new sh owner here again....

if i put the beastly sh in neutral, rip it up to 7k, hold then drop , it backfires out of the MIG high mounts. i dont hear anything comin from the airbox.... jus the pipes. dont think the bikes jetted seeing how i just got it and havent looked(dont even know the signs to look for) , it jsut will pop on anything higher than 3k and deceleration or how some would call natural engine braking. a friend said its runnin too RICH -which is proportedly better than too lean- and need to change the needles or something? i would still like to fix it so i can gas it to 5k in first and engine brake to the next stop light without any poping. i know this is a waste of your time to reply, cus its so adolescent and easy of a question... but im just new to the 90 degree twin world.
on a side note..... it seems quite a few people play with the carbs all the time.... work on em all day to perfect em...... sometimes pulling out hair... but NOW I SEE why its so worth it to have carbs, from the smooth predictable linear power with no flat spots, to no jerky cornering when pulling from the twisties. just a little sidenote. i want her to bark healthy.. no popping. please help.