40 CFR §86.409-78

1. (a)No motorcycle shall be equipped with a defeat device.
2. (b)Defeat device means any element of design which:
   1. (1)Senses temperature, vehicle speed, engine RPM, transmission gear, manifold vacuum, or any other parameter for the purpose of activating, modulating, delaying or deactivating the operation of any part of the emission control system and
   2. (2)Reduces the effectiveness of the emission control system under conditions which may reasonably be expected to be encountered in normal urban vehicle operation and use, unless
      1. (i)Such conditions are substantially included in the Federal emission test procedure, or
      2. (ii)The need for the device is justified in terms of protecting the vehicle against damage or accident, or
      3. (iii)The device does not go beyond the requirements of engine starting or warm-up.