On the front Nissin brake there is a small rubber-covered knob of some sort. The manual of course doesn't mention it (almost like they want you to pony up and buy the service manual!) and as I was feeling around for the source of some noise issues I rotated it. What does it do and is there a default/factory setting that I should return it to? Thanks much for helping a Kawi newbie

That is the rubber cap covering the brake bleed screw.
Rotating the rubber cap is fine

Thanks! I assumed there wouldn't be an easily accessible "Don't touch that!" adjustment without a warning in the manual

IF you rotated your 'bleed-screw', be prepared for a brake-fluid leak IF you didn't get it re-tightened enough, and MAYBE a 'brake-bleed' to get rid of any bubbles....

Don't want to be an *ss, but if you don't know wht that little black rubber thing was, maybe you should not fiddle with it, especially on the brake caliper, which btw, never have "ajustements"

Bring it to a mechanic and look at what he is doing to learn the chops

I have a complete theorical knowledge of the mechanical on my bike, but they are things I won't take over

My 2 cents

LOP

Ha ha, I love this.

As others already mentioned that is the brake caliper bleeder screw which is used to drain fluid and air out of the brake lines; all hydraulic braking systems have these.

Hopefully you just rotated the rubber cap, which likely did nothing.

Curiosity and fiddling is how I've learned pretty much everything in my life... However always do lots of research when fiddling with your motorcycle because there is not much room for error.

Trust me, particularly when it comes to brake parts, there is nothing that I fiddle with. This was simply an object that inadvertently rotated while I was looking for the source of a noise in the front end, and I knew the forum would have an answer regarding it when the manual made no mention of it and I have not yet purchased a service manual.

1000 miles and loving the V. Great great bike.