* The VIN begins with the prefix "JKA", "JKB", "JK1", "JSA", or "LM4" * On all motorcycles it is stamped on the side of the steering head. On street-legal motorcycles, the VIN also appears on the Safety Certification Label affixed to, or near, the side of the steering head. * On ATV's it is stamped on the lower frame tube, to the left of the engine. * On MULE® utility vehicles, look for a plate welded to the frame at or near the front of the vehicle. On some MULE models, the VIN is located on the frame, just below the front of the seat. The above is a quote from the Kawasaki website. I found the VIN numbers on both of my Kawasaki ATV's on the lowest frame tube parallel to the ground. The Prairie 700 had the number on the left under the front differential. The Bayou 250 had the number directly under the engine on the left side.
The numbers are stamped into the frame and not that obvious, but are easy to see once you know where to look.