Air, fire, fluid.... make sure your bike is getting all three...
Sometimes amounts don't matter with a single.
If your air cleaner is good...no worries
If your carb is getting gas...no worries
If your bike turns over...no worries
Now that said..
Test your carb for flow... pull the line going in... turn the petc0ck... fuel going to carb? good
Put a small drain hose on the bottom of your carb "the very bottom!"
With the petc0ck in the on position, loosen the carb bowl screw... got gas? good
And of course... if you turn the key and it, "the starter" turns over.. that's good, however, you might have to test the voltage on your battery as you turn it over, to insure that you have enough start voltage to fire off the gas.
Now if it doesn't start or "chug" like it wants to start, you can pull the "fuel enrichment handle" or "choke" (on this bike it is not a real choke as it doesn't move a butterfly valve to cut off air)
If it still does not start after about three tries, stop.... (about 10-15 seconds each)
Tap your float bowl with a screw driver handle pretty soundly (float could be stuck) try again
If it does not start after about five tries (total, twice after you whack the bowl).... I would pull the float bowl and see if your float needle is stuck.
Some would say before pulling the bowl to squirt some start fluid into your carb intake... if you want, do that.. and if it chugs a couple of seconds.. good.. it proves that it will run (but since it ran before.. it should)
Keep that air/fuel mix screw at 1.5 turns, it will run like that... you just want to get this thing started and chugging.
One last thing... sounds like you are getting the hang of ready and trying to fix your baby.... GOOD...
It is a single.. single everything.... you can eliminate things easily...
I personally think the carb change was a bad thing... can you "rebuild" the old one? buy a kit and clean it up, if it looks clean.. it probably wasn't the problem, pull the jets, spray a lot of cleaner.. put it back together and back on the bike... with the air/fuel mix screw 1.5 out.....
LOL, I wish I was closer.... I like a puzzle... and i'm kind of a mizer... so I fix it with what I got.
The above is what I would do... even if I had "known" variables.... start back at square one yourself... then you KNOW... it has been covered.
Good luck, should you accept this mission, you will save your world... this message will not self distruct in five seconds...but man it would be kewl if it did!