It is of vital importance, before attempting to operate your engine, to read the general 'SAFETY INSTRUCTIONS AND WARNINGS' section on pages 2-6 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.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE Remember that your engine is not a "toy", but a highly efficient internalcombustion machine whose power is capable of harming you, or others, if it is misused. As owner, you, alone, are responsible for the safe operation of your engine, so act with discretion and care at all times. If at some future date, your O.S. engine is acquired by another person, we would respectfully request that these instructions are also passed on to its new owner.
NOTES This engine was designed for model aircraft. Do not attempt to use it for any other purpose. If you remove the glowplug from the engine and check its condition by connecting the battery leads to it, do not hold the plug with bare fingers.Use an appropriate tool or a folded piece of cloth. Mount the engine in your model securely, following the manufacturers’ recommendations, using appropriate screws and locknuts.
NOTES Adjust the throttle linkage so that the engine stops when the throttle stick and trim lever on the transmitter are fully retarded. Alternatively, the engine may be stopped by cutting off the fuel supply. Never try to stop the engine physically. For their safety, keep all onlookers (especially small children) well back (at least 20 feet or 6 meters) when preparing your model for flight. If you have to carry the model to the take-off point with the engine running, be especially cautious.
STANDARD ACCESSOIES Glow Plug No.8 (suppplied with the engine) ABOUT THE ENGINE Two versions are available, the one is without silencer, extension adaptor and 90 degree adaptor and the other is with all of them. Needle Valve Extension Cable Set E-5020 Silencer Extention Adapter This is a high performance two stroke engine designed for sport and scale models. Silencer Extention Adapter Retaining Screw (M4x90 2pcs.
Reminder! FUEL The 120AXRING should be operated on a methanol based fuel containing not less than 18% (volumetric) castor oil, or a top quality synthetic lubricant (or a mixture of both), plus a small percentage (5-20%) of nitromethane for improved flexibility and power. (The carburetor is adjusted a little on the rich side at the factory for a fuel containing 20% lubricant and 15% nitromethane.) Some commercial fuels also contain coloring additives as an aid to fuel level visibility.
TOOLS LONG SOCKET WRENCH WITH PLUG GRIP Recommended for easy removal and replacement of the angled and recessed glowplug, the O.S.Long Socket Wrench incorporates a special grip. HEX Screwdriver Necessary for engine installation. 1.5mm, 2mm, 2.5mm, 3mm 8mm Phillips Screwdriver No.1, No.2, etc. End Wrenches 8mm, 12mm, 14mm, etc. SCREWDRIVER Necessary for carburetor adjustments. No.1, No.2, etc Needle Nose Pliers Socket Screwdriver 5.
BASIC ENGINE PARTS E-5020 Silencer Extention Adapter Glowplug E-5020 Silencer Cylinder head Carburetor Type 70D Propeller washer Cover Plate Propeller nut Beam Mount Propeller Locknut Crankshaft Crankcase Drive Hub 14 INSTALLATION Because the 120AXRING is a powerful, large-displacement, single-cylinder engine, it is essential to use very substantial engine mounting. Conventional wooden mounting beams should be of rigid hardwood and of at least 15mm or 5/8-in square section.
How to fasten the mounting screws. ● Hardwood mounting beams 4mm steel nuts Spring washer or lock washer 15mm min. 15mm min. Tighten second nut firmlydown onto first nut. Tighten this nut first. Hardwood such as cherry or maple. Steel washer Make sure that these mounting beams are accurately aligned and firmly integrated with the airframe, reinforcing the adjacent structure to absorb vibration.
In case of installing the silencer direct to the engine After the engine is securely mounted to a model or a test bench, secure the silencer to the engine by means of two retaining screws (M4x45) supplied. In case of installing the silencer with the extension adaptor to the engine Secure the silencer and the extension adaptor to the engine by means of two retaining screws (M4x90) supplied.
FUEL TANK LOCATION Suggested fuel tank capacity is approx 350cc. This will allow 10-12 minute flights. Locate the fuel tank so that the center of the carburetor is flush with the center of the fuel tank. Make sure that the tank is well rinsed out with methanol or glow fuel before installation and that the pickup weight is well clear of the bottom of the tank when held vertically. Be sure to use a pressurized fuel system by connecting the muffler pressure nipple to the vent-pipe of the fuel tank.
NEEDLE-VALVE EXTENSION THROTTLE LINKAGE The needle-valve supplied with this engine is designed to incorporate an extension so that, when the engine is enclosed within the fuselage, the needle-valve may be adjusted from the outside. For this purpose, Needle Valve Extension Cable Set is supplied with the engine.
Note: Some spinners without a removable nose cone cannot be used with the prop locknut supplied with the engine. In this case, optional locknut sets are available from O.S. – Propeller Locknut Set for Spinner (Code No.45910200) and Propeller Locknut Set for 4C Spinner (Code No.45910300). IMPORTANT Regardless of the type of propeller used, make a habit of always checking the tightness before starting the engine.
STARTING Be sure to use an electric starter to start the engine. ! Element glows when energized. Pliers Never fail to check the tightness of screws and nuts, especially engine mounting and moving parts (e.g. throttle lever). Replace the plug when the element does not glow or is burnt out. Starting procedure is as follows: 1. Fill the fuel tank with fuel. When filled, prevent fuel flowing into the carburetor with a commercially available fuel stopper, etc. Release the stopper before starting the engine.
VERY IMPORTANT! Before being operated at full power (i.e. at fullthrottle and with the needle-valve closed to its optimum setting) the engine must be adequately run-in, otherwise there is a danger of it becoming overheated and damaged. Attention : Do not choke the carburetor air intake when applying the starter. This could cause an excessive amount of fuel to be drawn into the cylinder which may initiate an hydraulic lock and damage the engine.
Optimum needle setting(1) Slowly advance the throttle to its fully open position, then gradually close the needle-valve until the exhaust note begins to change. (4cycle to 2-cycle) 4. During subsequent flights, the needle-valve can be gradually closed to give more power. However, if the engine shows signs of running too lean, the next flight should be set rich. After a total of ten flights, the engine should run continuously, on its optimum needle-valve setting, without loss of power as it warms up.
IDLING ADJUSTMENT CHART Start the engine. Make sure that the throttle is fully open. Disconnect the battery leads at mid speed. 20-45 open from maximum r.p.m. setting. Adjust the needle-valve. Close the throttle gradually. The position where the lowest possible r.p.m. ,with steady running, is obtained. Set the idle speed Set the throttle opening by means of the throttle trim on the transmitter so that the lowest practical speed, without risk of the engine stopping,is obtained.
throttle is reopened. Carry out adjustments patiently until the engine responds quickly and positively to the throttle control. MIXTURE CONTROL VALVE ADJUSTMENT With the engine running, close the throttle and allow it to idle for about five seconds, then open the throttle fully. If, at this point, the engine is slow to pick up and produces an excess of exhaust smoke, the mixture is too rich. Correct this condition by turning the Mixture Control Screw clockwise 15-30 degrees.
CARBURETOR CLEANLINESS The correct functioning of the carburetor depends on its small fuel orifices remaining clear. The minute particles of foreign matter that are present in any fuel, can easily partially obstruct these orifices and upset mixture strength so that engine performance becomes erratic and unreliable. O.S.’Super-Filters’(large and small) are available, as optional extras, to deal with this problem.
Symptom Engine fires intermittently but does not run. Engine fires once or twice, then fails to fire. Engine starts but rpm decreases and engine eventually stops. Engine starts, rpm increases and engine cuts out. Engine stops when the current to the glowplug is disconnected after starting. Factor Corrective action Cause 3 Incorrect heating of glowplug. Over priming. Voltage too high or too low. Re-check and readjust referring to "BEFORE STARTING" . Continue applying an electric starter.
When the engine is not to be used for some months (for example, as between flying seasons), a worthwhile precaution is to remove it from the airframe and, after washing off the exterior with alcohol (not gasoline nor kerosene), remove carefully the carburetor with intake pipe, glow plug and all silicone tubing and put them safely aside. Then, immerse the engine in a container of alcohol. Rotate the crankshaft while the engine is immersed.
ENGINE EXPLODED VIEW ENGINEN PARTS LIST C.M3x15 1 2 3 5 6 4 41 40 7 8 C.M3x8 14 9 13 11 12 17 16 15 10-1 Type of screw 10 C...Cap Screw B...Binding Head Screw M...Oval Fillister-Head Screw F...Flat Head Screw N...Round Head Screw S...Set Screw No. Code No.
CARBURETOR EXPLODED VIEW N.+M3x6 3 3-1 1 3-2 4 2 5 6 S.M3X3 N.+M3.5x6 8-1 9 8 7-2 7-1 7 10 Type of screw C...Cap Screw B...Binding Head Screw M...Oval Fillister-Head Screw F...Flat Head Screw N...Round Head Screw S...Set Screw 42 CARBURETOR PARTS LIST No. Code No.
O.S. GENUINE PARTS & ACCESSORIES O.S.GLOW PLUG (71608001) PROPELLER LOCKNUT SET FOR 4C SPINNER 5/16"-M5 (45910300) RADIAL MOTOR MOUNT For FS-120S No.8 /FS-120S-E (71904200) PROPELLER LOCKNUT SET A5 (45910100) (71605100) (For Spinner) (45910200) NON-BUBBLE WEIGHT (71531000) LOCK WASHER (10sets) M5 (55500004) CAP SCREW SETS (10pcs.
67.2 43.6 5 11.3 THREE VIEW DRAWING 2- 4.2 14 13 .6 48 A 15 40 105.4 21 40 15 40.6 21 48 58 27 2-M4x0.7 4- 5.1 25 .2 38 42.5 6.1 105.4 45.5 UNF5/16-24 23.5 33.8 1.4 65.2 35.1 45.5 79.5 85.7 27 46.5 39.7 67 69.8 30.4 139.9 Dimension(mm) 1.3 46 6-15 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003, Japan TEL. (06) 6702-0225 FAX. (06) 6704-2722 URL : http://www.os-engines.co.jp C Copyright 2005 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan.
