I understand that many people have successfully built Upshur's engines but that does seem a somewhat dubious design with the spark plug recessed at the end of a small hole and the limited engagement of the rocker tower holding bolt. A stud and nut would be a better solution.

Thanks Kim. Still fighting with the set up, but coming closer.


There was an additional machining necessary to give some space for later milling inside the crankcase.
That done both sides, given the opportunity now for the first real fixation of all at the mill.
After a small adjustment with additional shims left hand side, I archived a parallelism to the X axis with a deviation from 0,02 mm, measured at the two pins.
For me that is fine and nearly perfect.

Photos would be super cool! Whenever you have time, Thanks

Today I cut cylinder head fins and made up a couple of rocker arm support towers. Not terribly exciting, but it took up most of my day. There is something a little fishy about the bearing support tower in the drawing package from Upshur. Haven't quite figured out what it is yet, but there is something about the #5-40 threaded holes tapped in the rocker arm support towers and in the head.

See note #9 on the Upshur drawing. The rocker arm support is not drilled through. It is fastened with a threaded stem locktited in place.

Thanks Jeff and Chris! 
Kim