First off hello to everyone i know i need to go to the "introduce yourself" page and i will just stressed for time at the moment. So i have a 99 cbr f4 that ive been building for the last year or so i finally got it up and running well kind of. The issue im having is its starts up fine with a little choke let it warm up a bit kill the choke and go, about a 1/2 mile into the ride whenever i let off the gas it dies on me wont start and run unless i choke it barley got it back into the garage now im stumped as to what it could be? iff i lett it cool down for a bit it starts right up no problem. Recently cleaned the carbs and changed the plugs it has fuel and spark. The fuel pump has power to it and i can feel the pump turning on. One odd thing i can see is when the bike is running the pump pulses like its turning on and off is that normal?

 

Sounds like the tank is pulling a vacuum and stopping fuel flow. Since it started with choke after it stalled you have a lean/fuel starved condition.

Not sure if your bike has a vacuum operated petcock but check for one and make sure it's working properly.

Get it to stall and pull the gas cap off. If it starts back up again you have found the problem, you need to fix the vent.

 

Are the vacuum lines pugged?

 

Where does the Vent hose from the gas tank connect to?

 

The vacuum are all plugged in as far as i can see. When i got this bike it was completely torn apart had been sitting in a field for 12 year uncovered been slowly putting it back together over the last year. Finally got it up and running, just having this issue