Is the Kawasaki KX112 suitable for young riders?

Not really. The KX112 is a racing bike which is designed for experienced riders. It's not the best choice for young or new riders because it's designed for high-speed racing and might be too powerful and challenging to control for those who are just starting out. If you're new to riding, it's better to begin with a more beginner-friendly bike and gain experience before considering something like the KX112.