I hate to be the bearer of bad news.
If you snapped off an easy out in a stuck bolt inside the engine, you will need to completely disassemble the engine. To remove the bolt and easy out will require an EDM (electro discharge machining). The easy out is much too hard to drill out. You might be able to crack it into pieces. But, not likely and not without buggering the case. You need to find a shop with a good reputation for removing easy out from aluminum motorcycle cases. If done correctly your threads should be no worse than they are now.
In my experience, I had to Heli-coil the hole afterwards.
Unfortunately, there are no good shortcuts, especially with an easy out wedging things tight in there. Don't take shortcuts, you'll probably cause even more damage.
You should try penetrating oil. There are plenty of good suggestions on the forum. That might help loosen the bolt. You will still need to EDM the easy out. But once the the easy out is out the bolt may not be stuck. Or most likely you will need remove them both using an EDM.
When reinstalling the bolt use Loc-Tite. The should hold the bolt from backing out and seal out corrosion. If bolt is installed dry, inside an engine, the threads can stay dry, react with the aluminum and seize over time. Anti-seize will work, but you'll always be worrrying about the bolt backing out with catatrophic results. It happened to me on a stock, unopened engine.