Hi all,
I am finally flying my X-mas present after many months of sitting in the shop. Got to fitting the cowl on the plane, and am having trouble fitting the muffler through the cowl. I meticuliously cut the proper size hole to accomidate the darn thing, but now am wondering how I'm going to get the cowl over the muffler? I'm sure the answer is staring me right in the face, however, this is my first plane with a fully enclosed engine. Any help would be appreciated.

Mike

Think you're going to need a bigger hole.

I've done muffler cutouts a couple different ways. If it's for a 2 stroke and the muffler cutout is fairly close to the back of the cowl, I cut a slot to allow me to slip the cowl around the muffler. On a 4 stroke I've made the hole large enough to let the muffler exit the cowl and removed the muffler before attaching or removing the cowl. Note that there are also flexible muffler extensions for 4 strokes that would allow you to route it to a more convenient, less obvious, place.

Your photos show a 4 stroke.

NO PROBLEM !

Since you already have the hole cut, install the muffler after putting the cowl on. Disconnect the header pipe from the muffler itself, then screw the header pipe on the engine. Stop the header pipe when it is ABOUT 1/8 turn before where you want it. Here is the "fun" part - reach into the hole with a pair of LONG NOSE pliers and run the nut up against the engine. Now, while holding the nut, turn the header pipe AND nut (with the pliers of course ) into its final position. Now put your muffler on. You may need to play with putting the muffler on before final tightening of the header, depending on the clearance available for turning the muffler. (This is the one I usually use for my 4 strokes )

Sounds harder than it actually is to do.

Another option is to get a flex exhaust extension to route the muffler further back on the plane.

The final option, if you do not want to use a flex exhaust, is to get another header pipe and a 12 mm threaded both ends UNION and connect the 2 header pipes together. This provides a rigid header/exhaust extension that will be shorter than the flex one (and cheaper also ).