YS FZ70S User 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 A from the check valve,
then fill the tank. (CAUTION: If tank is filled or under pressure re
move tube A first, 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. A good
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 R PM 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 a time 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.

NO. PARTS# IDESCRIPTION
1
Gl00l iCrankcase
2
3
4
5
6
7
8
9
~
10
11
GlO02S
GlO02
F5103
F5104
F9106
F9107
i F3108
' F5110
F5111
F5112
Cylinder head assembly
···CYlinder head
Valve cover
J QTY
1 1
I
1 1
~~~~~~-c~~~~~C~~:i~sc~re~w~s~ ____ ~ __ ~~~
12
F5113
13 F5114
r-
14
'Fii115
r-j5G1015
Intake pipe 0 rings 2
Crankshaft 1
16 Gl016 C 1
L~--+~~:--f.:R",e",ar~b:;:e:::a::..ri,,:,n,,:g:-- _______ ....... ~1
Front bea~ir1!;1 ..
17
GIOl7
18 F5118
I.F .... ront bearing seal 1
JDrive washer 1
19 F5119
~
~
20 F5120
21 F5121 iDrive washer retainet 1
IProp washer 1
t=~~=t~~~~~=~i~p~ro:p:.:nc::u:.:t.::s:::et'::"""_~ ________ 1 _.2
1
_.-
22 F1266
! 23 F2267
24
G1024 'Piston
25 G1025 IPiston ring 1
26 G1026
27 F5127
29 F1213
1~~~~~~w~r~~t~Pi~n~==~~~~~
r- Wrist pin retainer
Valve adjuster set
30 F1214
31 F5131 Adjuster
nut set 2
1
32
F5132 IRocker arm screw 1
33 F1217
F5134
__ ~lip.::S::::etO- ________ -t __ -;,2---j
Cam 1
F5135
Cam cover 1
F5136 Cam cover 0 ring 1
F5137
38 iF5138 Cam cover
scre.:.:.w.::.s ______ -:-~2;;__1
Cam bearing set 2
39
I F5139 Cam follower set 2
40 F5140
41 Gl041 Push rod set _ 2 r-'
Push-rod cover set ~
42 i F5142 Push rod cover 0 rings 4
43 i G1043 Con rod
I G lO44A Back plate assembly
44 J G1044 Back plate
45 i G1045 Disc valve
46 i G1046 Disc valve pin
47 'G1 047 Disc valve set screw
48 F5149 Back plate gasket
~ F5150·~~B:::a:.:c~k~p~la:::te~sc=r~e~w~s-------!~
1
iThrottle barrel
50 GlO51 :Carburetor bo£lL __ -~r-----c
51 G1052 i
i······----,-------
52 F5153 iThrottle barrel 0 ring
~ Rs124 ITHrottle barrel retainer 1
1
1
~
1260S Throttle arm set
258 Throttle stop scr~
F1259 Throttle stop spring
G1057~ Needle valve set
57 i F5158 Needle valve 1
58 F1546 Needle valve 0 ring 1
59 G1059 Needle socket 1
.. :3..
1
60 G1060 I Needle socket 0 ring
~1-F15::::5~7--t---:IN:-:e:::ed::::;;:le~de:':t:::en---=t:-r .. :.:.'.:,,--... j ........... -:;---~
1
1
62 i F5186J~()"'!lPEled needle.
1':3 jE~187 iLow speed needle 0 ring
64 J F5164 Carburetor gasket 1
65 I F5165 Carburetor screws
I G1 066A ,Regulator assembly
~r----_·.::.66~·····_·····rls~1~O~3=6~~~~~R~~e:::gu:':l~at~o:::r:::b~od~y~A~------r----~~
~
7 S1038 : Diaphram
68 $1039 Regulator valve
Regulatorvalve 0 ring
. Regulator body B
1
t --:
1
.-+:~R:::eg~u=l=at=o~r~se~t~sc __ re_ws ______ r----~~
72 G1072 Regulator spacer 2
I
I_
F5l73SMuffier set I
L.....
: 1
~
1
3
13
73 F5173A Muffler assembly
§ltE
74 F5174 C:';=k~~~='~~e~pe~ __ ~~ __
set
set
8
28
F5128 Rocker arm set

WARRANTY
Strict quality control is implemented by our factory in all phases,
70
from parts manufactiring to final assembly.
If performance deteriorates ora part fails within one year of
purchase due to a manufacturing error,YS will repair or replace the
engine at no charge. Warranty will not cover normal wear.
Should the engine be modified, incorrectly assembled or abused,
there will be a normal charge for parts and labor. The use of four
cycle fuel due to low oil content will also void warranty.
DErAILA
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YAMADA MFG.GO.,LTD
67 Tsuchitori InuyamaAichi 484-0917 JAPAN
tel [phone]
[email protected]