Carb Problems

My motorcycle ran great last year. This year when I open the throttle up past a 1/4, the engine bogs down. I have taken off the carbs and cleaned them twice, new battery, new spark plugs, new oil. But I can not get the engine to rev at high RPM's. I have checked the air box and that is clean also. Does anyone have any suggestions. I am pretty handy with taking this bike apart, so no steps are too far. I have put seafoam in with the gas to try and take care of this also, but this is not working yet. Should I be looking at the throttle or some other area?