HOLES burned in pistons are usually associated with the word preignition. There are, however, other causes for piston burning, such as, detonation and excessive temperatures, and these as well as the fundamental factors causing preignition, are discussed in this paper.
The author suggests that spark-plug condition is probably the most important factor involved in preignition.
Considering the other causes of piston burning, operation, maintenance, and possibly fuel variations, all become important because each may contribute to conditions conducive to piston burning.