Design and implementation of an electronic fuel injection retrofit system for a four-stroke motorcycle engine
Keywords:
Electronic fuel injection retrofit, Motorcycle engine, Mombustion efficiency, Fuel economy, Exhaust emissionsAbstract
Fuel delivery systems play a critical role in determining combustion stability, fuel efficiency, and exhaust emission characteristics of small spark-ignition (SI) engines. Conventional carburetor-based motorcycles, which remain widely used in developing countries, inherently suffer from limited air–fuel ratio control, particularly under transient operating conditions. This study presents the design and experimental implementation of an Electronic Fuel Injection (EFI) retrofit system applied to a four-stroke carbureted motorcycle engine using original equipment manufacturer (OEM) Yamaha components. The retrofit configuration integrates a Yamaha Vixion ECU, injector and fuel pump from Yamaha Jupiter Z1, and standard engine sensors including crankshaft position, throttle position, and engine temperature sensors. Performance evaluation was conducted through chassis dynamometer testing, fuel consumption measurement, and exhaust gas analysis. Experimental results demonstrate that the EFI retrofit significantly improves fuel economy and reduces hydrocarbon (HC) and carbon monoxide (CO) emissions compared to the original carburetor system, while exhibiting a minor reduction in peak torque and power output. The observed trade-off is attributed to conservative OEM fuel and ignition mapping optimized for emission compliance rather than peak performance. The findings confirm that OEM-based EFI retrofit offers a practical and scalable pathway for enhancing combustion cleanliness and fuel efficiency in legacy motorcycle engines without extensive mechanical modification.
References
[1] J. B. Heywood, Internal Combustion Engine Fundamentals, 2nd ed. New York, NY, USA: McGraw-Hill, 2018.
[2] M. Pulkrabek, Engineering Fundamentals of the Internal Combustion Engine, 3rd ed. Boston, MA, USA: Pearson, 2014.
[3] S. Rakopoulos and E. Giakoumis, “Impact of fuel injection systems on SI engine emissions,” Energy Conversion and Management, vol. 192, pp. 239–251, 2019.
[4] A. Boretti, “Advances in electronic fuel injection systems for small engines,” SAE International Journal of Engines, vol. 12, no. 4, pp. 567–575, 2019.
[5] M. Lapuerta, J. Hernández, and O. Armas, “Emission behavior of small SI engines with EFI systems,” Applied Thermal Engineering, vol. 166, 2020.
[6] Y. Wang et al., “Fuel economy improvement of motorcycle engines using EFI,” Energy, vol. 215, 2021.
[7] R. Kumar and S. Sharma, “Retrofitting carbureted motorcycles with EFI: A review,” Renewable and Sustainable Energy Reviews, vol. 146, 2021.
[8] A. Gupta et al., “Programmable ECU versus OEM ECU in motorcycle EFI retrofit,” SAE Technical Paper, 2020-32-0045, 2020.
[9] D. C. Montgomery, Design and Analysis of Experiments, 9th ed. Hoboken, NJ, USA: Wiley, 2017.
[10] J. H. Lee and K. Min, “Emission-oriented calibration of motorcycle EFI systems,” Fuel, vol. 286, 2021.
[11] M. Shahbakhti and J. Koch, “Trade-offs between performance and emissions in SI engines,” Progress in Energy and Combustion Science, vol. 77, 2020.
[12] A. Payri et al., “Effect of air–fuel ratio control on SI engine emissions,” Energy Conversion and Management, vol. 196, 2019.
[13] S. H. Park et al., “EFI retrofit impact on HC and CO emissions of small motorcycles,” Applied Energy, vol. 277, 2020.
[14] T. Nguyen et al., “Comparative study of carburetor and EFI systems in motorcycles,” Journal of Cleaner Production, vol. 296, 2021.
[15] A. D. Lucas and J. P. Meyer, “Modern calibration strategies for low-emission SI engines,” Fuel, vol. 319, 2022.
Downloads
Published
Conference Proceedings Volume
Section
License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.