ORIGINAL: turdfergerson
I think that I might get some copper rtv and try to use that as a thread lock on the screw and where it attaches to the forward part of the muffler. Double nutting it sounds like a great idea as well. This engine is giving me all kinds off running problems as well..........frustrating.
You need to tighten the screw where it attaches at the rear of the muffler, the front isn't threaded. Then snug down the bolt at the end of the muffler. A lock nut on top of it is also a good idea. Tighten the screw first.