yea, my bad. My pipe is right next to the computer. It's the first thing I see when I come in to break from wrenching.
Anyway, yea, it doesn't make sense, especially with a circuit. Raising the exhaust would decrease the distance from TDC to the exhaust port and thus advance the exhaust port timing, lengthening the port duration, and decreasing the compression ratio giving it more rev's for a pipe that can't support them and robbing it of bottom end.
for simples like me: don't make da exhaust hole bigger front to back, instead widen them, but don't go more than 62% of the bore. So if you have a bore of 38.6 mm, (that's about 49cc), you COULD widen it to about 23 mm, so long as the exhaust and every other f@$ing variable can support that. Also the rings, make sure you don't fuck with how the rings sit. Everything you do matters though and is a compromise, the shape, length, height, and texture of the port. Keep shape on the ports. Just start mild, and go bigger if you are feeling it.
I'll try to port pics. No promises though, it's the civil war game tonight.