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<DIV><FONT size=2>Jim,</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>the NMP replacement viton o-ring is sized to accept the NMP
header NOT the Hatori header. The Hatori is 15mm and the NMP is 5/8" the
difference between the or-rings is about 3.5-4 thousands on the ID. This will be
enough to cause it to leak.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>If you are using the Hatori header you need to replace the
o-ring with the Hatori original o-rings. And yes 50-75 flights is normal
replacement time frame. The Hatori original replacements are available from
Central Hobbies.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Proper cooling on your engine and exhaust system will extend
the life of the o-ring, improper cooling and abuse will eat the o-ring in as
little as 5-10 flights.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>The NMP o-ring replacement for the NMP header is a much more
robust material than the Hatori Original. The Viton material on the NMP will
tend to last quite a bit longer than the Hatori originals. I have models
using both the NMP header with the replacement o-ring to fit that header and the
Hatori header-and o-ring versions. I can get about 50% better life out of the
NMP header/NMP o-ring version. I think it has to do with the cooling properties
of the NMP header. </FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>I have been running the replacement o-rings for several
years.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Troy Newman</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2></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=jim.woodward@baesystems.com
href="mailto:jim.woodward@baesystems.com">Woodward, Jim</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> Tuesday, December 11, 2007 11:49
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] Hatori Short
Pipe O-Rings</DIV>
<DIV><BR></DIV>
<DIV><FONT size=2>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hi
Guys,<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">What is the final verdict on these
O-rings? Will a warm run “melt” the O-ring? Does the viton
replacement fit tight enough over the header? Recently my plane is
getting really messy, where as before there wasn’t a drop of burnt fuel ahead
of the exhaust stinger. I replaced the o-ring but still had the
mess. I pull the motor last night and checked out everything and the
motor looks great, bolts were tight, with no indication of any leakage from
the motor or header to motor/flange attachment.
<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I am using the Nishioka spring
clamp mount. All things considered and experienced, I think I prefer the
stock Hatori mount that comes with the pipe. The Nishioka seems to allow
for more fore and aft pipe slippage during running due to the thin vertical
white plastic supports (checked while running the plane upside down to try and
determine spray pattern and such - in which I didn’t find one, which
leads me to believe that it starts to happen maybe later in the flight or heat
cycle, versus the small amount of running I did as a cursory
check.<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thanks,</SPAN></FONT><O:P></O:P></P>
<P class=MsoNormal><ST1:PERSONNAME w:st="on"><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Jim</SPAN></FONT></ST1:PERSONNAME><O:P></O:P></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><O:P></O:P></SPAN></FONT></P></DIV></FONT></DIV>
<DIV><FONT color=black><SPAN
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face="Times New Roman"><FONT size=2></FONT></FONT></SPAN></FONT> </DIV>
<DIV><FONT color=black><SPAN
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<DIV> </DIV>
<DIV><FONT size=2></FONT></DIV>
<DIV><FONT size=2></FONT></DIV></SPAN></FONT>
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