Top end (rpm)

Hello all, I had just picked up my bike- 83 Kz440 - Did the usual valves, carbs, boots, plugs and oil. The thing starts perfectly and idles like a champion. But i notice sometimes ( only sometimes ) when winding out on an on-ramp to the highway lets say- sometimes it feels like the power is easing out around 5-6 grand. Where as other times it'll scream all the way through the powerband.... any thoughts?

thanks in advance

i had a problem like that one time on my 77 kz 650, i found a few loose wires in the harness. i connected them and havent had a problem since. hope that works for you. happy motoring