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<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=914220415-07032006>Let me
add to what Dave and Jerry said,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=914220415-07032006>With
my OS 140, I have a two plug head, higher than normal compression, the old
richer carb metering barrel. My adjustable/throttle-coupled needle valve is
actually set slightly richer than the baseline, in the midrange, in order to get
a run that makes me happy. My pipe is just a little long, and the compression is
high: explaining why. I'd like to confirm how a crispy-lean idle messes up the
"settle" into a nice slow idle.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=914220415-07032006>With
the 3-blader, you can get some excellent braking.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=914220415-07032006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=914220415-07032006>That's
okay, as electric will offer better brakes than anything wet,
eventually.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=914220415-07032006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=914220415-07032006>later,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=914220415-07032006>Dean</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=914220415-07032006></SPAN></FONT> </DIV>
<DIV> </DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman">d.pappas@kodeos.com</FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org]<B>On Behalf Of
</B>DaveL322@comcast.net<BR><B>Sent:</B> Tuesday, March 07, 2006 9:17
AM<BR><B>To:</B> NSRCA Mailing List<BR><B>Subject:</B> Re: [NSRCA-discussion]
Fuel Regulation in 2C Engines<BR><BR></FONT></DIV>
<DIV>Jerry is right on target.</DIV>
<DIV> </DIV>
<DIV>More power generally means more fuel is being burned (or being burned
more efficiently) - a tuned pipe on a 2C can do both (add power and/or add
efficiency). So when the pipe is added (and tuned) to increase power,
the main needle is richened up - and when the engine is "off the pipe" in the
midrange, the midrange is slightly richer due to the richer main needle.
A common "trap" with the 2Cs is to lean the idle to alleviate the richness in
the midrange and this is really only a partial cure.</DIV>
<DIV> </DIV>
<DIV>As Jerry noted, lengthening the pipe generally leans the midrange, and
adding nitro generally leans the midrange.</DIV>
<DIV> </DIV>
<DIV>Good pipe design (and tuning) and concurrent design of the pipe and carb
reduce pipe jump and mixture irregularities across the throttle curve.</DIV>
<DIV> </DIV>
<DIV>Way back, OS changed (leaned) the fuel metering on the 140RX carb to
alleviate a rich spot in the midrange that was popuarly blamed on the carb -
this change appeased the majority - but I actually like the original carb
better using a longer tune length (compared to the majority at the
time).</DIV>
<DIV> </DIV>
<DIV>Regards,</DIV>
<DIV><BR>Dave Lockhart</DIV>
<DIV><A href="mailto:DaveL322@comcast.net">DaveL322@comcast.net</A></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>> > -----Original Message----- <BR>> > From:
nsrca-discussion-bounces@lists.nsrca.org <BR>> >
[mailto:nsrca-discussion-bounces@lists.nsrca.org]On Behalf Of Jerry Budd
<BR>> > Sent: Tuesday, March 07, 2006 12:28 AM <BR>> > To: NSRCA
Mailing List <BR>> > Subject: Re: [NSRCA-discussion] Fuel Regulation in
2C Engines <BR>> > <BR>> > <BR>> > >5. It is clear that
all 2-cycle engines will have this behavior. <BR>> > <BR>> > I
guess I have to offer a different opinion on this. If you have the <BR>>
> low end set lean (and most running the OS140Rx are running the bottom
<BR>> > lean to get the mid-range somewhat reasonable) you will not be
able <BR>> &g! t; to get the motor to settle into a low idle quickly.
And that <BR>&g t; > presents itself as poor down line breaking, as
well as the occasional <BR>> > flameout. When I ran the OS140's I bought
four motors and then <BR>> >! ; picked the two with the best carbs (aka
midrange) so I could set the <BR>> > low end where it belonged. I also
used higher nitro fuel (Magnum #1) <BR>> > to help lean the midrange,
which also allowed me to run the pipe <BR>> > about an inch longer
(which helped soften the pipe "bump"). <BR>> > <BR>> > I had good
luck (post '02 Nats) and good power (8400 rpm, APC 17x12) <BR>> > with
the OS's, but I found that the throttle response wasn't the best <BR>> >
if you used a lot of throttle to control speed. When I switched to <BR>>
> the Webra 160 I was able to set the top end rich and still have more
<BR>> > power than I knew what to do with (because of the enormous
<BR>> > torque/very conservative exhaust timing), and also set the idle
<BR>> > sligh! tly rich so the motor would quickly settle into a low
stable <BR>> > idle. Of course this was a lot easier to do with the MC
carb since I <BR>> > didn't! have to compromise on the mixture settings.
<BR>> > <BR>> &g t; But, anyway, to bring this back to point. The
most prevalent reason <BR>> > for a 2c to have an erratic idle with poor
down line braking is a too <BR>> > lean idle and a hot motor (like Evil
Eric said). Adding a fuel pump <BR>> > or a pressure regulator or
whatever won't fix that. <BR>> > <BR>> > Just my $0.02 worth,
<BR>> > <BR>> > Jerry <BR>> > -- <BR>> > ___________
<BR>> > Jerry Budd <BR>> > Budd Engineering <BR>> > (661)
722-5669 Voice/Fax <BR>> > (661) 435-0358 Cell Phone <BR>> >
mailto:jerry@buddengineering.com <BR>> > http://www.buddengineering.com
<BR>> > _______________________________________________ <BR>> >
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