Header,teflon, Muffler?

[jed241 at msn.com]

Buddy,

I've been running a 140L with a 1/2 Teflon coupler and Hatori pipe and getting about 8,400rpm with a 16x11 using Wildcat 15% Nitro / 18% all Synthetic oil. I've been told it will run better with more Nitro. I haven't ried it yet as I didn't want to change anything during the season.

I'm wondering if the pop you heard was a backfire and split the coupler. My coupler is about 9 inches long and have about 100 flights on it this season with no problem.

None the less the Focus ran strong all year with this set up and fuel, with good vertical performance.

Engines are not my strength, so I'm not much help with what could be wrong. I think the problem is in the 140L though.

See ya,

Larry
  ----- Original Message ----- 
  From: BUDDYonRC at aol.com 
  To: discussion at nsrca.org 
  Sent: Saturday, September 27, 2003 8:49 AM
  Subject: Header,teflon, Muffler?


  I have been having occasional problems with RPM and what seems like overheating on my YS-140-L. I have come to believe the problem is restriction in the muffler, but the muffler seems to be open and OK
  The problem seems to have something to do with the prop size also. 
  Running a 15-1/2 x 13N rpm at about 8200 everything is fine, switched to a 16 x11 and running @ 8400 rpm and later in the flight the power back's off, I think it is heating up.
  Yesterday I switched to a 16 x10 prop turning 8800 rpm and half way through the flight I heard a loud pop, After that the engine would not turn up. I landed and found that the Teflon coupler had split long ways about three inches long and had curled inward restricting the flow. This has happened on two different mufflers a Hatori and a Johnson that is shaped like the Hatori Has anyone run into this problem before? and what is the solution?  Is there another Aluminum muffler that will work? I have another setup using a CF muffler and have not had problems with it even at 9000rpm with a 16 x11 prop but choke when I think of spending $175.00 for another muffler.
  Buddy    
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