The combustion chamber is taking shape. The sparkplug angle had to be changed to accomodate the cam towers. Not a lot of finning for a 500cc cylinder...
Head fins all in place, and rocker shaft position has been finalized.
Middle support between the valve guides was taken out, a "valley" was needed between intake and exhaust to help define the final head shape. The mesh is the start of the shaping of the ports.
And the days just go by... never done anything like this before, and the first time always takes longer. I want to get it "right"... the shapes, dimensions, and functions. I want it to be simple and effective, and easy to work on. 1919 on the outside, and modern inside .
Shape is finished, and a flycutter in the mill does the hole for sparkplug clearance .