When you ty-wrapped the pipe to the mount,  did it touch the wing surface to put stress on it ?
I wouldn't think you would do that, but its the only thing I could think of other than defect in the pipe.

Hard to guess what could happen just from photos but if the coupler was kinked from raising the pipe mounting as you mentioned it could cause the engine and pipe to run hot.  This could cause the damage indicated.  Also the pipe could be stressed at the coupling by bending the coupling.
This could happen if the pipe was leaking at the coupling also.

These are just educated guesses but I have seen damage similar to this caused by leaks.

Randy Cuberly

I can see the faint line on the pipe end of the tie wrap.  So it must have been tight.  I suspect the angle the pipe was in plus the high heat in that area led to the failure.

    It must have been much hotter than normal as well. Brian's pipes can handle much higher heat than any of the others we have used and I have never seen one with any more than superficial color changes, never any distortion or degradation.

    Brett

Most folks up here seem to run two tie-wraps at each end of the coupler, offset a bit so there will be a better seal at each end. No idea if this would have any effect on your pipe failure. It does look like maybe the aluminum tube insert was absent. ?

My understanding of the Heli engines being ringed is because when an ABN/ABC/AAC engine is thrown into idle, it cools off quickly and the cylinder pinch at TDC then stops the engine.  Steve

Those Enya 61s can have a very hot run. A fellow club member had a hot run that burned the head to the point the glo plug came out because there was not enough head left.

Those Enya 61s can have a very hot run. A fellow club member had a hot run that burned the head to the point the glo plug came out because there was not enough head left.

   I was going to ask about that. If I set up a PA or Jett with any sort of power for a 13-3.75 3b and 5.5 oz of fuel, I would expect it to run EXTREMELY hot. That's a lot of power and not much fuel going through it, meaning it is running very lean, and little oil to cool it off. Depending on which prop it was. I ran a 13.5-3.9 Eather 3B on the Jett, and no heat problems but it was using around 7.5 oz.

   This wouldn't be FAI fuel, would it? That's going to run much hotter than conventional fuel for a given power level.

    Brett

My new pipes will flow up to an 88, maybe bigger but that is the largest 2 cycle I have ran them on.
Also the pipes are tuneable by  opening up either end, if the pipe seem too large and open, closing down the intake makes it act smaller..this work very well

If the pipe acts too small, opening up the venturie makes the pipe act more open.  this also works very well.

Other things that can be dome to tweek the systems are to use 8, 9, 10, or 11mm size exhaust deflectors

Kaz for example uses my 75 pipe on a PA 75 with a longer smaller tube inserted into the silicone exhaust end, with a large venturie  , others use the pipe as is with a smaller venturie

  I think this is how the myth about outlet restrictions for the Jett started, they were having venturi issues and restricting the outlet is similar to restricting the input. But not the same, for instance, while it has a similar power effect, the fuel draw is not enhanced by restricting the outlet, if anything, it's made worse (since you are getting less flow and less velocity - if you made the venturi smaller instead, you reduce the power but it increases the fuel draw).  What I think some of the Jett users missed was that there was something wrong with their venturi setup - like, it was too large for the power level they needed, they restricted the outlet, which just reduced the fuel draw and made it act even funnier. Add that to the incorrect pipe lengths that were promulgated at the time and, no chance. I think you almost always want to control the power with the venturi, not the pipe restriction, just for that reason. Once I figured out what to do with the venturi and fuel flow, then all that outlet restriction does is act, literally, like a potato in the exhaust.


  A point that is sometimes missed and in our case is somewhat misleading from the  "Two-Stroke Tuner's Handbook" is the relationship between the outlet and the boost from tuning. With a conventional motorcycle pipe as described, you want to make the outlet smaller because you get a larger reflecting surface. The limit is overheating due to flow restriction. But we have baffles, and if we are using them as the reflecting surface, the area of the tail cone doesn't make any difference and then a flow restriction in the outlet stinger is just a heat and power loser.

    Brett

Martin

You may find that the pipe is too short at 19 inches, with that timing you may need a 20 ich lenght, what can , and does happen if you run the pipe too short is you push hot exhaust back into the motor, I have had a few here that I rebuilt that even had the intake ports, and case intake by passes burned from this. Maybe you should at least try a longer pipe setting, not a shorter one, and if it is charging you can lower the nitro or raise the head, try both and see what works better for you.
I will email a lenght chart to you, if you do not have one

Randy