1. What is Bore To Stroke Ratio?

The bore to stroke ratio is a fundamental measurement in engine design that compares the diameter of the cylinder (bore) to the length of the piston travel (stroke). This ratio significantly influences engine characteristics including power delivery, torque, and engine speed capabilities.

2. How Does the Calculator Work?

The calculator uses a simple formula:

Where:

• \( Bore \) — Cylinder diameter in millimeters
• \( Stroke \) — Piston travel length in millimeters

Explanation: The ratio indicates whether an engine is "oversquare" (ratio > 1), "square" (ratio = 1), or "undersquare" (ratio < 1), each with distinct performance characteristics.

3. Importance of Bore To Stroke Ratio

Details: This ratio determines engine behavior - oversquare engines typically favor higher RPM operation and peak power, while undersquare designs produce more torque at lower RPMs. Motorcycle manufacturers carefully balance this ratio based on intended use (sport, cruiser, touring, etc.).

4. Using the Calculator

Tips: Enter both bore and stroke measurements in millimeters. These values are typically found in motorcycle specifications. Ensure both values are greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good bore to stroke ratio?
A: There's no single "good" ratio - it depends on the motorcycle's purpose. Sport bikes often have ratios around 1.2-1.5, while cruisers may have ratios around 0.8-1.0.

Q2: How does bore to stroke ratio affect engine performance?
A: Higher ratios (oversquare) allow higher revving engines with peak power at higher RPM, while lower ratios (undersquare) provide better low-end torque and smoother power delivery.

Q3: Can I change my motorcycle's bore to stroke ratio?
A: Yes, through engine modifications like boring cylinders or changing crankshafts, but this requires significant mechanical expertise and may affect reliability.

Q4: Does bore to stroke ratio affect fuel efficiency?
A: Yes, generally undersquare engines are more efficient at lower RPMs, while oversquare engines may be more efficient at higher RPMs under load.

Q5: Where can I find my motorcycle's bore and stroke measurements?
A: Check your owner's manual, manufacturer specifications, or reputable motorcycle databases online. These are standard engine specifications.