If I try to go visit someone in jail will my juvenile warrant pop up ?

Perhaps.

Normally anyone who visits in a jail or prison will have a criminal history done. I would suspect you would be arrested after you go in.

The only issue may be if the Juv warrant is not out in the system and the Juv people are going to try and do the arrests theirself, but my guess is that it is in the system.

Is this an open warrant or has the case been resolved? An open warrant will very likely show, but if the case was discharged it may be sealed.