https://www.amazon.com/Motorcycle-Ca...7766912&sr=8-6
This is the one I use, dropped in a 120 main, left the 42 slow, and moved the needle position up one slot. Kinda had the same result as you - are you using a paper filter or an oiled foam type filter? When I got my TwinAir oiled filter, all backfiring and pops magically went away. Waiting for my cat delete pipe to come in, but that one I listed should be just fine. No issues with the new one so far - though my previous Chinese PZ30 clone did kind of fall apart. This one has "Japan" stamped on the side; so at least it's of Japanese bike quality lol
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
These are the jets, main only. If you want some slow jets which you shouldn't need to change, you can also get the same Mikuni slow jets. If you do get this carb, the jets are loose from the factory so pop open the bulb and swap jets or whatever, then snug them down nice'n tight. This one, I can get to the mix screw and not have to take the carb off to adjust. With the 120 main 42 slow, I'm at 1 3/4 turns out on the mix. Try 1 1/2 turns to start, then go a quarter turn more if need be. You can also raise the idle, and listen for the highest RPM rev when backing the mix out - just pay attention to how many turns lol Once you get it to rev highest backing out the mix, that should be the right fuel / air ratio. Getting the mix right is a pain in the butt, man. You may need to move the needle one spot, depends on how throttle response is on idle blip and with 3/4 to WOT. I skipped the needle last carb and man, is there a difference in throttle response now. I'm not holding the throttle wide open to get 55-60MPH steady, instead it's more like 3/4 to keep it paced. None of the stock carbs come tuned like you want and depending on you elevation, may be too lean as well. You'll get it man, took me about 3 - 4 tries before getting it right. Idle will settle as you break it in though, so it may dance around and raise after a few rides. Just drop it down when it does, it's getting worked in and springs and everything are settling. Good luck, brother!