YS 91 AC problem

[Paul Horan]

Hi Bob,
    Thanks for the reply.  I am aware that the idle adjust is an air bleed screw, thanks (sincerely) for the reminder.
The butterfly is closing completely, without the idle set screw I can definitely get it to a closed position.
I do not think air is getting in through the empty idle set screw but that is a possibility, I have a new one
comming from Central Hobbies next week.  The tubing from the front of the engine to the carb appears
OK but I replaced it anyway.  Right now my suspicions are the diaphram or the idle set screw causing
an air leak.
Thanks,
Paul
  ----- Original Message ----- 
  From: WHIP23 at aol.com 
  To: phoran at vvm.com 
  Sent: Thursday, May 15, 2003 7:27 PM
  Subject: Fwd: YS 91 AC problem


  In a message dated 5/15/03 5:09:08 PM Pacific Daylight Time, phoran at vvm.com writes:


      Now the engine idles at approx 2500 but I cannot get it below that even
    if I completely close the butterfly; also, the idle mixture screw has no
    effect !  I notice air bubbles between the pump body and the carb when
    idling, no bubbles in the tank side and there are no bubbles at mid to high
    throttle.  Only at idle.
      Any ideas ?
    Thanks,
    Paul



  Hi

  First the idle screw is an air bleed screw, not a mixture adjust, so it works reverse of normal thinking (turning it in will richen, out will lean)  Since it is an air bleed and you indicate it has no effect, I would suspect an air leak larger/more significant than the air bleed adjust.  I don't remember the layout on the .91, but the intake tube from the carb to the head is a prime suspect on the 120/140's, but anywhere that it can suck air will distrub the idle.  I assume you have checked the obvious, like the butterfly is really closing etc.

  Bob
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