It is a popping resonating sound generated by a lean condition on deceleration. When you suddenly close the throttle, the incoming air is choked off and the closed throttle also causes the bike to return to idle on the very lean idle circuit.
The reactivity series of metals was deduced by performing several experiments in the lab which enabled scientists to arrange metals according to their reactivity with dilute acid, oxygen (air), and water.xides of iron and copper are insoluble. Metals that are less reactive than copper like silver, gold and platinum do not react with oxygen. Note: When aluminum reacts with oxygen, a layer of aluminum oxide adheres and covers the aluminum.
Silver is the most electrically and thermally conductive metal. Other metals with a high level of electrical conductivity are copper and gold. Conductivity is measured by an element's ability to transmit energy. If an element is considered to be electrically conductive, it means that it has the ability to conduct electricity. Thermal conductivity refers to the transfer of heat. Most metals are able to conduct electricity. Although silver is the most electrically conductive element, copper and gold are more commonly used in wiring and electronics. Copper is used because it is less expensive. Gold is used because it does not corrode as easily as other metals.