Dave wrote on 08/05/19 at 18:14:19:The good news is that when changing spark plugs........nothing will fall into the cylinder!

They put upside down engine in airplanes years ago - I guess having the propeller up high while the cylinders were down low and did not block your view was a big advantage. I don't see the advantage in a motorcycle.
This one is a diesel!
General walks in, barking orders,,,
Gentlemen, design me an engine that is easy to warehouse and doesn't need an engine stand.