I had something similar in my R5K
It sounds like air runing in the carbs.
I noticed in my bike that the air could enter before the filter in the two hoses that attach the filter box to the carbs.
I sealed the tubes with heat silicone in the outer part of the air box were the tubes attach to the filter box, so the air enters only through the filter holes fitted the top cover.
Also check all the air hoses, maybe one is blocked or maybe is leaking.