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Note 1:    The engine outputs 70 – 80% power at a half throttle position.    Adjust the throttle stick position of 
transmitter at around neutral for hovering using throttle curve and pitch curve setting functions.

 

Note 2:    The needle adjustment of the engine in aircraft is closely related to the adjustment of throttle 
curve, pitch curve, and governor functions of transmitter.    So the total combination of these adjustments is 
important.

 

Note 3:    Applying spark plug ignition system to the engine, you can see rich adjustment symptoms relatively 
easily and the engine hardly stalls because of stable ignition timing, on the contrary, it is hard to notice lean 
adjustment and the engine sometimes stalls and overheats, so always start the adjustment with the needles 
on rich side.

 

 

19.      INSPECTIONS BEFORE FLIGHT

 

Check the following items after starting and warming up the engine.

 

GT120THU inspection contents

 

items

 

contents

 

Inspection Method 

 

idling

 

Check if the engine runs stable at idling. 

 

hearing/ using 

tachometer

 

response

 

Move the throttle stick up and down during hovering to see if the 
aircraft responses and if the speed of engine goes up and down.

 

Visual /hearing 

inspection

 

Engine stop 
switch

 

Check if the engine stops switch works.

 

Visual inspection

 

ignitor switch

 

Check whether the engine stops when the ignitor switch is turned 
off.

 

Visual inspection

 

noise

 

Check if you hear unusual noise.

 

Hearing the sounds

 

smell

 

Check if you smell abnormal odor.

 

Smell the whole engine

 

radio control 
system

 

Check if all the equipment work correctly when the engine is 
running.      (do the distance test and also see if it is working 
normally during pirouetting)

 

visual inspection

 

 

Check and follow the instruction of UAV for inspection before flight.     

 

 

20.      FLIGHT

 

(1) Be prepared for unexpected troubles such as engine stall during flight.

 

(2) Using the engine management system ‘EM-100’, which is sold as an option by us, is recommended for 

monitoring the engine speed, temperature, fuel level, the power supply voltage of igniter by the telemetry 
function during flight.     

 

 

(3) Cooling is more vitally important to gasoline engines than to a glow engines.      If overheating symptoms 

(loss of power at full throttle or the stick position of throttle goes up when hovering) are observed during 
flight, immediately stop flying and carry out the following measures.

 

 

① Adjust the slow needle and high needle to make the air/fuel mixture as rich as possible within the range 

you can continue flying.

 

② Set the throttle curve or pitch curve to make the overall engine rpm going up. 

 

③ Prevent the air leakage from a cooling shroud if the engine is equipped with it.

 

④ Enlarge the cooling fan size.

 

 

(4) When an interval between two flights is short and the engine is still hot, although the overheating 

symptoms could not be observed right after the first flight, the high temperature created by the former 
flight can be transmitted all over the engine before the next flight, so the engine might show overheating 
symptoms during the next flight.    In this case, leave the engine until it is fully cooled down (in hot weather, 
it may take more than one hour.) or run the engine for 4 to 5 minutes at idling.

 

 

21.      INSPECTIONS AND TIGHTENING SCREWS AFTER THE FIRST FLIGHT

 

Check the following after the first flight of mounting the engine in an aircraft 

 

(1)

 

Tighten the screws of silencer again

 

Summary of Contents for GT120THU

Page 1: ...2 stroke gasoline engine for UAV GT120THU Instruction manual Ver1 02 2020 OCT 26 O S ENGINES MFG CO LTD...

Page 2: ...switch 2 Wirings of starter switch 3 Regulate rectifier output wirings 13 MIXING OF OIL 8 14 BREAKING IN 9 15 START UP INSPECTION 9 16 PROCESS OF STARTING ENGINE 9 10 1 Getting gas in carb 2 Choke 3...

Page 3: ...tion and storage of gasoline Ask details at fire station in each district Never operate your engine in an enclosed space Model engines like automobile engines exhaust deadly carbon monoxide Run your e...

Page 4: ...he onboard generator OGA 200 of is a 3 phase alternating current AC generator with an excellent cooling system 6 The regulate rectifier is equipped with an open regulate circuit for high efficiency Th...

Page 5: ...Maximum input voltage 100 V AC Rated input voltage 60 V AC Maximum output power 200 W 10 min Maximum output voltage 28 V Minimum output voltage 6 V Maximum output current 16 A Rated output power 140...

Page 6: ...5 18 Fig 2 Fig 3...

Page 7: ...lve 32 Throttle lever 6 BATTERIES 1 Throttle servo choke servo and starter switch batteries Power supply 4 8V 8 4V Use the radio control system receiver battery 2 Ignition battery Attention Power supp...

Page 8: ...e higher than 12 9 which can be used as cap screws Also the screws for meshing part with the engine are suggested to around 7 8mm tightening torque 5 4 N m 2 Silencer Mount the silencer which is inclu...

Page 9: ...determines on or off at the threshold of 1 500 s PWM signal which is neutral position So when you set the fully open close position 1 500 s PWM signal should be included in the range of turn on off t...

Page 10: ...peller clutch cooling fan Check if the propeller clutch cooling fan are mounted correctly and there is no loose screws and bolts Visual Exhaust pipe Check the exhaust pipe if there is foreign material...

Page 11: ...ter lead wires and battery may get damaged 4 Countermeasures when the engine doesn t start Possible reason Over rich over choke over lean not enough choking the fuel mixture incorrect throttle opening...

Page 12: ...the aircraft In case rpm does not increase with sluggish acceleration and the engine dies quickly the fuel mixture is lean Turn the slow needle out counter clockwise by to richen the fuel mixture 3 A...

Page 13: ...g do the distance test and also see if it is working normally during pirouetting visual inspection Check and follow the instruction of UAV for inspection before flight 20 FLIGHT 1 Be prepared for unex...

Page 14: ...ng time total operating time remarks 23 PERIODICAL INSPECTION AND MAINTENANCE Refer to the maintenance manual 1 Inspection after 25 hour operation Propeller Fuel tubes Fuel filter Plug cap high tensio...

Page 15: ...14 18 25 EXPLODED VIEW FIG 8...

Page 16: ...13 1 79820406 M4X6 10 SET SCREW M4X6 10 SET Torque 1 5N m 14 4AA07050 3GT 255 10 BELT 3GT 255 10 15 4AA32000 BALL BEARING GENERATO R 16 54059001 GENERATOR ADAPTER 17 79871515 M5X15 10 CAP SCREW M5X15...

Page 17: ...6 10 WASHER 2 6 10 SET 48 4AA07060 LINKAGE BALL 49 79850020 M2X0 4 10 NUT M2X0 4 10 SET 50 4AA07310 BOLL LINK 51 4AA07330 L39 5 LINK ROD L39 5 52 4AA07320 L48 LINK ROD L48 53 54055000 ORF 200 REGULATE...

Page 18: ...ue 5 4N m 74 4AA84000 PK 7E AIR CLEANER PK 7E ACCESSORIES 78300000 S GASOLINE FUEL FILTER S 70000001 6 5 HOSE CLIP 6 5PCS SET OPTION 75 4AA07390 E 6030R SILENCER E 6030R 76 4AA07380 E 6030L SILENCER E...

Page 19: ...18 18 27 3 DEMENSIONAL DRAWING unit mm...

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