Jan:

Almost without exception this sag is from going lean.

On the BattleFloyd there's not much way to get the tank out of position so you must be setting the mixture too lean on the ground.

There is one other possibility, you didn't say if your engine was mounted upright or on the side. The real reason for side mounting is just this problem. A lot of people do it without knowing about fuel feed problems, just think it just looks better.

So, if you're already side mounted richen it up a bit. If the engine is upright lay it over and enjoy.

Bill.