Hey guys...

Is the OS 120 4 stroke with a pump strong enough to hover the Yak 54 67". And do y'all know the recomended prop size? I want to hover and it seems like the 120 is not doing enough... Let me know! Thanks!

Properly equipped it will hover a 10lb plane at full throttle. Assuming yours will be 8.5-9 lbs it will have a little power on tap for pull out.
Adam

it will depending on the weight of the airplane. Keep it light or move up to a 160-180 engine if possible to hover with more of a cushion.

good luck