Aftermarket ECU Conversion – Honda RC51

This wiki documents the process of converting a Honda RC51 to run on an aftermarket ECU, most specifically a FuelTech FT550 ECU. The goal is to provide a clear, technically sound guide for enthusiasts and builders who want more control, flexibility, and diagnostic capability than the OEM ECU allows.

A guide like this would have been so useful when I started all of this. I didn't spend hours and hours looking for a guide on applying an aftermarket ECU onto a motorcycle. I am sure they are out there, albeit maybe a bit less thorough. A lot of what I have seemed to find was bits here and pieces there. You may find good documentation on one topic but then spend more time trying to figure out how it applies to your application.

Hopefully this guide will not only serve as a resource for the Honda RC51, but ultimately other motorcycles or cars as well. If I can inspire just one person to start a build, all of this work will be worth it to me. Plus, I have already done all of the work—why not share it? It is bound to help someone out there even if it is not specific to the RC51.

Why Did I Decide To Do This?

Why did I decide to take this build on? I actually had the FT550 laying around for a different motorcycle that I was going to build. A 2001 Yamaha R1 to be exact. Unfortunately, I decided to move on from that project since I had the RC, and the Yamaha would be much more involved as it needed engine work. Plus, a lot more engineering would have been needed since that model year was carbureted.

However, the ultimate thing that led me to start this build was my curiosity for engines and motorcycles. Driving them is fun, working on them is okay, but there is just something different about wiring and tuning the bike from scratch. I feel like it makes you more connected with the bike and gives you a little bit of pride knowing all the work you put into something ends up with an amazing result... Or all of this could be a big waste of time and money. I am hoping it's more of the first than the latter.

Getting Started

I suggest you read the rest of the introduction material to get a better overview of the scope of this project and how to navigate the documentation. This wiki is designed to guide you step-by-step through most of the sections of this build.

With that said, it is possible and almost a guarantee that I have either missed something, documented the wrong information, had trouble relaying what is in my head into words, or am just plain simply wrong. I am not perfect, and this is honestly the first time that I am attempting this build. Makes sense for me to get some things wrong despite my best attempts.

If you see incorrect or misrepresented information, please reach out with questions or suggestions. Even if it is something that needs to be explained in more depth. I am looking to have the best documentation possible.