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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 2-5 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 
vehicle, radio control equipment, etc., are accessible for 
checking at the same time.

1

CONTENTS

SAFETY INSTRUCTIONS AND 
WARNINGS ABOUT YOUR O.S. ENGINE

ENGINE CONSTRUCTION, NOTES WHEN 
APPLYING AN ELECTRIC STARTER

ABOUT THE WARRANTY
ABOUT THE ENGINE

TOOLS, ACCESSORIES, etc.
BASIC ENGINE PARTS 

INSTALLATION OF THE STANDARD 
ACCESSORIES, GLOWPLUG

INSTALLATION ,
CARBURETOR CONTROLS 12F(B)

2-5

6-7

8-9

13-14

15-17

18-22

STARTING THE ENGINE & RUNNING-IN 
('Breaking-in)

FINAL ADJUSTMENT

CARE AND MAINTENANCE

TROUBLE SHOOTING

ENGINE EXPLODED VIEW &PARTS LIST 

CARBURETOR EXPLODED VIEW &PARTS LIST

O.S. GENUINE PARTS & ACCESSORIES

THREE VIEW DRAWING

36-37

10-12

38

26-27

28-31

32-33

23-25

34-35

Summary of Contents for 12xz Spec II

Page 1: ...ctions supplied with the vehicle radio control equipment etc are accessible for checking at the same time 1 CONTENTS SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O S ENGINE ENGINE CONSTRUCTION NOTES WHEN APPLYING AN ELECTRIC STARTER ABOUT THE WARRANTY ABOUT THE ENGINE TOOLS ACCESSORIES etc BASIC ENGINE PARTS INSTALLATION OF THE STANDARD ACCESSORIES GLOWPLUG INSTALLATION CARBURETOR CONTROLS 12F B 2 ...

Page 2: ... extreme circumstances even fatal injury These cover the many other possibilities generally less obvious sources of danger but which under certain circumstances may also cause damage or injury 3 WARNINGS Model engine fuel is poi sonous Do not allow it to come into contact with the eyesormouth Alwaysstore it in a clearly marked con tainer and out of the reach of children Model engine fuel is also h...

Page 3: ...ttle arm is secure For their safety keep all onlookers especially small children well back at least 20 feet or 6 meters when preparing your model for running NOTES 5 NOTES To stop the engine fully retard the throttle stick and trim lever on the transmitter or in an emergency cut off the fuel supply by pinching the fuel delivery line from the tank Warning Immediately after a glowplug ignition engin...

Page 4: ...ct running clearance when they reach operating temperature Near TDC Slight taper When the engine is cold When the engine is hot 7 NOTES WHEN APPLYING AN ELECTRIC STARTER Do not over prime This could cause a hydraulic lock and damage the engine on application of the electric starter If over primed remove glowplug close needle valve and apply starter to pump out surplus fuel Cover the head with a ra...

Page 5: ...ndard accessories Glow Plug RP6 T type head Turbo head 1piece Exhaust Seal Ring 1piece ABOUT THE ENGINE The O S SPEED 12XZspec is a high performance engine meeting IFMAR specification produced by O S s SPEED TEAM technicians Major parts such as cylinder piston assembly crankshaft and crankcase are have been refined to have a powerful potential equal to more expensive specially tuned or modified en...

Page 6: ...TOOLS ACCESSORIES etc The following items are necessary for operating the engine 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 FUEL FILTER To be installed in the fuel line between fuel tank and carburetor to prevent foreign matter from entering the...

Page 7: ...t the Head Gasket These engines are equipped with two head gaskets of 0 1mm thick and 0 2mm thick It is suggested to adjust the total thickness according to atmospheric temperature humidity and glowplug used At early stage of running in when a glowplug tends to burn out early or when high nitromethane content fuel is used try to run the engine with both gaskets or removing the 0 1mm gasket When lo...

Page 8: ...hen to replace the glowplug Filament surface has roughened and turned white Filament coil has become distorted Foreign matter has adhered to filament or plug body has corroded Engine tends to cut out when idling Starting qualities deteriorate Since the compatibility of the glowplug and fuel may have a marked effect on performance and reliability it is suggested to use the O S RP6 plug when it is n...

Page 9: ...ase to touch chassis 17 CARBURETOR CONTROLS 12F B The Needle Valve Adjusted at the factory The Mixture Control Valve Four adjustable controls are provided on this carburetor For adjusting the mixture strength when the throttle is fully open For changing the mixture strength at mid speed and acceleration Do not rotate the screw more chan one turn The Throttle Stop Screw Adjusted at the factory For ...

Page 10: ...l in the fuel becoming gelled and the piston liner becoming stuck together Please do not run on a public street this could cause serious accidents personal injuries and or propetry damage Please do not run near pedestrians or small children Please do not run in small or confined areas Please do not run where loud noises can disturb others such as hospitals and residential areas While Operating RUN...

Page 11: ...sed position Do not force the needlevalve to turn beyond a lightly closed position 21 It is vitally important to set the throttle at the correct position before starting the engine If the engine is allowedtorunwiththethrottle too far open under no load conditions i e with the driving wheels not in contact with the ground it will rapidly over heat and may be seriously damaged Attention Next disconn...

Page 12: ... fuel delivery tube to the carburetor Fuel How to stop the engine 23 FINAL ADJUSTMENT Throttle Stop Screw Needle Valve Metering Needle Open Close Close Open Needle Valve Metering Needle More fuel Less fuel More fuel Less fuel Run the vehicle with throttle fully open over the longest available straight course in order to observe the model s speed Next return the car to the starting point close the ...

Page 13: ...leration Remember that if the engine is operated with the fuel air mixture slightly too lean it will overheat and run unevenly As with all engines it is advisable to set both the needle valve and metering needle slightly on the rich side of the best rpm setting as a safety measure 25 If the engine runs too fast with the throttle closed the throttle stop screw should be turned counter clockwise to ...

Page 14: ...and rotate the engine with an electric starter for 4 to 5 seconds to distribute the oil to all the working parts Note Do not inject after run oil into the carburetor as this may cause the O rings inside the carburetor to deteriorate These procedures will reduce the risks of starting difficulties or corrosion after a period of storage 27 Dirt and dust may lodge in marked places CHECKING THE ENGINE ...

Page 15: ...ce if necessary Incorrect servo linkage Connect correctly after setting servo at neutral Reverse rotating direction of starter box Mare sure it rotates counter clockwise seen from crankshaft side 29 Symptom Cause Corrective action Engine fires intermittently but does not run Insufficient fuel in the tank Fill the tank with fuel Deteriorated glowplug Replace glowplug Clogged fuel filter Air cleaner...

Page 16: ...ng Check the connections and secure them Fuel tubing from tank is split or broken Replace the tubing 31 Symptom Cause Corrective action Symptom Cause Corrective action Poor response Deteriorated glowplug Replace glowplug Incorrect carburetor settings Readjust low r p m range with metering needle and mixture control valve Incorrect setting of transmitter Exponential function Check the transmitter s...

Page 17: ...mited time One year after discontinuing the production Outer Head Inner Head Head Gasket Set 2pcs Cylinder Piston Assembly Piston Pin Piston Pin Retainer 2pcs Connecting Rod Built Up Parts Set No 4 5 6 7 Carburetor Complete Type 12F B Carburetor Retainer Assembly Crankshaft Ball Bearing Front Crankcase Crankshaft Ball Bearing Rear Crankshaft Cover Gasket Cover Plate Glow Plug RP6 Exhaust Seal Ring...

Page 18: ...o 14 Universal Nipple Assembly Carburetor Reducer 5 5mm Red O Ring 1pc Throttle Stop Screw O Ring S 2pcs Carburetor Body w Thermo Insulator Slide Valve Metering Needle Assembly O Ring S 2pcs Dust Cover Ball Link No 5 Set Screw Thermo Insulator Carburetor Rubber Gasket Code No No Description 1 1 1 1 2 2 2 1 2 2 3 3 1 4 4 1 5 6 7 7 1 8 9 9 1 10 11 21982700 27881820 22781800 21681900 27881820 2188195...

Page 19: ...1410300 71411200 71411250 71412300 71413550 71413600 71413700 O S SPEED HEX WRENCH DRIVER 1 5 O S SPEED HEX WRENCH DRIVER 2 0 O S SPEED HEX WRENCH DRIVER 2 5 O S SPEED HEX WRENCH DRIVER 3 0 O S SPEED HEX BALL WRENCH DRIVER 2 0 O S SPEED HEX BALL WRENCH DRIVER 2 5 O S SPEED FLAT HEAD SCREWDRIVER 3 0 O S SPEED NUT DRIVER 5 5 O S SPEED NUT DRIVER 6 0 O S SPEED NUT DRIVER 7 0 71520100 71415100 7141520...

Page 20: ...13 8 mm 0 543 in 14 0 mm 0 551 in 5 000 44 000 r p m 1 75 ps 35 000 r p m 220g 7 76 oz 25 4 39 70 6 15 1 34 9 29 5 UNF1 4 28 1 11 31 4 4 3 3 C Copyright 2010 by O S Engines Mfg Co Ltd All rights reserved Printed in Japan 60092370 061000 TEL 06 6702 0225 FAX 06 6704 2722 6 15 3 Chome Imagawa Higashisumiyoshi ku Osaka 546 0003 Japan ...

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