I could be mistaken, but I think the EX500 has handlebars that bolt to the top triple clamp, not "clip ons" that connect directly to the fork tubes...
Your options are:
#1 - purchase some bar risers. These are small spacers that fit between the bars and the triple clamps to raise the bars slightly. This will then let you slide the tubes up in the triple clamps a little farther.
#2 - change the existing handlebars to clipons. If you are raising the tubes far enough, you can mount the clipons above the top triple clamp.