Can I increase the Aprilia RS 125 max speed after derestriction?
After derestriction, there isn’t a lot you can do to improve the Aprilia RS 125 max speed. The bike was designed to handle well and it can out pace much bigger bikes through twisty roads. You can throw an awful lot of money at your bike but you aren’t going to gain much on the top end. You can play with the front and rear sprockets to trade off acceleration for top speed (or vice versa) but you can’t go too far in either direction or the bike will be unrideable.
