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26

Having provisionally set the idle mixture, the next 
step is to adjust the mixture for hovering flight.
Hover the model and actuate the throttle to observe 
response  over  the  medium  speed  range.  lf  the 
engine smokes excessiveIy and throttle response is 
poor, the mixture is too rich ; in which case, land the 
model  and  turn  the  High-Speed  Needle  Valve 
clockwise.  Do  not  close  the  High-Speed  NeedIe 
Valve  more  than  the  recommended  initial 
adjustment (3 to 4 clicks) at a time, keeping it a little 
on the rich side at this stage. 

lf,  on  the  other  hand,  hovering  is  not  stable  and 
response to the throttIe is over-sensitive, or if the 
engine  tends  to  overheat,  this  indicates  that  the 
mixture  is  too  lean  and  should  be  corrected  by 
turning  the  High-Speed  Needle  Valve  counter-
clockwise.

2.

After  about  10  seconds  of  idling,  open  the  throttle  to 
'float'  the  model.  lf  the  transition  is  smooth,  the  idle 
mixture is O.K. If the symptoms of either rich or Iean 
running  are  observed,  readjust  the  Idle  Mixture 
Control Screw accordingly.

When satisfactory hovering flight has been achieved, 
land  the  modeI  again  and  re-check  the  engine's  idle 
qualities.

27

For helicopters, good throttle response 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 balanced adjustment of both the Needle 
Valve and the Mixture Control Valve.

Now  adjust  the  High-Speed  Needle  Valve  to 
achieve the best performance when the model is 
flying at full throttle. lf, at full throttle, acceleration 
is poor, the exhaust unduly smoky and the model 
fails  to  reach  expected  straight  line  speed,  the 
mixture  is  too  rich  and  the  High-Speed  Needle 
Valve setting will need to be reduced. 
lf,  however,  after  smoothly  acceIerating  to 
satisfactory  high-speed  straight  and  level  flight, 
power is lost when the model is puIled up into a 
climb, the mixture is too lean. ln this case, land the 
model immediately and readjust  thw High-Speed 
Needle Valve to a richer setting.

3.

4.

Having  now  found  the  optimum  setting  for  the 
High-Speed Needle Valve, re-check the engine's 
idle  performance,  fine  tuning  the  Idle  Mixture 
Control Screw, if necessary, to perfect the idle.

If both controls are alreday at their optimum setting, 
some  modification  to  these  settings  may  be 
necessary to achieve satisfactory mid-range throttle 
response,  but  such  readjustments  should  only  be 
made within the rarge where idling reliability and high 
speed performance are not undnly compromised.

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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