I recently bought a CBR 600 F2 and it's got some pretty serious fueling problems.

The bike bogs down heavily between around 2500 and 3000 rpm to the point where it will decelerate at anywhere other than the tinyest bit of throttle.

The second problem is that the bike runs horribly over 50 mph. It will surge and decelleate like someone has pushed the kill switch constantly. It does this in any gear and the faster you go the worse it gets. I have noticed the effects are reduced with the choke on full.

Finally, because of the previous problem, the bike tops out at about 100 mph. The carbs have just been cleaned and they are balanced so I'm really confused what the problem is. There is no in line fuel filter to be clogged and it the position of the petcock makes no difference to the way it runs.

 

Just to add to this, the bike has a fully aftermarket exhaust and an "adjustable jet" apparently according to a mechanic. The air filter may also be aftermarket, I'm not sure.

 

When the bike is at 2500-3000 rpm and idling, hit the kill switch. Pull the plugs and inspect them. That will tell you basically what's going on with the F/A mixture.
I would fix that before worrying about the 2nd issue.

 

Are you sure your vacuum lines are routed correctly and are not pinched in any way?