A small washer positioned around the front pulley rod of your Honda SFX50 scooter's variator system is all that restricts its performance and top speed. Removing this small washer is a simple procedure, requiring minimal mechanical acumen and few tools. Once the washer is out, your SFX50's variator system can operate at maximum capacity and your scooter can travel faster.
Loosen the bolt pin on your Honda's kickstart with a socket wrench. When the bolt pin is loosened sufficiently, pull it out slightly and remove the kickstart from the outside of the scooter's variator case.
Unscrew the three bolts holding the plastic intake case onto the side of your scooter. Though the piece is not a part of the system you are working with, removing it will give you better access to top bolts on the variator case lid.
Access the inside of the variator case by removing the six bolts that hold the case's lid on. Three of the bolts are located on top of the case, the other three are located on the bottom.
Remove the bolt holding the front pulley wheel in place using an air-powered impact wrench. Attempting to remove this bolt with a standard socket wrench will only succeed in turning the wheel without loosening the bolt at all. An impact wrench operates with enough power to loosen and turn the bolt without turning the wheel.
Take the small washer off of the front pulley rod. You may need to use a pair of needle-nose pliers to reach the bolt if your fingers are too big.
Put the front pulley wheel back in place. Start the centre bolt by hand and finish it off with the impact wrench.
Replace the variator case lid. Lubricate the edges of the lid with some motor oil and ensure that each bolt is tightened one quarter to one half of a turn past its stopping point. The motor oil and the tightening of the bolts will help to prevent water from entering the belt system.
Reattach the intake case and the kickstart.
Check your state laws regarding the top speed of 50cc scooters. Though removing the restricting washer does not change the output of your SFX50, it may enable the scooter to travel faster than 30mph, which in most states is the maximum allowable speed for 50cc scooters.