SB 200 exhaust build port issues

[Sakaboela]

I am in the process of builing a SB200 caféracer. I am looking into building a set of expansion chamber exhausts. I've been to a few bike shops and searched the internet looking for specs regarding the exhaust port diameter and port duration. Can anyone tell me the port diameter and duration or where I can find it or in the worst case measure it myself? Any help and advice regarding this would be much appreciated.

[tz375]

Port data is rarely published except on specialist web sites where someone might have measured them. It's not hard to measure yourself and there are a few Youtube videos on the subject. There are basically 2 ways. One is to remove the barrels and do a port rubbing and measure the shapes that you traced. The second is with e barrel on teh motor and head off. You can measure port width with a pair of calipers or inside micrometer. To get the port opening and closing in degrees you have to carefully measure how far down the piston is when the port just starts to crack open.

https://www.google.com/search?q=port+ma ... rt+mapping&*" onclick="window.open(this.href);return false;

https://www.google.com/search?q=2+strok ... 47&bih=894" onclick="window.open(this.href);return false;

https://www.youtube.com/watch?v=r6s7qpyRRDU" onclick="window.open(this.href);return false;

https://www.youtube.com/watch?v=JWqdBqJSJ8Y" onclick="window.open(this.href);return false;

https://www.youtube.com/watch?v=zyGDZWIWB2A" onclick="window.open(this.href);return false;