Ys 50ST User Manual
OPERATOR'S MANUAL
42.3 17.5
37
Fuel Filter
Low Speed Needle
Main Needle Valve
Tube (B)
Tube (A)
Check Valve
Tube (C) : 35mm
37
44
B
A
High Speed 100%
Hover 40%
Low Speed 0%
50ST
(Part No.YS0030)
STARTING PROCEDURE
HIGH SPEED ADJUSTMENT
Fig,1
Bore 22,0mm
Stroke 21,5mm
Displacement 8,17cc
Weight 398g
Practical rpm 2,000-20,000rpm
SPECIFICATION
For the best overall performance with your 50ST Helicopter
Engine, we recommend 30% nitro fuel blended especially for
helicopter use. Lower nitro percentages may be used, but
reduced performance will result.
1. Always remove tube (A) at the check valve rst. The fuel
tank is pressurized by the engine and you need to relieve
the pressure. Then, disconnect tube (B) and ll between
the lter and the tank. If you make a mistake in the proce dure, fuel will squirt out. An easy method is to use T-Fittings
tings between the check valve and the tank, and between
the fuel lter and the tank with plugs that can be removed
for pressure relief and fuel lling.
2. From the fully closed (clockwise) position, open the main
needle valve 1,75 turns. Close the idle needle fully (clockwise)
and open 1 turn.
These are the initial settings and will be re-adjusted as you
set up the engine and helicopter.
High speed is also adjusted with the main needle valve.
Turning the needle valve clockwise will lean the fuel mixture,
and counter-clockwise will richen the fuel mixture.
Adjust carefully as this setting will also affect the hover adjustment.
THROTTLE LINKAGE
Set the throttle stick on the transmitter at the center, and
adjust the linkage to put the mark on the carb body and the
mark on the throttle barrel in line. Hovering should take place
with the throttle stick near the center position if the linkage
ratio is properly set. If the ratio is incorrect, the throttle bar-
rel will be too far open at the center position on the stick and
hovering will commence at a lower stick position.
Fig.2
FEATURES
The YS 50ST Engine features the patented YS regulated
fuel system for positive fuel ow during all types of ight
conditions.
Factory authorized parts and service available worldwide.
CAUTIONS
1. Take care not to touch the engine immediately after shut-
down to avoid painful burns.
2. Do not attempt to y with engine problems as it can be
dangerous. Fix the problem prior to ying.
3. When starting the engine, do not use full throttle but set
throttle to low speed before applying the glow driver.
4. This engine is intended for helicopter use. Aircraft conver sion parts are available from our service department.
5. This engine is intended for use by experienced modelers
only. If you are not properly trained to operate this engine,
please get assistance from a skilled modeler.
6. The user is responsible for operating this engine in a safe
safe manner.
INSTALLATION
1. The fuel lines should be connected to the fuel tank as
shown in the above diagram. Be careful to install the
check valve in the correct direction. Since the tank is
exposed to high pressures, be sure that all connections
are secure to prevent pressure leakage.
2. Since the engine is sensitive to dirt in the fuel, a fuel lter
must be used.
3. Tube (C) should be set exactly at 35mm between the
engine and the check valve.
4. The check valve is designed exclusively for the 50ST.
Use only YS factory parts for replacement.
MUFFLER
1. Use an expansion chamber mufer intended for 50 size
helicopter engines. If there is a fuel tank pressure tting
on the mufer you choose, plug it, as it is not necessary
to use mufer pressure with the YS system.
2. Please note that the use of tuned pipes and tuned mufer
systems can interfere with the operation of the regulator
system and result in poor engine performance.
3. Open the throttle fully and run the engine with an electric
starter for about 10 seconds without connecting the glow
driver. This pressurizes the fuel tank and the engine is now
now ready for starting. Set the throttle barrel to low speed
and connect the glow driver before starting the engine
with the electric starter.
4. If the engine refuses to start, remove the glow driver, open
the main needle valve 2 turns from its present setting and
repeat Step 3. Return to low throttle and start the engine.
After starting, return the main needle to its running setting
before advancing the throttle.
IDLE ADJUSTMENT
Begin with the idle needle with 1 turn open from closed
(clockwise) and adjust from that point. Turning this needle
clockwise will lean the fuel mixture, and counter-clockwise
will richen the fuel mixture. Changes in fuel and weather
conditions may require re-adjustment.
HOVER ADJUSTMENT
Hover is adjusted with the main needle valve. There is some
interaction between the hover setting and full throttle setting,
so be aware that one adjustment will affect the other.
BREAK-IN
It is not necessary to mount this engine on a test stand for
break-in. However, the engine should be adjusted slightly on
the rich setting for the rst few ights to ensure proper breakin. Always use a good quality fuel which contains 30% nitro
and an oil content of 20-30%.
GLOW PLIG
1. We have found that the glow plugs listed below will give
the best engine performance;
YS #2
OS #8
Enya #3
2. Replace the glow plug when idling or top end performance
decreases.
IMPORTANT!
Silicone rubber is used in many parts of the YS Engine. Use
only glow fuel for cleaning. Gasoline or other solvents will
damage silicone if used.
2
3
5
10
11
13
15
18
24
21
22
20
32
33
37
41
9
30
6
9
17
12
14
7
4
27
28
31
29
8
38
40
25
34
26
23
35
19
16
1
2
3
5
11
13
15
18
24
21
22
20
32
33
37
9
30
6
9
17
42
12
14
7
4
28
31
29
8
38
25
34
26
23
35
19
16
1
39
36
NO. PART# DESCRIPTION QTY
YS5180 Crankcase 1
1
2 YS5185 Cylinder head 1
3 YS5190 Head gasket 1
4 YS5195 Head set screws 6
YS5200 Liner and piston set
5 YS5205 Liner 1
6 YS5210 piston 1
7 YS5215 Piston ring 1
8 YS5220 Wrist pin 1
9 YS5362 Wrist pin retainers 2
10 YS5230 Con rod 1
11 YS5235 Crankshaft 1
1 2 Y S 1 0 5 0 F r o n t b e a r i n g 1
13 YS5240 Rear bearing 1
14 YS5243 Drive washer spacer 1
15 YS5245 Prop nut 1
16 YS5250 Back plate 1
17 YS5255 Back plate O ring 1
18 YS5260 Back plate set screws 4
19 YS5270 Carburetor body 1
20 YS5275 Carburetor gasket 1
21 YS5280 Carburetor O ring 1
22 YS5285 Carburetor insulator 1
23 YS5290 Insulator set screws 4
24 YS5295 Insulator gasket 1
25 YS5300 Throttle barrel 1
26 YS0380 Throttle barrel retainer screw 1
YS5305 Needle valve set
27 YS5310 Needle valve 1
28 YS2695 Needle valve O ring 1
29 YS5315 Needle socket 1
30 YS5320 Needle socket O ring 3
31 YS2710 Needle valve detent 1
32 YS4845 Low speed needle 1
33 YS4150 Low speed needle O ring 1
34 YS0200 Throttle arm set 1
35 YS5325 Carburetor screws 2
36 YS5332 Regulator body A 1
37 YS5335 Regulator body B 1
38 YS5340 Diaghram 1
39 YS5343 Regulator valve 1
40 YS5345 Regulator O ring 1
41 YS5362 Regulator set screws 2
42 YS5365 Crankcase plug 1
YS2510 Check valve 1
YS5370 Gasket set 2
YS5375 O ring set 8
WARRANTY
Strict quality control is implemented by our factory in all phases, from
parts manufacturing to nal assembly.
If performance deteriorates or a part fails due to a manufacturing error,
YS Parts and Service will repair or replace the engine at no charge in the
period of one year from date of purchase.
Warranty does not cover normal maintenance.
Should the engine be modied, incorrectly assembled or abused, there will
be a normal charge for parts and labor.
Specications may be changed without prior notice. 2007 JAN
YS Parts and Service
1370PorterDriveMindenNV89423
Phone:775-267-9252
Fax:775-267-9690
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