99′ foreman 450s transmission acting up

Few months back I purchased a 99′ foreman 450s with 450 hours and 1700 miles. I put my 28" vampire edls on it. Haven’t rode it much but when I do and I’m getting after it a little going from 2nd to 3rd it will start going in 3rd but then feels like it goes into neutral then slam into 1st. Any idea what it could be?