The fact that it starts with starter fluid indicates it is not related to ignition or compression. So it has air and it has spark. I know it took me 3 times pulling the carburetors on my 1000F a few years back in order to get them cleaned properly. I would suggest pulling them again. Did he completely disassemble them from the rail into the individual bodies like in the pictures above? That's what it takes to make them work.

 

I think he did. Not positive though. He says he is going to take em off and clean em again just in case. I will let you know how it goes.

 

Need to dump tank and clean it out as well. And petcock. Fact that it takes a little while to clog is due to crud in tank taking time to flow towards carbs and clog them.

Many expert mechanics have had to pull carbs 4-5x to do ever deeper carb cleaning before bike would run right. I recommend going all way and do complete restoration job 1st time around... Well 2nd time around now.

 

He cleaned carbs again, replaced radiator, and then cleaned carbs a 3rd time & it is finally running again. Thank you for making him realize that it might take more than cleaning carbs just once 😏