Terry Syd
Addicted to ArboristSite
That is an already high exhaust port duration, I doubt you want to take it any higher unless you know that the engine needs it. As far as the chamfer, yes, the chamfer should be greater in the center. However, on an exhaust port the flow is going out the port so a chamfer can actually assist the flow as it enters the port (unlike a transfer port where the excessive chamfer diffuses the flow).
Since the engine is already running with the existing chamfer, I'd leave it alone at the edge of the cylinder lining and trim a bit off the inside of the port where the chamfer is excessive. That should give you a 'flatter' opening of the exhaust port.
Since the engine is already running with the existing chamfer, I'd leave it alone at the edge of the cylinder lining and trim a bit off the inside of the port where the chamfer is excessive. That should give you a 'flatter' opening of the exhaust port.