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20

CARBURETOR CONTROLS

With  a  fixed-wing  model,  power  failure  is  rarely  a 
serious threat to the safety of the aircraft since it can 
usually  glide  down  to  a  safe  landing.  In  a  helicopter, 
on the other hand, it is vitally imporant that the engine 
keeps  running  and  that  there  is  a  quick  and  reliable 
response to the throttle in order to ensure safe ascent 
and descent of the model.

The High-Speed (Main) Needle Valve

When  set  to  produce  maximum  power  at  full 
throttle,  this  establishes  the  basic  fuel/air  mixture 
strength. This is then maintained by the carburetor's 
automatic  mixture  control  system  to  cover  the 
engine's requirements at reduced throttle settings.

The  Idle Mixture Control Screw

This  provides  the  means  of  manually  adjusting  the 
60K's  mixture  control  valve.  By  setting  the  Mixture 
Control  Screw  for  the  best  idling  performance,  the 
mixture control valve automatically ensures that fuel is 
accurately  metered  to  maintain  the  correct  mixture 
strength as the throttle is opened. 

Two  adjustable  mixture  controls  are  incorporated  in  the 
Type 60M. They are as follows.

A

B

Idle MIxture Control Screw

High Speed Needle Valve
(Main Needle)

Needle
Adjusting screw

As the idle mixture control screw is applied with LOC-
TITE, at first times it is felt stiff, and it is suggested to 
use  a  littli  oversized  screwdriver.  The  screw  can  be 
turned only 90 degrees either way. Do not force to turn 
further, or it may break or cause trouble.

NOTE

90 degrees

90 degrees

one-way valve

21

BASIC POSITION  OF  MIXTURE  CONTROL  VALVE
(Mixture Control Screw)

Thick

Mixture Control Valve

MIxture Control Screw

Lean

With a model helicopter, adjustments may vary due to 
various  factors  such  as  climatic  conditions,  fuel, 
muffler, main rotor, weight of the model, gear ratio, etc.

89 degrees

When the triangle mark on the carburetor rotor meets 
the far right mark, the throttle is fully closed.  When the 
triangle mark meets the top mark, the throttle is fully 
open.  The range is 89 degrees.  You may use the other 
three  marks  as  the  reference  marking  of  throttle 
opening to your preference when hovering.

WARNING!
Never try to check the triangle mark position while 
the engine is running and rotor is
rotating, or you may be hit by rotating rotor which 
results in serious injury. Stop the engine and rotor 
before checking the triangle mark position.

Graduations on the carburetor body

Carburetor Rotor

Carburetor Body

Fully closed
position

Fully opened position

HEX KEY NEEDLE ADJUSTMENT

The knurled head of the main needle valve (High-Speed) 
is provided with diagonal slots for use with a screwdriver. 
Alternatively,  formore  positive  location  via  an  Allen 
hexagonal key, these heads also have M2.6 internal 
threads, into which M2.6x5mm Allen cap-head screw 
may  be  fitted.  To  avoid  risk  of  damage  to  the  fuel 
passages when tightening these screws, remove the 
needle  valves  from  the  carburetor  and  use  'Loctite' 
thread-lock compound to secure the screw. 

As  delivered,  the  Mixture 
Control Screw is positioned 
at the center as shown in the 
sketch.  Mixture  gets  lean 
when  the  Mixture  Control 
Screw is turned right, while 
mixture  gets  rich  when  the 
Mixture  Control  Screw  is 
turned left.

Therefore,  the  Mixture  Control  Screw  position  will 
vary with each model and set- up, and it is normal if 
the Mixture Control Screw position is off center.

As shown in the sketch,
the carburetor has 
graduation marks.

Содержание MAX-91SX-HRING C Spec PS VIPER

Страница 1: ...LE SERVO CARE AND MAINTENANCE EXPLODED VIEW PARTS LIST O S GENUINE PARTS ACCESSORIES THREE VIEW DRAWING MEMO 7 8 13 16 30 10 36 22 24 24 27 29 32 35 37 38 It is of vital importance before attempting t...

Страница 2: ...many other possibilities generally less obvious sources of danger but which under certain circumstances may also cause damage or injury 3 WARNINGS Never touch or allow any object to come into contact...

Страница 3: ...head down securely Take care that the glow plug clip or battery leads do not come into contact with rotating parts Adjust the throttle linkage so that the engine stops when the throttle stick and tri...

Страница 4: ...oove onto the connecting rod BDC position Rotate the crankshaft so that the connecting rod comes to this position 7 Note on installing the engine Note on heating the glow plug Cooling fan cover from s...

Страница 5: ...h torque type starter DO NOT however confuse tightness with the symptoms of hydraulic lock caused by an excess of fuel within the cylinder often the result of over priming Attempting to force the engi...

Страница 6: ...the under surfaces of the engine s mounting lugs are in contact with the engine mount 11 ABOUT THE PUMP SYSTEM Please understand the pump construction before piping Pump functions in accordance with t...

Страница 7: ...el in the pump Stop the fuel flow to the pump with the stopper and run the engine at idling to use out the fuel in the pump After stopping the engine rotate the engine by electric starter to eject fue...

Страница 8: ...1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1...

Страница 9: ...and connections carefully for any cracks on the tubes and loose connections as the engine runs ejecting excess fuel 17 4 Glowplug battery The power source for heating the glowplug may be either a lar...

Страница 10: ...is disconnected the heat retained within the combustion chamber remains sufficient to keep the plug filament glowing thereby continuing to keep the engine running Ignition timing is automatic under re...

Страница 11: ...Ixture Control Screw Lean With a model helicopter adjustments may vary due to various factors such as climatic conditions fuel muffler main rotor weight of the model gear ratio etc 89 degrees When the...

Страница 12: ...ating a dangerous situation 23 In case the engine does not stop Hold the rotor head and pinch the fuel line to stop the fuel supply If it still does not stop pull off the fuel line from the carburetor...

Страница 13: ...15 30 nitromethane Bear in mind that fuels containing relatively large percentages of power boosting nitromethane operate at richer mixture settings than are needed for mild fuels and will therefore r...

Страница 14: ...se at medium r p m e g hovering speeds is most important since this is a power range widely used in helicopter flight The optimum fuel air nixture strength at medium speeds is dependent on obtaining b...

Страница 15: ...mostly accumulate here SUBSEQUENT READJUSTMENTS Once the engine has been run in and the carburetor controls properly set up it should be unnecessary to alter the mixture settings except to make minor...

Страница 16: ...re Close the High Speed Needle Valve Turn clockwise Land the model Idle for approx 10 seconds then reopen throttle to observe transition Float the model Idling OK Lean mixture Rich mixture High Speed...

Страница 17: ...ide your refueling container will prevent the entry of foreign material into the fuel tank It is also recommended that a good in line filter be installed between the tank and carburetor 1 Finally inje...

Страница 18: ......

Страница 19: ...881810 27881800 27881820 45581820 29084100 27881330 27681340 27081900 27981910 24981837 46181940 46181941 26711305 46181950 Ratchet Spring Needle Needle Valve Assembly Fuel Inlet Rotor Guide Screw O R...

Страница 20: ...MP 10set Cap Screw Set M2 6x5 10pcs set 79871010 M3 5x10 79871070 7091 71530500 For 70SZ H 91SX H Needle Adjusting Screw 5pcs M2 6x5 41621100 37 THREE VIEW DRAWING Displacement Bore Stroke Practical R...

Страница 21: ...d 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 LLEDQ U A LIT Y P R E C IS IO N P E R F O R M A N C...

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