Bogging Down (elevation problem?)

[West.nick.j]

I have a 1978 honda cb750f that i have put over 25K on in the last 2 years.  I lived in a town in northern Utah that had an elevation of 4,500 feet. I personally tuned up the bike and sinked the carbs about a month ago and it ran like a top.  Recently i moved to the town gallup New Mexico, elevation  6,468 feet.  I just took my bike for a spin and was very disappointed  in its performance.  It can get up to its normal top speed but when i wack on the throttle, it does not have its usual crisp performance that i am used to.  About the time it hits 5 thousand RPM it feels like it is bogging down.  Logic tells me it is probably the carbs.   I pull on the choke and it has a negative effect.  Before i tear into them i would like to hear some others advice.  Anybody have any suggestions?

Things to note:
In the morning when i try to start it, if i give it any gas it dies. ( this leads me to believe it is getting to much fuel and not enough air (( possibly due to elevation?))  )

It has a kerker exaust system, but i have had it for the last 2 years with no problems,

Everything else is stock. Carbs, air box, the works

Thanks so much for your help,
Nick

[Re-run]

pull out the air filter and see what happens. If response is better, you got your answer.