Originally Posted by
Cooter
I totally agree with 34:19.
If it's popping through the carb when you give it gas off idle, it's going lean.
When you give it gas off idle it is transferring from the idle circuit (that's fine because it idles) to the main circuit (jet and needle) and going lean because gas can't get through it... the jet is clogged and a common problem.
IIRC a 170 is stock but you can go up to a 175 if you added a muffler or did intake mods. The jet size is the decimal equivalent of the drill size, so If you have a 170 drill you can clean it or open it up to 173-175 yourself. It's $6 new from HD and the same as an old Sportster.
Take off the float bowl again and the big brass thing in-between the floats, in the middle, is the main jet. A 5/16" driver and the whole assembly will pull out. The jet itself is a flat head on the end of that assembly. Clean all the little holes. Re-assemble. Boom.