JUSTIN BIEBER Kicks Lil Za, Lil Twist Out AFTER HIS JEWELERY WENT MISSING

EXCLUSIVE

Justin Bieber has finally had it ... TMZ has learned Lil Twist and Lil Za are both persona non grata at his Calabasas mansion after expensive jewelry went missing.

Sources connected to the Biebs tell TMZ ... Justin was furious earlier this month when he discovered the jewelry and other items were nowhere to be found.  Twist and Za had both been staying at the house and they had thrown several parties in Justin's absence.

We're told Justin had no idea who stole the items, but blamed Twist and Za because it was on their watch.  He ordered them out and our sources say both of them are PISSED.

We're told Justin has finally seen the light that he's gotta change ... or else.  Justin just performed in Singapore (above) and actually showed up 15 minutes early, but not before he gave 30 tickets to kids from a local orphanage.

Our sources say Justin is privately saying he knows he's been on a bad path, and it seems at least for now he's moving in the right direction.