[Jake Raby]

The 3.8 bore is much harder to build. You must set ring tensions (fish scale) yourself, and its not nearly as straight forward as a 99mm bore engine would be. The 101mm bore also requires a lot more port to keep from being a narrow power range pig.

The class is universally applicable, we work with 3 and 5 chain engines, and I even go over how to swap components between the engines.
Bigger isn't better. You won't believe me till you learn it first hand, though.