766-8666A43 – Mercury Starboard Piston Kit (.015 Oversize)

Upgrade your V6 outboard’s performance and reliability with the Mercury Starboard Piston Kit, part number 766‑8666A43. This .015″ oversize piston assembly ensures a precise fit and extends the lifespan of motors running on worn cylinders.

It’s a genuine OEM part designed for rugged applications, including XR4, MAG II, and 6-cylinder models from 175 to 225 HP (1978–1990). The kit includes the piston, rings, pin, and retaining clips to get you back on the water quickly.

Key fitments include:

• Mercury, Mariner, and Force engines with 3.375″ bore

• Models like XR4, MAG II, V‑175, V‑200, V‑220, and V‑225

• Production years spanning 1978–1990

Many boaters trust this piston kit to restore engine compression and reduce oil consumption. It removes the need for costly re-boring jobs by offering a factory-sized solution with proven fit. As a bonus, its chrome-faced ring ensures enhanced sealing and durability.

Key Features:

• Mercury OEM part no. 766‑8666A43

• Starboard piston kit with .015″ oversize bore fit

• Includes piston, rings, wrist pin, and clips

• Fits V6 175–225 HP engines with 3.375″ bore (1978–1990)

• Chrome ring technology for improved durability

• Keeps engines in spec without needing re-bore

At Arizona Outboard Dismantlers, we specialize in genuine Mercury parts and the models they support. This .015″ Starboard Piston Kit is a solid, dependable solution for any V6 restoration or engine refresh project.