Jet sizes and what they mean? Carburetor Jet Sizes
[FREE Guide] Learn how to easily tune the air/fuel screw in just a few minutes: 2 stroke - 4 Jettings of your motorcycle Most jets are stamped with the orifice diameter in metric or English units. On a metric carburetor, a number such as 120 means 1.2 mm.; on most US units, 50 ...