SAFETY NOTE: Disconnect your battery (negative) terminal frist, as gasoline is very flammable.
A tutorial on how to disassemble a Kawasaki Vulcan 900 and inspect valve clearance gaps.
For US and CA it is recommended to inspect every 15k miles (24k km), and everywhere else it is recommended every 26k miles or 42k km (maintenance guide page 2-2 "periodic maintenance").
Service Manual link:
https://drive.google.com/file/d/1FTZVGyOX1WwLvwDD0eV7GvShLlwYNmJQ/view?usp=sharing