yes. i skipped a step...
2010 honda shadow
2 x 750 cc = 1500 cc
1500 cc ÷ 45 hp = 33 cc / 1 hp
1992 honda cb 750
4 x 750 cc = 3000 cc
3000 cc ÷ 75 hp = 40 cc / 1 hp
in other words the v2 only needs 33 cc to make one hp were as the old i4 needs 40
I sense you're being serious.
Total displacement for both engines is only 750cc. Actually the CB750 is 739cc and the VT750 is 745cc. You are multiplying when you need to be dividing.
739cc / 4 = 184.75cc
745cc / 2 = 372.55cc
Note that the calculation of the specific output of any engine does not take into account how many cylinders it has