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.
CONTENTS SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S.
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.
WARNINGS • Never touch, or allow any object to come • Model engine fuel is also highly flammable. Keep it away from open flame, excessive heat, sources of sparks, or anything else which might ignite it. Do not smoke or allow anyone else to smoke, near to it. into contact with, the rotating propeller and do not crouch over the engine when it is running.
NOTES • If you remove the glowplug from the engine • This engine was designed for model aircraft. Do not attempt to use it for any other purpose. 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 • Always check the tightness of the propeller • Discard any propeller which has become nut and retighten it, if necessary, before restarting the engine, particularly in the case of four-stroke-cycle engines. If a safety locknut assembly is provided with your engine, always use it. This will prevent the propeller from flying off in the event of a "backfire", even if it loosens. • split, cracked, nicked or otherwise rendered unsafe. Never attempt to repair such a propeller: destroy it.
NOTES • Adjust the throttle linkage so that the engine • 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. Keep the propeller pointed away from you and walk well clear of spectators. stops when the throttle stick and trim lever on the transmitter are fully retarded.
INTRODUCTION BASIC ENGINE PARTS The FS Series engines are up-to-date overhead-valve four-stroke-cycle engines for model aircraft use and are the outcome of a long period of technical development. The FS Series engines are produced by the world's oldest and largest model engine manufacturing company; a company which also pioneered the quantity production of model four-cycle engines.
How to fasten the mounting screws. INSTALLATION Installation in the model A typical method of beam mounting is shown below,left. 3mm steel nuts for FS-26S 3.5mm steel nuts for FS-40S Spring washer or lock washer O.S. radial motor mount (Available as an optional extra part. See parts list) Tighten second nut firmly down onto first nut. Tighten this nut first. Hardwood such as cherry or maple. 3mm steel screw for FS-26S 3.5mm steel screw for FS-40S Rigid hardwood (e.g.
INSTALLATION OF CHOKE ROD NEEDLE VALVE EXTENSION 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. Cut the L-shaped rod supplied to the required length, insert it into needle's centre hole and secure it by tightening the set-screw in the needle-valve knob with 1.5mm. Allen key supplied. The FS Series engines are equipped with selfreopening choke valves.
SILENCER LINKAGE OF THROTTLE LEVER The FS-26S and FS-40S are supplied with silencers as standard equipment. First, ensure that the throttle rotor is fully closed when the throttle-lever is in the closed position. Adjust rotor stop screw if necessary. Then couple the lever to the throttle-servo so that the rotor is fully closed when the transmitter throttle stick and trim lever are in the fully retarded position.
4 Glowplug battery The power source for heating the glowplug may be either a large heavy-duty 1.5volt dry cell, or preferably, a 2-volt rechargeable lead-acid cell (accumulator). 5 Plug wrench Used for tightening glowplug. The O.S. long plug wrench is available as an optional accessory. If a 2-volt cell is employed, use a resistance wire, as shown, to reduce applied voltage, otherwise element will overheat and burn out. 6 Battery leads These are used to conduct current from the battery to the glowplug.
9 Electric starter and starter battery An electric starter is recommended for starting. 10 Fuel can filter Install a filter in the outlet line of your refuelling container to prevent entry of foreign matter into the fuel tank. (Refer to of 3 STARTING THE ENGINE section.) Note: When cutting silicone tubing··· Silicone tubing Use knife or razor blade Do not use wire cutters or pliers. *If you should need to clean the silicone tubing, use methanol or glow-fuel, not gasoline or kerosene.
ADVICE ON SELECTION OF FUEL, GLOWPLUG & PROPELLER Fuel Use a good quality commercial fuel or one of the blends shown in the table. Fuel "A" is suitable for running-in and ordinary use. Fuel "B" is for use when more power is required and for improved flexibility. Note that even a small quantity of nitromethane (3-5%) will improve flexibility, making the needle-valve adjustment less critical and improving throttle response. Use only materials of the highest purity.
Reminder! Glowplug life Particularly in the case of very high performance engines, glowplugs must be regarded as expendable However, plug life can be extended and engine performance maintained by careful use, i.e.: Install a plug suitable for the engine. Use fuel containing a moderate percentage of nitromethane unless more is essential for racing events. Do not run the engine too lean and do not leave the battery connected while adjusting the needle.
3 Filling the fuel tank STARTING THE ENGINE Preparations Re-connect fuel line to engine after tank is filled. 1 Installing the glowplug Install the washer on the glowplug and screw carefully into cylinder-head, making sure that it is not cross-threaded before tightening firmly. Glow plug Washer Do not let dirt or dust enter fuel can.
Starting 7 Priming 4 Opening and closing of the needle-valve Turn needle-valve clockwise to close (for leaner mixture). Turn needle-valve counter-clockwise to open (for richer mixture). Fuel will flow from tank to carburettor as propeller is turned. Close 5 Setting the needle-valve Close the air intake by operating the choke control. Open Turn the needle-valve in the direction of arrow slowly, without forcing, until it stops. Turn the propeller four revolutions while watching fuel line.
8 Hold model securely when starting 10 Heat glowplug Assistant should hold the model so that it cannot move forward when the engine starts. Glowplug battery. Place as far to the rear as possible. Starting battery Assistant Connect battery leads as shown (polarity is immaterial.) Starter Be careful not to be hit by propeller! 9 Setting the throttle 11 Apply electric starter Fully opened position Fully closed position Set at this Position.
13 Needle-valve adjustment(1) Check that the throttle is one-third open from the fully closed position. Bring the starter into contact with the spinner nut or spinner and depress the starter switch for one or two seconds. Repeat if necessary. When the engine fires, withdraw the starter immediately. Slowly advance throttle to its fully open position, then gradually close the needlevalve until the exhaust sound changes pitch.
15 Needle-valve adjustment(2) 16 Needle-valve adjustment(Summary) As the needle-valve is closed beyond the initial readjustment, the rpm of the engine will be increased and a continuous highpitched exhaust note, only, will be heard. Practical best(optimum) needle-valve setting Maximum rpm setting("Lean"). 20~30° ev d e olu cr tio n s ea t se. tstart o de Key to the needle-valve adjustment. (Turn 15-30˚ at a time.
Subsequent starting procedure On starting from cold, with the needle-valve set at the rich starting position: Once the optimum needle-valve setting has been established (see 16 "Needle-valve adjustmentSummary") the procedure for starting is simplified as follows: 1) Open the needle-valve one half-turn (180˚) from the optimum setting. 2) Open the throttle fully, place your finger over the carburettor intake and rotate the propeller through two revolutions to prime the engine.
17 How to stop the engine RUNNING-IN ("Breaking-in") All internal-combustion engines benefit, to some degree, from extra care when they are run for the first few times - known as running-in or breaking-in. This is because the working parts of a new engine take a little time to settle down after being subjected to high temperatures and stresses. However, because O.S.
CARBURETTOR These engines are equipped with a throttle type carburettor which provides a wide range of engine speed control. With the throttle lever linked to a suitable servo in the model, movement of the throttle control on the transmitter will enable engine to be varied, proportionally, from idling speed to full power.
Start the engine. Make sure that the throttle is fully open. 20-30° open from maximum r.p.m. setting. Adjust the neede-valve. Close the throttle gradually. The position where the lowest possible r.p.m. ,with steady running, is obtained. Find the idling position. 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. Fix the idling position. Re-set the idling position at a little higher r.p.m.
CARBURETTOR AIR-BLEED ADJUSTMENT Pre-Flight Check Start engine and adjust needlevalve as previously described. Close the throttle gradually. Find the idling position. 24 Repeat the procedure while opening and closing the throttle until the best result is obtained. approx. 15˚ Hold the model. Hold model level, then slowly raise its nose. If rpm increases. If engine runs unevenly or stops. Stop the engine. Note: Stop engine by pinching fuel line Do not touch needle-valve.
TROUBLE SHOOTING WHEN THE ENGINE FAILS TO START Four key points For quick, reliable starting, the following four conditions are required. 1 Good compression. 2 Adequate "glow" at glowplug. 3 Correct mixture. 4 Sufficient electric starter rotating speed. If the engine fails to start, or does not keep running after being started, check symptoms against the following chart and take necessary corrective action.
Symptom Engine fires intermittently but does not run. Factor 2 ★★ 3 ★★ Corrective action Cause Incorrect heating of glowplug. Over priming. . . . . . . . Voltage too high or too low. Re-check and readjust referring to "BEFORE STARTING" paragraph 4. . . . . . . Continue flipping propeller. If engine does not start after more than 10 flips, disconnect battery from glowplug and leave for a few minutes, then reenergize plug and flip prop again.
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: VALVE ADJUSTING ALL O.S. four-stroke engines have their valve(tappet) clearances correctly set before they leave the factory. However, if, after many hours of running time have been logged, a loss of power is detected, or if the engine has to be disassembled or repaired as a result of an accident, valve clearances should be checked and readjusted, as necessary an O.
Note: If the gap is found to be less than 0.04mm, it is not necessary to readjust the clearance if the engine has good compression and starts easily. Equally, if the gap exceeds 0.10mm but is not more than 0.14mm (i.e. the thickness of both feeler gauges inserted together), it is not necessary to readjust the clearance if the engine runs satisfactorily. (2) If a clearance is found to be outside either of these limits, it should be reset as follows. 1.
5. Remove 0.04mm feeler, rotate prop through two revolutions and recheck gap. 3. Insert 0.04mm feeler gauge between valve stem and rocker-arm and gently turn adjusting screw clockwise until it stops.(Fig.4.) 6. If clearance is correct, loosen the locknut on the other rocker-arm and repeat steps 1 to 5 above. Finally, replace rocker box cover. Turn with fingers until it stops. Remember: Excessive valve clearance will cause loss of power, due to valve (s) not opening sufficiently.
3. Do not leave raw fuel in the engine at the conclusion of a flying session: it may cause corrosion. The best practice is to disconnect the fuel line from the carburettor while the engine is running. Remaining fuel in the tank should also be drained off. CARE AND MAINTENANCE To ensure that you obtain long life and peak performance from your engine, observe the following. 1. Avoid running the engine under dusty conditions.
THREE VIEW DRAWING FS-26S/FS-40S FS-26S Specification ■ Displacement 4.41 cc (0.269 cu.in.) ■ Bore 18.5mm (0.728 in.) ■ Stroke 16.4mm (0.648 in.) ■ Practical R.P.M. 2,200~12,000 r.p.m. ■ Power output 0.41 bhp / 11,000 r.p.m. ■ Weight 268g (9.45 oz.) FS-40S Specification ■ Displacement 6.49 cc (0.396 cu.in.) ■ Bore 21.2mm (0.835 in.) ■ Stroke 18.4mm (0.724 in.) ■ Practical R.P.M. 2,200~12,000 r.p.m. ■ Power output 0.65 bhp / 12,000 r.p.m. ■ Weight 355g (12.5 oz.
FS-26S ENGINE EXPLODED VIEW C.M2.6X12 2 C.M2.6X18 4-2 3-1 4-1 3-2 5-4 5-3 5-2 3 4 1 5 7 8-1 C.M2.6X7 5-1 6 8 32 9 ] 0 = - \-2 \-1 q \ \-2 a w g s u y-1 y e t ✽ r Type of screw d f C.M2.6X7 o i p [ C.M2.
FS-26S PARTS LIST 33 No. Code No.
FS-40S ENGINE EXPLODED VIEW C.M2.6X12 2 C.M3X18 3-1 4-2 4 4-1 3 3-2 5-3 5-4 5-2 5 8-1 C.M2.6X7 7 8 5-1 34 6 1 9 0 - ] \-2 = q \-1 e w u s y t o C.M3X8 ✽ Type of screw r \ \-2 a i d f g [ C.M2.
FS-40S PARTS LIST No. Code No.
TYPE FS-26S No. Code No. CARBURETTOR EXPLODED VIEW & PARTS LIST 1 1-1 2 3 4 5 6 6-1 6-2 6-3 6-4 6-5 7 TYPE FS-26S/FS-40S 4 5 C.M2.6X7 N.+M3X6 3 1-1 1 2 6-5 6 M2.6X5 7 Description Throttle Lever Assembly Throttle Lever Retaining Screw Carburetor Rotor Carburetor Body Carburetor Retaining Screw(3pcs.) Throttle Stop Screw Needle-valve Assembly Needle Set-screw Nozzle Assembly Ratchet Spring Nozzle Retaining Screw(2pcs.
PARTS & ACCESSORIES ■ O.S.
MEMO 38
Q U A L IT 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 URL : http://www.os-engines.co.jp C Copyright 2000 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan.
