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os 55ax installation problems

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Old 09-12-2017, 04:49 PM
  #1
andrewskj
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Cool os 55ax installation problems

I just finished a new U can do SF but having problems with my engine and was wondering if its because of the position the engine is in that causes the problems . I changed the tank just for good measure , run it in on test stand , use power master 15 fuel even tried another fuel. I also went to a K$B idler plug . the engine starts and runs great for a few min however if I go to mid throttle and stay there a little it dies when i advance to full.throttle . I ve tried to reset high end and low end but still problem there . could i perhaps have a bad carb ? has anyone had this problem with this set up ? Im going crazy because I have not gotten to fly the plan yet ... I have the same band engine in another plan with the engine up right and it works flawless. Could the barrels inside the carb be in wrong position ? I would not know how to reset them unless you can tell me how to do it..I did notice that some fuel drilling out the muffler and last but not least i notice it loads up in mid range and i think that is what causes it to die even if I let it run mid throttle it will die . I would really appreciate and help on this matter and I want to thank you in advance .
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Old 09-13-2017, 04:33 AM
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bruceal
 
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I would say that the low end is too rich or too lean. It depends what it does when it quits. if you try to open the throttle and it sputters, it could be too rich, if it shuts off sharp it could be too lean. Try the pinch test. If you're not sure what that is, it's just pinching the fuel line while the engine is at idle. The rpm's should rise before the engine quits. That's what I would look at first.
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Old 09-13-2017, 09:00 AM
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hsukaria
 
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Quote:
Originally Posted by bruceal View Post
I would say that the low end is too rich or too lean. It depends what it does when it quits. if you try to open the throttle and it sputters, it could be too rich, if it shuts off sharp it could be too lean. Try the pinch test. If you're not sure what that is, it's just pinching the fuel line while the engine is at idle. The rpm's should rise before the engine quits. That's what I would look at first.
First, adjust the high speed needle to achieve peak RPM's at WOT. Do not back it out to richen yet, do the pinch test first. With the pinch test, the rpm's should rise at most a little or not at all and the engine quit after a while. If the engine speed picks up noticeably and runs a long time before quitting, then it is too rich. If it quits soon after pinching, then too lean. Adjust the low speed needle accordingly and re-run the pinch test. When the pinch test is set, do the throttle up test as described above. Once satisfied with the setting, go back and richen the high speed needle a bit. Then re-check the idle, transition, and WOT for good performance.

The carbs on these engines are perfect, unless you have a bad o-ring. The o-ring on the high-speed needle on my 55AX tore up within the first couple of years of use. So check that o-ring and the o-ring at the base of the carb. Replace if they look bad.

By the way, what prop are you using on this engine? Is it within the recommended range by OS? That can also mess things up.

Last edited by hsukaria; 09-13-2017 at 09:02 AM. Reason: added the prop question
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Old 09-14-2017, 06:54 PM
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Try a new OS glow plug also. Had a similar problem on an OS61. Changed the plug and all was well.

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