X30 Big Bore

Hello, I race unlimited karts on the dirt. We are free to combine or alter engines in any form or fashion we would like. I am seeking knowledge on how far an X30 cylinder can be bored before it becomes inefficient. My end goal is to have dual IAME Nordam style engines to power this monstrosity. Thank you for any help and criticism.

I don’t know offhand, but could you possibly use the IAME 175 super shifter as a reference point. That uses a 63mm slug, but I’m not 100% sure if that’s the same casting as the x30.

If you’re willing to forgo having an iron liner in the x30
Cylinder you could bore it out further and plate it. I’m not sure how much room there is to make the transfer port angles better with the larger bore though.