Pictures do help sometimes you will notice things in photos you didnt see when looking at it. For example see the little bit of green corrosion on the wire where the insulation is gone, that didnt just happen that wire was corroded before this happened the insulation may have been gone may have even been stripped back it doesnt really look fresh. Now the shiny part does that is where it melted through the tape and grounded out. Still got to see whats under that other mass of tape.

A break wouldn't blow fuses; it would have to be a short. I find it odd that two wires would somehow short under electrical tape unless they are being twisted or pulled on at a common point, like the harness getting pulled when turning the steering. I found a circuit diagram that might help. I'm not sure of the year, but I doubt it changes much. One way to troubleshoot is to use a multimeter with a continuity setting. Put the black lead on ground, then use the other lead on a plug to see if it grounds out when it shouldn't. This isn't a perfect test if a relay or other component needs to engage to complete the circuit, but it's a good start. Make sure the battery is not connected when doing this too to be safe. https://www.manualslib.com/manual/830446/Yamaha-Yfm-400-Fwa-P.html?page=33#manual