Suzuki dt55 idles, but dies under load

[Mr_mn]

I have a Suzuki dt55 that was given to me that had been sitting for a year or two. It runs perfectly on ear muffs, but as soon as I push the throttle down on the lake it will die, usually with a loud chirp. I rebuilt the carburetors, and the fuel pump, and replaced all of the fuel hoses, as well as the spark plugs, but it still does this. any ideas on what it could be?
Thanks!

 

[99yam40]

Lean sneeze would be my guess.
probably need to do a better job on cleaning the carbs.

there are off idle ports that should help it transition to higher RPMs