OPERATOR’S MANUAL
YS 140Limited
fig.1
Supercharged
63
128
25
High Speed Needle
Low Speed Needle
SPECIFICATIONS
Bore 32mm
Stroke
Diaplacement
29.0mm
23cc weight 890g
Practical rpm 2,000 -12,000rpm
Check Valve
Tube （ A ）
Tube （ B ）
YS Fuel Filters
(YS1195/not included)
FEATURES
The YS140 Limited was developed for the serious competitor in mind.
As aircraft increases in size, so does the need for power. With a few modifications internally, YS was able to generate more power in the same
140 case. The YS 4 cycles are so unique, almost every square inch is used in some way to produce power.
* Supercharged
* Fuel Injected
* Regulated and Pressurized Fuel System
* High and Low Speed Adjustments
GLOW PLUG
Select the most appropriate glow plug from those designed specifically for
4 cycle engines. Glow plug selection greatly affects the maximum engine output and low idle. If RPM’s decrease or stop when the booster cord is removed, replace the plug. We recommend the OS Type F plug for maximum performance.
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. Always use a fuel filter. We recommend YS filter.
3. Match the direction of the check valve arrow in fig.1, with the arrow facing towards the tank.
PROPELLER INSTALLATION
Due to the high torque of the140L engine, we have equipped it with a double locknut system for safety.
1. Mount the propeller and tighten the rear nut. Next, tighten the front nut as shown in fig.2. The rear nut has a offset shoulder so the front nut will secure itself to the rear nut.
2. Select a good quality propeller that will allow the engine to run at maximum speed between 8,000 to 9,000rpm range. We recommend sizes 14x14,(15x12 through 14),(16x11 through 14).
fig.2
Front Nut Rear Nut
START UP
1. Remove tube A from the check valve, (CAUTION) Tank pressure must be release first before tube B is opened. Remove tube B and begin to fill fuel tank.
2. Open the high speed needle 2 1/2 turns from the closed position.
3. Open the throttle fully and slowly turn the propeller 10 times. This will prime the engine and pressurized the fuel tank.
4. Close the throttle to the idle position and connect the glow driver.
The engine is now ready for starting.
DO NOT ATTEMPT TO START ENGINE AT FULL THROTTLE, AS THIS
IS VERY DANGEROUS. ALWAYS USE EXTREME CAUTION WHEN
ENGINE IS RUNNING.
BREAK-IN
To maximum engine performance and increase durability, please follow this break-in procedure.
1. Use the same size (or slightly smaller) propeller than you intend to use in flying.
2. Use a good quality fuel which contain 15-30% nitromethane and an oil content of Low Viscosity oil 20-24% oil. Synthetic or castor oil can be used, or a combination of both.
DO NOT USE FOUR CYCLE FUEL DUE TO LOW OIL CONTENT.
3. After the engine has started, slowly bring the throttle up to full.
Set high speed needle so it is running at a good rich setting without the glow driver. Run engine at this setting for approximately 20 minutes with the throttle moving from low to high speed.
4. After the initial 20 minute break-in, mount the engine in the aircraft and set the high speed to a richer than normal setting for the first 10 flights. This will help to lubricate all moving parts.
HIGH SPEED NEEDLE ADJUSTMENT
1. Adjustment of the 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 1/2 turns open from the fully close 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 1/8-1/4 turns from full RPM to achieve best performance. The engine may stop if the throttle is opened to full immediately after starting. Wait until the engine has warning up and pressure has developed in the tank.
LOW SPEED ADJUSTMENT
This engine is equipped with a new low speed needle valve to adjust the mixture from low to mid throttle. See fig.1 for location.
1. Factory starting position is 1 1/2 turns open from the fully closed position. The low speed needle should be set after the high speed needle has been adjusted.
2. Close the throttle gradually to an idle (approximately 2,000rpm). Let it idle for 15-20 seconds and then slowly advance the throttle.
The adjustment is set when low to high speed has a smooth transition.
3. If the engine is running rough at idle or to rich, turn the low speed needle counterclockwise to lean out the low end.
4. If the engine speeds up at idle , the low speed mixture is to lean.
Turn the low speed needle clockwise to richen the mixture.
5. If the engine is to lean on the low end, it can detonate and stop when transition from low to high RPM.
REGULATOR ADJUSTMENT
The regulator is preset at the factory. The top of the brass adjusting screw is flush with the top of the regulator housing. Turning the regulator screw will not change the pressure the engine develops. The adjustment screw is used to adjust the amount of fuel to the carburetor. Turning the screw in will decrease the amount of fuel and turning the screw out will increase the amount of fuel to the carburetor.
fig.3
Tappet Clearance
TAPPET ADJUSTMENT
Tappet clearance is preset at the factory. Adjustment if needed should be checked after the initial break-in. For maximum performance, valves should be checked as normal maintenance.
1. Clearance adjustment should be done when the engine is cool.
2. The proper clearance should be set 0.04-0.1mm or 0.002-0.004 in.
The adjustment is achieved by losing the locknut (fig.3) and turning the adjustment screw. The engine must be at top dead center on the compression stroke before any adjustment are made.
CAM GEAR TIMING
If for some reason you have to disassemble your engine, please follow these important steps on reassembling the cam gear.
1. Remove the carburetor and backplate assembly. Notice the impression mark or dot opposite the rod journal on the crankshaft. This mark is to point straight down or lined up with the outer case seam line at the bottom.
2. Reinstall the cam with the dot facing you and is pointing slightly to the left. This will allow the cam to turn to the right when properly installed.
The dot should be pointing starting up when cam is fully installed.
Reinstall cam cover and timing is now set.
DIAPHRAGM AND CHECK VALVE DISASSEMBLY
Diaphragm;
1. Remove the regulator assembly by removing the two allen head screws.
2. Disassemble the regulator and clean with alcohol or appropriate cleaner.
3. When reinstalling the regulator, use a new gasket and note that the small casting tab on the regulator goes towards the propeller.
Check Valve;
1. Open the check valve by rotating the body counterclockwise.
Note the small clear silicone disc. DO NOT LOSE.
2. Clean and reassemble. Check to make sure air will only past though the check valve one way.
IMPORTANT! Silicone rubber is used in the YS engine. Only use glow fuel or methanol for cleaning. Gasoline and other volatile solutions will damage the silicone if used. Do not use petroleum based oils as after run lubricants.
YS 140Limited Parts LIST
37 F1537
38 F1538
39 F1239
40 F1240
41 F9122
42 F1341
43 F1242
44 F1543
F1244A
45 F1244
46 F1245
47 F1246
48 F1247
49 F1248
50 F1249
51 F1250
52 F1251
F1752A
54 F1752
55 F1753
56 F9156
57 F9157
F1545S
58 F1545
59 F1546
60 F1555
61 F1556
62 F1557
63 F1483
64 R6124
65 F1258
66 F1259
67 F1260S
68 F1463
69 F1564
70 F1565
71 F1568
72 F1269
73 F1382
74 F1266
2
3
4
5
F1701
F1202S
F1202
F1203
F1204
6
7
8
F1505
F1506A
F1506
F1407
F1408
9 F1409
10 F1410
11 F1411
12 F1212
13 F1213
14 F1214
15 F1215
16 F1216
17 F1217
18 F1518
19 F1719
20 F1520
21 F1521
22 F1222
23 F1523
24 F1524
25 F1525
F1426A
26 F1426
27 F1427
28 F1492
29 F1429
30 F1230
32 F1232
33 F1233
34 F1234
35 F1535
36 F1236
# Part# Description QTY
Crankcase
Head Cover Set
Head Cover
Head Cover Gasket
Valve Cover Screw Set
Head Gasket
Head Assembly
Cylinder Head
Intake Valve
Exhaust valve
Valve Spring Set
Spring Retainer Set
Valve Spring Retainer Clips
Rocker Arm Set
Tappet Adjusting Screw Set
Tappet Adjusting Rock Nuts
Rocker Arm Shaft
Rocker Arm Shaft Screw
E Ring Set
Head Bolt Set
Crankshaft
Cylinder Liner
Piston
Wrist Piston
Wrist Pin Retainer Set
Piston Ring
Connecting Rodfi
Back Plate Assembly
Back Plate
Disc valve
Rear Disc Valve Retainer
Retainer Screw
Back Plate Gasket
Cam Gear Cover
Cam Gear Cover O-Ring
Cam Gear Cover Screw
Cam gear
Cam Followers Set
Push Rod Set
Push Rod Cover Set
Push Rod Cover O-Ring
Front Bearing
Front Bearing Oil Seal
Rear Bearing
Cam Gear Bearing Set
Fuel Nipples Set With Washers
Regulator Assembly
Regulator Body
Regulator Adjusting Screw
Regulator Adjusting Screw O-Ring
Diaphragm
Regulator Plunger
Plunger Spring
Regulator Gasket
Regulator Screw Set
Carburetor Assenbly
Carburetor Body
Throttle Barrel
Low Speed Needle Valve
Low Speed Needle Valve O-Ring
Needle Valve Assembly
High Speed Needle Valve
High Speed Needle Valve O-Ring
High Speed Needle Valve Seat
Needle Valve Socket O-Ring Set
Needle Valve Detent
Throttle Barrel Seal
Throttle Barrel Retainer
Throttle Stop Screw
Throttle Stop Spring
Throttle Arm Set
Carburetor Gasket
Drive Washer
Drive Washer Retainer
Intake Pipe
Intake Pipe O-Ring
Wrist Pin Access Plug
Propeller Washer
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
2
4
1
2
2
1
2
1
2
2
6
1
1
1
1
6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
1
2
1
1
1
5
1
1
2
1
2
2
1
4
2
2
2
1
1
1
2
1
1
1
1
4
75
17
15
12
13
14
11
10
16
9
39
37
23
22
38
39
36
34
32
33
43
35
43
8
44
74
69
70
40
41
51
48
49
45
52
49
50
47
46
2
3
18
6
7
5
24
21
23
25
20
73
1
44
42
# Part# Description
75 F1267
76 F1475
F1473S
Propeller Nut Set
Crankshaft Ring
Gasket Set
F1574S
M0010
M0020
M0021
M0022
M0023
M0030
M0031
M0032
M0033
M0040
M0050
M0060
M0070
O-Ring Set
Super Mount Set
Front Mount Assembly
Front Mount Case
Inner Ring
Inner Rubber
Rear Mount Assembly
Rear Mount
Rear Mount Arm
Arm Screw
Rear Mount Screw Set
Rear Mount Spacer
Oil Damper #200
Ball Support
72
71
19
76
67
27
55
63
57
56
64
29
31
28
72
65
66
68
44
54
31
61
31
60
62
59
58
26
30
QTY
2
1
4
14
2
3
1
1
1
1
2
1
1
1
WARRANTY
Strict quality control is implemented by our factory in all phases, from parts manufactiring to final assembly. If performance deteriorates or a part fails with-in 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 or incorrectly assembled, 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.
YAMADA MFG.CO.,LTD
67 Tsuchitori Inuyama Aichi 484-0917 JAPAN
TEL: 0568 67 0265 FAX: 0568 67 7801
