a n

equal

weight

nearer

the

hub.

Re-

moving weight

at

shaded

area

(E) will

affect

engagement

rpm

to a

greater

degree

while

removal

from

shaded

area

(X) will

have

greater

effect on

shift

pattern

. Do

not

remove

material

from

fulcrum

point

(F)

of

kidney

weight

(right)

or from

roller

contact

area

of

hammer

weight

(left)

when

lightening

the

weights.

Paint, rust,

gum

or

grease

must

be

removed

from

belt

contact

surfaces

of

pulley

faces

and

the

surfaces

kept

clean. Bushing

surfaces,

pivot

pins,

rollers

and

other

friction

points

must

c

315