Defence lawyer Peter Stevens told the court Weston had put a lawnmower engine on a bike and "got it going", driving about 250 metres before being stopped by police.
Judge Walsh noted her age and concerns he had about her appearing in court at such a young age.
"You need to be careful what you doing with your life," he said. "You need to understand this is serious offending, you could go to prison for seven years ... you have been given a lot of opportunity to help yourself.
"Keep going the way you are, and you are setting yourself up for more serious options."
Weston was remanded on bail until November 25 to give her a chance to gain her learner's licence.