With high reving engines of modern sports bikes, low octane fuel can cause lots of engine nocks/pings. This is caused because of the gas sprayed into the cyclinder is not burning in the correct area (when the piston is all the way up, where max compression is). The gas, depending on the octane, would prematurely dedinate. This is because the higher the octane, the slower it burns so in high compression engines, the gasoline will not light up until it hits the correct compression and ignited by the spark plugs.
What's wrong with premature dedination? Well this can cause engine wear and damage. Because the premature dedination causes the gas to burn, which turns the oxygen and liquid gas thats sprayed in there from either carbs or injectors into carbon monoxide in the form of gas of which pushes the cyclinder back down to its fully extended state. Since the expanding pressure of the CO is formed before the piston reaches its max compression it causes extra force in the opposite direction on the pistol and the connecting rod. This causes stress on the metal and lead to microfissures (small cracks) and could end up reducing the life span of the engine.