For some reason, it ate my link earlier. Copy and paste, I guess.
And yes, you can put a new jet in your carburetor by yourself. I think first you need to take your carb apart and figure out exactly what jet you have, although I also think that a jump of 10 sizes for just an air filter (if it really was already jetted for the Biturbo) is overkill. Probably one or two sizes up would be fine.
For tips, go to the wiki. Look under "Repair Tutorials" for "Repair Tutorial Videos." On that page, there is a link to a video about cleaning a Dellorto. You have a different moped and a different Dellorto, but it's essentially the same concept. You don't need to clean it since you're putting in a new jet, but you'll see where the jet is, how to get at it, and how to remove it.