carbs 380 a model 1976

Hi, I wonder whether you guy's can help me out there .
I'm having problem's with my carb's when trying to start the bike only run's on left hand cylinder and I have found out that no petrol was getting into the other two carb's .
so decided to set the float's to recommended setting's did this, still the same, If I put the seting's lower the carb's leak on the overflow pipe, don't kow why this is can you help? not very good with carb' so you will have to explain thoughly, thank's steve from leeds,
P.S. I have cleaned all jet's and other relevant thing's out so no blockage's.

Sounds like it could be your crank seals gone. If they are you won't get enough pressure to pull in the air to get fuel mixture.

Is it a bike you just got? If has been standing some years the seals go hard and you don't get a seal.

Could be the intake seals to the cylinders are leaking. You should do a vacuum test to find out.