Poping up the intake

Popping up the intake
My type 4 engine with twin dellorto drla carbs runs well apart from a consistent pop up the intake at high torque in the lower end of revs . I’m at a loss to the reason . Is it the lockdown pumps possibly ?

 

A”pop” or “sneeze” out the top is lean running.

My guess is a blocked idle jet. Not uncommon.
You can pull your plugs and see which one is white or just clean all the jets.

 

What's a lockdown pump?

 

Is it what Matt Hancock did during covid

 

No, that was popping up the intake.

 

Rebuilt both carbs this holiday . Both pumps weee full of rust . Test drive in a couple of days following a full engine service

 

Jetting?