Off the top of my head, I've lowered a KX500, KX250, KX85, KX65, and a Harley Sportster. I know it effects handling but I'm no racer, just a weekend woods plunker. They ride just fine by me. My kids don't notice it either. Kawasakis are easy to lower with the rear suspension links. Lower the triple clamps on the forks and you're good to go. I even cut the seat foam on my KX500.
If you give it a try this cheap way first and don't like it, you can easily have the susupension redone at a shop.