Own custom exhaust

[x6itru]

Hello there!
I'm going to do my own custom exhaust. I need only some information about derbi senda stock cylinder. (i cant get these informations by myself for now)
I need :
Duration of the exhaust port
Diameter of the exhaust port
Length of the exhaust port
for stock senda50 cylinder.

Maybe someone already know it? Please post it here, or somebody have stock cylinder on the desk and will be able to give me these numbers?
I'll be grateful for help.

[Pieke]

Why would you do a custom exhaust on a stock cylinder? It's slow.

[x6itru]

Maybe it is slow, but i just want to learn how to make good sport exhaust.

[Smitbram]

I think it is cheaper to buy a second-hand, because twostroke exhausts are not the easiest to make by yourself. But if you have got the time and the tools you can give it a try.