The Importance of Cylinder Honing in Four-Stroke Engine Rebuilds

Cylinder honing is a critical process in four-stroke engine rebuilds, as it ensures the engine’s longevity, performance, power, fuel efficiency, noise, vibration, and environmental impact are all optimized. This comprehensive guide delves into the technical details and measurable data that demonstrate the significance of cylinder honing in engine rebuilds.

Understanding Cylinder Honing

Cylinder honing involves using an abrasive tool to create a precision surface on the inside of a cylinder, smoothing out any irregularities caused by boring. The abrasives used in honing can include silicon carbide, aluminum oxide, or diamond, with diamond abrasives being preferred for their ability to hold a cutting edge longer.

Honing Abrasives and Their Characteristics

Abrasive Type Cutting Ability Edge Retention
Silicon Carbide Moderate Good
Aluminum Oxide Good Moderate
Diamond Excellent Excellent

The honing process is designed to achieve the following goals:

  1. Improve cylinder wall surface finish
  2. Increase cylinder diameter by a few thousandths of an inch
  3. Establish the correct cylinder wall cross-hatch pattern
  4. Ensure proper seating of piston rings

Importance of Proper Honing Technique

When honing is done correctly, it results in proper seating of the piston rings, ensuring optimal oil flow and preventing negative consequences. However, honing is a delicate process that requires specialized tools and technical skills, making it challenging for the average shade-tree mechanic to reproduce an OEM cylinder bore finish.

Measurable Benefits of Cylinder Honing

the importance of cylinder honing in four stroke engine rebuilds

The measurable data demonstrates the significant impact of cylinder honing on engine performance and durability.

Increased Cylinder Diameter

Honing a cylinder can increase its diameter by a few thousandths of an inch, typically between 0.001 and 0.003 inches. This increase in diameter can result in the following benefits:

  • Improved engine performance and power output
  • Enhanced fuel efficiency
  • Reduced engine noise and vibration

Precision and Speed of Honing

The OEMs typically spend only about 15 to 20 seconds honing a cylinder, while it can take several minutes to manually hone a bore using a power honing machine. This highlights the precision and speed required for honing, as well as the importance of using the right honing equipment and techniques.

Emissions Compliance and Honing

In parts of the country with emissions testing, improperly honed cylinders could result in a vehicle failing the test, further emphasizing the importance of professional honing services. Proper cylinder honing ensures that the engine’s emissions are within the acceptable limits, contributing to environmental sustainability.


Cylinder honing is a critical process in four-stroke engine rebuilds, as it ensures optimal engine performance, longevity, and emissions compliance. The measurable data, such as increased cylinder diameter and improved bore geometry, demonstrate the significant impact of honing on engine performance and durability. By understanding the technical details and importance of cylinder honing, engine builders and enthusiasts can ensure their four-stroke engines operate at their best.

The Smooth Science of Cylinder Honing
Honing Engine Cylinder
Boring, Honing, and Balancing Your Engine