The carburator is a part for the Satsuma. There are two carburators: the stock carburator, which is slow and has a separate air filter that is held on by 2x6 bolts and a race dual carburator, which has its built-in air filters.If you are using the stock carburator, always put on the air filter. Not doing so will result in it getting dirty, which will make the engine response worse and won't help performance at all.
Idle adjust Edit
To adjust the fuel mixture you use the screwdriver on the carburetor.
"Carburator" is a misspelling; it should be spelled "carburetor". Nevertheless, this is the spelling used in the game, so it is also used here.