Crankvolume , how much is it related to everything ?

[ids987]

Thanks mate. In my superkart racing days the bridge in the port was to help keep the ring from poping out (something nitro guys don't have to deal with) being able to widen the port as much as possible but maybe the effect was 2 fold.

Although you don't have a ring to pop out, keeping the piston in can be a bit of a problem - especially when the top of the rod starts to wear a bit. I guess that's one of the reasons for wedge shaped exhaust ports ?