To the O/P,
I applaud you in taking the initiative of DIY porting but with D shaping the intake,the D is at the spigot opening only not the entire length of the port. The floor needs to be FLAT up to the short turn with a slight rolling of the corners to the outside walls. Roof must be aligned with floor radius corners. The ONE CRUCIAL ELEMENT to this D porting is the cross sectional area of the spigot, get it wrong and that port will fall flat on it's face with no velocity. You need to raise the entire floor! You want the height of the floor to the center of the roof at the spigot between 30 to 31MMs and depending on carb 34 to 36mms in width. You want the port to taper out to the valve seat, narrowing the port at the seat corners will cause a CFM loss. When working the short turn,you can bias the flow more at lower lifts or bias the flow in the upper range of the flow curve,it just depends on cam selection or what you trying to achieve. Also working the valve guide boss will also bias the flow. Total port volume will be in the neighborhood of 75 to 78 ccs when the port is restructured. Get the port right and the velocity will shoot the moon and the CFM flow should be between 185 to 195+ CFM at around .430 lift with flow hitting hard after .200 lift
I applaud you in taking the initiative of DIY porting but with D shaping the intake,the D is at the spigot opening only not the entire length of the port. The floor needs to be FLAT up to the short turn with a slight rolling of the corners to the outside walls. Roof must be aligned with floor radius corners. The ONE CRUCIAL ELEMENT to this D porting is the cross sectional area of the spigot, get it wrong and that port will fall flat on it's face with no velocity. You need to raise the entire floor! You want the height of the floor to the center of the roof at the spigot between 30 to 31MMs and depending on carb 34 to 36mms in width. You want the port to taper out to the valve seat, narrowing the port at the seat corners will cause a CFM loss. When working the short turn,you can bias the flow more at lower lifts or bias the flow in the upper range of the flow curve,it just depends on cam selection or what you trying to achieve. Also working the valve guide boss will also bias the flow. Total port volume will be in the neighborhood of 75 to 78 ccs when the port is restructured. Get the port right and the velocity will shoot the moon and the CFM flow should be between 185 to 195+ CFM at around .430 lift with flow hitting hard after .200 lift
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welcome to the XS650 club dave
