It is of vital importance, before attempting to operate your engine, to read the general 'SAFETY INSTRUCTIONS AND WARNINGS' section on pages 2-4 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.
CONTENTS SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE WARNINGS • 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 • This engine was designed for model aircraft. Do not attempt to use it for any other purpose. • Mount the engine in your model securely, following the manufacturers' recommendations, using appropriate screws and locknuts. • Be sure to use the silencer (muffler) supplied with the engine. 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.
NOTES • Take care that the glow plug clip or battery leads do not come into contact with the propeller. Also check the linkage to the throttle arm. A disconnected linkage could also foul the propeller. • After starting the engine, carry out any needle-valve readjustments from a safe position behind the rotating propeller. Stop the engine before attempting to make other adjustments to the carburettor.
INTRODUCTION The FS-120S3 is the latest mid-range model in the well-established FS-120S series of 20cc four-stroke engines. This series extends from the standard suction-feed FS-120S-E to the unique ultra-high performance FS-120S-SP, the world's only production model engine to be equipped with a genuine crankshaft-driven supercharger. The FS-120S3 is fitted with the new O.S. PD-07 diaphragm type fuel pump and matching Type 70N carburettor incorporating a built-in pressure regulator.
RELOCATION OF CARBURETTOR CONTROLS FS-91S2-P As supplied, the FS-120S3 has its throttle lever on the right hand side and needle-valve control on the left. However, where more convenient for certain installations, these positions may be reversed after rotating the carburettor through 180˚ horizontally. Proceed as follows: Intake Pipe Mounting Screw 1.
Make sure that these mounting beams are accurately aligned and firmly integrated with the airframe, reinforcing the adjacent structure to absorb vibration. Use 5mm or larger steel screws, preferably Allen type hexagon socket head cap screws, with washers and locknuts, for bolting the engine to the bearers. As an alternative to wooden beam mounting, a special O.S. cast aluminium radial motor mount, complete with 5mm mounting screws, is available as an optional extra part (Code No.
EXHAUST HEADER PIPE & SILENCER NEEDLE-VALVE EXTENSION Fit these in the following sequence. Screw the header pipe into the cylinder head until it " bottoms ", then unscrew sufficiently to achieve the desired exhaust angle and tighten the locknut securely with a 14mm wrench. Screw the silencer onto the outer end of the header pipe and tighten the other locknut.
FUEL LINE The function of the various tubes connected to the engine and tank (see sketch) are as follows: Make sure there is adequate ventilation. Pipe A: To draw fuel from tank to pump nipple marked 'IN'. Pipe B: To deliver fuel from pump nipple marked 'OUT' to carburettor. Pipe C: To connect crankcase breather nipple (behind camshaft housing) to intake pipe. Pipe D: To deliver crankcase pressure pulses to pump diaphragm.
• NEVER disassemble the fuel pump or pressure regulator. PROPELLERS Their original performance may not be restored after reassembly. The choice of propeller depends on the design and weight of the aircraft and on the type of flying in which you will be engaged. Determine the best size and type after practical experimentation. As a starting point, refer to the props listed in the accompanying table.
When to replace the glowplug GLOWPLUGS Apart from when actually burned out, a plug may need to be replaced because it no longer delivers its best performance, such as when: The FS-120S3 is supplied with an O.S. Type F glowplug, specially designed for O.S. four-stroke engines. The role of the glowplug With a glowplug engine, ignition is initiated by the application of a 1.5-volt power source.
3. Add the special tapered and slotted locknut and secure with a 14mm wrench while holding the prop nut with the 17mm wrench. Reminders: AII model engine fuel is poisonous.Do not allow it to come into contact with the eyes or mouth. Always store it in a clearly marked container and out of the reach of children. Though not as volatile as gasoline, model engine fuel is also highly inflammable. Keep it away from on open flame, excessive heat, sources of sparks, or anything else that might ignite it.
7. Check these conditions and, instead of pressing the starter button after applying the starter, have the starter spinning before applying it to the engine, to give it a "running start". When the engine starts, slowly open the throttle, leaving the needle-valve at its rich starting setting to promote cool running conditions. However, if the engine slows down because the mixture is excessively rich, the needle-valve may be closed a little to speed it up until it runs evenly.
1. Start and adjust the engine as detailed in the starting instructions. 7. With each successive flight, close the needle-valve very slightly until, at the end of about 10 flights, the needle is set for full power. Do not "over-lean" the mixture in an attempt to extract more power. 2. Now open the throttle fully and run the engine for no more than 5 seconds with the needle-valve tuned to produce near maximum r.p.m.
Realignment of Mixture Control Screw IDLING MIXTURE ADJUSTMENT In the course of making readjustments, it is just possible that the mixture control screw may be inadvertently screwed in or out too far and thereby moved beyond its effective range. The factory setting can be re-established as follows: Set the throttle at the fully closed position. Now carefully rotate the mixture control screw clockwise until it stops. Finally, turn the mixture control screw back exactly 2.5 turn. 1.
(2) If a clearance is found to be outside either of these limits, it should be reset as follows. Note: Valve clearances of all O.S. four-stroke-cycle engines must be checked and reset ONLY WHEN THE ENGINE IS COLD. Procedure is as follows. 1. Carefully loosen the locknut on rocker-arm 1/4-1/2 turn with 5mm wrench. (Fig.2.) (1) 1. Remove the cover from the rocker-box on top of the cylinder-head, using the correct size Allen hex key. Locknut Loosen approx. 1/4 to 1/2 turn. Wrench 2.
4. Re-tighten locknut while holding adjusting screw stationary. (Fig.5.) Hold at the screw head. 5. Remove 0.04mm feeler, rotate prop through two revolutions and recheck gap. Fig.5 CARE AND MAINTENANCE Please pay attention to the matters described below to ensure that your engine serves you well in regard to performance, reliability and long life.
Do not leave unused fuel in the engine at the conclusion of a day's flying. Accepted practice is to cut off the fuel supply while the engine is still running - at full throttle - then, expel as much fuel residue as possible by turning the engine over for 5-10 seconds with the electric starter. Finally, inject some after-run oil through the glowplug hole and turn the engine over several times by hand.
O.S. GENUINE PARTS & ACCESSORIES ■ RADIAL MOTOR MOUNT (71904200) ■ O.S.GLOW PLUG TYPE F ■ EX EXHAUST HEADER PIPES (71615009) (72109200) (45910200 For Spinner) ■ PROPELLER LOCKNUT SET ■ FLEXIBLE EXHAUST PIPES FOR TRUTURN SPINNER (72200130) ■ ADAPTOR 1411 (For 1114A-1114D) (45910300) ■ BOOSTER TERMINAL KIT (72403050) Outside Inside ■ PROPELLER LOCKNUT SET ■ SUPER FILTER (L) (72109300) (72108500) Code.No.
EXPLODED VIEW C.M2.6X15 2 2 C.M3.5X20 3-2 3 (C.M3.5X12) 3-1 4-1 4 4-2 5-4 5-3 5-2 6-4 6-2 6-3 6 1 8 5-1 6-1 7 9-1 9 9-2 20 C.M3X10 - 1 o N.+M3X22 = s w 0-1 0-2 d-2 q e 0 d-1 d d-2 f i r [ u y k j-1 gh C.M4.0X10 a p N.+M3X15 ✽ Type t j 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 ] \ ] C.M2.
PARTS LIST No. Code No.
CARBURETTOR EXPLODED VIEWS & PARTS LIST S.3X3 1-3 1-2 8 2 1-5 1-1 3 1-4 1 5-2 2-1 N.+M3X22 5-1 4 No. Code No. 1 1-1 1-2 1-3 1-4 1-5 2 2-1 3 4 5 5-1 5-2 6 7 8 9 2 7381 900 2 9081 952 2 4981 837 2 6381 501 2 7381 940 2 6711 305 4 5582 100 4 5582 400 4 5581 820 2 2681 953 4 5582 300 4 6066 319 2 4881 824 4 5582 200 2 7881 400 4 6115 000 4 5581 700 N.
THREE VIEW DRAWING Dimensions(mm) Specifications ■ ■ ■ ■ ■ ■ Displacement Bore Stroke PracticalR.P.M. Output Weight 19.96cc/1.218cu.in. 30.4mm/1.197in. 27.5mm/1.083in. 2.000~12.000r.p.m. 2.1bhp/12.000r.p.m. 920g/32.5oz.
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Q U A LIT Y PRECISION & P ERFO RM AN NC E UN ES LED CE UAL EQ T AB L IS H IN G T H E STA N D A R D S O F EXCE LLE 6-15 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003, Japan TEL. (06) 6702-0225 FAX. (06) 6704-2722 C Copyright 2000 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan. URL : http://www.os-engines.co.
