Joshua,

I use file folders. I mount everything but the cowl then cut the file folder and tape it to the fuse side so the "flappy" part is overlapping the engine (and whatever else is sticking out). Now I use some scissors (Exacto, etc.) and carefully cut where the protruding object is. I trim until I have the fit I am looking for.

Now, fold back the folder out of the way, remove the engine and muffler. Now install the cowl. Flip the folder back into position and trace your cut-out onto the cowl. I then use my moto-tool to cut the holes.

Simple, EXACT, and you get a good looking, tight install every time. Hope this helps you !

CJ