YAMADA FZ70S Operator's Manual

OPERATOR'S

MANUAL

FZ70S

Fig.1

Front

Nut

Rear

nut

FEATURES

The

FZ70S

is

the

most

powerful 4 cycle

engine

of

its

size

and

was

de-

veloped

for

sport

flying

as

well

as

power

demanding

acrobatics.

•

Supercharged

system

•

Fuel

injected

•

Regulated

and

pressurized

fuel

system

•

Muffler

The

pressurized

fuel

and

injection

system

makes

throttle

response

supe-

rior

and

is

unaffected

by

tank

level.

GLOW

PLUG

Select

the

most

appropriate

plug

from

those

designed

specifically

for

4

cycle

engines.

Glow

plug

selection

greatly

affects

the

maximum

engine

output

and

low

idle.

We

recommend

the

YS

#4.

INSTALLATION

I.

Connect

the

engine

to

the

tank

as

shown

in

fig.1.

Since

high

pres

sure

is

applied

to

the

tank,

tighten

all

connections

carefully.

Care

must

be

taken

to

prevent

pressure

leakage

due

to

under

tightening

of

the

check

valve

or

by

kinking

the

fuel

lines.

2.

Always

use a fuel

filter.

We

recommend

the

YS

fuel

filter.

3.

Match

the

direction

of

the

check

valve

arrow

fl9.1

with

the

arrow

fac

ing

to

wards

the

tank.

SPECIFICATIONS

Bore 27.7mm

19.0mm

Stroke

455g·

Weight (engine)

(muffler)

33g

2,OOO-15,OOOrpm

Practical

RPM

Tube

Fuel

Filter

PROPELLER

INSTALLATION

Due

to

the

high

torque

of

the

FZ63

engine,

we

have

equipped

it

with

a

double

lock

system

for

safety.

1.

Mount

the

propeller

and

tighten

the

rear

nut.

Next,

tighten

the

front

nut

as

shown

in

Fig.1.

2.

Select a good

quality

propeller

that

will

turn

in

the

9,000

to

12,000

rpm

range.

We

recommend

sizes

12x8, 13x7.

STARTUP

1.

Remove

tube B from

the

filter:

remove

tube Afrom

the

check

valve,

then

fill

the

tank.

(CAUTION:

If

tank

is

filled

or

under

pressure

re

move

tube Afirst,

then

tube

B.

Fuel

will

eject

if

tube B is

removed

while

the

tank

is

pressurized.

)

2.

Open

the

needle

valve 2 turns

from

the

fully

closed

position.

3.

Open

the

throttle

about

10%

from

the

idle

position ( not

fully).

And

tum

the

propeller

10

times.

This

primes

sending

fuel

to

the

carbure

tor.

4.

Close

the

throttle

to

the

idle

position

and

connect

the

glow

plug

bat

tery.

The

engine

is

now

ready

for

starting.

DO

NOT

ATIEMPT

TO

START

FULL

THROTILE,

AS

THIS

IS

VERY

DANGEROUS.

BREAK

IN

To

maximize

engine

performance

and

increase

durability,

please

follow

this

break-in

procedure:

I.

Use

the

same

size

(or

slightly

smaller)

propeller

than

you

intend

to

use

in

flying.

2.

Use a good

quality

fuel

which

contains

15"30%

nitromethane

and

oil

content

of

20-24%.

Synthetic

or

castor

oil

can

be

used,

or a combina

tion

of

synthetic

and

castor.

Do

not

use

four

cycle

fuel

due

to

low

oil

content.

3.

The

needle

valve

should

be

set

so

that

the

engine

is

running

at a rich

setting.

Run

the

engine

approximately

20

minutes

with

this

setting.

4.

Mount

the

engine

to

the

model

and

fly

ten

times

with

this

setting.

This

concludes

the

break·in

procedure.

it

is

advisable

to

always

use

a

slightly

rich

setting

to

keep

the

moving

parts

lubricated,

even

after

the

break-in

period

.

HIGH

SPEED

ADJUSTMENT

1.

Adjustment

of

high

speed

is

done

by

the

carburetor

needle

valve.

When

the

needle

valve

is

turned

clockwise.

the

mixture

is

leaner.

When

it

is

turned

counterclockwise.

the

mixture

is

richer. Agood

starting

position

for

the

high

speed

needle

valve

is 2 turns

open

from

the

fully

closed

position.

2.

When

the

engine

is

started.

open

the

throttle

gradually.

Next.

find

the

peak

position

(highest

RPM)

by

adjusting

the

needle

valve.

Then

the

needle

valve

should

be

opened

approximately

1/8

of a turn

from

full RPM

to

achieve

best

performance.

The

engina

may.

stopJf

the

throttle

is

opened

to

full

immediately

after

starting.

Wait

until

the

en

gine

temperature

rises

and

then

open

the

throttle

slowly.

3.

For

flying,

it

is

advisable

to

use a slightly

richer

mixture

setting.

By

using a richer

mixture,

the

engine

temperature

is

maintained

and

RPM

stability

improves.

LOW

SPEED

ADJUSTMENT

This

engine

is

aquipped

with a new

low

speed

needle

valve

to

adjust

the

mixture

from

low

to

mid

throttle.

This

needle

valve

is

located

on

the

side

of

the

throttle

barrel

opposite

the

throttle

arm

(Rg.1).

1.

Open

the

low

speed

needle

to 1 turns

from

fully

closed

pOSition.

2:

The

low

speed

needle

valve

should

be

set

after

the

high

speed

nee

die

valve

has

been

adjusted.

Close

the

throttle

gradually

to a idle

(approximately

2500rpm).

Let

it

idle

for

20

to

30

seconds

and

then

slowly

advance

the

throttle.

The

adjustment

is

satisfactory

at

low

speed

if

transition

is

smooth

at

this

time.

3.

If

the

engine

is

running

rough

on

idle.

the

low

speed

mixture

is

rich.

If

the

engine

starts

to

speed

up

and

dies

on

idle

or

starts

to

detonate.

when

advancing

the

throttle.

the

mixture

is

lean.

Turn

the

low

speed

needle

valve

clockwise

to

richen

and

counterclockwise

for a leaner

mixture

(note

that

the

direction

of

the

low

speed

needle

valve

is

opposite

the

high

speed

needle

valve).

Adjustments

to

the

low

speed

needle

valve

should

be

1/8

to

1/4

of

a

turn

increment

at atime

to

achieve

smooth

throttle

response.

IMPORTANT!

The

regulator

adjusting

screw

on

this

engine

is

factory

set.

No

further

adjustments

are

necessary.

If

for

some

reason

you

have

to

disassemble

the

regulator

assembly.

the

regulator

adjusting

screw

should

be

set

flush

with

the

regulator

body.

TAPPET

CLEARANCE

ADJUSTMENT

1.

Tappet

clearance

is

factory

preset.

No

adjustment

is

necessary

until

after 1 hour

of

operation

(including

break-in

period).

2.

Clearance

adjustment

should

be

done

when

the

engine

is

cool.

When

the

engine

temperature

is

high,

clearance

is

higher

due

to

thermal

expansion.

3.

The

proper

clearance

setting

should

be

at

0 -

0.1

mm.

The

adjustment

is

achieved

by

loosening

the

locknut

(fig.2)

and

turning

the

adjusting

screw.

Tighten

the

locknut

after

the

adjustment

is

achieved.

Alter

the

initial 1 hour

adjustment.

this

procedure

should

be

performed a.few

every 2 hours

of

use.

Fig.2

0-

O.1mm

CAM

GEAR

TIMING

ADJUSTMENT

If

for

some

reason

you

have

to

disassemble

your

engine.

please

fol·

low

these

important

steps

on

reassembling

the

cam

gear.

1.

Remove

the

carburetor

and

backplate

assembly.

Notice

the

imp

res

sion

made

on

the

crankshaft

counterweight.

Position

it

directly

straight

down

or

in

line

with

the

case

outer

seam

line.

2.

When

reinstalling

the

cam

gear,

the

side

with a point

mark

should

befacing

the

opening

of

the

gear

box.

Note

that

it

should

also

be

mounted

with

the

point

mark

located

towards

the top

of

the

engine

just

below

the

cam

followers.

DIAPHRAGM

AND

CHECK

VALVE

DISASSEMBLY

Diaphragm
1 .

Remove

the

adjustment

screw

of

the

valve.

and

then

remove

the

inside

valve

and

spring.

2.

Clean

the

inside

with

alcohol

or

appropriate

cleaner.

Reassemble.

3.

Screw

in

the

regulator

screw

until

flush

with

the

diaphragm

body.

Check

valve

1.

Open

the

valve

by

rotating

the

body

counterclockwise.

2.

Reassemble

the

check

valve

carefully.

IMPORTANT!
Silicone

rubber

is

used

in

many

parts

of

the

YS

engine.

Use

only

glow

fuel

or

methanol

for

cleaning.

Gasoline

and

other

volatile

solutions

will

damage

the

silicone

if

used.