Those white connector boxes really aren't up to the job.
Some people on here recommend soldering the yellow wires together. I'm sure that's fine if you can make a decent job of it, or know a man who can.
What the guy who services my bike suggests (and I've done this on my own bike) is to use the old-fashioned type block connectors, where there's a little screw that clamps the wire in place, similar to in a domestic 3-pin mains plug. They look crap
, but they're hidden behind the fairing. These connectors can take a lot more current, and they're easy to inspect.
Some people also suggest up-grading to a heavier cable size. The cable size *could* be bigger (maybe should be), but the connectors are the weakest link on the stock set-up.