Might be in left field here, but I don't think that chain inertia is very significant in terms of keeping the chain speed constant or to prevent bogging, here is why
the inertia is far greater from of all other parts that are rotating at 12000 rpm (the crank, clutch, sprockets, piston, conecting rod, fly wheel....) Noted: Piston only provides momentary inertia during stroke.
If inertia added performance, they would not be trimming fly wheel weights to bare minimum, and maybe thay would even add tiny lead weights to the chains, or better yet even tungsten.
Is this is why carbide chains are better? LOL
Take a 5 lb brick and tie it to a rope, them swing it above your head in a circle til your tired, then take a 10 lb brick and do the same thing, your tired much quicker as more effort is exerted.