[Bsvulcan1500]

I'm working on a friend's 99 Vulcan 1500 and I can't get it to go above 75 bike runs good until I get in to 4th then it is gutless I've never worked on a vtwin before. Any advice would help. The work I've done to the bike before discovering this issue. Cleaned the carb, changed the plugs. Rebuilt the clutch master cylinder and changed the clutch fluid . My only guess is maybe the floats need adjusted. Has any one had something similar happen to them?

 

[9094]

I would inspect the diaphram for proper seating, pinholes or splits and clean the vacuum passage to the diaphram.

Other thought is fuel pump. could be gravity feeding and not keeping up. by the time you get to 4th, bowl could be too low on fuel. or Plugged tank vent?