Worn or damaged valve.

1. Inspect the valves.
2. Inspect the valve guides.
3. Repair or replace damaged components as required.

Worn, damaged or improperly installed piston rings.

Piston rings must be installed with the mark, or dimple, on the top of the piston ring, facing up.

1. Inspect the spark plugs. Refer to Spark Plug Inspection .
2. Verify engine compression. Refer to Engine Compression Test .
3. Inspect the cylinder bores.
4. Inspect the pistons.
5. Inspect the piston pins.
6. Inspect the connecting rods.
7. Repair or replace damaged components as required.