Are you trying to pick up a little extra acceleration by opening the rotary valve 6 deg earlier?
Is that why you added 5mm to the pipe?

What rpm are you trying to develop peak HP at? Or do you know what rpm your prop allows the
engine to rev up to. It would help if you posted a picture of the pipe and its length.

Did you figure out your transfer port timing? It would be helpful to know your BDT (blow down time).
The BDT will determine how effective your pipe is. If it is too mild, it will effect the pipe's performance.


Bill M.