WSM 100-120-05K OMC 3.187 Bore Piston +0.020 Oversize

The WSM 100-120-05K is a +0.020" oversize piston designed for OMC (Outboard Marine Corporation) engines with a 3.187-inch bore diameter. This piston is a direct replacement for Johnson and Evinrude outboard motors that have been bored or honed to the 0.020-inch oversize specification, restoring proper compression and engine performance.

WSM (Water Sports Manufacturing) engineers these pistons to meet or exceed OEM tolerances, ensuring a precise fit and reliable performance in demanding marine environments. Using the correct oversize piston during engine rebuilds is critical to maintaining proper ring seal, combustion efficiency, and long-term durability.

Key Features:

• +0.020" oversize — designed for cylinders bored to the first standard oversize
• 3.187" bore diameter — matches the specified OMC engine bore size
• Engineered for Johnson and Evinrude OMC outboard motors
• Manufactured to OEM specifications for proper fit and function
• Ideal for engine rebuilds and top-end overhauls
• High-quality materials for corrosion resistance in marine applications

Whether you are performing a full engine rebuild or a top-end overhaul, the WSM 100-120-05K piston delivers the precision fit needed to restore your OMC outboard to peak operating condition.