Exhaust Muffler for 912ULS

[jiott]

My exhaust muffler for my Kitfox SS7 with 912ULS has finally cracked beyond reasonable repair. It was purchased in 2012 and has over 1300 hours on it, so I am not complaining. It is the muffler and header pipes Kitfox had custom made for them (not a Rotax factory muffler). It is cracked where the exhaust pipe comes out of the end of the muffler, and is also cracked loose internally where the end of the exhaust pipe welds to the far end of the muffler, so the whole pipe is loosey goosey. There is no way to weld the internal breaks without cutting the muffler can open, so I need to bite the bullet and buy a new one.

I only need the muffler can, not the 4 header pipes which are still in excellent condition. The problem is, Kitfox no longer sells that muffler and header pipes; the engines now come with a genuine Rotax muffler and headers. My questions are: (1) If I buy a new Rotax muffler can, will my old header pipes fit into it? (2) Will the new exhaust stinger pipe fit perfectly thru the existing hole in the bottom of the cowl?

Has anyone else been thru this and can comment on any problems or lack of problems?
Thanks in advance.

[jiott]

I guess no one has had this issue?
I find that hard to believe because Kitfox quit selling their own muffler system several years ago, and mufflers do fail on a regular basis, so surely someone has had to replace the old "Kitfox" muffler with a new Rotax one or maybe something else.

[Dave S]

Jim,

This might not be a lot of help with sourcing parts; however, if a person does a search on "muffler cracks" it appears that there have been others with the same damage you describe - seems most folks resort to welding.

There is an experimental aircraft exhaust and repair shop down the river a bit from me at lake city, MN. Their website is http://experimentalexhaust.com/
might be worth a call. I haven't had any direct experience with them (yet).

[avidflyer]

I bought a muffler from the outfit in Mn a couple of years ago. It fits the Kitfox 3 and 4 mount. If you have the ring style mount, the exhaust pipes and muffler are different. I got mine welded up before I got the new one and the repairs have held up so far. I was happy with the muffler I got from them even though I have yet to use it. Price was $825 for just the muffler. JImChuk

[jrthomas]

I've had the same problem and have had mine welded 2 times. The problem is those slip joints where the pipes from each cylinder slide into the muffler. The new mufflers have the ball and socket type joints which should be a much better system. It looks like you can use your existing pipes and mate them to the new type muffler. I have a model 4 and the new type looks in the picture like it might be a larger diameter. My existing muffler is a tight fit now. Not much room for a larger one. I need to learn more before I take the plunge. Exhaust-SS Kit for 912 - 978489 ? Sideslipaviationsupplies.

[jrthomas]

Here's another possibility. Toucan Exhaust Systems

[Av8r3400]

I have rebuilt two mufflers, so far, on my Kitfoxes. I have another busted on on the bench to do. (I don't do these for hire, just for my own plane spares). My next one will be done with ball and socket joints instead of the sleeve joints used OEM.

I bought perforated 304 stainless sheet off Amazon to make a new blast tube, rolled it to size, reassembled the muffler and had the can TIG welded back together.

https://www.amazon.com/Perforated-St...09TKXF6M2&th=1

[Floog]

After 1,000 hours on the original muffler, I had a new muffler built for me in 2018 by Plane Exhaust Corp. I sent the original muffler to them which was used as a template. It's made from more robust stainless steel. I am still using the original headers. Now at 2,400 hours with no issues. Cost then was $750. You got good life out of your original.

[jiott]

Thanks for all the helpful replies. I will start running them down.

It sounds like no one just bought the new Rotax factory brand muffler and installed it with no issues.

[napierm]

I saw a vid showing a new Kitfox 4 exhaust system.

Got a quote from Experimental Aircraft Exhaust, Inc. They said $3500 was their standard price with a lead of 6 weeks.