Regulation of iron absorption and transport. Iron for use in synthesis of heme, iron-sulfur centers and other non-heme iron proteins is obtained from the diet and via release of recycled iron from macrophages of the reticuloendothelial system that ingest old and damaged erythrocytes (red blood cells).
Four-stroke oil is more like the oil used in cars but both 2-stroke and 4-stroke oil serve the same purpose - to keep the engine lubricated. Four-stroke dirt bike oil comes in a variety of weights like 10w-40, 20w-50 and so on. It is not mixed with gas.
Quick Answer. Dirt bikes in the 125-cubic-centimeter-engine category have top speeds that range from 55 to 60 miles per hour. Heavy riders and downhill road conditions can push the operating speed above this range although it is not recommended by dirt bike manufacturers to let this intentionally happen. Continue Reading.