While the Delorto is a better carb, I think that’s a bit too expensive a path for you to run down right now, since you’re clearly just getting your feet wet. If you are just puttering down the street you’re going to be overcarbed even with the Delorto. You need to take it out on a real track.
Switch to a 52 low jet and a 172 main. That will lean you out quite a bit but still should be plenty safe. Check the plug after a few laps–black is rich but at least it won’t explode, brown is what you want, and white/chalky means too lean. Move up or down from this baseline setting as required. If you meet other drivers at your local track, they can probably help too.
Incidentally, forgive my preaching but driving a shifter kart down the street is a real bad idea. Maybe its okay to make sure the brakes actually work, no parts are falling off, etc., but in addition to being dangerous and illegal, it will give you almost no useful data. My Skip Barber instructor said the next step up from a shifter is an Indy car. How much data would we get puttering a Dallera-Chevy around in the local cul-de-sac ? You’ve got a real race car and it needs a real race track.
BTW, based on the photo, the vent below the carb looks like it is tapped into the crankcase and is a vent for running a fuel pump off the pulse. If your pump is running off another vent then plug it.
November 15-19, 2017
Las Vegas, Nevada
SKUSA SuperNationals 21
2018 Events TBA