Description
Crankshaft Function in Outboard Motors:
The crankshaft is a critical rotating component that converts the piston’s linear up-and-down motion into rotational torque. As the pistons fire sequentially, their connecting rods push on the crankshaft’s offset journals (crank pins), causing the shaft to rotate. This rotation ultimately transfers power through the gearbox to turn the propeller shaft and propel the boat.
Key Characteristics:
- Torque Conversion – Transforms combustion energy into usable rotational force
- Precision-balanced – Counterweights offset piston momentum for smooth operation
- Multi-Bearing Design – Supported by main bearings to minimize friction
- Hardened Steel Construction – Withstands extreme combustion pressures (up to 1,000+ psi in modern engines)
- Timing Reference – Often includes keyways/sprockets for synchronizing camshaft(s) and oil pumps
Outboard-Specific Features:
- Compact design to fit vertical engine configuration
- Saltwater-resistant bearing surfaces
- Integrated flywheel mounting flange
- Splined or tapered propeller shaft connection
Maintenance Considerations:
- Requires periodic lubrication inspection
- Bearing wear can cause vibration issues
- Crankshaft seal failure leads to oil leaks
- Rarely serviceable – typically replaced as an assembly
Performance Impact:
- Stroke length determines engine displacement
- Journal size affects load capacity
- Rotational mass influences throttle response
- True running condition essential for engine longevity
This component represents the “backbone” of the outboard’s power delivery system, with typical rotational speeds exceeding 5,000 RPM in high-performance models.
Search Yamaha part by OEM part numbers: 6G5-11411-00, 6G5114110000, 6G5-11411-00, 6G51141100, 6G5 11411 00
New part Crankshaft, Yamaha, 6G5-11411-00-00 is
- For Outboard: Yamaha L200, Yamaha D150, Yamaha L150, Yamaha 150, Yamaha 175, Yamaha 200, Yamaha 220, Yamaha 225
