Simplify the following text for a Grade 5 native English-speaking person.
Original: Karts vary widely in speed and some ( known as Superkarts ) can reach speeds exceeding 160 m , while go-karts intended for the general public in amusement parks may be limited to speeds of no more than 15 m. A KF1 kart , with a 125 cc 2-stroke engine and an overall weight including the driver of 150 kilograms has a top speed of 85 m. It takes a little more than 3 seconds to go from 0 to 60 mph with a 125 cc shifter kart ( 6 gears ) , with a top speed of 115 m on long circuits .
Simplified: Karts vary widely in speed . Some known as Superkarts can reach speeds exceeding 160 m. Go-karts for the general public used for fun may be limited to speeds of 15 m.