ISO 4106:2026

Overview

ISO 4106:2026, Motorcycles - Engine test code - Net power, is an international standard developed by ISO. This document specifies standardized methods for evaluating the performance of motorcycle engines, focusing on the presentation of net power curves and specific fuel consumption at full load as a function of engine speed. The standard applies to reciprocating internal combustion engines (both spark-ignition and compression-ignition, but excluding free-piston engines) and rotary piston engines, whether naturally aspirated or pressure-charged (with either mechanical pressure-chargers or turbochargers).

The objective of ISO 4106:2026 is to ensure reliable, consistent, and comparable net power measurement of motorcycle engines, providing a technical foundation for manufacturers, testing facilities, regulators, and other stakeholders.

Key Topics

• Net Power Assessment
  Defines procedures to determine engine net power-measured at the crankshaft or its equivalent-under controlled test conditions.

• Measurement of Specific Fuel Consumption
  Specifies how to measure and report the amount of fuel consumed per unit of power and time during engine operation at full load.

• Standard Reference Conditions
  Establishes reference barometric pressure, air temperature, and relative humidity to ensure comparable results internationally.

• Testing Procedures
  Details the configuration of required engine auxiliaries and systems for accurate measurement, including calibration and accuracy requirements for measuring equipment (torque, speed, temperature, pressure, and humidity).

• Correction Factors
  Provides methods for correcting measured net power and torque to standard reference conditions, enabling fair comparison between different engines and laboratories.

• Reporting Requirements
  Outlines mandatory data to be included in test reports, such as essential engine characteristics, operating conditions during tests, and test results (corrected net torque, net power, and specific fuel consumption at various engine speeds).

Applications

ISO 4106:2026 has significant practical value in the following contexts:

• Motorcycle Engine Design and Development
  By using a uniform test methodology, manufacturers can optimize engines for performance and efficiency in compliance with internationally recognized criteria.

• Regulatory Compliance and Certification
  Authorities and certification bodies rely on ISO 4106:2026 to verify that motorcycles meet net power and fuel consumption requirements, supporting fair market access.

• Quality Assurance in Manufacturing
  Routine engine testing according to this standard allows motorcycle manufacturers to maintain product consistency, detect deviations, and ensure customer satisfaction.

• Comparative Engine Performance Analysis
  Researchers, engineers, and consumers can use standardized test data to make objective comparisons between engine models and brands.

• Technical Communication
  Clear and consistent test methods and reporting facilitate communication between manufacturers, suppliers, regulatory bodies, and end-users globally.

Related Standards

For comprehensive guidance, refer to related ISO standards:

• ISO 3833: Road vehicles – Types – Terms and definitions (for definitions related to motorcycles)
• ISO 2710-1: Reciprocating internal combustion engines - Vocabulary - Part 1: Terms for engine design and operation
• ISO 15550: Internal combustion engines - Determination and method for the measurement of engine power - General requirements

These standards complement ISO 4106:2026 by providing terminology, general test principles, and additional requirements for engine testing in broader contexts.

Using ISO 4106:2026 ensures accurate, reproducible, and comparable net power data for motorcycle engines, fostering innovation, compliance, and consumer confidence in the global motorcycle industry.