Two stroke gasoline engine for airplanes GT55 It is of vital importance, before attempting to operate your engine, to read the general 'SAFETY INSTRUCTIONS AND WARNINGS' section on pages 2-5 of this booklet and to strictly adhere to the advice contained therein. Also, please study the entire contents of this instruction manual, so as to familiarize yourself with the controls and other features of the engine. Keep these instructions in a safe place so that you may readily refer to them whenever necessary.
WARNINGS SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE Never touch, or allow any object to come into contact with the rotating propeller and do not crouch over the engine when it is running. Remember that your engine is not a " toy ", but a highly efficient internal-combustion machine whose power is capable of harming you, or others, if it is misused or abused. As owner, you, alone, are responsible for the safe operation of your engine, so act with discretion and care at all times.
NOTES When checking a spark plug with the power source on, do not hold the plug, plug cap, high tension cord nor grounding wire, or you will get a shock. Always check the throttle linkage. If it is disconnected, throttle action becomes uncontrollable, which may result in a serious accident. Install a top-quality propeller of the diameter and pitch specified for the engine and aircraft. Take care that loose clothing (ties, shirt sleeves, scarves, etc.) do not come into contact with the propeller.
ABOUT THE ENGINE This engine is designed for experienced fliers. Beginners and newcomers should not use this engine. STANDARD ACCESSORIES Spark Plug CM-6 The engine unit, carburetor and igniter are specially designed. It offers broad power characteristics suitable for sport flight as well as acro flight. Exhaust Gasket GT55 The large and dense cooling fins ensure sufficient cooling against overheating.
SILENCER / INSTALLATION Be sure to use an effective silencer (muffler). Frequent exposure to an open exhaust may eventually impair your hearing. Such noise is also likely to cause annoyance to others over a wide area. Use 5mm steel hex socket head bolts to install the engine. (Do not use brass, soft steel nor aluminum screws, because they are not strong enough.) Also, use the Nord Lock Washers (optional extra) and other anti-loosening washers or apply locking agent. The GT55 does not come with a silencer.
CARBURETOR WLA-2 PARTS NAME Carburetor Body Choke Valve Lever High Speed Needle Idle Speed Stop Lever Idle Speed Stop Screw (No need to adjust. Factory adjusted.) Slow Speed Needle Spring Throttle Return Air Vent Fitting (No need to connect in normal use.) Throttle Valve Lever Retaining Screw High Speed Stop Lever Throttle Valve Lever Fuel Inlet High Speed Stop Lever Retaining Screw 10 CARBURETOR LINKAGE NOTE Connect the throttle linkage so that the engine can be stopped via radio operation.
Connect the linkage so that the throttle valve is fully opened when the throttle stick on the transmitter is fully advanced. (Adjust the movement so that the pushrod does not bind when the throttle valve is fully closed and fully opened.) Before connecting the throttle linkage, make sure that the throttle valve lever does not interfere with the bulkhead or mount of the model when it is fully closed and opened.
Precautions Do not disassemble the ignition module and plug cap. (The ignition module is irreparable. Replace it when necessary.) Check the ignition module for spark when installing the plug cap on the plug and be careful about getting a shock. Make sure there is no flammable material or gasoline vapors near by that could ignite. Be careful not to mount the ignition module so that it can be hit by water, gasoline or exhaust.
INSTLLATION OF PROPELLER Install the propeller on the shaft so that the curved face of the blades faces forward – i.e. in the direction of flight. Firmly tighten the propeller washer and propeller retaining screws using the correct size wrench. Always check the tightness of propeller retaining screws and retighten them, if necessary, before restarting the engine.
RUNNING-IN / STARTING Use a fuel with increased oil content and set the needle a little on the rich side. Too rich a needle setting may cause misfiring or erratic running due to fouling of the plug. Always check the throttle linkage. If it is disconnected, the engine becomes uncontrollable, which may result in a serious accident. Use a 25:1 fuel/oil mixture if the particular brand of oil states 30:1. If the oil states 50:1, use a 30:1 mix. Set the high speed needle l00~200 below maximum rpm.
Second and later starting of the day 4. Flip the propeller until the fuel runs out of the carburetor, then flip 3~4 times more (6~7 times in winter). (In case of upright and side installation, flip 7~8 more time after the fuel reaches the carburetor.) 1. Set the throttle stick on the transmitter at bottom or 1/8 (2~3 clicks) advanced from the bottom. 2. Make sure the choke valve is fully opened. 3. Turn on the ignition switch. 5. Open the choke valve fully.
Starting with a Chicken stick or gloved hand No.2 (It is suggested to use an electric starter.) Note If the engine does not start after more than 5 times repeat the procedure, over-priming is suspected. Check whether the plug is wet or not. If the plug is wet, replace it or wait until it is dried. Then, flip the propeller swiftly (15~20 times) with the plug removed to eject the fuel in the cylinder. Then, install the plug and repeat the starting procedure. Fist starting of the day 1.
NEEDLE ADJUSTMENTS The slow speed needle is effective through the high speed range, while the high speed needle is not effective in the low speed range. Both needles are effective in the mid speed range, while the slow speed needle is the most effective. (Refer to the diagram below.) 2. Start the engine. Open the throttle valve slowly until fully open and run the engine for 10 seconds to warm the engine. 3.
FLIGHT & MAINTENANCE Maintenance after the day’s flights Checking prior to flight Please pay attention to the matter described below to ensure that your engine serves you well in regard to performance, reliability and long life. When the engine is started, make sure the radio control system works normally (distance test). Engine does not run erratic with full throttle. Check the tightening of each screw, especially engine installing screws and silencer installing screws each time.
Code No. 29704000 29714100 29703100 29703400 29703200 29706000 29717000 29705000 29781300 29781000 29781110 29781500 29701200 29701210 29709000 29702100 29708000 29708100 29708200 29730000 29701000 29701300 29701310 29731000 29702000 29714200 29707000 74002000 74002200 71669000 29714300 No. 1 1-1 2 3 4 5 6 7 8 9 10 11 12 12-1 13 14 15 15-1 15-2 16 17 18 18-1 19 20 21 22 29 The specifications are subject to alteration for improvement without notice.
CARBURETOR EXPLODED VIEW N4-40x5 11 12 4-4x40 9-1 2 9 1 10 3 4 20 21 12 4-4x40 22 24 6 5 23 15 13 24-1 14 8 16 7 17 24-3 24-6 24-5 18 N4-40x5 24-2 4-4x40 12 25 19-1 26 19 27 24-4 28 Type of screw N...Round Head Screw 30 CARBURETOR PARTS LIST No. Code No. Description No. Code No.
O.S. GENUINE PARTS & ACCESSORIES SUPER FILTER (S) SUPER FILTER (L) (72403051) (72403050) NON-BUBBLE WEIGHT (S) (71531010) BLIND NUT (10pcs.) M5 (79870050) LOCK WASHER (10sets) M5 (55500004) The specifications are subject to alteration for improvement without notice. 32 THREE VIEW DRAWING 47.4 Specifications 47.4 40.5 Displacement Bore Stroke PracticalR.P.M. Output Weight 75 40 20 54.93 cc / 3.352 cu.in. 41.2 mm / 1.62 in. 41.2 mm / 1.62 in. 1,500-8,000 r.p.m. 5.5 ps / 7,000r.p.m.
MEMO 34 URL : http://www.os-engines.co.jp C Copyright 2009 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan. 6-15 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003, Japan TEL. (06) 6702-0225 FAX.
