usually when a bike revs up like that it is a sign that there is to much fuel present at the motor first thing to check is make sure your carbs are synced. This can be difficult or expensive if you dont have the right tools. second check to see that your mixture screws are adjusted right. next you need to check the needle and seat to make sure they hold at least five psi on a pop off tester. Then check all your cables to make sure of their adjustment.