You can't get the jets at a local lawn mower place. Those places do not service carbs made for mopeds.
If you are going to try another jet, then you better get more then one jet because getting it right the first time with one jet is like playing the lottery and winning millions by just playing the first and only time in your life.
Start a buy post here for a used 12.12 carb and a used pipe instead of buying that new pipe at treats.
You will need a new white intake plastic piece as I mentioned above to rule out air leaks. You NEED this, so get it unless you buy a new carb altogether.