Yamaha - Oil Pump Assembly Engine Lubrication System YF1-68513-50-10. Overview. If you've worked around Yamaha engines long enough, you know the oil pump is one of those parts that never gets attention until something goes wrong. The Yamaha Oil Pump Assembly YF1-68513-50-10 keeps oil moving through the engine so bearings, pistons, and internal components stay properly lubricated. It quietly does its job every second the engine is running. When the lubrication system is working right, the motor r