Goldwing GL1200 Fuel Injection Conversion

The Honda Goldwing GL1200 is a legendary touring motorcycle, renowned for its comfort and capability. For owners of the carbureted models, a common question that arises is the possibility of converting to a fuel injection (FI) system, mirroring the later GL1200 Aspencade models. This article delves into the intricacies of such a conversion, examining the potential benefits, the significant hurdles, and whether it's a project worth undertaking for the average enthusiast.

Understanding Fuel Injection Systems

Before diving into the conversion, it's crucial to understand how a fuel injection system works. Unlike carburetors, which rely on vacuum to draw fuel into the engine, fuel injection systems use an electronic control unit (ECU) to precisely meter fuel delivery. The ECU receives data from various sensors, including the throttle position sensor (TPS), engine coolant temperature sensor, manifold absolute pressure (MAP) sensor, and oxygen sensors. Based on this data, the ECU commands fuel injectors to spray a fine mist of fuel directly into the intake manifold or combustion chamber at the optimal time and quantity. This results in improved fuel efficiency, better throttle response, easier cold starts, and more consistent performance across varying altitudes and temperatures.

The GL1200 Fuel Injection Advantage

The Goldwing GL1200 models that came factory-equipped with fuel injection (typically the 1985 SEi and 1986 SEi Aspencade) generally offer a smoother and more refined riding experience. Owners often report better fuel economy and a more direct throttle response compared to their carbureted counterparts. The system is designed to automatically adjust for atmospheric conditions, eliminating the need for manual carburetor adjustments when riding at different elevations. For those seeking the pinnacle of performance and efficiency from their GL1200, a factory FI system is often seen as the ideal setup.

Challenges of a GL1200 FI Conversion

However, retrofitting an FI system onto a carbureted GL1200 presents a significant undertaking, fraught with challenges. As highlighted by experienced riders, the primary obstacle is sourcing the correct and functional fuel injection components. Early Honda FI parts, especially for a model as old as the GL1200, are becoming increasingly scarce and expensive. This includes the fuel pump, injectors, ECU, wiring harness, and the associated sensors. Adapting parts from other Honda models or even different manufacturers can turn the project into a "nightmare," particularly when troubleshooting or performing repairs on the road.

Component Compatibility and Sourcing

One of the most significant technical hurdles is the difference in the engine cases. Fuel-injected GL1200s often feature a slightly different engine case design to accommodate a larger stator and a more robust charging system. This is necessary to power the additional electrical components required by the FI system, such as the fuel pump, injectors, and ECU. While it might be possible to work around case modifications with ingenuity, integrating the larger rear cover and stator is often desirable for reliable operation. The availability of these specific parts for an older model is a major concern.

ECU and Sensor Issues

The heart of any FI system is its ECU. For the GL1200, finding a company that can refurbish the original ECU is crucial. Similarly, the Throttle Position Sensor (TPS) is another critical component that can fail. While workarounds may exist for the TPS, their reliability and effectiveness can be questionable. The complexity of integrating these electronic components and ensuring they communicate correctly with the engine is a substantial engineering challenge.

Custom FI Systems

Some enthusiasts consider building a custom FI system from aftermarket auto parts or adapting components from other motorcycle FI systems. While this offers a degree of flexibility, it often becomes a full-time project. It involves extensive modifications, countless hours of trial and error, and a deep understanding of engine management to achieve correct and reliable operation under all riding conditions. The results of such custom conversions have historically been "dismal at best," with few achieving the performance or reliability of a factory-integrated system.

Is the Conversion Worth the Headache?

The question of whether the FI conversion is "worth the head ache" is subjective and depends heavily on the owner's goals, resources, and technical expertise. For a motorcycle that is already in excellent condition, as described by one owner, modifying it with non-production or adapted parts might detract from its originality and potentially introduce reliability issues.

Carburetor Tuning: A Viable Alternative

It's important to remember that the Keihin carburetors on the GL1200 are fundamentally good units. With proper tuning and maintenance, they can perform nearly as well as a factory FI system, with only a slight difference in peak power output. Addressing known issues with the 1984 model's carb jetting, possibly by updating to later Honda parts or implementing a service bulletin update, can significantly improve off-idle response and light cruise speeds. A well-tuned carburetor system offers advantages in terms of altitude compensation and ease of roadside repair, especially compared to a custom or poorly integrated FI system.

Cost Considerations

The cost associated with acquiring all the necessary FI components, potential engine case modifications, and the labour involved in the conversion can be substantial. For a "very low budget retiree," as one forum member expressed, the expense alone makes the conversion prohibitive. The significant cost is often the primary deterrent, especially when the potential for "dismal" results exists.

The Forum Perspective

Discussions on enthusiast forums reveal a mixed sentiment regarding FI conversions. While some express a long-held desire for FI on their carbureted Goldwings, the lack of successful, readily available conversion kits or widely documented successful projects is notable. There's a sentiment that custom FI attempts often fall short of improving upon the stock FI systems found on the later models. Furthermore, the tendency for some forums to "discount" or dismiss modifications like FI conversions or single-carb conversions highlights the importance of seeking out knowledgeable communities where such projects are discussed constructively.

Frequently Asked Questions

Q1: Does the Goldwing GL1200 have fuel injection?

A1: Yes, specific later models of the GL1200, such as the 1985 SEi and 1986 SEi Aspencade, came factory-equipped with a Central Fuel Injection (CFI) system. The earlier models, like the 1984 Aspencade, are carbureted.

Q2: Can I convert my carbureted GL1200 to fuel injection?

A2: While technically possible, it is a very complex and challenging conversion. It requires sourcing scarce and expensive parts, potentially modifying engine cases, and a deep understanding of electronic fuel injection systems. Many attempts have yielded less than satisfactory results.

Q3: What are the advantages of fuel injection over carburetors on a Goldwing?

A3: Fuel injection generally offers improved fuel efficiency, better throttle response, easier starting in various conditions, and automatic compensation for altitude and temperature changes. This can lead to a smoother and more refined riding experience.

Q4: What are the main difficulties in performing a GL1200 FI conversion?

A4: Key difficulties include the scarcity and high cost of genuine FI components, differences in engine case design requiring potential modifications for larger stators and covers, the complexity of the ECU and sensor integration, and the lack of readily available, reliable custom FI solutions.

Q5: Is it better to tune the existing carburetors or attempt an FI conversion?

A5: For most owners, tuning and properly maintaining the existing carburetors is a more practical and cost-effective approach. Addressing known jetting issues or performing factory updates can significantly improve performance and reliability without the extensive challenges of an FI conversion.

Conclusion

The allure of converting a carbureted Goldwing GL1200 to fuel injection is understandable, given the benefits that FI systems offer. However, the reality of such a conversion is a significant technical and financial undertaking. The scarcity of parts, the need for potential engine modifications, and the complexity of electronic systems make it a project best suited for highly experienced mechanics with ample resources and a willingness to overcome substantial obstacles. For the majority of GL1200 owners, focusing on meticulous maintenance and optimal tuning of the existing carbureted system will likely provide a more reliable, cost-effective, and ultimately satisfying riding experience. It's a case where preserving the bike's original character and ensuring its ongoing reliability might be the wiser path.