RE: My battleaxe is built! But I need engine help
Take the muffler off, put a thin film of Copperseal RTV on the clean muffler and let it set up for 15 minutes (or follow the instructions) then mount the muffler back on. Then use the RTV to seal the backplate, carb mount and anything else you can think of.
RTV is your best friend, you best get familiar with it.