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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I’m running a 15-10 with Cool Power
15% and as I remember, it turns around 8500 RPM. The engine has < 30 runs on
it and I’m still running a little richer than necessary. I did have to
adjust the idle mixture.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The engine was purchased 3 months ago and
has the squared-off idle needle that withdraws completely.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<div>
<p><b><i><font size=4 color=navy face="Brush Script MT"><span style='font-size:
13.5pt;font-family:"Brush Script MT";color:navy;font-weight:bold;font-style:
italic'>Jay </span></font></i></b><b><i><font size=4 color=navy
face="Brush Script MT"><span style='font-size:13.5pt;font-family:"Brush Script MT";
color:navy;font-weight:bold;font-style:italic'>Marshall</span></font></i></b><font
color=navy><span style='color:navy'> </span></font></p>
</div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'>-----Original Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> </span></font><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>nsrca-discussion-bounces@lists.nsrca.org</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> [mailto:</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>nsrca-discussion-bounces@lists.nsrca.org</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>] <b><span
style='font-weight:bold'>On Behalf Of </span></b>J N Hiller<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, October 22, 2007
8:55 PM<br>
<b><span style='font-weight:bold'>To:</span></b> </span></font><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>NSRCA Mailing
List</span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [NSRCA-discussion] OS
120AX header?</span></font></p>
<p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'> </span></font></p>
<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle24><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>What size prop are
you running and fuel mix? I felt that more RPM’s or running leaner (more
heat) would produce more exhaust gas volume thus more back pressure and probably
be better. I am running a 16-10 APC on 10 or 15% nitro, cool enough that the
discharged oil is the same color as the fuel. I purchased the first engine 8-03
and the second 4-05. The carburetors were different (see attached photo). The
one on the left is from the first engine. The idle mixture (tapered needle)
didn’t completely withdraw from the fuel delivery tube and the barrel had
a small hole through the side like the parts drawing on page 42 of the manual.
The second one didn’t have this hole. I felt that when the barrel pulled
out at full throttle without fully withdrawing the idle mixture needle
presented a second fuel restriction, a condition I have seen in the past. When
inquiring as to which carb was correct (revision or Mfg error?) from the
service center I got the expected response. They either didn’t know or
were not about to explain the difference to me after all I am a small fish on
their pond and have never read anything about a revision. </span></font></span></p>
<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle24><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>Which carb do you
have?</span></font></span></p>
<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle24><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>Jim Hiller</span></font></span></p>
<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle23><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'> </span></font></span></p>
<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle23><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'> </span></font></span></p>
<p class=MsoNormal style='margin-left:1.0in'><font size=2 color=black
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;color:black'>-----Original
Message-----<br>
<b><span style='font-weight:bold'>From:</span></b>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org]<b><span style='font-weight:
bold'>On Behalf Of </span></b>Jay Marshall<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, October 22, 2007
3:51 AM<br>
<b><span style='font-weight:bold'>To:</span></b> 'NSRCA Mailing List'<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [NSRCA-discussion] OS
120AX header?</span></font></p>
<p class=MsoNormal style='margin-left:1.0in'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'> </span></font></p>
<p class=MsoNormal style='margin-left:1.0in'><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy'>I believe
that the stock silencer for the 120AX has quite a bit of back pressure.
In my Venus I moved the fuel tank to the most reward possible position and
tried it w/o a pump. No difference in performance from the forward position
even on long verticals.</span></font></p>
<p class=MsoNormal style='margin-left:1.0in'><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p style='margin-left:1.0in'><b><i><font size=4 color=navy
face="Brush Script MT"><span style='font-size:13.5pt;font-family:"Brush Script MT";
color:navy;font-weight:bold;font-style:italic'>Jay Marshall</span></font></i></b><font
color=navy><span style='color:navy'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=2 color=black
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;color:black'>-----Original
Message-----<br>
<b><span style='font-weight:bold'>From:</span></b>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Bob Richards<br>
<b><span style='font-weight:bold'>Sent:</span></b> Saturday, October 06, 2007
9:22 PM<br>
<b><span style='font-weight:bold'>To:</span></b> NSRCA Mailing List<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [NSRCA-discussion] OS
120AX header?</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'>Jim,</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'>I have not
run my 120AX enough to conclude anything yet, but the little bit that I have
run it left me thinking there was not enough muffler pressure either. I tried with/without
the internal baffle, but I think the best combo would be to leave the internal
baffle out and try restricting the tailpipe as you say.</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'>There are a
couple of guys in our club that have the 120AX running the Jerry Smith mousse
can mufflers and get MUCH better performance, and more reliable running as well
since there is considerably more muffler pressure. They also fly several Outlaw
delta planes with .32 size engines and do incredible manuevers, using the
same type muffler setup. The only way they can pull the Gs they do and still
run is because of the much higher backpressure.</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'>With a large
volume muffler (the larger the better) the more pressure you can run in the
muffler and the engine still run fine. In fact, you will burn less fuel as well
since less excess fuel/air mixture blown out of the exhaust during the exhaust
scavenging.</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'>I did a lot
of muffler/prop experimenting (sport planes) many years ago. :-) I learned a
LOT.</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'>Bob R.</span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'><br>
<b><i><span style='font-weight:bold;font-style:italic'>J N Hiller
<jnhiller@earthlink.net></span></i></b> wrote:</span></font></p>
<div style='border:none;border-left:solid #1010FF 1.5pt;padding:0in 0in 0in 4.0pt;
margin-left:111.75pt;margin-right:.5in'>
<p class=MsoNormal style='border:none;padding:0in'><span class=emailstyle20><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>16 x 10 should be
no problem. I have run one all season with stock muffler. I didn’t like
how many RPM’s the 16 x 8 turned in horizontal flight.</span></font></span></p>
<p class=MsoNormal style='border:none;padding:0in'><span class=emailstyle20><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>This may be a
little off subject but may be of interest to other 120AX users.</span></font></span></p>
<p class=MsoNormal style='border:none;padding:0in'><span class=emailstyle20><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>I fought a rich
midrange (poor transition) from day one in order to keep from running too lean
on a long vertical pull, which seamed to get worse in cool air. I have two
motors that have different carburetors and focused on this as a problem even
though both acted similar eventually concluding that there wasn’t enough
muffler pressure. I have never gotten along well with pumps so I tried
restricting the muffler outlet using a short exhaust tube (3/8” ID) with
a brass tube insert. I tried a couple different sizes settling on 13/32 OD,
which is pinched on the end from cutting with a tubing cutter (.350” ID).
Flaring the other end keeps it in the exhaust tube without clamps. I also tried
an OS-“F” plug which I thing may be better than the #8. It will be
9 months before I can run it in hot weather but I was able to run leaner
without starving in the verticals and the transition is immediate.</span></font></span></p>
<p class=MsoNormal style='border:none;padding:0in'><span class=emailstyle20><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>Jim Hiller</span></font></span></p>
<p class=MsoNormal style='border:none;padding:0in'><span class=emailstyle20><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'>Spokane</span></font></span></p>
<p class=MsoNormal style='border:none;padding:0in'><span class=emailstyle20><font
size=2 color=navy face=Arial><span style='font-size:10.0pt'> </span></font></span></p>
</div>
<p class=MsoNormal style='margin-left:1.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font></p>
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