Some Motorbikes produce considerable interference signals through ignition system, alternator, etc.
When using electronic devices on the motorcycle, these interferers often cause crackling or singing background noise and impair the reception sensitivity of a connected radio, two-way radio or mobile phone.
For an effective interference suppression, one must first find out in which way the interference gets into the devices, (more about that, see here:Help with vehicle interferences on the motorbike.)
Vehicle interferences are often transmitted by so-called "ground loops". Especially with motorbikes that are prepared to be equipped with a car-radio, this problem can occur, if other electronic devices like helmet intercom systems, two-way radios etc. are connected and not all devices and antennas can be grounded over a common ground point.