Honda CRF250 300 L/LA/Rally XL750 Transalp Accessory Plug 12v Power Connector

The Honda has a switched and fused mating socket taped to the wiring harness under the left hand fairing on the Rally (you may need to expose by unwrapping a few turns of tape), and behind the headlight shroud in a black PVC "wiring pouch" on the 300L.