Marco holding wires from harness

HOW-TO: Tidy up the Wiring Harness on your R3

If you are like me and spend lots of time at the race track, you’ll understand how much easier it is to service your bike when you don’t have a bunch of extra connectors and wires that continuously get in the way when you mount your bodywork.  

While researching this topic, I was surprised to see that some racing organizations won’t let the riders modify the OEM harness. I was also surprised to see how many people are reluctant to alter the wiring harness on their bikes – This fear is quite often related to a lack of understanding and knowledge. An additional interesting discovery was that most of the info I found was on websites or YouTube channels that were focusing on building custom bobbers, choppers, and café racers. If track day enthusiasts modify their harnesses, they certainly don’t advertise. All of these revelations were enough for me to start documenting the process of modifying the wiring harness on my Yamaha 2018 YZF-R3. 

I definitely had to follow the 80/20 rule for this project. I spent 80% of my time researching, learning, and testing. Doing the actual hands-on work was the easy part.  

I first started the project by purchasing a digital version of the shop manual for the R3. It turns out that the resolution of the wiring diagram was terrible, and I had to buy another manual from a different supplier (this new manual didn’t even have the wiring diagram). I eventually found a free PDF version of this manual with a wiring diagram that was good enough to get me started.  

The next step was to remove the bodywork, the tank, the airbox, and the cable assembly’s unwrapping. After that, I was able to start mapping out the various circuits that were of interest. I knew I wanted to tackle five different things: 

  • Remove all the connectors for the lights (headlight, flashers, brake light, license plate aux light). I also wanted to remove the associated relays (headlight and turn signal) 
  • Remove the remaining O2 sensor wires and the Air Induction Solenoid 
  • Bypass and relocate the kickstand bypass switch 
  • Do the clutch bypass 
  • And finally, I decided to remove the radiator fan and all the material related to this circuit 

Once all the wires were exposed, I started doing my own simplified diagrams to help me pinpoint the items I could cut/modify/remove. As a result, I ended up with some elementary and simplified wiring diagrams that can be found here

Once I had all these documents, it was straightforward to start the clean-up and remove the various components. The most challenging part was to unpin the wires from multiple types of connectors. I even ordered some special tools from Amazon to help with the process. It turns out that a tiny screwdriver and an oversize needle are the best options to complete this type of work. The multi-display connector was by far the most “challenging” connector to deal with.  

After completing the removal of the extra wires, fuses, and relays, I started wrapping the harness. As you will see in the video, multiple options are available to tape your harness. You will need to factor in numerous facets: quality of the tape, temperature resistance, material, and price.  

Overall complexity for this project was a 3 out of 5. The work itself is not very complicated, but you need to have a basic understanding of the electrical components found on your bike.  

The video is longer than unusual but covers quite a bit of material. I’ve added some timecodes to facilitate and speed up the navigation. 

Geek during the day, wine and cigar aficionado in the evening. You can find me on a race track in the summer time and wrenching on motorcycles during the winter months.