In my experience working on other Keihin carbs, I've found the brass to be of a different hardness and have broken jets (twisted off at the base) while installing them. When I checked, they were
not genuine Keihin jets but aftermarket jets I had bought from the local motorcycle shops around here.
Upon closer inspection, I noticed that the aftermarket jets mar or misshape easier than the genuine Keihin jets I also had in my jet case that I've built up over the years.
With finding that, I have to wonder of the quality control of the holes they drill for the jets. Are they really the correct size or might they be off from what they should be?
In any case, I now purchase only Keihin jets when I have a choice.
Keep in mind, the jets I talk about have been installed and removed numerous times, so if you work on your jetting only a few times, you
may be okay w/ aftermarket jets. Just be really careful when removing and installing them. I now make sure I always use the proper sized box wrenches and screwdrivers when rejetting my carbs.
