The Aprilia RS 125 is a race motorcycle manufactured by Aprilia to race in the Grand Prix motorcycle World Championship, built to replace the old . It was debuted in 1991, and it had many upgrades since. The bike won ten World Championship (one rebranded as Derbi and one as Gilera). In 1991 the original tank was 12 liters, which became 13 in 1994 and 14 in 1995; the original carburator was a Dell'Orto VHSB 39, which was upgraded to a Dell'Orto VHSD 41 in 1996 and to a Dell'Orto VHSG 42 in 2006.