the bike will start but with full choke and giving it some gas dies if let go of gas.but when i rev it hard it bogs and back fires.so dose anyone know what would cause that. any info will help.

 

B/f getting into more extensive repairs, its possible that you may be keeping it in a flooded state?

What do you have your idle screw set for rpm's? It should be set btwn 1300-1500. Once you start it w/ choke on, it should run & warm up w/o using the throttle at all. Does it do this? Many new F4 owners think that they're supposed to rev the throttle after getting the bike started...but w/ the F4, that's actually not what you want to do. Not saying that's what you're doing...just trying to work through the info w/ you.

If you can get the bike started, let it run & warm up...& it should burn off that extra fuel in the carbs. If this doesn't work, then you may need a carb service.

 

Try starting the bike without choke and catching it on the throttle. It may be too rich and using the choke will make the mixture even richer causing the symptoms you describe. If the bike starts ok without choke, reset your carbs to the basic settings on the air mixture screws then see if that makes a difference. During this spell of unusually warm weather it may be that the bike doesn't need full choke or any choke at all. The only other cause could be an air leak on the inlet side. Also if you can keep the bike running on idle, check the ignition timing with a decent timing light to make sure it isn't over advanced.