FEATURES
These engines features superior fuel delivery incorporat-
ing the YS pressurization system, butterfly type throttle and
new carburetor design. The carburetor uses simplified con-
struction that does not require adjustment other than the fa-
miliar needle valve.
Both version of the YS 45F are suitable for the novice as
well as expert R/C flyer.
GLOW PLUG
Select the most appropriate glow plug from those designed
specifically for R/C operation. The selection of glow plug
greatly affects the maximum engine output and low flying
stability. If rpm’s decrease or stop when the booster cord is
removed, replace the plug.
INSTALLATION
1. Connect the engine to the tank as shown in fig.1. Since
high pressure is applied to the tank, tighten all
connections carefully. Care must be taken to prevent
pressure leakage due to undertightening of the check
valve or by kinking the fuel lines.
2. Use a fuel filter in the fuel line. We recommend the YS filter.
3. Match the direction of the check valve arrow to fig.1.
START-UP
1. Remove the tube (B) from the filter, remove tube (A) from
the check valve, then fill the tank.
(Caution; If tank is filled, remove tube (A) first; then tube (B).
Fuel will eject if tube (B) is removed first while the tank is
pressurized.)
2. Open the needle valve three turns from the fully closed
position.
3. Open the throttle fully and slowly turn the propeller ten
turns. This primes the system by pressurizing the tank
and feeding fuel to the carburetor.
4. Pour several drops of fuel into the carburetor.
5. Close the throttle approximately 25% and connect the glow
plug cord.
6. Start the engine.
BREAK-IN
To maximize engine performance and increase
durability, use this break-in procedure;
1. Use the same size or smaller propeller as you intend to
use in flying(11
×
6 to 11
×
7).
2. Use any good quality 2 stroke fuel, which includes
synthetic or castor oil additives.
3. During the break-in operation, open the throttle fully.
4. Rotate the propeller two or three turns, operating the
needle valve as far as needed without stopping.
Then rotate the needle valve 1/2 turns back from peak
position and run for 30 minutes.
5. Mount the engine and fly it ten times at a speed 1,000rpm
lower than peak rpm. This concludes the break-in
procedure. It is advisable to keep the needle valve open
a bit more than necessary so as to keep the moving parts
lubricated, even after the break-in period.
HIGH SPEED ADJUSTMEN
T
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.
2. When the engine is started, open the throttle gradually.
Next, find the peak position(high rpm) by adjusting the
needle valve. Set the rpm slightly less than peak (the
needle should be turned 30-45 degrees to the left of peak
position). The engine may stop if the throttle is opened to
full immediately after start-up. Wait until the engine
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
Carburetor adjustment for low speed is factory pre-set.
No adjustment is required until after the break-in period.
After break-in use this procedure if necessary.
1. Adjustment of low speed revolution is done by the
diaphragm/regulator valve screw.When the diaphragm is
turned clockwise, the mixture is leaned. When it is turned
counterclockwise the mixture is richened.
(For reference: The engine is assembled with the head of
the diaphragm valve screw flush with the regulator body.
Adjustments should be made in 1/8 to 1/4 turn increments.)
2. The diaphragm valve can be set after the high speed
needle valve has been set. Close the throttle gradually;
then fully open the throttle just before the engine stops.
The adjustment condition is satisfactory at low speed if
revolution is smooth at this time. Set the number of idling
revolutions by throttle barrel limit screw. If the throttle is
quickly opened and the mixture is too rich, turn the
diaphragm adjustment screw clockwise 1/8 to 1/4 turn at
a time to achieve smooth throttle response. If the mixture
is too rich it is possible to stop the engine (flooding) when
the throttle is opened.
3. When the revolution is stabilized, close the throttle
further and repeat the above adjustment to idle evenly at
2,500rpm or less.
PROPELLER AND MUFFLER SELECTION
The YS engine is designed for use with a tuned pipe.
The intermediate length between the muffler and exhaust
adaptor depends mainly on the propeller size and the type of
fuel. Generally, when the diameter and pitch of the propeller
increase, the intermediate(header) length should increase
as well. It must also be increase with lower nitro content fuel
blends.
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 valve adjustment screw until flush with the
diaphragm body. Refer to “LOW SPEED ADJUSTMENT”.
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.
TROUBLE SHOOTING
OPERATOR’S MANUAL
YS45FS
(Side Exhaust)
YS45FR
(Rear Exhaust)
PROBLEM
CAUSE
SOLUTION
Unstable high speed
1,Needle valve set too lean
Readjust peak position
2.Foreign material in carburetor or filter
Clean each
3.Low tank pressure
(See below)
4.Inappropriate glow plug or fuel
Unstable low speed
1.Incorrect fuel/air ratio
Readjust diaphragm
2.Low tank pressure
(See below)
3.Check valve malfunction
Clean
4.Foreign material in the carburetor
Clean
5.Incorrect glow plug or fuel
Low tank pressure
1.Bent or damaged fuel line
Check each tube
2.Damage to the tank or pressure leakage Inspect
Weak mixture
1.Foreign material in the throttle
Clean
2.Foreign material in the filter
Clean
3.Foreign material in the carburetor
Clean
4.Low tank pressure
(See below)
5.Bent or damaged tube
Check each tube
Fuel flows after stopping
1.Check valve malfunction
Clean
2.Foreign material in the carburetor
Clean
3.Loosened valve adjustment screw
Readjust
Tube (A)
Tube (B)
Check Valve
36
45
54
20
Filter
51
70
28
FIG.1
SPECIFICATIONS
Bore
21.8mm
Stroke
20.0mm
Displacement
7.45cc
Weight
400g
Practical rpm
2,000-18,000rpm
WARRANTY
Strict quality control is implemented by our factory in all
phases, from parts manufacturing to final assembly. If
performance deteriorates or a part fails with-in one year of
purchase due to a manufacturing error,YS performance will
repair or replace the engine at no charge.
Warranty will not
cover normal wear.
Should the engine be modified or incorrectly assembled, there
will be a normal charge for parts and labor.
