If you look at the end of the bar, you will see three small tack-welds holding the plug in. If you grind through these tacks, you can remove the plugs. I just took a hammer and pounded them in far enough to attach the handguards. Not exactly high-tech, I know, but it works if you don't want to spring for new bars yet.:) I think another option would be to drill them out to accept the pro-taper sized bar ends. I don't know which handguards you have, but some come ready to mount to the (smaller inside diameter) pro-tapers. Good luck!