If you use a stinger with a smaller ID it will increase back pressure , restrict exhaust. Depends what you desire as to whether or not it's best for your engine. It might not be enough to even notice.. .
        One way to find out,  John L.

The exhaust gases will eventually burn a hole in a plain silicone sleeve, and the resonance at least doesn't make situation better.
So, when doing adjustment we used to fill the gaps with short lenghts of header tubing.
So in my opinion it's better to play safe. It's not nice to find a hole in middle of a contest.

       I think he is talking about the rubber angle at the exhaust end, called (here, anyway) the "stinger". Those do not melt.

      I have also been using silicone couplers, and while they get pretty crusty on the inside after a while, I have never had one melt or otherwise fail causing a leak. Even the really big type, which was intended as an outlet tube for chainsaw engines, not a coupler.   One difference is that we also are perfectly OK running 7-8-9 ounces of fuel through it, instead of 3-4 for the same power, so we are definitely burning it at lower temperatures than you do.

     Brett

Larry and I both have new RoJett BSE 61s to go into Thundergazer-ish models. Is the Hattori an aluminum pipe, or is Brett referring literally to just the end of the tailpipe, where the grey rubber deflector normally goes? And, is the Hattori pipe (if that is what Brett is referring to) available these days? Are they made by Hattori Hanzo of "Kill Bill" fame? Failing a Hanzo pipe, what would those in the know suggest in a CF pipe from Randy Smith or Brian Eather or any other maker, as to overall length, baffle placement, and other critical features? Thanks in advance.

Hi Mike,

For my RO-Jett BSE 61 setup I'm using a Rich Oliver pipe that was purchased through Dub Jett. Attach is a PDF with some pictures of this setup. Also included is pictures of the Randy Smith "Slimline" pipe that I haven't used.

BTW, I will be at the Napa flying site tomorrow (Thursday) morning. If you would like to try this pipe, come by site if you can and pick it up. If not, we can make other arrangements to get it to you. Just let me know.


Dennis

Well, think of the stinger as one acoustic element that has a certain volume. Acoustics is all about volume.
By varying the volume (lenght) you can tune it (like a minipipe) to have either positive or negative backpressure, or to be neutral. Whatever suits you the best.
So it doesn't mean that longer is allways better, you've got to optimize it.
But if you want to test things, I'd recommend something stiffer than silicone hose. L

   Generally he idea is to either getting more boost by the reflecting cone larger by having a smaller outlet, or more flow and less boost with a bigger outlet which makes the reflecting cone surface area smaller.

   The practical length for stingers probably puts it at far too high a frequency for any useful additional boost. And, you *don't need more boost" if the intent was to (selectively) kill power in the first place.

    Brett

  I found it interesting the way this guy explained 2smoke tuning to me. Really doubt much of what he told me applies to our stuff.
  John L.

  It's a different problem. The "rules of thumb" generally won't work, but the principles are the same, just used in a different way. But even "The Two-Stroke Tuner's Handbook" discussed the use of a tuned pipe as a rev-limiter.

    Brett

Larry, Brett, Mike, Dennis, et. al,

We should just have a tuned pipe session at Napa or Alameda in a few weeks! I've got my 46vf running pretty good in the garage, just haven't had the chance to put it in the air yet and see what goes wrong.