yeah you can, you just need to take out the clipon insert, they way i got mine out of my NT400 was, get a bolt that fits the end of the insert, tap the insert in a little way into the clip on, turn it about a 1/16th of an inch then pull it out, the insert have little clips that are 1 way, so tapping them in , removes the barb from the little notch it sits in, turning it gets it way from the notch so you can pull it out.
there was one missing on my lil honda and i bought universal barend weights, that wouldnt work with the standard bar inserts.
hope this helps.
peace