Noise (like a bang) from Breathing System

[emi_24it]

Is it normal that on my 1999 Flstc EVO, I can hear sometime expecially when the engine is cold, some bangs coming from the umbrella valves, and I feel a lot of air coming out from the air filter

 

[emi_24it]

I have got an 38mm Edelbrock carburator Quick silverII, But I had this problem since I was with the CV carburator

 

[07FLHX]

This can also be caused by a leak in the intake manifold. Or a leaking vacuum line from the carb to the petcock (if your using the stock vacuum petcock) Look for this type of problem before changing jets, as uping the jet could just mask the problem and not really fix it.
Good Luck!
Dave

 

[Z-Man]

Don't forget to chech the timing while you're at it.

 

[emi_24it]

Ok I'll check what you all said to me, I will let you know soon...

Thank you
Emiliano