Listening for the EXUP servo operating
1. If the Engine is stopped using the kill switch, when the engine stops you will hear the servo return the valve to the default position.
2. If the engine is stopped using the ignition key you will hear the servo returning the valve to the default position when the ignition is switched on, however as previously mentioned the sound may be masked by the ticking of the fuel pump.
Best way to listen to it is start the bike, leave it tick over and then hit the kill switch. Sounds like a whirr at the front of the tank.