Merc transfer ports

[H2OPERF]

I was talking with a friend about how the 2.5 transferports are wider on one end than the other making the top edge angled slightly.I allways thought they did this to help progress the rings across the top of a straight wide port without much chamfer.He disagrees saying the shape is for flow design reasons,anybody know for sure?dave

[dangerousd]

I've heard too that it adds a certain increase or advanatage somehow like maybe a swirl effect, but it probably serves dual purpose for helping the rings not to catch. I'm not sure if all 2.5's are this way, but the only one I've ever had apart and measured was my 1998 150XR6 and it had the slope or angle. I can't recall exactly, but it seems like it was .060 or .100 slope from one end to the other.

[us1]

Yes they are all sloped. The stockers are higher on the boost port side and the drags are higher on the exhaust side. It will slightly change the power curve characteristics of the motor. The ring wont catch if you chose to make them flat, its not wide enough for that.