<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.6000.16587" name=GENERATOR></HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT size=2>For the 120NC just prop it down a size...maybe 2 sizes. The
15-10 might work well. You might also look at a 15-9 or 15-8 will likely be bit
too light. Personally the props used are usually about the same. The 120's
didn't have that huge of a power difference. The 120SC was the strongest, and
the 120SF-120NC-120FZ were all about the same..the 120AC was in between the two
levels. The problem with the AC was the air box and the extra
weight.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>What you want to do is run the engine at about 8500-8800rpm as
a target rpm. What ever fuel/prop combo gives you this rpm will work the best on
the engine. Regardless of the engine turn the rpm range an it will be happy and
make good power.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>For reference there were some 14in props that were really good
too. The 14-12...and the 120AC liked the 14.5-14N. </FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>My guess is try the 15-10 and see how it performs on the top
end rpm. If you are below say 8400 then either up your nitro or lighten the
load.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>As for replacing the sleeve. If there are deep scratches, or
when the crosshatch pattern is completely gone. If its just smoothed out at TDC
this is typical and happens pretty quickly. but when it starts to wear down
about 1/3 to 1/2 way down the pistons travel then its time to start looking for
a new sleeve. Any of the 120 sleeves will work. Same way for the piston....check
it to see if its round in all directions. Look for play on the wrist pin.
Inspect the ring groove. The best piston to run is the original 120FS as its the
most robust. For maximum power and performance the magnesium pistons are awesome
but they are more fragile. The dished pistons again better power but more
fragile. Don't run them lean and they will be good to go.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>As for the fuel that was left in them....not sure what fuel
you are using but I have not had this problem with the Cool Power. Some other
fuels that are highly touted by some...well I had problems there. Another
note if the engine is going to sit for a long time. I place it in a plastic bag
and put it back in the box. It resides in the house. Temperature changes are
minimal...you don't want to leave it where the temps will go through extremes.
This will invite condensation and moisture. That is where the rust comes
from.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>Troy Newman</FONT></DIV>
<DIV><FONT size=2>Team YS</FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=paul.horan@sbcglobal.net href="mailto:paul.horan@sbcglobal.net">Paul
Horan</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, December 30, 2007 9:31
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] YS 120
NC/SC prop recommendation</DIV>
<DIV><BR></DIV>
<DIV>Troy,</DIV>
<DIV> Thanks for the info. </DIV>
<DIV> I have one 120 NC and one 120 SC, the NC will go on an Aires
and the SC will be a backup. Both required a rebuild, looks like they
were left with some fuel in them and left that way for years. All the
bearings needed replacement, including the camshaft bearings. The SC has
a piston with a concave top, (dished ?). Of the two engines the SC
is in the best shape, the crosshatch tooling marks are visable in the
cylinder. The NC compression could be better. Any
suggestions for running the NC ? How do I know when I need to replace
the cylinder sleeve. </DIV>
<DIV>Thanks again for the info, in this case more is better.</DIV>
<DIV>Paul</DIV>
<DIV><BR><B><I>"Troy A. Newman" <troy_newman@msn.com></I></B>
wrote:</DIV>
<BLOCKQUOTE class=replbq
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">
<META content="MSHTML 6.00.6000.16587" name=GENERATOR>
<STYLE></STYLE>
<DIV><FONT size=2>15-10 is an excellent prop on the 120SC, if its a strong
one you can with the 15-11</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Of special note the 120SC likes Nitro. It is a fairly high
compression engine and can be a little finicky. It was the strongest of the
120's In fact I had one that gave the 140FZ a run for the
money.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Being this soupped up highly tuned 120...the extra nitro
broadens the mixture settings. The other thing it does is higher nitro
require richer settings to get the mixture correct and as a result they will
run a bit cooler and better. More fuel flow means more oil flow and better
cooling also.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>I strongly recommend the Cool Power 30% heli
fuel.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>By the way, on the 120SC because its more a higher
compression soupped up version, don't run it out of fuel. If you are flying
and too long and the engine runs dry it can backfire and can cause damage.
Its never a good idea to run any of the pattern engines 2 or 4 stroke out of
fuel, however the 120SC, 120AC, and the 140DZ tend to be a little brutal
when this happens. Try to run the 120SC at the higher end of rpms. I would
say the goal rpm for that engine would try to be up at 8600-8800 maybe as
high as 9000. On the 15" props it will make noise with ease in most
cases(read exhaust systems)</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>The 120SC is an awesome engine. Like I said it was the
king the of the 120's. There were some folks that had issues with them, but
my experience was always good with the SC. There were some piston of the
month changes to the 120SC. Namely they had a dished piston, and some
magnesium pistons. The goals behind these were to get more power out of the
120 case. Back then the FAI rules had not changed to allow larger than 120
displacement. So YS was trying to lighten the piston, and get the engine
making max power from the little box. At the time there were a few models
that were getting bigger than the 2 meter box as the 2m box didn't exist. No
size limit just the engine limit and the weight limit existed at the time.
On the piston front just stick any ole 120 piston in it....the 120SC piston
could be a little fragile if run lean (meaning running it out of fuel). The
original 120SF piston was bullet proof and works in the 120SC. The dished
and designer pistons are really able to change the behavior of the engine. I
have played with this "super" or the "hyper" pistons on the
current 160DZ and 170DZ engines. Its cool how changing the piston by putting
a dished top and closing off the bottom of the piston can change the way the
engine reacts to certain prop loads, or it will change the noise. Some of
the things they can do make more power and some of the pistons make it run
super smooth and quiet. Yamada doesn't do the testing in production like
they once did with the pistons. I have been fortunate to try some of the
super cool, "hyper" pistons they have played with on the DZ's. I wish I had
the knowledge back then that I have now. Some of the smallest changes in a
piston can really totally change the way an engine performs. Its kinda neat.
I remember the need was for more power more power back then and now I know
which piston designs would have done it better. </FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Any of the current exhaust systems will work very well on
the engine. Even the short hatori 821 pipes and the NMP header will work
excellent on that engine.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>I have a couple of 120AC's that we carved up the
heads to get more power...I wish I still had the 120SC as it would be a
really good engine for my war bird project I'm planning. I actually need a
pair of the 120SC's for it. Right now the 120AC's are a little heavier than
I would like and have been considering putting a pair of 140 Sports in the
model.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>I know this was likely way way more information than
you needed to know. But its a good engine and you'll love it.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Troy Newman</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=flyintexan@comcast.net
href="mailto:flyintexan@comcast.net">flyintexan</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, December 29, 2007
8:53 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] YS
120 NC/SC prop recommendation</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>Should be able to run a 16x8 on
30%...</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=paul.horan@sbcglobal.net
href="mailto:paul.horan@sbcglobal.net">Paul Horan</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, December 29, 2007
6:09 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] YS 120
NC/SC prop recommendation</DIV>
<DIV><BR></DIV>
<DIV> Any suggestions for a YS 120 prop ? It will be on a
Aires ?</DIV>
<DIV>Thanks,</DIV>
<DIV>Paul<BR></DIV>
<DIV>
<HR>
<DIV></DIV>_______________________________________________<BR>NSRCA-discussion
mailing list<BR><A
href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</A><BR><A
href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</A></DIV></BLOCKQUOTE>
<DIV>
<HR>
<DIV></DIV>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</DIV></BLOCKQUOTE>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE><BR>
<P>
<HR>
<P></P>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE></BODY></HTML>