Just an FYI...
My K3 has had intermittent symptoms of running lean.
I found the problem (or so it seems).
The OEM airbox has warped & deformed a bit over the years.
The raised plateau thingy inside the bottom half of the airbox (the thing that holds the filter in place) was preventing the filter from seating completely. The back of the filter was hitting the back part raised bit - toward the rear wheel. This kept the airbox from closing completely along the back where I couldn't see it. There was a credit card width gap. Voila, too much air.
I shaved a tiny bit of the filter seating rubber back with an Exacto so it fit around the raised retaining bump. Now it closes completely & seems to run better.
