The carburator is a part for the Satsuma. There are currently three carburators in game: the stock carburator, which is slow and has a separate air filter that is held on by 2x6 bolts, an aftermarket twin carburator, which has its built-in air filters and an aftermarket racing 4 barrel carburators without 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.