Yamaha RAPTOR YFM80R Owner's Manual page 10

Once the ATV rider can operate with skill at the
top speed permitted by adjusting the speed lim-
iter alone, the air intake restrictor plate can be
removed. Since removal of this plate will result
in a significant increase in power, turn the speed
limiter completely back in again; adjust it out in
stages as you did before.
If your child is a beginner or is inexperienced, he
or she should take a training course.