The speed and performance of your Yamaha Neos 100 scooter is restricted by a small washer, which can be found in the pulley system that transfers power from the engine to the rear wheel. This system, known as the variator, can be accessed by removing the kickstart and the case lid. Once you gain access to the variator system, it is simply a matter of removing the front pulley wheel and the aforementioned restricting washer, and your Neos can perform at maximum capability.
Loosen the bolt on the end of your Yamaha's kickstart, using a socket wrench. The bolt will not entirely unscrew, but when it is sufficiently loosened, you can pull the bolt out slightly to remove the kickstart from the side of your scooter.
Unscrew the three bolts located along the bottom edge of your scooter's variator case, and then the three bolts on the top edge of the case. The variator case is the metallic, cylindrical case to which the kickstart was attached.
Wrap the strap end of a strap wrench around the front pulley wheel and jam the handle underneath the rear pulley wheel, which is located inside the variator case.
Remove the bolt that holds the front pulley wheel in place, using a standard socket wrench. The wheel may turn slightly while you are loosening the bolt. If this happens, tighten the strap wrench.
Pull the small washer off the front pulley rod, using a pair of needle-nosed pliers. The washer restricts the variator system, slowing your Neos' top speed.
Reassemble your Yamaha's variator system and reattach the kickstart.
Check with your local DMV about speed restrictions for your Yamaha Neos 100. Derestricting your scooter could allow it to travel faster than the maximum speed allowable for a scooter of its size.