Do you know it's the injector for sure?
have you checked the voltage regulator? or, even sillier question, have you checked your spark plug connections?
I'm only saying this because one day I cleaned my bike thoroughly, removed the belt covers, put them back in, and I had not pushed the plug cap all the way in, which caused the bike to run on one cylinder. I figured it out quickly and it solved the problem, which is why I'm suggesting this. (and make sure the engine is off...

)