Piston and Rings .030 Oversize – Complete Rebuild Solution for OMC/Johnson/Evinrude Outboards
Restore your outboard’s performance with the OEM .030 Oversize Piston & Rings. Designed for engine rebuilds requiring a 0.030″ overbore, this piston and ring set helps restore proper compression, improve engine efficiency, and return worn cylinders to reliable operating condition.
Over time, cylinder walls can become worn, scratched, or damaged from normal use, overheating, or component failure. During a rebuild, cylinders are often bored oversize to create a fresh sealing surface. This piston and ring .030 oversize assembly is designed to match those rebuilt cylinders, providing the proper fit needed for dependable performance and long engine life.
A properly fitted piston and ring package is critical to engine performance. Good ring seal helps maximize compression, improve combustion efficiency, increase power, and reduce unwanted blow-by. Whether you’re rebuilding a recreational outboard or a high-performance engine, quality piston components are essential.
At Liquid Revolutions, we’ve rebuilt countless Johnson and Evinrude race power heads over the years with new Piston and Rings .030 oversized. Proper piston to cylinder fitment is one of the most important factors in achieving reliable performance and longevity.
Common Signs an Engine Needs Rebuilding
- Low compression readings
- Excessive piston or cylinder wear
- Loss of power
- Increased blow-by
- Excessive fuel consumption
- Piston damage or scoring
Key Features & Benefits
- .030″ Oversize Piston – Designed for engines bored .030″ over standard size
- Complete Piston & Ring Set – Includes piston and matching rings for proper fitment
- Restores Compression – Helps improve engine efficiency and performance
- Improves Reliability – Ideal for worn, damaged, or rebuilt cylinders
- Precision Engine Rebuild Component – Critical for proper ring seal and combustion efficiency
- Designed for Johnson & Evinrude Applications – Compatible with select outboard engines
Why Oversize Pistons Are Used
When cylinder wear exceeds factory specifications, simply replacing rings is often not enough. The cylinder must be machined to a larger diameter to restore proper geometry and surface finish. An oversize piston is then installed to match the newly bored cylinder.
Benefits include:
- Restored compression
- Improved ring sealing
- Better combustion efficiency
- Increased reliability
- Longer engine life
Whether you’re rebuilding a fishing motor, restoring a classic outboard, or freshening up a race engine, the Piston and Rings .030 Oversize provide the fit, compression, and reliability needed to bring your Johnson or Evinrude outboard back to life.
Replaces: 0391417, 0396581, 0778389
