Do a little search and read on fuel pumps. Stockers have points (like an old school distributor) which make and break the circuit to the pump. Various upgrades--all probably a lot less $ than OEM. Facet automotive/aircraft pump, Dr. Bean mod which replaces points with solid state setup and vacuum pump. For my 2 cents, OEM is out of the question. I have had great luck with the Facet--readily available, durable and cheap.
KTMs--300, 518, 990