1. Remove the cam cover.
2. Set the engine to TDC. This can be done inserting a long stick into the spark plug hole until the piston is at its highest point.
3. Using a feeler gauge, measure the clearance between the cam lobe and valve stem. For the C50, the recommended clearance is 0.006 - 0.010 inches (0.15 - 0.25 mm) for both intake and exhaust valves.
4. To adjust the clearance, use a screwdriver to turn the adjuster until the feeler gauge fits between the cam lobe and valve stem.
5. Tighten the lock nut on the adjuster.
6. Repeat these steps for the remaining three valves.
7. Replace the cam cover and gasket.
