2008 GV250 not wanting to start.

I have to spray ether into the air intake to get the bike running and once I get the bike running I have to keep the throttle over half way open to keep the bike running. The bike doesn’t want to idle or start without the shot of ether. I rebuilt the carbs on the bike and replaced the whole fuel system “due to the last person to own it left fuel in the lines for over a year”. I have ran out of ideas on what could be causing this issue. Any help would be greatly appreciated.