upshifting

I have a 2000 FE 501 that is sticking in gear when I try to up-shift under power. 1st to 2nd is fine but all the rest do it. I have tried clutch no clutch, rev it a bit all to no avail. I don't seem to have any trouble on the trails only when I hit an open section and nail it.Especially on the...

I usually tend to not use the clutch lever when upshifting, especially when I need to concentrate on my steering. The 501 seems to do fine but yesterday I shifted without reducing the throttle and I heard a bad noise coming from inside the clutch basket. Is that bad, how bad, and is my...