To clarify my opinions & experience, I have continuously owned Lambrettas since 1973, the majority which have been tuned. My history includes a fair amount of racing.
I mention the above as it has not been practicable to run to a dyno operator. Also, like many of my contemporaries, we learnt 'work-arounds' as in the case of the Dell"Orto VHB which only nowadays seems to have other slides than the 50 they all came equipped with!
Nowadays, I know how to fit a two-stroke atomiser to a VHB. Also, I know how to convert slides to 40 or 45.
I only say the above because it truly makes for a cracking, responsive carburettor (with it's flat guillotine type slide) & would have been a far better evolution than the PH range. Opinionated
![Shocked :shock:](./images/smilies/icon_eek.gif)
Me?
Anyway, even better than either of the above are the current two stroke specific Dell'Orto range VHBC''s etc. Sorry folks, but I don't think you'll find PH's being used on the track Lambrettas....
However, a PWK carburettor made under license from the originators Keihin is my current best choice for the road tunes.
The KOSO's, OKO's, STAGE6 etc are all good but should be checked over like ANY carburettor. Blue-printed if necessary. Information is available on t'internet.....
They work well with filters & have anti-flood. Easy & incredibly cheap to set up.
They work well, fuss-free across quite a range of capacities/states of tune. For example, a 30 mm venturi might be considered oversize for a 185 by other readers, but it would work well.
Conversely, a smaller Venturi would also work well & be just as happy on a 240 plus.
For your current engine, I'd look @ what best fits the spigot & orifice sizes of what you have then make a decision based on that.
Good Luck!