The speed of your 4-stroke, 50CC scooter is restricted by a small washer found in the scooter's variator system. Removing this washer will derestrict the speed, allow your scooter to accelerate quicker and travel faster. Accessing the washer requires several basic hand tools and a rudimentary understanding of how to disassemble your scooter's variator system. Derestricting your 4-stroke 50CC scooter is an accomplishable task with the right tools and know-how.
Detach the kickstart from the variator system. It is attached to the system by a pin that is tightened into place with a small bolt. Loosen the bolt and pull the pin and you can remove the kickstart from the scooter.
Open up the variator system. In some 50CC scooters, this will require you to first remove the intake case. The intake case is the plastic moulded piece to which the kickstart was attached. It is held in place by two to three bolts. If your scooter does not have an intake case on its exterior, you will simply need to unscrew the six bolts that hold the lid of the variator case in place. The variator case looks like a flattened hot dog, long, thin and somewhat tubular. Three of the bolts are on the top of the lid, three are on the bottom.
Disengage the front pulley wheel from the pulley system. The wheel is held in place by a bolt secured through the centre of the wheel. You will either need to secure the wheel before attempting to remove the bolt by hand, or you will need to use an air-powered impact wrench. Secure the wheel by wrapping the strap end of your strap wrench around the wheel and positioning the handle of the wrench underneath the rear pulley wheel.
Extricate the washer from its position around the front pulley rod. This washer restricts the speed of your scooter by adding space between the pulley belt and the pulley rod, preventing the belt from pulling on the rod at its maximum capability.
Put your variator system back together.
Reregister your scooter if you find that its top speed increases past 30mph. Though removing the washer doesn't increase the CCs of your scooter, it does allow your scooter to travel at a faster top speed. If this top speed crests 30mph, it may require you to register your scooter with the DMV in states that have a speed maximum for 50CC scooters.