This is how Kawasaki says to check oil level-- Must be done this way or SEVERE engine damage can occur.
After you have verified that the engine contains oil, start the engine and bring it to operating temperature by allowing it to idle for several minutes, then shut it off. DO NOT REV THE ENGINE AND SHUT IT OFF AT HIGH RPM. Doing so can leave a significant amount of oil in the crank room and clutch area, leading to a false oil level reading.
Allow the oil to settle for a few minutes. Place the motorcycle level from front to back and side to side and remove oil filler cap/dipstick and wipe the dipstick clean. Continue holding the motorcycle perpendicular and reinstall the dipstick, threading the cap completely in. Remove the dipstick and check the engine oil level. The engine oil level should be between the high and low level lines on the dip stick. Adjust oil level accordingly.