PIÑON ATTACK 647-45551-00

Function and technical context

The drive pinion is the drive gear of the outboard motor starting system, responsible for meshing with the flywheel ring gear to transmit rotational force from the electric starter motor to the engine block. This component works under conditions of very high instantaneous load during each ignition cycle, being critical for the engine to start reliably. Any wear, fracture or misalignment of the pinion prevents correct engagement with the ring gear, causing difficulty in starting, characteristic metallic noises or even the complete inability to start the engine, especially in cold water conditions or after prolonged periods of non-use.

When to replace this part?

Typical symptoms of wear include grinding or squealing during starting, progressive difficulty in turning the engine, lack of mesh between the pinion and the flywheel crown, or movement of the pinion without transmission of power to the engine. It is recommended that the condition of the sprocket be inspected at each seasonal inspection, especially if the engine has recurring starting problems or has been idle over the winter. Preventive pinion replacement prevents unexpected stalls and protects the starting system from more costly secondary damage to the starter motor or flywheel.

Compatibility with Yamaha engines

Equivalent manufacturer part numbers