720° ÷ 6 = 240°, firing order is the usual 1 5 3 6 2 4, one pair of rods & pistons at opposite ends of the center main are at the same position (but different parts of the combustion cycle). 1 & 6, 2 & 5, 3 & 4.

Balance? But... how do you do that?

Boffin Emeritus