I ran across a Verithing(tm) (as in "Ah! The Very Thing!") at the motorcycle show a few years ago and snagged one. It's called the BeadBuster and it's awesome... makes the job a piece of cake. One of those times where asking "Gee, do I really need to buy a gadget to do this?" returns "Well, no, but I don't regret it a bit."
https://beadbuster.com/
Link to original page on YouTube.
I also have a few tire irons, and the best are the curved ones from Motion Pro. The curve really does make a difference when trying to get the iron in to hook the rim. I made do with one curved and some straight for awhile. Just recently picked up a second curved one.
Biggest tip is to make SURE the opposite side of the bead is down in the low spot on the rim. It will want to walk out of there, so keep on pushing it down.
And yeah.. LUBE......
PS: Grab a bicycle wheel and remove/replace the tire before you try it on your motorcycle. Exact same principle and easier... you'll learn a lot.