They outdraw more than 1/4, since theres 2 streets still to come.

They're 1.86:1 or 35% to hit their flush. Fnords right that they may have other outs, but with two overs on the board, unless I'm pure bluffing they're unlikely to win with 1 pair, so we'll discount them for now.

Effective Pot is 1380 + 140 = 1520, and they need to put in 1240, so approximately 15:12 => 5:4 or 44%. This means I need to be bluffing 10% of the time or more for this to be profitable, however its not quite right as even if I'm bluffing I may either have a Q or hit a lower pair sometimes as well.

Probably not as definately bad as it first appeared, but definately still a bad play.