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4

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.

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.

Take care that loose clothing (ties, shirt sleeves, scarves, etc.) do not come into contact with the propeller. 
Do not carry loose objects (such as pencils, screwdrivers, etc.) in a shirt pocket from where they could fall through 
the propeller arc.

Do not start your engine in an area containing loose gravel or sand. The propeller may throw such material in your 
face and eyes and cause injury.

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.

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  casually  flipped  over  compression 
WITHOUT the glowplug battery being reconnected. Remember this if you wish to avoid the risk of a painfully rapped 
knuckle!

NOTES

5

INTRODUCTION

INSTALLING THE GLOW PLUG

Glow plug

Carefully  insert  plug,  with  washer, 
fingertight only, before final tightening 
with the correct size plug wrench.

Washer

The  O.S.  FS-120S-E  is  an  aircooled,  overhead-valve  four-
stroke-cycle  engine  for  model  aircraft  use.  It  is  produced 
by the world' s pldest and largest model engine manufac-
turing  company:  a  company  which  also  pioneered  the 
quantity production at model four-stroke-cycle engines.

BASIC ENGINE PARTS

Rocker Cover

Cylinder Head

Push Rod Cover

Drive Hub

Propeller Washer

Propeller Nut

Lock Nut

Carburettor 

Cover Plate

Crankcase

Beam Mount

Standard Accessories

Exhaust Header Pipe Assembly 

Silencer Assembly 

Glow Plug Type F 

Please  note  that  this  engine  is  not  supplied  with  any 
tools (e.g. Allen keys, wrenches, etc.)

Summary of Contents for FS-120S-E

Page 1: ...he aircraft radio control equipment etc are accessible for checking at the same time 1 14 15 SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O S ENGINE INTRODUCTION INSTALLING THE GLOWPLUG BASIC ENGINE PARTS RELOCATION OF CARBURETTOR CONTROLS CHOKE VALVE FUEL TANK INSTALLATION EXHAUST HEADER PIPE AND SILENCER THROTTLE LINKAGE NEEDLE VALVE EXTENSION PROPELLERS PROPELLER AND SPINNER ATTACHMENT FUEL GLOW...

Page 2: ...your engine in an enclosed space Model engines like automobile 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 Contact with the muffler silencer cylinder head or exhaust header pipe in particular may result in a serious burn 3 NOTES This engine was designed for model aircra...

Page 3: ...aring 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 cas...

Page 4: ...ng time when some part throttle operation is included Locate the fuel tank so that the centre line of the tank is 10 to 15mm below the centre line of the needle valve Make sure that the mounting beams are parallel and that their top surfaces are in the same plane How to fasten the mounting screws Hardwood mounting beams O S radial motor mount cast aluminum Tighten second nut firmly down onto first...

Page 5: ...er joints which may loosen when they are hot use a thick folded cloth for protection 9 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 Slightly larger or even slightly smaller props t...

Page 6: ... Use a good quality well balanced spinner enclosing the propeller boss Make sure that it is of precision made and sturdy construction so that the spinner shell cannot loosen when the starter is used Make sure the spinner notches do not interfere the propeller If they do cut the notches to clear off 11 GLOWPLUGS The role of the glowplug Glowplug life Particularly in the case of very high performanc...

Page 7: ...being insufficiently charged 1 2 3 4 5 6 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 th...

Page 8: ... to fine tolerances and from the finest quality materials a relatively brief running in period is sufficient and can be completed with the engine installed in the aircraft The recommended procedure is as follows 15 Start the engine open the throttle fully and set the needle valve slightly rich 30 45 from the highest r p m setting Close the throttle to the idle position Allow the engine to idle for...

Page 9: ...eeler gauge 0 04mm Valve clearances are correctly set before any O S engine leaves the factory and in normal use will seldom require abjustment However if after a very considerable amount of running time has been amassed a loss of power is detected or if the engine has been disassembled for repair these clearances should be checked and reset as necessary For this purpose a valve adjusting kit comp...

Page 10: ...il through the plug hole and carburetor intake again rotating the shaft to distribute the protective oil to all working parts Gasoline thinner kerosene and light machine oil cause swelling and deterioration of plastic parts O rings and fuel tubing Use methanol for cleaning these engines Avoid unnecessary dismantling of your engine 3 4 5 6 Do not leave raw fuel in the engine at the conclusion of a ...

Page 11: ...1 28 2 29 30 31 32 32 1 33 71615009 45526400 45526300 45526200 45526100 45526010 45525011 45525001 Description Code No No Description Code No No Screw Set Rocker Cover Rocker Support Assembly Rocker Support Rocker Arm Retainer 2pcs Rocker Arm Assembly 1pair Rocker Arm 1pc Tappet Adjusting Screw Intake Valve Assembly 1pair Intake Valve 1pc Valve Spring 1pc Valve Spring Retainer 1pc Split Cotter 2ps...

Page 12: ...Oval Fillister Head Screw F Flat Head Screw N Round Head Screw S Set Screw Description Code No No Needle Valve Assembly Needle O Ring 2pcs Set Screw Needle Valve Holder Assembly Ratchet Spring Carburetor Body Rotor Guide Screw Fuel Inlet Mixture Control Valve Assembly Carburetor Retaining Screw 2pcs Throttle Lever Assembly Set Screw Carburetor Rotor O Ring 2pcs Rotor Spring Carburetor Rubber Gaske...

Page 13: ...served Printed in Japan 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 U N E Q U A LLED QUALITY PRECISION PERFOR M A N C E E S T A BLISHING THE STANDARDS OF EXCELLE N C E 60090510 061103 ...

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