I did not remove any bushings when I had my stock S2R rearsets powdercoated.
Due to the design of the castings I'm assuming they were never meant to be removed, kind of a one-way press-fit. Although it looks like the parts manual has a part# for them which is weird. If you could use one of those blind pullers & heat the casting up with a heat gun or something you might be able to ease the bushings out without destroying them, but in my opinion it's not worth the trouble.
I used two large fender washers and a short 1/4"/20 bolt to shield the bushings from the powder. The washers I used fit nearly perfectly on both sides. I then glassbeaded the castings, degreased, and had them powdercoated semigloss black by a guy that probably never bathed, visited a dentist, or graduated from high school. Along with a bunch of other parts, I got the lot powdercoated by this guy for $25.
Those stock rearsets came out perfect, with no problems that I could ascertain stemming from leaving the bushings in for powdercoating. Try it out, worst that could happen is you get some Rizoma rearsets or something you are probably going to get anyway.
I know from personal experience the bushings will be fine, so don't worry.
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