Specs for different vespa cylinder kits

Hey folks,
Seeing as I am always complaining about the cost of pipes for scoots I have decided to put my tig welding skills to the test and see if i cant make me a decent expansion chamber. However There are certain bits of info that I need such as

: exhaust port effective diameter

: Diameter at the barrel flange

: length from piston face to flange

Exhaust port opening angle (degrees at top dead centre)

: engine speed at maximum power

:exhaust temperature

I need to find this info for as many different types of vespa cylinder kits both for px200’s and smallframes (polini 135 pref.)
If you guys know of anywhere on the net where I can find this kind of info that would be great

The following website has port timing information for various P200 cylinder kits and also dimensioned drawings for standard P200 cylinders, might be of some use:



excellent mate much appreciated