Use the Buell rattle can (part# MO310.1AAYBP ) not the nail polish brush touch up. Also the frames/swingarms are not powder coated they are just paint.
I have had a lot of success with the graphite grey frames. The fluid silver (xb9) does not come out as good, the flake is not as thick and it comes out kinda flat.
Just make sure you sand it with 600 grit then clean the area with 100% rubbing alcohol.
Then spray three light coats and it will blend in to where you can not tell its been touched up.