83 vf750f stumbles over 6-7000rpm

Heya. 1983 vf750f runs well enough for its age save that it stumbles/has no power/whatever you would call it over about 6-7,000 rpms in all gears. I have replaced the exhaust from the collector back with a homemade project that is baffled and the stock air box has been removed and single pod filters attached to each carb. The carbs themselves have the stock jets and nothing is clogged and seems to be within specification. I'm assuming I need a larger highspeed jet? I have an extra set of carbs so I can drill out any of the jets if finding a jet size is not easy enough. maybe the bowls are emptying too quickly? Might I need to raise the float level? I'm lost, any ideas would be great.

 

Too lean ...

Hello:

If you did that much to the exhaust, without re-jetting, you are probably running way, way too lean. This is not good. You can truly harm your motor.

Here is a Dynojet after-market jet kit:

http://www.dynojet.com/pdf/1108.pdf


Gray Market

 

yeah, I figure it's time to rejet the whole enchilada. Thanks a million.