Yamaha Pinion - 6BX-45551-00-00. Genuine Yamaha Pinion Gear for Smooth, Reliable Gearcase Operation. The Yamaha - Pinion - 6BX-45551-00-00 is a factory-original pinion gear designed to deliver smooth, precise power transfer within your Yamaha outboard's lower unit. As a critical gear in the drivetrain, this pinion ensures optimal engagement with the forward and reverse gears, helping maintain efficient propulsion and reliable performance.. Constructed to exacting Yamaha specifications, this gear