At least in NA English, the orifices that regulate the amount of fuel supplied by a carburetor are called jets, and replacing a jet or set of jets with a different size (typicall with motorcycles, which often have a separate carburetor for each cylinder) is called rejetting.

sample refs:

THeory of Rejetting
This is not the definitive statement on carb rejetting, but it will give .... The jets are accessible by removing the carburetor fuel bowls located at the ...
home.comcast.net/~manjo1111/BUBF/BUBF_rejetting.htm

The Sportster Home Page
Rejetting the CV Carburetor. contributed by L. Maurice Riggins (1998) .... Looking at the bottom of the carb, find the two jets. The main jet will be more ...
www.sportster.org/tech/carb/rejetting.shtml

Jetting the Carburetors on a Yamaha V-Star 1100.
to discuss the process before we go inside the carburetors. There are many reasons that you may want to rejet your carburetors, but the only jets we will be ...
www.vstar1100.com/1100jetting.pdf

Re-jetting Dommie carb - Honda Trail Bike Forums
10 posts - 4 authors - Last post: 10 Mar
Re-jetting Dommie carb Dominator / FMX. ... And therefore will need to rejet the carb (Kehnin). After a lot of hassle ie almost taking my ...
www.xrv.org.uk/forums/showthread.php?t=30978

Duke II exhaust Mod and rejet - UK KTM Forum
1 post - Last post: 1 Mar 2007
Changed the 47 idle jet with a 47.5 idle jet (the idle jet change requires the removal of the carb float chamber). ...
www.ktmforum.co.uk/showthread.php?p=48201