Original Dell'Orto 'SMALL-thread' (i.e. 5mm thread size) standard type jet for MA - MB - SH1 - SH2 - SHB (+ many other models of DellOrto carburettor*).
This is an original Italian made Dell'Orto spare part and is the standard type MAIN jet for all Lambretta scooters.
Choice of numbers between No.30 up to No.195, including ALL standard main jet sizes for Lambretta scooters, and all other available numbers, for fine tuning and / or tuning use (example: this type of jet is the MAIN jet for Dell'Orto SH/2 22mm carbs as fitted to Lambretta GP200 models, whereas this is the PILOT 'idle' tick-over jet for a (non-original Lambretta) Dell'Orto PHBH 28/30mm carburettors).
How do jet sizes affect my carburation? The larger the number is on the jet, the more fuel it supplies to the engine ("richer"). The smaller number is on the jet, the lesser amount of fuel that will be supplied to the engine ("weaker"). For example, if you fit a performance type exhaust to a standard Lambretta, then you will probably need to increase the main jet (and perhaps the tick-over idle jet) size by a few numbers to increase the amount of fuel needed for perfect running, as more power is produced. If your standard main jet is a No.118, you may need to increase the number of the jet to No.120, or perhaps to No.122.
*Dell’Orto FHB + PHBE + PHBH + PHBL + PHBN + PHF + PHM + PHSB + PHVA + PHVB + VHSA + VHSB + VHSC + VHSH + VHST + SHB 25