Welcome, 18 is a little late (think Science/shop...if they still have it class) in life to be able to know the difference in a 2 cycle and a 4 cycle, but not too late to learn. In my generation, at 18 we already knew how to rebuild engines...at least the group I hung out with did. Looking back, I rebuilt a 3 speed transmission at 16. Had to..no money, and a used transmission cost about $30 - $40 dollars. Then at 17 was making $7.00 a hour, no problem. As long as you have the ability lo learn, and can follow directions, you came to the right place. Look at previous post (stickies $ search) for answers, if can't find it...by all means ask. Just about every conceivable questions about engines have been asked already.