First off... an 80 doesn't rev any higher than around 12,000-13,000 RPMs....
But lets hear more about your problem in order to help. Does the engine die or just bog when you twist the throttle? Does the bog go away and clean out and run okay after the initial bog? If you twist the throttle slow or a little bit, does it bog as well? Did this just start happening and the bike was running fine before hand? How/why/when did it start running bad? More info would be helpful.... as there could be SEVERAL things to check (compression, top end, reeds, ignition, carb, spark plug, clutch, gas, exhaust, air filter, etc.)