Just bought this bike. Head needed replace when I bought it (PO drilled sparkplug hole too big). had been setting all winter so I decided to clean the carb since the top end was off and allowed extremely easy access. Bought a kit and tore the carb apart and let it soak for 2 days. put all new jets and needles in. will fire up and idle nice. but as soon as you hit the throttle it boggs down. what am I overlooking. Set pilot air screw at 1.5 turns out. and throttle stop screw is somewhere between 2 and 5 (was adjusting to get good idle)

 

Did you blow the carb orifices and channels out with an air gun? Still sounds like either you still have something blocking fuel flow in the carb, float level may not be adjusted properly or fuel line to the carb may be partially stopped not allowing enough fuel to the carb. Plus small things like deteriorating fuel hoses leaving little black specks of rubber in the fuel can partially shut down fuel coming in through a needle and seat.