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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.
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

These  cover  events  which  might  involve  serious  (in 
extreme circumstances, even fatal ) injury.

NOTES

These cover the many other possibilities, generally less 
obvious  sources  of  danger,  but  which,  under  certain 
circumstances, may also cause damage or injury.

SAFETY INSTRUCTIONS AND 

WARNINGS ABOUT YOUR 

O.S. ENGINE

The  advice  which  follows  is  grouped  under  two 
headings according to the degree of damage or danger
which might arise through misuse or neglect.

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.

A weakened or loose propeller may disintegrate or be thrown 
off and, since propeller tip speeds with powerful engines may 
exceed 600 feet(180 metres) per second, it will be understood 
that such a failure could result in serious injury, (see 'NOTES' 
section relating to propeller safety).

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 an 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.

Never  operate  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.

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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.

If you remove the glowplug from the engine 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.

Install a top-quality propeller of the diameter and pitch specified for the engine and aircraft. Locate the propeller on 
the shaft so that the curved face of the blades faces forward-i.e. in the direction of flight. Firmly tighten the propeller 
nut, using the correct size wrench.

Always  check  the  tightness  of  the  propeller  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.  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.

Discard  any  propeller  which  has  become  split,  cracked,  nicked  or  otherwise  rendered  unsafe.  Never  attempt  to 
repair such a propeller: destroy it. Do not modify a propeller in any way, unless you are highly experienced in tuning 
propellers for specialized competition work such as pylon-racing.

Use an electric starter for this engine. The wearing of safety glasses is also strongly recommended.

Summary of Contents for FR7-420

Page 1: ...h the aircraft radio control equipment etc are accessible for checking at the same time Seven cylinder radial overhead valve four stroke engine 1 SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O S ENGINE NOTES WHEN APPLYING AN ELECTRIC STARTER ABOUT THE ENGINE ENGINE PARTS NAME INSTALLATION FUEL TANK LINES GLOWPLUG MIXTURE CONTROLS PROPELLER GLOWPLUG HEATING FUEL AND LUBRICATION CONTENTS STARTING RUN...

Page 2: ... 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 aircraft Do not attempt to use it for any other purp...

Page 3: ...ontaining 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...

Page 4: ...RIES Glow Plug Type F installed on the engine Valve adjusting tool kit Feeler gauge 0 04mm Feeler gauge 0 1mm Hex key 1 5mm Wrench 5mm Plug Cable Set Plug Cable Plug Terminal 7pcs 7pcs w silicone tube Radial Mount Retaining Screw Set Engine mounting screws M5X25 Lock washers ø5 Blind nuts M5 5pcs 5pcs 5pcs Lead for ground 5 1pc Needle Valve Extension Cable Set STANDARD ACCESSORIES Drain Plug Carbu...

Page 5: ...loosening 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 For this purpose a Needle Valve Extension Cable Set is supplied with the engine If a longer extension is reguired cut a commercially available rod to the required length bend one end to an L shape inse...

Page 6: ...mostly accumulate here Dirt and foreign matter mostly accumulate here Needle valve holder 11 FUEL TANK LINES Make sure that the tank is well rinsed out with methanol or glow fuel before installation and that the pickup weight is well clear of the bottom of the tank when held vertically A 700cc tank will allow approx 10 minutes medium speed flight Locate the fuel tank as close as possible to the ca...

Page 7: ...set to produce maximum power at full throttle this establishes the basic fuel air mixture strength The correct mixture is then maintained by the carburetor s built in automatic mixture control system to cover the engine s requirements at reduced throttle settings The Mixture Control Valve This meters fuel flow at part throttle and idling speeds to ensure reliable operation as the throttle is opene...

Page 8: ...of more than 40mm dia Ream the propeller shaft hole to 9 7mm bore with an appropriate reamer checking that the hole is exactly centered Install the prop to the engine shaft followed by the retaining washer and prop nut and tighten firmly with a 17mm wrench not supplied 2 15 3 Add the special tapered and slotted locknut and secure with a 14mm wrench while holding the prop nut with the 17mm wrench n...

Page 9: ...glowplug leads are extended together as a single cable use heavier wire e g cross section area of 2 0mm multi strand copper core as supplied for earth lead Earth ground lead Fasten to the motor mount FUEL AND LUBRICATION Fuel Suitable fuel for this engine is a methanol based fuel containing 5 8 nitromethane and 8 10 lubricant It is suggested to dilute commercially available 15 nitromethane and 18 ...

Page 10: ...e tubing Drain Plug Breather Nipple 19 STARTING Precautions For safety please observe the following instructions before starting the engine Start the engine by turning the propeller counter clockwise i e normal running direction Do not start the engine with the throttle fully opened otherwise the model will tend to move forward suddently due to the strong thrust of the propeller Hold both wings of...

Page 11: ...ary to arrive at the optimum setting Practical best optimum needle valve setting Approx 45 90 Maximum rpm setting Lean Rich needle valbe setting when starting the engine Rpm starts to decrease Close the needle valve gradually and slowly Engine stops With a propeller which the engine turns approx 6 000rpm with full throttle one misfiring cylinder will drop approx 500rpm and two misfiring cylinders ...

Page 12: ...TTLE VALVE ADJUSTMENT Needle valve adjustment Adjust the needle valve following the instructions given in STARTING section Mixture control valve adjustment The carburetor of your enigine has been factory set for the approximate best result with the fuel tank located in the normal position i e close to the back of the engine and where the level of the needle valve is at 1 3 height of the tank refer...

Page 13: ...l be necessary to turn the Mixture Control Valve counter clockwise approximately 1 12 turn 30 Thirdly if the rpm increase but the engine appears to run with reduced power it is probable that one of the cylinders has ceased firing You may detect this by the difference in exhaust note and rpm compared with previous full throttle running The cutting out of the cylinder may be caused by the idle speed...

Page 14: ...tromethane in the fuel can also contribute to the problem Care and Maintenance Sound at full throttle changes when one or two cylinders are not firing With a propeller which the engine runs approx 6 000rpm with full throttle one misfiring cylinder will drop approx 500rpm and two misfiring cylinders will drop approx 1 000rpm 27 Do not close the needle valve and mixture control valve too far as this...

Page 15: ... gap exceeds 0 1mm 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 Fig 1 If a clearance is found to be outside either of these limits it should be reset as follows 0 0 4 m m 29 Carefully loosen the locknut on rocker arm 1 4 1 2 turn with 5mm wrench Fig 2 1 Loosen approx 1 4 to 1 2 ...

Page 16: ...00 47101700 47181140 47181000 71912110 71912100 71615009 46471000 72200060 72200200 72200170 72200171 72200190 72200180 47181210 72200080 71912150 79870050 79871525 Description Code No No Description Code No No Rocker Cover Rocker Arm Tappet Adjusting Screw Rocker Arm Thrust Washer 2pcs Rocker Arm Shaft Cylinder Head W Valve Assembly Cylinder Head Valve 1pc Valve Spring 1pc Valve Spring Retainer 1...

Page 17: ...rburetor Retaining Screw 2pcs 1 2 2 1 3 4 5 6 7 7 1 7 2 8 9 9 1 10 47181970 27381940 26711305 47181100 22681953 46115000 45581820 47181600 46066319 24881824 47181200 22081408 22081313 45581700 N M3x6 S M3x3 1 2 3 4 5 6 7 8 9 9 1 N M3x22 2 1 7 1 7 2 10 33 46210300 71531000 72403050 79870050 55500004 71521000 71531010 COLLECTOR EXHAUST PIPE NON BUBBLE WEIGHT SUPER FILTER L LONG SOCKET WRENCH WITH PL...

Page 18: ...2 UNF3 8 24 9 95 cc x 7 0 607 cu in x 7 24 0 mm 0 945 in 22 0 mm 0 866 in 1 500 7 000r p m 3 167 g 111 71 oz C Copyright 2010 by O S Engines Mfg Co Ltd All rights reserved Printed in Japan 60092360 081002 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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