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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.

It  is  suggested  that  any  instructions  supplied  with 
the  aircraft,  radio  control  equipment,  etc.,  are 
accessible for checking at the same time.

1

2-6

8

9

10

20-21

22

27-30

33

15-17

SAFETY INSTRUCTIONS AND WARNINGS 
ABOUT YOUR O.S. ENGINE

MAX-75AX ENGINE CONSTRUCTION

NOTES WHEN APPLYING AN ELECTTRIC STARTER

ABOUT THE ENGINE

BASIC ENGINE PARTS

BEFORE STARTING

INSTALLATION

INSTALLATION OF THE STANDARD ACCESSORIES

FUEL TANK LOCATION

MIXTURE CONTROLS

GLOWPLUG

STARTING

CONTENTS

RUNNING -IN, IDLING ADJUSTMENT CHART

MIXTURE CONTROL VALVE ADJUSTMENT

REALIGNMENT OF MIXTURE CONTROL VALVE,
SUBSEQUENT STARTINGPROCEDURE

SUBSEQUENT READJUSTMENT,
CARBURETOR CLEANLINESS

TROUBLE SHOOTING WHEN THE 
ENGINE FAILS TO START

CARE AND MAINTENANCE

ENGINE/CARBURETOR EXPLODED
VIEWS & PARTS LIST

O.S. GENUINE PARTS & ACCESSORIES

THREE VIEW DRAWING

MEMO

31

32

34-35

36-37

38-45

48-49

11-14

18-19

23

46-47

50

24-26

7

Summary of Contents for MAX-75AX

Page 1: ... checking at the same time 1 2 6 8 9 10 20 21 22 27 30 33 15 17 SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O S ENGINE MAX 75AX ENGINE CONSTRUCTION NOTES WHEN APPLYING AN ELECTTRIC STARTER ABOUT THE ENGINE BASIC ENGINE PARTS BEFORE STARTING INSTALLATION INSTALLATION OF THE STANDARD ACCESSORIES FUEL TANK LOCATION MIXTURE CONTROLS GLOWPLUG STARTING CONTENTS RUNNING IN IDLING ADJUSTMENT CHART MIXTURE...

Page 2: ...sonous 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 Never operate your engine in an en closed space Model engines like auto mobile engines exhaust deadly carbon monoxide Run your engine only in an open area Model engines generate considerable heat Do not touch any part of your engine until it has cooled C...

Page 3: ...s check the tightness of the propeller nut and retighten it if necessary before restarting the engine Also check the tightness of all the screws and nuts before restarting the engine If you install a spinner make sure that it is a precision made product and that the slots for the propeller blades do not cut into the blade roots and weaken them Preferably use an electric starter The wearing of safe...

Page 4: ...ng 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 Warning Immediately after a glowplug ignition engine has been run and is still warm conditions sometimes exist whereby it is just possible for the engine to abruptly restart if the propeller is casual...

Page 5: ...h the engine Needle Valve Extension Cable Set E 4040 Silencer Assembly Silencer Retaining Screw M4x40 2pcs ABOUT THE ENGINE E 4040 silencer POWER BOX develops very effective muffling Also the compact body enables it to be fit within most cowls These are high performance two stroke engines designed for sport and aerobatic models Ample power enables to turn a one size larger propeller with lower rpm...

Page 6: ...e table may be used but remember that the propeller noise will increase due to higher rpm or if a larger diameter lower pitched prop is used 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 Reminder Warning Make sure that the propeller is well balanced An unbalanced propeller and or spinner can cause serious vibra...

Page 7: ...oke or allow anyone else to smoke near to it Reminder Fuel Tank A fuel tank of approximately 350cc capacity for 75AX and 450cc capacity for 95AX is suggested This allows around 10 minutes flying time dependent upon the type of fuel used the size of propeller and on the amount of full throttle to part throttle operation throughout the flight 13 S GLOWPLUG IGNITER Commercialy available handy glowplu...

Page 8: ...ssible engine mounting for highest performance and safe running Conventional wooden mounting beams should be of rigid hardwood and of at least 15mm or 5 8 in square section Use at least 3mm steel screws such as Allen type with locknuts for bolting the engine to the bearers INSTALLATION CORRECT Top surfaces are in the same plane INCORRECT Front view Side view Re align the surfaces as necessary Oppo...

Page 9: ...hers and locknuts for bolting the engine to the bearers O S Radial Motor Mount A special O S radial motor mount Code No 71905200 is available as an optional extra for use where firewall type mounting is required 17 THROTTLE LINKAGE Before connecting the throttle to its servo make sure that the throttle arm and linkage safely clear any adjacent part of the airframe structure etc as the throttle is ...

Page 10: ...ALLATION OF THE STANDARD ACCESSORIES 19 INSTALLING SILENCER E40400 Silencer Model engines generate considerable heat Do not touch any part of your engine until it has cooled Contact with the muffler silencer cylinder head or exhaust header pipe in particular may result in a serious burn Keep your hands and face away from exhaust gas or you will suffer a burn Reminder The exhaust outlet of the sile...

Page 11: ... a suitable length of best quality 5mm OD x 2 5mm ID silicone tubing for fuel tubing The Fuel line pickup weight should be 10mm away from the back of the tank Position the fuel tank so that approximately 1 3 of the tank height is above the center line of the needlevalve Suggested fuel tank capacity is approx 450cc This will allow 12 13minute flights 75AX 95AX 21 Attention to tank height Plug comme...

Page 12: ...gh performance engines glowplugs must be regarded as expendable items 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 With a...

Page 13: ...d nuts especially engine mounting and moving parts e g throttle lever 25 Connect battery leads to glowplug 3 4 Open the throttle approx one quarter This is to avoid unnecessarily high r p m when the engine starts Turn needle valve clockwise to close for leaner mixture Turn needle valve counter clockwise to open for richer mixture Mark Close Open Fully closed position Fully opened position Set at t...

Page 14: ... disconnected closed the needle valve to the point where the engine does not stop Run the engine for one minute with the throttle fully open but with the needle valve adjusted for rich slow four cycle operation RUNNING IN Breaking in Now close the needle valve until the engine speeds up to two cycle operation and allow it to run for about 10 seconds then reopen the needle valve to bring the engine...

Page 15: ...essary to arrive at the optimum setting Optimum needle setting 1 Optimum needle setting 2 Slowly advance the throttle to its fully open position then gradually close the needle valve until the exhaust note begins to change 4 cycle to 2 cycle 29 20 45 degrees Needle valve adjustment diagram This diagram is for reference purposes only Actual needle positions may differ from those shown Note Practica...

Page 16: ...r 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 If the mixture is excessively rich engine rpm will become unstable opening the throttle will produce a great deal of smoke and rpm may drop suddenly or the...

Page 17: ...ecessary to alter the mixture settings except to make minor adjustments to the Needle Valve occasionally to take account of variations in climatic conditions The use of a different fuel however particularly one containing more or less nitromethane and or a different type or proportion of lubricating oil is likely to call for some readjustment of the Needle Valve Remember that as a safety measure i...

Page 18: ...tive action 2 3 1 2 3 3 3 3 2 Voltage too high or too low Re check and readjust referring to BEFORE STARTING Continue applying an electric starter If the engine dos not start after more than 4 tries disconnect the current to the glowplug and leave for a few minutes then re energize plug and apply starter If the engine still does not start remove glowplug and pump out excess fuel by applying the st...

Page 19: ...se the needle valve and mixture control valve too far as this will cause a lean setting and over heating of the engine This can in turn create nitromethane oxide leading to internal rusting of the engine Always adjust the needlevalve slightly on the rich side of peak rpm 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...

Page 20: ...in Piston Pin Retainer 2pcs Connecting Rod Carburetor Complete Type 61A Lock Nut Set Drive Hub Thrust Washer Crankshaft Ball Bearing F Crankcase Crankshaft Ball Bearing R Crankshaft Cover Gasket Cover Plate Glow Plug No 8 Needle Valve Extension Cable Set E 4040 Silencer Assembly O Ring Assembly Screw Pressure Nipple No 7 Silencer Retaining Screw C M4x40 2pcs 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ...

Page 21: ...ice Throttle Lever Assembly Carburetor Rotor Mixture Control Valve Assembly O Ring L 2pcs O Ring S 2pcs Carburetor Body Roter Guide Screw Fuel Inlet No 1 Needle Assembly O Ring 2pcs Set Screw Needle valve Holder Assembly Ratchet Spring Carburetor Rubber Gasket Carburetor Retaining Screw 1 2 3 3 1 3 2 4 5 6 7 7 1 7 2 8 8 1 9 10 27881400 27482200 25781600 46066319 22781800 27482100 45581820 22681953...

Page 22: ...iston Pin Retainer 2pcs Connecting Rod Carburetor Complete Type 61C Lock Nut Set Drive Hub Thrust Washer Crankshaft Ball Bearing F Crankcase Crankshaft Ball Bearing R Crankshaft Cover Gasket Cover Plate Glow Plug No 8 Needle Valve Extension Cable Set E 4040 Silencer Assembly O Ring Assembly Screw Pressure Nipple No 7 Silencer Retaining Screw C M4x40 2pcs 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1...

Page 23: ...ice Throttle Lever Assembly Carburetor Rotor Mixture Control Valve Assembly O Ring L 2pcs O Ring S 2pcs Carburetor Body Roter Guide Screw Fuel Inlet No 1 Needle Assembly O Ring 2pcs Set Screw Needle valve Holder Assembly Ratchet Spring Carburetor Rubber Gasket Carburetor Retaining Screw 1 2 3 3 1 3 2 4 5 6 7 7 1 7 2 8 8 1 9 10 22081408 29087200 29181620 46066319 22781800 29087100 45581820 22681953...

Page 24: ...3050 79870050 M5 SUPER FILTER BLIND NUT L 79870040 M4 71605100 No 10 Former A5 71608001 No 8 71607100 No 7 Long 47 The specifications are subject to alteration for improvement without notice M5 55500004 72515300 71521000 M3x8 79871110 M3x16 79871160 LONG SOCKET WRENCH WITH PLUG GRIP LOCK WASHER 10sets CAP SCREW SETS 10pcs sets M4 55500003 BE CONVERSION KIT 75AX BE Cylinder Head Assembly Carburetor...

Page 25: ...5 16 24 48 8 130 2 25 66 6 27 9 43 25 22 81 5 4 42 6 61 36 8 24 31 7 42 5 103 29 1 52 38 5 54 1 42 35 7 57 7 49 Displacement Bore Stroke Power output at recommended R P M range Recommended R P M range Power output Practical R P M Weight SPECIFICATIONS Dimensions mm 95AX THREE VIEW DRAWING E 4040 Silencer 15 55 cc 0 949 cu in 27 7 mm 1 091 in 25 8 mm 1 016 in 1 9 ps 1 93 hp 10 000 r p m 2 000 11 00...

Page 26: ...right 2009 by O S Engines Mfg Co Ltd All rights reserved Printed in Japan 60092190 061102 TEL 06 6702 0225 FAX 06 6704 2722 6 15 3 Chome Imagawa Higashisumiyoshi ku Osaka 546 0003 Japan URL http www os engines co jp ...

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