There's no way you can cast an engine block with that many holes in it!
Oh wait, someone used that line already. I think they were talking about the ford flathead V8...
I dunno on this, I mean...other than increasing total displacement (which I don't see as an issue we've already got 2 liter v-twins...) is there a real benefit to an inline 6 as a motorcycle engine?
Why not a v6, or a boxer 6, or, really crazy, a W 6?
I'm not sure that the extra width over an inline 4 of that displacement is worth the ? benefit.
Inline 6 has perfect balance = smooth, plus modern packaging and water cooling reduce width. design can be based on current k1300 architecture.
V6 either 90 deg or narrow angle = never smooth even with balance shafts
W6.. Packaging & smoothness
Flat 6 perfect balance = smooth but the major competitor already has that engine format and the boxer 6 suffers the same issues of width that BMW struggle to solve in the flat twins.