YS63!

I have the Saito 72 on my Venus and climbs like mad, the YS63 is even more powerful by all accounts and has the pressurized fuel system. I have weighed both and the YS is less than one ounce heavier than the Saito so there is no reason not to use the YS63.

Stay away from any OS 4 stroke for this plane as they are all waaaaay to heavy. The OS70 weighs 3 ounces more than a Saito 72, in other words it weighs as much as a Saito 100!! The OS91 is again a few ounces heavier and this will give you a 5.75lbs+ plane and that would be a disaster for wing loading.

Mine weighs in at 4lbs 15 ounces dry with the Saito 72 and it flies very light.

I might install my YS63 in the Venus at some point at least to break it in before I mount it on a Seduction, I think it will be monster with that motor.

So again I strongly suggest you get the YS63 as the best overall engine.

But if you want more weight and some more power then you should get the Saito 100.

Filip