Simplify the following text for a Grade 6 native English-speaking person.
Original: Amusement park go-karts can be powered by 4-stroke engines or electric motors , while racing karts use small 2-stroke or 4-stroke engines .
Simplified: Amusement park go-karts can be powered by 4-stroke engines or electric motors . Racing karts use small 2-stroke or 4-stroke engines .