newly built motor fail, need advice

All this time trying to get a new build to start! Yes it started twice, but not a third time.
Why? Because I assumed the carb was fine since I had used it on a dual set-up recently.
It wasn't. With another carb it starts 1st pull and revs easier than before.
As much as I cleaned the 1st carb it must still have a dirty jet in it.
Thank-you to those that helped me, This thread is done! Hallelujah!