Formula K (FK) is the predecessor of the Formula Super A (FSA) class as the highest non-gearbox CIK FIA karting category.
100cc engines were used for most of Formula K's existence, however 135cc engines were run from (and including) 1981 up until (and including) the 1989 season, after which 135cc was abandoned for lack of support. The 135cc engines hardly attracted a following outside the top CIK championships and were therefore expensive and commercially less interesting to manufacturers. A move back to 100cc was made for the 1990 season. Formula K lasted for the 1991 and 1992 seasons after which Formula Super A (FSA) was introduced as its replacement.