On the right side of your bike, where your throttle is located, there is a bolt (as shown in image6 with red arrow below). You would unscrew the bolt and place it in any of the slots located above (as shown with the yellow arrows). This would limit the distance the throttle can be pulled back, thus limiting the speed.
How long is the break-in period for my bike?
When the bike is brand new, the first 3-4 tanks of gas is the break-in period. It is recommended to not run your bike at max RPM's for more than 1 minute at a time during the initial break-in period. After the break-in period, you can run the bike as hard as you want!