To set up carb mixtures easier/more accurately, I installed a O2 sensor bung in a spare set of headpipes. I used silicon bronze with my TIG. I have very limited experience doing this with tig. After a bit, I started getting the hang of it. Seemed what worked was moving the tig torch around at first to get everything hot. Then heat it up just enough to melt/flow the rod.
It appeared to do a nice job and since the pipe was thin and the bung thick, no worries about blowing through the pipe. Plus it IS a very old 2-stroke pipe. I cleaned it up best I could with vaporhoner, but I’m sure it still had contaminates.
I will fit soon and rig up my ‘readout box’ so I can see what sort of mixture I have when riding. I have a kit to make a much nicer readout, but I always seem to have other things to do and have not ever finished building it. There are a LOT of parts to solder and I need to get into that mode. The one I made decades ago still works, just looks pretty hokey.