I have found a couple threads all over the net with people asking about this same problem but if they fix it they never post what the solution was.

Here is the dilemma. When you pin the throttle it is not a smooth acceleration. About a quarter of the way through the RPM range it picks up and accelerates faster. Then when you get to around 7000 RPMs it completely dies and will not come back to life until you completely let off the throttle. If you get to 7000 rpm's and roll through The next 2000 you can make it to redline but pin it at anytime and it will die.
I have tried shimming the needles but the problem didn't go away. Also tried new plugs with the same result. The plugs didn't seem to show any signs of the bike running to lean or two rich. The bike has a stock Kerker exhaust with a big resonator( The baffling from the can has been removed) and a K&N air filter.
The jets currently in the carbs right now are a 108 Main and a 38 Pilot.
I used a rejet calculator and it recommended a 115 Main and 40 pilot for the set up I have now.

Any help would be greatly appreciated.
Thanks!

 

What do your spark plugs look like?

 

They look fine. Not white, not crusty and gummed up either