I believe mine is in the 37mm range.
I like boats, and anchors, but wouldn't want to have to drag one around.
Entrance into intake side is roughed slightly to improve the break-up of fuel droplets that may try to adhere to side of wall, thereby improving vaporization of fuel/air mixture
In this one you can see the early stages of the preparation of the transition from rough to smooth in the intake tract. More work was done after this to improve the gradual change from rough to smooth but I could not find the pic right now. Ideally, just before reaching the valve itself the intake tract should be POLISHED GLASS SMOOTH, I am not quite at that level and lack a few tools needed for that perfect finish....but working toward it.
Smoothing and opening of right side of exhaust port
Smoothing and opening of the left side of the exhaust port
I am following the techniques of a dude from California who builds HD engines for WORLD RECORD RUNS ON THE SALT FLATS, so this is a VERY LOFTY GOAL I am working toward.