Nothing will give carbs a bad rap faster than an ill-prepared (read: wrong jets and bad tuning) set of carburetors. Yes, they're old school and yes, they can be finicky but so is your girlfriend and you still love her. If you're having a love/hate relationship with your carbs. give them the love they deserve. Maybe it's time to get those jets set up properly.
These Weber main jets control how much fuel is sent from the float bowl to the various circuits of the carburetor. Main jet sizing nomenclature refers to the flow rate in hundredths of a millimeter (0.01mm). A 150 main jet, for example, flows the same as a perfect hole with a 1.50mm diameter. Larger numbers make the engine run richer from off-idle to about midrange RPM.