Aha, you're not from the northern parts of Italy then.
Thomas Aschenbrenner's site has some good pictures. You now what they say: "A picture is worth a thousand words". You want to look at these two subpages:
http://home.vr-web.de/~thomas_aschen...-Eigenbau.html http://home.vr-web.de/~thomas_aschen.../3Motoren.HTML
And you can use
http://translate.google.com/translate_t to get the idea.