I just finished putting mine together, used a Satio 91 (had it laying around so !) anyway is the CG checked on top of wing ( upside down) or right side up?
As of now it is a little tail heavy if plane is inverted and checked at 3 1/2" at fuse.

Check it upside down with a empty tank....mine flew better at 4" at the fuse...Bill

I want to get a Seagull Extra 300S and I'd like to put a Saito 4 stroke on it. From reading all the previous posts in this thread, it seems a .61 2 stroke might be about the right amount of power for this plane. Can anyone tell me which Saito 4 stroke would have about the same amount of power?

Also, I'm having a little trouble figuring out how the plane will balance. If it balances with a Thunder Tiger Pro .61 2 stroke with the battery & rx under the fuel tank, it should need about 6 oz. of nose weight to balance with a Saito .91 based on the weight specs I've been able to find for those engines. The TT Pro is about 26+ oz. and the Saito is about 20 oz. I know there are other factors such as where the balance point actually is, number of elevator servos used, muffler used, etc.

So, if anybody has any more specifics on their setups, I sure like to hear them.

Thanks.