The argument about educational systems is unecessary. Though I too think that the continental (German or French) system of education is better than the Anglo-American, that's not the point w/ the simple piston question. Also, what someone does or does not know is not a fault of that person. Igor genuinely asked a question. He was interested; he wanted to know. Just because he did not already know, does not mean that we should criticize him. So, no, I don't think the original response by Daniel was appropriate.
All Igor wanted was for someone to help him explain how his moped's engine works. I think that's wonderful. Igor could've just handed his moped to someone else to fix. Or he could've just said "to hell w/ this!" and sold his moped and avoid the hassle. Instead, he had the courage to admit that he did not know something. And then he had the determination to learn about this thing. And then he had the character to humbly ask for help from other people. For these three things, Igor should be highly commended. I would not count him as an ignorant or stupid person. Whatever education he received, he obviously knew enough to seek for help. That's perhaps one of the most important definitions of wisdom: "To know that you know what you know; and to know that you don't know what you don't know."
So next time, please, let's remember that everyone comes to this forum with different levels of understand about mopeds. And also keep in mind that different mopeds are VERY different. So someone might not know how a Motobecane works, but might tell you everything about a Piaggio Ciao. Finally, keep in mind that people of all ages, cultures, and languages come to this forum. They all deserve respect and consideration. Well .... except for maybe some of the flamers who hit this site. That's why SWARM and DESTROY is such an appropriate motto. Moped lovers unite! ("swarm") and then we hit back against all the moped-haters ("destroy"). But first we have to stick together and help each other out!