82 GPZ 750 help

Need help figuring out what this running issue may be, bike runs real well under "normal" riding conditions, idles even, lower gears will pull clean to redline, but opening throttle in 5th gear, will not pull beyond 5k RPM. Carbs were rebuilt last year by Kawasaki dealer, valves clearances checked. Plugs are clean, petcock working properly. Put new plugs, air filter, battery, vacuum lines and carb caps look good. Any ideas would be appreciated. Bike is all stock, carbs, air box, and exhaust.
Thanks
Mike

Take the air cleaner out and see what it does. Check the spark advance , that it moves smoothly and goes to the advance mark with a timing light.
Steve

Has your exhaust been serviced? If the exhaust is leaking it will cause top end issues. It needs to have 4 pipe gaskets and 4 good exhaust port gaskets at the head and the mufflers properly packed or it will run lean.

Double check your carb balance and make sure the diaphragms aren't punctured.