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.
Glowplug Cylinder head INTRODUCTION THE MAX-10LA,15LA,25LA have been developed to meet the requirements of beginners and sport flyers. Of modern design and having a separate needlevalve unit mounted at the rear, where manual adjustment is safely remote from the rotating propeller, they offer the advantages of reliability and easy handling, at lower cost. Like all O.S.
How to fasten the mounting screws. INSTALLATION Installation in the model A typical method of beam mounting is shown below,left. Tighten second nut firmly down onto first nut. O.S. radial motor mount (Available as an optional extra part. See parts list) 3mm steel nuts Spring washer or lock washer 12mm min. Tighten this nut first. Hardwood such as cherry or maple. Steel washer Rigid hardwood (e.g. maple) At least 12mm(1/2") 12mm min.
NEEDLE-VALVE EXTENSION Assembly screw The needle-valve supplied with these engines 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 a commercially available rod to the required length, bend one end to an L shape, insert it into needle's center hole and secure it by tightening the set-screw in the needle-valve knob with 1.5mm. Allen key.
Warning (Very hot) Never touch the nichrome wire while the battery is connected. BEFORE STARTING Tools, accessories, etc. The following items are necessary for operating the engine. Resistance coil (nichrome wire) 1 Fuel Model glowplug engine fuel of good quality, preferably containing a small percentage of nitromethane. (See "Advice on selection of fuel, glowplug and propeller") to ge ss. e olta er v ightn Low uce br red e Raisage to volt ease . c in r htness brig 2 Glowplug O.S.
6 Battery leads These are used to conduct current from the battery to the glowplug. Basically, two leads, with clips, are required, but, for greater convenience, twin leads with special glowplug connectors, as shown on the right, are commercially available. 9 Fuel can filter Fit a filter to the outlet tube of your refuelling container to prevent entry of foreign matter into the fuel tank. (Refer to 4 of STARTING THE ENGINE section.
Silencer (muffler) pressurized fuel system To reduce variation in fuel "head" and ensure steady fuel delivery at the carburettor, it is advisable to employ a silencer (muffler) pressurized fuel system, i.e. to use the silencer outlet nipple to pressurize the fuel tank as shown left. Fuel and pressure lines Connect suitable lengths of silicone tubing, as illustrated, after installing the engine.
A B Methanol 75% 65% Castor Oil 20% 20% 5% 15% Nitromethane LA Series 10LA 15LA 25LA Reminder! 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. Model engine fuel is also highly flammable. Keep it away from naked 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.
Glowplug life 1 Installing the glowplug 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.: Inatall 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.
4 Filling the fuel tank Warning: When using a spinner assembly, make sure that the notches in the spinner shell are large enough to clear the propeller blades and so do not cut into and weaken the blade roots. Do not allow fuel to overflow into silencer when refuelling, otherwise engine may become flooded and difficult to start. Tighten the spinner nut firmly so that compression is first felt around this position (i.e. with blades horizontal) when turning the propeller in the direction of arrow.
7 Open the throttle fully 5 Opening and closing of the needle-valve Close Close Fully closed position Open Open Turn needle-valve clockwise to close (for leaner mixture). Turn needle-valve counter-clockwise to open (for richer mixture). Fully opened position Throttle 8 Priming 6 Setting the needle-valve Fuel Tube Open the needle-valve 4 turns(for 10LA), 3 turns (for 15LA), 11 2 turns (for 25LA) in the direction of arrow from the closed position.
Priming quantity 9 Do not energize the glowplug at this stage. After fuel has been drawn to the carburettor, flip the propeller two more revolutions, with intake choked, to draw fuel into engine. Above procedure is called priming. NOTE (IMPORTANT) The quantity of fuel drawn into the engine by priming is an important factor in starting the engine successfully. When the engine is being started for the first time, turn the propeller two revolutions after fuel reaches the fuel inlet, as described above.
12 Heat glowplug 10 Hold model securely when starting Assistant should hold the model so that it cannot move forward when the engine starts. Starting battery Glowplug battery. Place as far to the rear as possible. Assistant Starter Connect battery leads as shown (polarity is immaterial.) Be careful not to be hit by propeller! 13 Apply electric starter 11 Setting the throttle Fully closed position 13 Fully opened position 2 3 Set at this Position.
15 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 needle-valve until the exhaust sound changes pitch. Listen to the sound carefully.
17 Needle-valve adjustment(2) 16 Disconnect battery leads 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. Disconnect the battery leads from the engine with care so that the plug clip does not touch the rotating propeller. Key to the needle-valve adjustment. (Turn 10-15˚ at a time.) Turn the needle-valve 10 -15˚ in the direction of arrow, and wait momentarily for the change of r.p.m.
18 Needle-valve adjustment(Summary) 6 7 Practical best(optimum) needle-valve setting Clear, high-pitched two-stroke exhaust note 5 20~30˚ 3 Exhaust note starts to change. 1 "Rich" needle-valve setting when starting the engine. E n gin e s t o ps On starting from cold, with the needle-valve set at the rich starting position: a good deal of white smoke is emitted, accompanied by a relatively low-pitched "four-stroke" exhaust note.
Subsequent starting procedure 19 How to stop the engine Once the optimum needle-valve setting has been established (see 18 "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.
RUNNING-IN ("Breaking-in") CARBURETTOR 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.
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. approx. 15˚ 25 Repeat the procedure while opening and closing the throttle until the best result is obtained. Hold the model. Hold model level, then slowly raise its nose. If revolutions increase. If engine runs unevenly or stops. Stop the engine. Note: Stop engine by pinching fuel delivery tube. 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.
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.
O.S. GENUINE PARTS & ACCESSORIES ■ RADIAL MOTOR MOUNT ■ SILENCER EXTENSION ■ EXHAUST (71909110) for 10LA (71909310) for 15LA (71908100) for 25LA ■ NEEDLE VALVE EXTENSION CABLE SET ADAPTORS ADAPTORS (21125108) for 10/15LA (22325100) for 25LA (21125502) for 10/15LA ■ LONG PROPELLER NUT SET (73101000) for 25LA ■ GLOW PLUG A3 (71605300) No.
EXPLODED VIEW (MAX-10LA) M.+M2.6X10 1 = 2 q 30 3 9 3-1 M.+M2.6X7 8 7 S.
ENGINE PARTS LIST (MAX-10LA) Description 31 No. Code No.
EXPLODED VIEW (MAX-15LA,25LA) M.+M2.6X10(15LA) N.+M3X12(25LA) 1 q 2 w 32 3 4 5-1 5 5-2 N.+M3.5X5 0 B.+M2.6X8 9 S.
ENGINE PARTS LIST (MAX-15LA,25LA) Code No. 15LA Description 25LA 1 21754000 22554000 Cylinder Head 2 21753000 22553000 Cylinder & Piston Assembly 3 21706000 22606009 Piston Pin 4 21205040 22405013 Connecting Rod 5 5-1 5-2 Carburettor Complete (10G) 21783000 22581000 21015001 22615000 23081706 Carburettor Complete (20H) Carburettor Rubber Gasket Carburettor Retaining Screw(2pcs.
CARBURETTOR EXPLODED VIEW & PARTS LIST TYPE 10H TYPE 10G,20H 1 N.+M2X14(10G) N.+M2.6X15 1-1 2 N.+M3X6 4 4 N.+M2.6X6 2 3 5 N.+M2X6(10G) M.+M2.6X7 3 1- 1 N.+M3X4 1 N.+M3.5X5 4 6 7 5 ✽ Type of screw Code No.
4-ø3.3 MAX-10LA THREE VIEW DRAWING M5x0.8 31.4 10LA SPECIFICATIONS ■ Displacement 1.76 cc (0.107 cu.in.) 13.44mm (0.529 in.) ■ Bore 12.4mm (0.488 in.) ■ Stroke ■ Practical R.P.M. 2,500~18,000 r.p.m. 0.27 bhp / 17,000 r.p.m. ■ Power output 112g (3.95 oz.) ■ Weight 11 33.2 38.7 19.2 27.5 11.7 23.5 44.3 2-ø2.8 15.9 23 38.6 23.
MAX-15LA/25LA THREE VIEW DRAWING 36 (33) 15LA SPECIFICATIONS ■ Displacement 2.49 cc (0.1517 cu.in.) 15.2mm (0.598 in.) ■ Bore 13.7mm (0.539 in.) ■ Stroke ■ Practical R.P.M. 2,500~18,000 r.p.m. 0.41 bhp / 17,000 r.p.m. ■ Power output 138g (4.87 oz.) ■ Weight Dimensions(mm) UNF1/4-28 (M5) 39 (30.8) 14 (14.4) 46.5 (39.5) 25LA SPECIFICATIONS ■ Displacement 4.07 cc (0.249 cu.in.) 18.0mm (0.709 in.) ■ Bore 16.0mm (0.630 in.) ■ Stroke ■ Practical R.P.M. 2,500~16,000 r.p.m. 0.6 bhp / 15,000 r.p.m.
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 C Copyright 2000 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan.
