[NSRCA-discussion] OS 140Rx pump question

[Lance Van Nostrand]

[NSRCA-discussion] OS 140Rx pump questionJohn,
OS doesn't want you to touch it, but if you do it works like this: screw it out to decrease pump pressure.  There is a range of adjustment that you can do without damaging the pump.  However before trying this, inspect the breather hole in the center of the pump screw.  Even a fragment of dirt will totally screw the pump operation.  If you have to reduce the pressure, don't sweat it.  You are out of warranty.  Just do it.  I suggest 1/2 turn.  If the change is minimal, try again.  YOu should have +- 1.5 turns from the factory setting.

Remember that good ground running can be had with too little pump pressure, so be very careful to listent to the engine on uplines in your test flight.  Let me know.
Good Luck.
--Lance

  ----- Original Message ----- 
  From: John Pavlick 
  To: NSRCA Mailing List 
  Sent: Sunday, September 24, 2006 1:50 PM
  Subject: Re: [NSRCA-discussion] OS 140Rx pump question


  Dean,
   I don't know if it ever ran right. I bought it used. I started it for the first time on Friday. It has a new ring and new bearings. It has the OS dual-plug head. "F" in the center, "8" in the rear. None of this work was done by myself, this is how I got it.The entire mixture curve is too rich. Idle, top-end, mid-range. In other words too much fuel pressure. I set the pipe way long just so that I could fly it. The idle adjustment is full clockwise and it still loads up eventually. It's just too fat everywhere. I'm going to pull it and see what the pump looks like. Is there any way to put it back to the original setup if I find out that somebody adjusted something? OS doesn't give any reference - I guess they don't want you to touch it.

  John Pavlick
  http://www.idseng.com
    

    -----Original Message-----
    From: Dean Pappas [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Dean Pappas
    Sent: Sunday, September 24, 2006 12:23 PM
    To: NSRCA Mailing List
    Subject: RE: [NSRCA-discussion] OS 140Rx pump question


    Hi John,
    Did it ever run properly, before? If the adjustment screw wasn't moved, then the first thing to do is disassemble and clean. A piece of crud in the right spot will kill the regulation. Has the engine been decompressed with additional head gaskets? That add richness in the midrange. If that doesn't help, then you are stuck with either lengthening the pipe or fixing the carb metering curve with a throttle to remote needle curve coupling in the radio. 
    Dean
      -----Original Message----- 
      From: nsrca-discussion-bounces at lists.nsrca.org on behalf of John Pavlick 
      Sent: Sun 9/24/2006 1:29 AM 
      To: NSRCA Discussion 
      Cc: 
      Subject: [NSRCA-discussion] OS 140Rx pump question


      I'm having some trouble with my OS 140Rx and it seems to me that maybe
      somebody played with the pump (I bought this motor used). Here's what's
      going on. The main needle wants to be at about 3/4 turns out. Not even a
      full turn. If I open it to 1 1/4 turns it's slobbering rich. The idle is
      rich even with the adjustment turned fully clockwise. It is flyable, but I
      know something isn't right. This motor also has a dual-plug OS head. I have
      an "F" plug in the center and an "8" in the rear. The transition isn't
      great, especially at about 1/2 throttle. On the ground it will actually load
      up sometimes. In the air it's not so bad but it doesn't sound right. If it
      had a Perry pump I'd back off the pressure and that would probably fix it.
      Like I said, I'm thinking someone played with the pump for whatever reason.
      Is there any way to set it up as it was originally or do I have to send it
      back to the service center?

      John Pavlick
      http://www.idseng.com

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