Thanks for the update. I don't think it likely it has a 0.34 mm jet, because that is not a standard drill size, and is way too small for a main jet, even of a whipper snipper. However if you get a set of jet drills, they will certainly extend across the size you need. The only jet I've found to date that is smaller than 0.45 mm is the idle jet in the small GX & GXV Honda engines - main jets are normally 0.5 mm or so.
I've been doing that solder-and-drill trick on brass jets for quite a lot of years, it is the easiest way to tune old carburetors for which jets are not easily or cheaply available.
