Yes there is a lot to gas . Just a couple points here . No , lead is not required in a 2 stroke ,lead will not harm a 2 stroke although extended use you may see some really fluffy debris on top of the piston during a top end rebuild. Lead was originally used in fuel for two reasons ,one it is an inexpensive way for the fuel designers to increase the octane rating [octane is the resistance to detonation or preignition if you will ].Two , it was used to protect the steel valves and seats of the day. Lead acts as a lubricant on the face of the valve and cushions the landing of the valve on seat.Todays 4 strokes have valves that have either coatings or are made of materials that resist seat damage in that respect.So no you don't need lead in todays 4 strokes , but , it will not harm them either. The pump gas today is so bad [ ethanol ] that , that in itself is reason to use straight , low octane , non-enhanced race fuel.Its not that expensive when due to its better control you can pretty much double your engine life. We have taken apart 200 hour honda 450's and the pistons and valves are clean , that have lived on low octane straight race gas.