Sorry, but torque has nothing to do with time. Torque is simply rotational force. T=F x r. When you re-gear the bike, you are effectively increasing the force transmitted from the engine to the rear wheel, as the radius of the rear wheel stays constant. This is why putting a worn tire makes the horsepower read higher: The torque at the rear wheel gear is the same, but the ratio of that gear to the radius of the tire increases, thus showing 'apparent' horsepower increase at the road. Horsepower = T x RPM / 5252.

The force available from the engine, assuming no change except gearing between dyno runs, is constant, thus the torque curve shape will be the same. What will change is the torque/horsepower vs road speed. With horsepower in the vertical, and road speed in the horizontal, the graph will move up and left. The goal in re-gearing is to get the graph to move up more than left, so you run out of 'gear' and 'motor' at approximately the same speed. This is why some stock geared bikes won't pull redline in 6th (Gear ratio too tall), and why a stunt-geared bike will pull redline in 6th, but tops out way slower (gear too short). People often state that when you re-gear, you're trading horsepower for torque. This is incorrect. You're trading speed for both torque and horsepower.