Sorry if anything in this post screams of "do your fucking research"... but I have read the tuner spreadsheet, both articles in the wiki and the dellorto manual so cut me a _little_ slack.
Peugeot 103, old-school 2 port cast-iron Polini 70cc, "Top One" exhaust, larger reeds, 16mm phbg w/ foam rubber-banned over the filterside.
I was running a 15.15 SHA w/ high-flow, but I had to jet up to 94 to four-stroke and drop down to 90 to run safely..... as a result I had shitty low-end, and it would hardly even idle. So I bought a 16mm phbg and I'm learning to tune it.
currently jetting is 60 choke, 50 Pilot, w7 needle at setting #2 (that's all pretty much stock, and going with what the tuner spreadsheet indicates others have done, although that's with 19-21mm carbs). My main jet currently is 76, coming down all the way from 90.
I followed the "how to (made easy)" wiki article and adjusted my mixture screw and idle screw accordingly so it idles well and has good response at 1/8 revs. I left my W7 needle at setting #2 because it seems to accelerate fine and that's where everyone has theirs' in the moped tuners spreadsheet.
I started main jetting at 90, where I had it before.... WAY rich, 4-stroked at WOT (but not at 1/2. I got down to 78 jet and it still four-stroked at WOT, so I dropped down to 76 and it doesn't four-stroke anymore, AT ALL. Maybe I just stumbled upon the magic safe spot (since I didn't have many jets b/w 78 and 84 to test the threshold), but I'm still paranoid about being too lean.
I'm also a little confused why a 15sha would require a 90 jet whereas a 16 phbg would be in the high 70s-- possibly because the needle is also delivering fuel in a phbg? but I dunno.
When I pull the choke at WOT above 30mph the ignition seems to cut, slow down and then it four-strokes really bad, that's a good sign that I'm not too lean, right?
Just looking for a little advice on whether that jetting, needle setting, etc. sounds about right, although I know every bike is different, so I appreciate any advice you have.