A Kisan signal minder flasher unit may work, and there are a number of units available from autoparts stores, and even at superbrightLEDs.com, depending upon your bike's setup (either 2 terminal or 3 terminal device). If you have a "new" BMW with CANbus then you need to take a different approach, because the signal relay controller is integrated into part of the main computer.. but BMW offers OEM accessory parts for those.