Remove the applicable spark plug. Make sure the applicable piston is at the top of its stroke with all four valves closed.
NOTE: If the air pressure fails to hold the valves closed while performing the following steps, valve or valve seat damage is indicated and the cylinder head must be removed.
Install the air line with an adapter in the spark plug hole and turn on the air supply.
NOTE: If removal is required, mark the position of the valve tappets for installation in their original positions.
Remove the camshafts and tappets as required.
Install the Valve Spring Compressor Set Pivot Bar and Valve Spring Compressor Adapter. Compress the valve spring. Remove the valve spring retainer and valve spring.
Inspect the valve spring, valve spring retainer and valve spring retainer key. Install new parts as required.
NOTE: If air pressure has forced the piston to the bottom of the cylinder, any loss of air pressure will allow the valve(s) to fall into the cylinder. A rubber band, tape or string wrapped around the end of the valve stem will prevent this from happening.
Use the Valve Stem Seal Remover and Slide Hammer to remove the valve stem seal.
CAUTION: If the valve has been damaged, removal will be required for repair.
Remove the air pressure from the spark plug adapter and inspect the valve for damage. Rotate the valve and check the valve for eccentric movement during rotation.
If the condition of the valve is satisfactory, apply clean engine oil to the valve stem and hold the valve closed. Apply the air pressure within the cylinder.
Lubricate the valve and guides with clean engine oil. Using the Valve Stem Seal Replacer, install the valve stem seals onto the cylinder head valve guides.
Place the valve spring in position over the valve and install the valve spring retainer.
Compress the valve spring using the Pivot Bar from the Valve Spring Compressor Set, the Valve Spring Compressor Pivot Set and the Valve Spring Compressor Adapter and install the valve spring retainer keys. Remove the valve spring compressor tools.