Which factor does NOT affect a motorcycle's torque?

The factor that does not affect a motorcycle's torque is the color of the motorcycle. Torque is a mechanical measurement that relates to the rotational force produced by the engine. It is influenced by various factors including engine design, fuel combustion efficiency, wheel size, exhaust pipe length, and engine temperature.

Wheel size can impact torque delivery to the ground, and exhaust pipe length can influence backpressure and thus affect engine performance, including torque. Engine temperature can impact the efficiency of combustion processes, hence affecting the torque output.

In contrast, the color of the motorcycle does not have any mechanical or physical effect on how the engine operates or how torque is produced and transmitted. This makes it irrelevant when considering the factors that influence a motorcycle's torque.