a harley does not torque steer because its crankshaft is a right angles to the direction of travel. this means the torque reaction transmitted to the frame when the engine is loaded would tend to lift the front wheel, not roll the frame to the side.
An air-cooled BMW, a moto guzzi v-twin, and the honda CX series v-twins all exhibit torque steer because their crankshafts point in the direction of travel. when you goose the throttle on any of these bikes, the torque reaction from the engine will roll the bike sideways. under way, the rider has to compensate for this torque roll with steering corrections.
Even in bikes with transversely-mounted engines, though, adding power will accelerate the bike, and adding power in a turn means the rider must also add bank angle to offset the added speed so as to maintain a constant turn radius. If the rider fails to do so, adding power in a turn will necessarily increase the turn radius and thereby may run the bike "wide"- that is, off the road to the outside of the turn. The way the rider experiences this is that adding power in a turn tends to make the bike go straight- which is why bikers often roll on the throttle and accelerate when coming out of a turn.
In this sense one might claim that there is a torque-steer effect in motorcycles, in which upping the torque applied to the rear wheel causes the bike to straighten out and stop turning.
However, this is completely different from the normal usage of the term "torque steer" in front-wheel-drive cars, in which hitting the gas in a turn pulls the front wheels straight and increases the amount of steering effort required to hold the car in the turn.
In a motorcycle, wheelbase, fork angle, bar length and fork trail have no influence on this effect.