O.S. engine 91sII Owner'S Instruction Manual Download Page 10

18

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 the engine is still running - at full throttle  - then, expel 
as  much  fuel  residue  as  possible  by  turning  the  engine  over 
for 5-10 seconds with the electric starter. 
Finally, inject some after-run oil through the glowplug hole and 
turn the engine over several times by hand.
When  the  engine  is  not  to  be  used  for  some  months  (for 
example, as between flying seasons) a worthwhile precaution 
is  to  remove  it  from  the  airframe  and,  after  washing  off  the 
exterior  with  alcohol  (not  gasoline  or  kerosene)  to  carefully 
remove  the  fuel  pump,  carburettor  with  intake  pipe  and  all 
silicone tubing and put them safely aside.
Make sure that the engine is reasonably clean externally, then 
remove the glowplug and immerse the engine in a container 
of  kerosene.  Rotate  the  crankshaft  while  the  engine  is 
immersed. If foreign matter is visible in the kerosene, rinse the 
engine again in clean kerosene, before removing it, vigorously 
shaking off the excess and wiping it dry.  

CARE & MAINTENANCE (laying up)

The  fuel  pump  assembly,  carburettor/pressure-regulator  and 
silicone  tubing  must  be  cleansed  separately  in  methanol  or 
glow  fuel.  On  no  account  must  they  come    into  contact  with 
kerosene. 
Before completely reassembling the engine, make sure  that 
no  kerosene  remains  inside  that  could  find  its  way  into  the 
pump  unit,  carburettor,  etc.  Inject,  sparingly,  preserving  oils, 
rust  inhibitors,  etc.  unless  approved  for  silicone-rubber 
products. 
An appropriate alternative here may be one of the high-quality 
synthetic lubricating oils.
Finally,  seal  the  engine  in  a  heavy  polyethylene  bag  until 
required for reinstalling the airframe.

Debris tends to

accumulate in

this area

19

RADIAL MOTOR MOUNT

O.S.GLOW PLUG
TYPE F

EX EXHAUST HEADER PIPES

FLEXIBLE EXHAUST PIPES

BOOSTER TERMINAL KIT

BOOSTER CABLE SET

PROPELLER LOCKNUT SET

(For Spinner)

NON-BUBBLE
WEIGHT

SUPER FILTER (L)

LONG SOCKET WRENCH
WITH PLUG GRIP

Type

Length 

(mm)

Inside

Outside

Code.No.

O.S. GENUINE PARTS & ACCESSORIES

For FS-91SⅡ/SⅡ-P

For 

FS-70SⅡ 

(71901100)

(71615009)

(72200130)

(72200110)

(71521000)

(72109500)

(72109600)

(71905000)

(72200060)

M2.6x12

(79871040)

M3.5x8

(79871060)

M3.5x15

(79871090)

M3.5x20

(79871100)

(72403050)

(71531000)

(72200080) 

(45910200)

(45910300)

72108100
72108110
72108120
72108130

1111A
1111B
1111C
1111D

120
240
170
330

NEEDLE VALVE
EXTENSION CABLE SET

5/16"-M5 PROPELLER 
LOCKNUT SET FOR SPINNER

VALVE ADJUSTING
TOOL KIT

CAP SCREW SET (10pcs.)

The specifications are subject to alteration for improvement without notice.

Summary of Contents for 91sII

Page 1: ...control equipment etc are accessible for checking at the same time 1 2 4 5 6 7 8 8 9 9 10 11 12 12 15 15 17 17 18 19 20 25 26 27 28 30 13 14 SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O S ENGINE INTRODUCTION INSTALLING THE GLOWPLUG RELOCATION OF CARBURETTOR CONTROLS FUEL TANK INSTALLATION EXHAUST HEADER PIPE AND SILENCER THROTTLE LINKAGE NEEDLE VALVE EXTENSION FUEL LINES CARE OF FUEL PUMP AND REG...

Page 2: ...ny 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 The advice which follows is grouped under two headings according to the degree of damage or danger which might arise through misuse or neglect 3 NOTES This engine was designed for model aircraft Do not attempt to use it for any other purpose M...

Page 3: ...y 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 The O S FS 70SⅡ FS 91SⅡ and FS 91SⅡ P are built like all O S engines to the highest engineering standards by a company that was established in 1936 to manufacture 2 stroke engines and which pioneered the production of four stroke cycle model ai...

Page 4: ...p to 12 13 minutes flying time dependent upon the type of fuel used the size of the propeller and on the proportion of full throttle to part throttle operation through the flight 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 see sketch To prevent the pickup from adher...

Page 5: ... with the header pipe or silencer may result in a serious burn If you need to tighten the silencer joints which may loosen when they are hot use a thick folded cloth for protection FUEL LINES For fuel line use heavy duty silicone rubber tubing of approximately 2 5mm inside and 5 0mm outside diameter Note Be sure to use a muffler pressurized fuel feed system It is advisable to fasten connections wi...

Page 6: ...ted on a methanol based fuel containing not less than 18 castor oil or a top quality synthetic lubricant or a mixture of both plus a small percentage 5 15 of nitromethane for improved flexibility and power The carburettor is adjusted at the factory for a fuel containing 20 lubricant and 10 nitromethane Some commercial fuels also contain coloring additives as an aid to fuel level visibility In some...

Page 7: ...ylinder automatically Starting procedure is as follows Check that the current to the glowplug is switched off Check that the polarity of the starter battery leads rotates the engine counter clockwise when viewed from the front Open the needle valve 3 3 5 turns from the fully closed position and temporarily set the throttle in the fully open position Apply the starter and press the starter switch f...

Page 8: ...y cause the engine to stall Therefore at this time the aircraft should as far as is possible be flown at an altitude sufficient to enable an emergency landing to be safely made if the engine stops 9 15 Feeler gauge 0 04mm ALL O S four stroke engines have their valve tappet clearances correctly set before they leave the factory However if after many hours of running time have been logged a loss of ...

Page 9: ...te prop through two revolutions and recheck gap 5 If clearance is correct loosen the locknut on the other rocker arm and repeat steps 1 to 5 above Finally replace rocker box cover 6 Remember Excessive valve clearance will cause loss of power due to valve s not opening sufficiently On the other hand a total loss of clearance may cause difficult starting due to valves not closing properly resulting ...

Page 10: ...g must be cleansed separately in methanol or glow fuel On no account must they come into contact with kerosene Before completely reassembling the engine make sure that no kerosene remains inside that could find its way into the pump unit carburettor etc Inject sparingly preserving oils rust inhibitors etc unless approved for silicone rubber products An appropriate alternative here may be one of th...

Page 11: ...925010 45910100 44014010 44001100 Cam Cover Camshaft Camshaft Ball Bearing 1pc Breather Nipple No 5 Crankcase Crankshaft Ball Bearing R Crankshaft Cover Plate Cylinder Liner Connecting Rod Piston Pin Piston Piston Ring Carburetor Complete Type 60R Breather Nipple No 5 Intake Pipe Intake Pipe Assembly Cylinder Head w valve Assembly Cylinder Head w Gasket Split Cotter 2pc 1pair Valve Spring Retainer...

Page 12: ...00 45925010 45910100 45903200 Description Code No No The specifications are subject to alteration for improvement without notice Description Code No No Cam Cover Camshaft Camshaft Ball Bearing 1pc Breather Nipple No 5 Crankcase Crankshaft Ball Bearing R Crankshaft Cover Plate Cylinder Liner Connecting Rod Piston Pin Piston Piston Ring Carburetor Complete Type 60P Breather Nipple No 5 Intake Pipe I...

Page 13: ... 45231100 45771000 45901010 45914010 45530030 45902010 45907010 72508001 46103100 45605000 45906000 71615009 45926000 45925100 45925010 45910100 Cam Cover Camshaft Camshaft Ball Bearing 1pc Breather Nipple No 5 Crankcase Crankshaft Ball Bearing R Crankshaft Cover Plate Cylinder Liner Connecting Rod Piston Pin Piston Piston Ring Carburetor Complete Type 60N Breather Nipple No 5 Intake Pipe Intake P...

Page 14: ...4081970 45984900 1 1 1 1 2 1 3 1 4 1 5 2 3 4 5 5 1 5 2 6 7 8 9 Description Code No No Needle Valve Assembly Needle Assembly O Ring 2pcs Set Screw Needle Valve Holder Assembly Ratchet Spring Carburetor Body Rotor Guide Screw Fuel Inlet No 1 Mixture Control Valve Assembly O Ring L 2pcs O Ring S 2pcs Carburetor Rotor Throttle Lever Assembly Carburetor Rubber Gasket Carburetor Retaining Screw 2pcs 27 ...

Page 15: ... Stroke PracticalR P M Output Weight Specifications THREE VIEW DRAWING C Copyright 2000 by O S Engines Mfg Co Ltd All rights reserved Printed in Japan TEL 06 6702 0225 FAX 06 6704 2722 6 15 3 Chome Imagawa Higashisumiyoshi ku Osaka 546 0003 Japan 60090990 061107 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 ...

Reviews: