Modern Vespa

i had a pinasco longstroke 225 with A 28MM DELORTO with a [redacted] expansion chamber and it ran well with a 122 main. i am going to a serie pro reworked malossi from SIP with either a 226 hbomb or the serie pro dse exhaust. i know 28mm is kinda small for this setup but how much upjetting is needed. I wanted to see what other people have for jetting in thier 220 malossi longstrokes with 28mm carbs. im thinking i might just go to liek 145 or so i think 122 is way to small.

There are no shortcuts to finding the correct jetting.

I always go really big so it bogs at WOT and work my way down from there till it just doesn't bog. Only at that point do I even think of plug chops for fine tuning.

I've used Mikuni 28mm and Dellorto 30mm carbs, but never a Dellorto 28mm. What I can tell you is that the 226 pipes need a lot of upjetting.

Like OCT said, start really rich and work your way down until full throttle cleans up.