Muffler & Exhaust Mods

Since both the FSII and the MKIII are based at a strip immediately next to a subdivision, we wanted them as quiet as possible, so both have intake silencers and after mufflers. Since I am aware of several people who have experienced various Rotax exhaust pipe failures over the years, such as cracking and splitting, it was determined that locating the muffler in the normal position off the side of the cylinder head was not an acceptable option. IMO, having it way out and up like that contributes to it being shaken about more vigorously. The closer you can get it to the centerline of the engine, the less it gets thrashed around. So it got located next to the engine and tied to the block and the motor mount bracket.

Notice the heat shield below the muffler, this is to keep the muffler from giving the Dacron a shrinking experience that Stits never intended. It works well, the wing stays cool. It is located by welded brackets at the front and back of the muffler, the silver strap is the stock strap for the Rotax after muffler, which runs alongside of the main muffler, & alongside the muffler mounting brackets, keeping the inertial mass of the muffler as close to the engine centerline as possible, once again reducing stress on the various portions of sheet metal. Muffler shock mounts are our usual Auto Zone muffler rubber hanger bits, they have proven themselves well. We also hold the ball joints snugly together using 5/16" spring loaded bolts instead of the standard Rotax spring system, thus no danger of spring bits going through the prop.

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