Probably a little under powered but it will fly. A 4s YS 70 or better yet, 80 would be much better.

The 63 is a good medium 45 size model engine. As an example, Hanno's Mystic 90 which is a large 45 size model approaching the size of the Calypso (which is a smaller 60 size model) flies well on the YS 70, even better on the 80. But, as the name indicates, it is designed for a standard 90 size 4s or a piped powerful 45 size as the YS 45 FR.

David