Older Honda Shadow won't start...
 

I've got an older Honda Shadow 500 from the 80s and it won't start. It turns over, spraying starter fluid into the carbs, still won't start. Tried different computer, nothing. Its got good spark from two of the plugs, didn't check the other two. Battery I completely dead but when hooked up the bike will turn over.

I just bought it for $300, it sat outside for a year....

Any advice?

Have you drained the old fuel and replaced with fresh?
If you've done that, maybe remove carbs, strip and give them a thorough clean