well your carb's only 13mm . . . i get maybe a touch over 40, but i have a 14mm carb. also, at least half of the people who think they're going 45 are actually going, like, 38. i know i thought i was going over 50, and i even saw one of those "your speed is" signs tell me i was going 51 . . . but then i got gps'd at 42.6, and it was pretty much the fastest i'd ever been going on a flat. true 40 on a moped is quite an accomplishment, actually.