Menghitung Rasio Kompresi Setelah Bore Up

Introduction

This tutorial guides you through calculating the compression ratio after a bore-up modification on your motorcycle. Understanding the compression ratio is crucial for optimizing engine performance, particularly for two-stroke engines. Follow these steps to accurately perform the calculation.

Step 1: Gather Necessary Information

Before starting the calculation, you need to gather specific values related to your engine:

• Bore Size: Measure the diameter of the cylinder bore.
• Stroke Length: Measure the length of the piston stroke.
• Head Volume: Determine the volume of the combustion chamber, which may require disassembly and measuring.
• Gasket Thickness: Account for the thickness of the cylinder head gasket.

Practical Tips

• Use calipers for accurate measurements.
• Document all measurements for reference.

Step 2: Calculate the Engine Displacement

The engine displacement can be calculated using the formula:

Displacement = π × (Bore/2)² × Stroke

Example Calculation

If your bore is 52 mm and stroke is 49 mm, the calculation would be:

1. Convert measurements to centimeters (if needed):
   • Bore = 5.2 cm
   • Stroke = 4.9 cm
2. Apply the formula:

   Displacement = 3.14 × (5.2/2)² × 4.9
   

Step 3: Calculate the Compression Ratio

The compression ratio can be calculated using the following formula:

Compression Ratio = (Displacement + Head Volume) / Head Volume

Example Calculation

Assuming you have a head volume of 10 cc:

1. Calculate the total volume:
   • Total Volume = Displacement + Head Volume
2. Plug in the values:

   Compression Ratio = (Displacement + 10) / 10
   

Step 4: Adjust for Gasket Thickness

If you have changed the gasket or its thickness, adjust the head volume accordingly before re-calculating the compression ratio.

Example Adjustment

If you previously had a head volume of 10 cc and changed the gasket thickness, determine the new head volume and recalculate using the previous formula.

Conclusion

In summary, you have learned to calculate the compression ratio after a bore-up modification by gathering necessary measurements, calculating engine displacement, and applying the compression ratio formula. For further adjustments or specific scenarios, consider consulting with a mechanic or referring to additional resources.

For detailed calculations, you can use the provided Google Sheets link to automate the process.