No matter how the cylinder head of my motorcycle (horizontal 100) is ground, the test water of the exhaust valve seat always leaks. What should I do? Is it abolished? thank you

Carefully check whether the valve stem is slightly deformed. If the valve is not bent, slight air leakage is not a big problem. Adjust the valve clearance slightly after installation, and it may automatically tighten after riding for a while. If the valve seat is badly worn, but grinding may be ineffective, the valve seat on the cylinder head should be reamed again with a valve reamer and then ground. In addition, do not use water to test whether the valve leaks, but use gasoline.