Original Dell'Orto tick over (idle) pilot jet for SH1 - SH2 - SHB carburettors (choice of sizes). This is an original Italian made Dell'Orto spare part.
Choice of numbers:
55 (non original Lambretta size, for tuning)
60 (non original Lambretta size, for tuning)
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 both the sizes of both the main jet and the tick-over ("idle") jet by a few numbers to increase the amount of fuel needed for perfect running, as more power is produced. If your standard tick-over idle jet is No.45, you may need to increase this by a few jet numbers to No.48, or perhaps to No.50.