Hi, 1998 gs500e 11,000 mi. and lately after warmed up it will consistently make a metallic rattle sound @4000 rpm exactly on acceleration and de- acceleration... sounds internal...ANY HELP would be appreciated , thanks.

Could be a loose bolt that resonates at that rpm.  Happened to me one morning I was warming her up and she went to 4k rpm and got a really loud rattle. But up or down in rpm it was completely gone.  Sourced the rattle on the right side cover, tightened all the bolts to spec, rattle gone.

- Bboy