[NSRCA-discussion] OS160FX/Perry Oscillator pump

[John Pavlick]

He's asking about the oscillating pump I believe - not the VP-30 . Jack -
sounds like there's not enough there with that pump - I would say use the
VP-30 instead. I'm using a VP-30 and my main needle is about 1.5 turns open.
That's where you want to be. I actually reduced the pump pressure a bit
too - this helps the low end and mid range. The engine should NOT quit on
the pinch. It might speed up about 200 RPM but it definitely shouldn't quit.
This means you are way too lean (not enough pump pressure  or volume). A
VP-30 will work fine.

John Pavlick
http://www.idseng.com



 -----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of
vicenterc at comcast.net
Sent: Tuesday, August 01, 2006 6:05 PM
To: NSRCA Mailing List; NSRCA Mailing List
Subject: Re: [NSRCA-discussion] OS160FX/Perry Oscillator pump


  Jack,

  I have been flying the same engine with the Perry Pump for a long time.
Depending on temperature, prop and fuel combination, I am usually between
1.0 and 2 turns.  I believe that the combination is very sensitive to the
low end adjustment.  Make sure that the low end is as rich as possible for
good transition from low to high as well from high to low.  If you lean the
low end too much the engine will have very poor down-lines.  Base on my
experience the best glow plug is OS F.  I use 20% nitro heli fuel.

  I have the following questions:

  1.- Is this engine new?  If not and you bought it second hand I will guess
that you have bad bearings.  The signal that you are giving in your e-mail
3.5 turns open and not responding to needle valve adjustment is one
indication that you have bad bearings.  In fly you will notice loss of
power.
  2.- What pipe are you using?  Make sure that you have at least 24" between
the plug and the first baffle.  If the pipe is too short it could cause the
problem you described in your e-mail.

  You have a good engine/prop combination.  The only problem with the OS 160
is that it is very sensible to cold weather.  It definitively does not like
to run around or below 50 oF.  Usually is fixed by richening both the low
end and high end.  That is good for me since I am a tropical guy.

  I am sure that others will have more useful information.  There is more in
the following web sites:

  http://www.rcpattern.com/2cycle.htm

  http://www.rcaerobats.net/OS160_Setup.htm

  Regards,

  Vicente "Vince"  Bortone

    -------------- Original message --------------
    From: "Jack Keiser" <jtkeiser at comcast.net>

    Does anyone know if the Perry Oscillator pump has enough capacity to
feed an OS 160 FX?  Although the engine seems to run OK, I'm concerned
because the needle valve seems to be open too far (about 3 1/2 turns) and
requires large changes, like one complete turn, to have any noticeable
affect on the mixture setting.

    The engine will maintain full throtttle RPM (about 8400 with an APC
17-10) without sagging (on the ground) and speeds up a little before quiting
when you pinch the fuel line. I haven't flown it yet but I'm concerned that
it may go lean in flight when the engine unloads.

    Any thughts before I fry an engine?

    Jack Keiser
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