Ported stock cylinder?

[Vroomy]

Looking for opinions on whether it's worth porting a stock cylinder? Will it be comparable to a 310? Is there any reliability benefits? Etc

[rsss396]

if you do a esr or older prox 295-310 cylinder they are very reliable but a 295 stock cylinder can give you issues, not that they dont work but tend to have head sealing issues.
As for performance, if they are given the same style port job the esr/prox is a better running cylinder. the stories you here of 250's out running the 310 is because of many different variables like rider abilities, engine tuning, exhaust pipes and porting.
Yes there are 250's that can out run a 310 no dought but if they are equally setup then my money is on the 310

[Jerry Hall]

Looking for opinions on whether it's worth porting a stock cylinder? Will it be comparable to a 310? Is there any reliability benefits? Etc

I can get as much or more peak power from an OEM cylinder that is 250cc than I can from a 310 cylinder.  The 310 cylinder properly set up will produce about 3 to 4 hp more from 6000 RPM to the RPM where it matches the peak power of a real good running 250cc OEM cylinder.

[Vroomy]

So being I'm after more midrange than top end the 310 would be better suited?

[etccb]

Thats where the displacement cc's will be showing up vroomy.

[Jerry Hall]

So being I'm after more midrange than top end the 310 would be better suited?

Yes this is true providing your 310 cylinders is set up with the right pipe, carb, reeds, ports, head etc......  

If the 310 is not set up correctly it may not have as much power as a properly set up OEM cylinder

[jadleybray]

all things equal, larger displacement will outperform across the board.  But damn I love my nasty stock cylinder!!!  However, my builder would not have the same feelings.