I use 10% fuel. But I dont have the stacks on any of them and it definatly had quite a bit of spit back. I never thought of that. But, my saito 72 flys my cub forever!! I love saitos and prefer them too. I wish tower still carried them. And, I had the 150 on an older Ultra Stick, those heavy hangar 9 ones and that might have been the reason for fuel suckin. So then, that 120 should do pretty good then huh?