If impact won't do it (buy a more powerful impact gun, but) put the wheel/chain back on. Put bike in neutral (don't want to mess up the tranny) get a 2x4 or some kind of thick wood and put it between the wheel and the swingarm. Wrap it in an old towel or something soft so that you don't damage the wheel or arm with the amount of torque you're about to put on it.
Mine (before I had impact tools) took a 4ft breaker bar. Get your breaker bar out, if you don't have one, buy the biggest one at Harbor Freight for like $10-$15 and "go retard" on it. If that still doesn't work, you can buy some thick steel pipe that's 5-6ft and put it over the breaker bar as you cheater bar, but it shouldn't come to that lol.
The front sprocket torque is only 83ft/lbs, which is about what a car lug nut takes. I'm not sure why some people think they need 1000 ft/lbs on there.